Updated on 2022/05/19

写真a

 
OYAIZU, Kenichi
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

Education

  • 1990.04
    -
    1995.03

    Waseda University   Graduate School, Division of Science and Engineering   Department of Applied Chemistry  

  • 1986.04
    -
    1990.03

    Waseda University   Faculty of Science and Engineering   Department of Applied Chemistry  

Degree

  • 早稲田大学   博士(工学)

  • Waseda University   PhD

Research Experience

  • 2012.04
    -
     

    Professor, Department of Applied Chemistry, Waseda University

  • 2007.04
    -
    2012.03

    Associate Professor, Department of Applied Chemistry, Waseda University

  • 2003.10
    -
    2007.03

    Associate Professor, Institute of Colloid and Interface Science, Tokyo University of Science

  • 1997.04
    -
    2003.09

    Lecturer, Advanced Research Institute for Science and Engineering, Waseda University

  • 1995.04
    -
    1997.03

    Research Assistant, Department of Applied Chemistry, Waseda University

  • 1992.04
    -
    1995.03

    JSPS Research Associate (DC1)

  • 1992.04
    -
    1995.03

    JSPS Research Associate (DC1)

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Professional Memberships

  •  
     
     

    Research Group on Materials for hydrogen and PEFC, SPSJ

  •  
     
     

    Research Group on Supramolecular Chemistry, SPSJ

  •  
     
     

    The Electrochemical Society of Japan

  •  
     
     

    American Chemical Society

  •  
     
     

    The Society of Polymer Science, Japan

  •  
     
     

    Chemical Society of Japan

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Research Areas

  • Polymer chemistry

Research Interests

  • Polymer Synthesis, Functional Polymers

Research Seeds

Papers

  • Quadruply fused aromatic heterocycles toward 4 V‐class robust organic cathode‐active materials

    Kan Hatakeyama-Sato, Choitsu Go, Tomoki Akahane, Takahiro Kaseyama, Takuji Yoshimoto, Kenichi Oyaizu

    Batteries & Supercaps    2022.04

    DOI

  • Poly(vinyl diphenylquinoxaline) as a hydrogen storage material toward rapid hydrogen evolution

    Kouki Oka, Miho Kataoka, Hiroyuki Nishide, Kenichi Oyaizu

    MRS Communications    2022.02

    DOI

  • Synthesis of colorless and high-refractive-index sulfoxide-containing polymers by the oxidation of poly(phenylene sulfide) derivatives

    Seigo Watanabe, Teru Takayama, Hiromichi Nishio, Kanta Matsushima, Yoko Tanaka, Seiya Saito, Yushun Sun, Kenichi Oyaizu

    Polymer Chemistry    2022

     View Summary

    A series of poly(phenylene sulfide) (PPS) derivatives can be bleached while maintaining high refractive indices, by partially incorporating sulfoxide bonds through their mCPBA oxidation, owing to the loss of lone pairs around the sulfide atoms.

    DOI

  • Hydrophilic isopropanol/acetone‐substituted polymers for safe hydrogen storage

    Kouki Oka, Yuka Tobita, Miho Kataoka, Kazuki Kobayashi, Yusuke Kaiwa, Hiroyuki Nishide, Kenichi Oyaizu

    Polymer International    2021.12  [Refereed]

    DOI

  • Alcohol-substituted Vinyl Polymers for Stockpiling Hydrogen

    Kouki Oka, Miho Kataoka, Yusuke Kaiwa, Kenichi Oyaizu

    Bulletin of the Chemical Society of Japan    2021.10  [Refereed]

    DOI

  • Synthesis of methylated phenylene sulfide polymers via bulk oxidative polymerization and their heat curing triggered by dynamic disulfide exchange

    Seigo Watanabe, Seiya Saito, Motoyasu Hirai, Kenichi Oyaizu

    Polymer Journal    2021.09  [Refereed]

    DOI

  • A PROXYL‐Type Norbornene Polymer for High‐Voltage Cathodes in Lithium Batteries

    Kan Hatakeyama‐Sato, Satoshi Matsumoto, Hirofumi Takami, Tomomi Nagatsuka, Kenichi Oyaizu

    Macromolecular Rapid Communications     2100374 - 2100374  2021.08  [Refereed]

    DOI

  • Catechol End-Capped Poly(arylene sulfide) as a High-Refractive-Index “TiO2/ZrO2-Nanodispersible” Polymer

    Seigo Watanabe, Kenichi Oyaizu

    ACS Applied Polymer Materials    2021.07  [Refereed]

    DOI

  • Synthesis of vinyl polymers substituted with 2-propanol and acetone and investigation of their reversible hydrogen storage capabilities

    Kouki Oka, Yuka Tobita, Miho Kataoka, Saki Murao, Kazuki Kobayashi, Shuhei Furukawa, Hiroyuki Nishide, Kenichi Oyaizu

    Polymer Journal   53 ( 7 ) 799 - 804  2021.07  [Refereed]

    DOI

  • Generative Models for Extrapolation Prediction in Materials Informatics

    Kan Hatakeyama-Sato, Kenichi Oyaizu

    ACS Omega   6 ( 22 ) 14566 - 14574  2021.06  [Refereed]

    DOI

  • Hydrophilic Anthraquinone-Substituted Polymer: Its Environmentally Friendly Preparation and Efficient Charge/Proton-Storage Capability for Polymer–Air Secondary Batteries

    Kouki Oka, Saki Murao, Miho Kataoka, Hiroyuki Nishide, Kenichi Oyaizu

    Macromolecules   54 ( 10 ) 4854 - 4859  2021.05  [Refereed]

    DOI

  • Anomalous potential shifts of redox-active molecules in highly concentrated electrolytes

    Kan Hatakeyama-Sato, Satoshi Matsumoto, Ikuma Aida, Kenichi Oyaizu

    Chemistry Letters    2021.04  [Refereed]

    DOI

  • Tackling the Challenge of a Huge Materials Science Search Space with Quantum‐Inspired Annealing

    Kan Hatakeyama-Sato, Takahiro Kashikawa, Koichi Kimura, Kenichi Oyaizu

    Advanced Intelligent Systems   3 ( 4 ) 2000209 - 2000209  2021.04  [Refereed]

    DOI

  • リチャージャブル燃料電池

    宮武健治, 小柳津研一, 三宅純平

    水素エネルギーシステム   46 ( 1 ) 6 - 11  2021.03

  • Facile reversible hydrogenation of a poly(6‐vinyl‐2,3‐dimethyl‐1,2,3,4‐tetrahydroquinoxaline) gel‐like solid

    Yusuke Kaiwa, Kouki Oka, Hiroyuki Nishide, Kenichi Oyaizu

    Polymers for Advanced Technologies   32 ( 3 ) 1162 - 1167  2021.03  [Refereed]

     View Summary

    Polymers bearing hydrogen storage units store hydrogen gas via chemical bond formation, and have inherent advantages as quasi-solid polymeric hydrogen carriers, such as handling easiness and high safety. A recent study demonstrated that a poly(6-vinyl-1,2,3,4-tetrahydroquinoxaline) gel-like solid was dehydrogenated over 5 h under 120°C and air, and then the material was reversibly hydrogenated under 60°C and ambient hydrogen pressure in the presence of an iridium complex catalyst. The present work aimed to improve the dehydrogenation rate via the substitution of methyl groups for hydrogen atoms on carbon atoms adjacent to the nitrogen atoms in the quinoxaline unit. The dramatic improvement was attributed to the electron donating property of methyl group, and stabilization of the dehydrogenated state. The poly(6-vinyl-2,3-dimethyl-1,2,3,4-tetrahydroquinoxaline) gel-like solid was rapidly dehydrogenated within 2 h under the same mild conditions. This article provides a guideline for the molecular design of nitrogen heterocyclic compounds for rapid dehydrogenation.

    DOI

  • TEMPO‐Substituted Poly(ethylene sulfide) for Solid‐State Electro‐Chemical Charge Storage

    Kan Hatakeyama‐Sato, Hisato Wakamatsu, Satoshi Matsumoto, Karin Sadakuni, Koji Matsuoka, Tomomi Nagatsuka, Kenichi Oyaizu

    Macromolecular Rapid Communications   42 ( 4 ) 2000607 - 2000607  2021.02  [Refereed]

    DOI

  • Unravelling kinetic and mass transport effects on two-electron storage in radical polymer batteries

    Kai Zhang, Yuan Xie, Benjamin B. Noble, Michael J. Monteiro, Jodie L. Lutkenhaus, Kenichi Oyaizu, Zhongfan Jia

    Journal of Materials Chemistry A   9 ( 22 ) 13071 - 13079  2021  [Refereed]

     View Summary

    <p>Electron transfer and mass transport kinetics between two redox couples in nitroxide radical polymers was investigated. Such impact on two-electron storage in radical polymer batteries was exemplified by two macromolecular structures.</p>

    DOI

  • Electrochemical characterization and thermodynamic analysis of TEMPO derivatives in ionic liquids

    Luke Wylie, Kan Hakatayama-Sato, Choitsu Go, Kenichi Oyaizu, Ekaterina I. Izgorodina

    Physical Chemistry Chemical Physics   23 ( 17 ) 10205 - 10217  2021  [Refereed]

     View Summary

    <p>In this study we tailor the reversibility of the reduction process of three TEMPO derivatives – TEMPOL, 4-cyano-TEMPO, and 4-oxo-TEMPO – using ionic liquids.</p>

    DOI

  • Nitroxide radical polymers for emerging plastic energy storage and organic electronics: fundamentals, materials, and applications

    Yuan Xie, Kai Zhang, Yusuke Yamauchi, Kenichi Oyaizu, Zhongfan Jia

    Materials Horizons   8 ( 3 ) 803 - 829  2021  [Refereed]

     View Summary

    <p>We review the electrochemical theory, material design, and device fabrication for nitroxide radical polymers in emerging plastic energy storage and organic electronics.</p>

    DOI

  • Charge- and Proton-Storage Capability of Naphthoquinone-Substituted Poly(allylamine) as Electrode-Active Material for Polymer–Air Secondary Batteries

    Kouki Oka, Saki Murao, Kazuki Kobayashi, Hiroyuki Nishide, Kenichi Oyaizu

    ACS Applied Energy Materials   3 ( 12 ) 12019 - 12024  2020.12  [Refereed]

     View Summary

    1,4-Naphthoquinone (NQ) undergoes a two electron and two proton redox process in one step at a potential of -0.05 V (vs Ag/AgCl) in 0.05 M H2SO4 aqueous solution. Its heterogeneous electron transfer rate constant is comparable to those of electrochemically reversible redox-active molecules. Therefore, NQ is a potential electrode-active material candidate in acidic aqueous electrolyte. Simple nucleophilic substitution of 2-bromo-1,4-naphthoquinone and poly(allylamine) yields NQ-substituted poly(allylamine) (PNQ), enabling us to adjust the hydrophilicity of the redox polymer according to the NQ introduction rate. A polymer-air secondary battery composed of the PNQ anode, the Pt/C cathode, and 0.05 M H2SO4 aqueous electrolyte displayed high cyclability (>100 cycles) and C-rate capability (∼15 C) with a moderate voltage of 0.8 V during discharging.

    DOI

  • Reversible Reduction of the TEMPO Radical: One Step Closer to an All-Organic Redox Flow Battery

    Luke Wylie, Thomas Blesch, Rebecca Freeman, Kan Hatakeyama-Sato, Kenichi Oyaizu, Masahiro Yoshizawa-Fujita, Ekaterina I. Izgorodina

    ACS Sustainable Chemistry & Engineering   8 ( 49 ) 17988 - 17996  2020.12  [Refereed]

    DOI

  • Integrating multiple materials science projects in a single neural network

    Kan Hatakeyama-Sato, Kenichi Oyaizu

    Communications Materials   1 ( 1 )  2020.12  [Refereed]

    DOI

  • AIを活用した新規イオン伝導性高分子の探索と開発

    畠山歓, 小柳津研一

    機能材料   40   33 - 45  2020.11

    Authorship:Corresponding author

  • Charge-Transfer Complexes for Solid-State Li+ Conduction

    Kan Hatakeyama-Sato, Momoka Umeki, Toshiki Tezuka, Kenichi Oyaizu

    ACS Applied Electronic Materials   2 ( 7 ) 2211 - 2217  2020.07  [Refereed]

    DOI

  • 有機電極活物質を用いた二次電池・レドックスフロー電池

    小柳津研一

    電池技術   32   53 - 58  2020

  • 有機ポリマー電池の研究動向

    小柳津研一

    高分子   69   104 - 106  2020

  • “Progress in Organic Polymer Batteries”, Digest for English Readers

    K. Oyaizu

    Kobunshi   69   93  2020

  • AI-assisted Exploration of Superionic Glass-type Li+ Conductors with Aromatic Structures

    K. Hatakeyama-Sato, T. Tezuka, M. Umeki, K. Oyaizu

    J. Am. Chem. Soc.   142 ( 7 ) 3301 - 3305  2020  [Refereed]

    DOI

  • Poly(dihydroxybenzoquinone): Its High-density and Robust Charge Storage Capability in Rechargeable Acidic Polymer-air Batteries

    K. Oka, S. Furukawa, S. Murao, T. Oka, H. Nishide, K. Oyaizu

    Chem. Commun.   56 ( 29 ) 4055 - 4058  2020  [Refereed]

     View Summary

    A rechargeable acidic polymer-air battery was firstly fabricated with poly(2,5-dihydroxy-1,4-benzoquinone-3,6-methylene) (PDBM) as the anode, the conventional Pt/C cathode catalyst, and acidic aqueous electrolyte (pH 1). This battery yielded a high discharging capacity of 349 mA h g with a long-lifetime of >500 cycles and high rate capabilities (up to 10C). polymer -1

    DOI PubMed

  • Metal-free, Solid-state, and Paper-like Rechargeable Batteries Consisting of Redox-active Polyethers

    K. Hatakeyama-Sato, T. Tezuka, R. Ichinoi, S. Matsumono, K. Sadakuni, K. Oyaizu

    ChemSusChem   13 ( 9 ) 2443 - 2448  2020  [Refereed]

    DOI

  • Ultrafast Charge/discharge by a 99.9% Conventional Lithium Iron Phosphate Electrode Containing 0.1% Redox-active Fluoflavin Polymer

    K. Hatakeyama-Sato, T. Akahane, C. Go, T. Kaseyama, T. Yoshimoto, K. Oyaizu

    ACS Energy Lett.   5 ( 5 ) 1712 - 1717  2020  [Refereed]

    DOI

  • Conducting Redox Polymer as a Robust Organic Electrode-active Material in Acidic Aqueous Electrolyte towards Polymer-air Secondary Batteries

    K. Oka, C. Strietzel, R. Emanuelsson, H. Nishide, K. Oyaizu, M. Strømme, M. Sjödin

    ChemSusChem   13 ( 9 ) 2280 - 2285  2020  [Refereed]

     View Summary

    Organic materials receive increasing attention as environmentally benign and sustainable electrode-active materials. We present a conducting redox polymer (CRP) based on poly(3,4-ethylenedioxythiophene) with naphthoquinone pendant group, which is formed from a stable suspension of a trimeric precursor and an oxoammonium cation as oxidant. This suspension allows us to easily coat the polymer onto a current collector, opening up use of roll-to-roll processing or ink-jet printing for electrode preparation. The CRP showed a full capacity of 76 mAh g even at a high C rate of 100 C in acidic aqueous electrolyte. These properties make the CRP a promising candidate as anode-active material; a polymer–air secondary battery was fabricated with the CRP as anode, a conventional Pt/C catalyst as cathode, and sulfuric acid aqueous solution as electrolyte. This battery yielded a discharge voltage of 0.50 V and showed good cycling stability with 97 % capacity retention after 100 cycles and high rate capabilities up to 20 C. −1

    DOI PubMed

  • Phenolic Antioxidant-incorporated Durable Perovskite Layers and Their Application for a Solar Cell

    K. Suwa, T. Suga, K. Oyaizu, H. Segawa, H. Nishide

    MRS Commun.   10 ( 2 ) 312 - 316  2020  [Refereed]

     View Summary

    Copyright © Materials Research Society 2020. The incorporation of small amounts of phenolic antioxidants, such as 2,6-di-tert-butyl-4-cresol and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], into photovoltaic organo-lead halide perovskite layers significantly suppressed the degradation of the perovskite compounds via light irradiation in the presence of ambient oxygen. While the facile incorporation of the antioxidants did not decrease both the quality of the formed perovskite crystal grains and the photovoltaic conversion performance of the cells, it enhanced the antioxidizing property and water repellency of the perovskite layer owing to the elimination of superoxide anion radical and hydrophobic molecular structure and improved the durability of the cells.

    DOI

  • Reversible Hydrogen Fixation and Release under Mild Conditions by Poly(vinylquinoxaline)

    K. Oka, Y. Kaiwa, S. Furukawa, H. Nishide, K. Oyaizu

    ACS Appl. Polym. Mater.   2 ( 7 ) 2756 - 2760  2020  [Refereed]

    DOI

  • Allylic Hydrocarbon Polymers Complexed with Fe(II)(salen) as a Ultrahigh Oxygen-scavenging and Active Packaging Film

    Y. Wang, K. Oyaizu, H. Nishide

    Pure Appl. Chem.   92   871 - 882  2020  [Refereed]

    DOI

  • A Conducting Redox Polymer as Organic Anode Material for Polymer-manganese Secondary Batteries

    K. Oka, R. Löfgren, R. Emanuelsson, H. Nishide, K. Oyaizu, M. Strømme, M. Sjödin

    ChemElectroChem   7 ( 15 ) 3336 - 3340  2020  [Refereed]

     View Summary

    Manganese-based aqueous batteries have attracted significant attention due to their earth-abundant components and low environmental burden. However, state-of-the-art manganese-zinc batteries are poorly rechargeable, owing to dendrite formation on the zinc anode. Organic materials could provide a safe and sustainable replacement. In the present work, a conducting redox polymer (CRP) based on a trimer of EPE (E=3,4-ethylenedioxythiophene; P=3,4-propylenedioxythiophene) and a naphthoquinone (NQ) pendant group is used as anode in polymer-manganese secondary batteries. The polymer shows stable redox conversion around+0.05 V vs. Ag/AgCl, and fast kinetics that involves proton cycling during pendant group redox conversion. For the first time, a CRP-manganese secondary battery was fabricated with pEP(NQ)E as the anode, manganese oxide as the cathode, and manganese-containing acidic aqueous solution as the electrolyte. This battery yielded a discharge voltage of 1.0 V and a discharging capacity of 76 mAh/g over >50 cycles and high rate capabilities (up to 10 C). anode

    DOI

  • Polymer Sheet-based Hydrogen Carrier

    K. Oka, Y. Kaiwa, M. Kataoka, K. Fujita, K. Oyaizu

    Eur. J. Org. Chem.   2020 ( 36 ) 5876 - 5879  2020  [Refereed]

     View Summary

    Hydrogen is an attractive future energy source. Developing a hydrogen carrier, without any safety risk, i.e., high pressure and toxicity, is an urgent issue. Herein we present a fluorenone/fluorenol polymer sheet as a hydrogen carrier featuring high safety, moldability, and ease of handling. An iridium catalyst allows the polymer sheet to fix and release hydrogen gas under milder conditions (< 100 degrees C and ambient pressure), compared to those required by other hydrogen carriers. The polymer sheet, swollen with a small amount of water including the iridium complex catalyst, was hydrogenated at 25 degrees C and ambient hydrogen pressure, stored hydrogen via chemical bond formation, and then released it within 5 h when simply being warmed to 95 degrees C.

    DOI

  • Methoxy-substituted Phenylenesulfide Polymer with Excellent Dispersivity of TiO2 Nanoparticles for Optical Application

    S. Watanabe, K. Oyaizu

    Bull. Chem. Soc. Jpn.   93   1287 - 1292  2020  [Refereed]

    DOI

  • Rechargeable Proton Exchange Membrane Fuel Cell Containing an Intrinsic Hydrogen Storage Polymer

    J. Miyake, Y. Ogawa, T. Tanaka, J. Ahn, K. Oka, K. Oyaizu, K Miyatake

    Communn. Chem.   3 ( 1 ) 138  2020  [Refereed]

     View Summary

    Proton exchange membrane fuel cells (PEMFCs) are promising clean energy conversion devices in residential, transportation, and portable applications. Currently, a high-pressure tank is the state-of-the-art mode of hydrogen storage; however, the energy cost, safety, and portability (or volumetric hydrogen storage capacity) presents a major barrier to the widespread dissemination of PEMFCs. Here we show an ‘all-polymer type’ rechargeable PEMFC (RCFC) that contains a hydrogen-storable polymer (HSP), which is a solid-state organic hydride, as the hydrogen storage media. Use of a gas impermeable SPP-QP (a polyphenylene-based PEM) enhances the operable time, reaching up to ca. 10.2 s mg , which is more than a factor of two longer than that (3.90 s mg ) for a Nafion NRE-212 membrane cell. The RCFCs are cycleable, at least up to 50 cycles. The features of this RCFC system, including safety, ease of handling, and light weight, suggest applications in mobile, light-weight hydrogen-based energy devices. HSP HSP −1 −1

    DOI

  • A Highly Flexible Yet >300 mAh cm-3 Energy Density Lithium-ion Battery Assembled with the Cathode of a Redox-active Polyether Binder

    K. Hatakeyama-Sato, R. Mizukami, T. Serikawa, K. Oyaizu, H. Nishide

    Energy Technol.   8 ( 3 ) 1901159 - 1901159  2020  [Refereed]

    DOI

  • Ultrahigh Oxygen-scavenging Norbornene Copolymers Bearing Imidazolyl Iron Complex for Fabricating Active and Sustainable Packaging Films

    Y. Wang, Y. Hasegawa, T. Serikawa, K. Oyaizu, H. Nishide

    Chem. Commun.   56   964 - 967  2020  [Refereed]

    DOI

  • Facile Synthesis of Isotactic Polyacrylonitrile via Template Polymerization in Interlayer Space for Dielectric Energy Storage

    Y. Wang, R. Nakamura, T. Suga, S. Li, Y. Ohki, H. Nishide, K. Oyaizu

    ACS Appl. Polym. Mater.   2 ( 2 ) 775 - 781  2020  [Refereed]

     View Summary

    Isotactic polyacrylonitrile (iso-PAN) is synthesized via template polymerization using the two-dimensional layered space of a CoCl2 crystal as a template. Isotacticity of polyacrylonitrile reaches a meso/meso triad = 93% (mm = 0.93), which indicates a superior packing of polymer chains, leading to a high breakdown strength. Tacticity enhancement is correlated with the interatomic (metal-metal) distance of template -layered crystals. Due to a large dipole moment (4.3 D) of nitrile group and a high stereoregularity, iso-PAN demonstrates a high discharge energy density of 6.7 J/cm(3) at 660 MV/m, nearly six times that of atactic polyacrylonitrile (ata-PAN) and biaxially oriented polypropylene (BOPP), a commercially available dielectric polymer film. Moreover, it exhibits a charge-discharge efficiency of ca. 90% in a wide applied electric field range, which is higher than the efficiencies of ata-PAN and BOPP. These results suggest that iso-PAN, exhibiting a large dipole moment and high stereoregularity, is a promising candidate for high energy density and low loss capacitor dielectrics.

    DOI

  • 有機系蓄電池の電荷貯蔵機構と将来性

    小柳津研一

    応用物理学会有機分子・バイオエレクトロニクス分科会誌   31   5 - 8  2020

  • Facile Synthesis of Poly(glycidyl ether)s with Ionic Pendant Groups by Thiol-ene Reactions

    K. Hatakeyama-Sato, S. Kimura, S. Matsumoto, K. Oyaizu

    Macromol. Rapid Commun.   41   1900399  2020  [Refereed]

    DOI

  • Anti-oxidizing Radical Polymer-incorporated Perovskite Layers and Their Photovoltaic Characteristics in Solar Cells

    K. Suwa, K. Oyaizu, H. Segawa, H. Nishide

    ChemSusChem   12   5207 - 5212  2019  [Refereed]

    DOI

  • Hole-transporting Diketopyrrolopyrrole-thiophene Polymers and their Additive-free Application for a Perovskite-type Solar Cell with an Efficiency of 16.3%

    H. Maruo, Y. Sasaki, K. Harada, K. Suwa, K. Oyaizu, H. Segawa, K. Carter, H. Nishide

    Polym. J.   51   91 - 96  2019  [Refereed]

    DOI

  • Synthesis of Lithium-ion Conducting Polymers Designed by Machine Learning-based Prediction and Screening

    K. Hatakeyama-Sato, T. Tezuka, Y. Nishikitani, H. Nishide, K. Oyaizu

    Chem. Lett.   48 ( 2 ) 130 - 132  2019  [Refereed]

    DOI

  • Hydrophilic Organic Redox-active Polymer Nanoparticles for Higher Energy Density Flow Batteries

    K. Hatakeyama-Sato, T. Nagano, S. Noguchi, Y. Sugai, J. Du, H. Nishide, K. Oyaizu

    ACS Applied Polym. Mater.   1 ( 2 ) 188 - 196  2019  [Refereed]

    DOI

  • Ultra-thin and Stretchable Rechargeable Devices with Organic Polymer Nanosheets Conformable to Skin Surface

    K. Hatakeyama-Sato, H. Wakamatsu, K. Yamagishi, T. Fujie, S. Takeoka, K. Oyaizu, H. Nishide

    Small   2019 ( 13 ) 1805296 - 1805296  2019  [Refereed]

    DOI

  • Toward Improved Performance of All-organic Nitroxide Radical Batteries with Ionic Liquids: A Theoretical Perspective

    L. Wylie, R. Kempt, T. Heine, K. Oyaizu, A. Karton, M. Yoshizawa-Fujita, E. I. Izgorodina

    ACS Sustainable Chem. Eng.   7   5367 - 5375  2019  [Refereed]

    DOI

  • Full Organic Aqueous Battery Based on TEMPO Small Molecule with Millimeter-thick Electrodes

    S. Perticarari, E. Grange, T. Doizy, E. Quarez, K. Oyaizu, D. Guyomard, P. Poizot, F. Odobel, J. Gaubicher

    Chem. Mater.   31   1869 - 1880  2019  [Refereed]

    DOI

  • Perovskite/TiO2 Interface Passivation Using Poly(vinylcarbazole) and Fullerene for the Photovoltaic Conversion Efficiency of 21%

    W. Okada, T. Suga, K. Oyaizu, H. Segawa, H. Nishide

    ACS Appl. Energy Mater.   2 ( 4 ) 2848 - 2853  2019  [Refereed]

     View Summary

    © 2019 American Chemical Society. Poly(vinylcarbazole) (PVCz) dispersed the typical fullerene derivative, PCBM, well in its solution, which was then coated onto a mesoporous titanium oxide (TiO2) layer. PVCz served as a scaffold to fix PCBM homogeneously and to prevent its elution out upon the following perovskite layer formation. A series of perovskite cells were fabricated upon the PVCz/PCBM-modified TiO2 layer. Many of the cells were characterized by a photovoltaic conversion efficiency of >20%, and the top cells had an efficiency of 21.1% (with an average of 21.0%). Fluorescence decay from the perovskite layer of the cell was unchanged with the PVCz/PCBM modification, suggesting an efficient charge transport to the electron-transporting layers. On the other hand, the PVCz/PCBM modification or passivation significantly reduced electroluminescence intensity under an inverse bias application, supporting an efficient suppression of carrier recombination at the TiO2 and perovskite interface.

    DOI

  • n-Type Redox-active Benzoylpyridinium-substituted Supramolecular Gel for an Organogel-based Rechargeable Device

    K. Hatakeyama-Sato, R. Ichinoi, Y. Sasada, Y. Sasaki, K. Oyaizu, H. Nishide

    Chem. Lett.   48 ( 6 ) 555 - 557  2019  [Refereed]

    DOI

  • Reversible Hydrogen Releasing and Fixing with Poly(vinylfluorenol) through a Mild Ir-Catalyzed Dehydrogenation and Electrochemical Hydrogenation

    R. Kato, K. Oka, K. Yoshimasa, M. Nakajima, H. Nishide, K. Oyaizu

    Macromol. Rapid Commun.   2019 ( 16 ) 1900139  2019  [Refereed]

     View Summary

    The radical polymerization of 2-vinylfluorenol, an alcohol derivative of vinylfluorene, gives poly(vinylfluorenol), which quantitatively releases hydrogen gas (≈110 mL per gram polymer at standard temperature and pressure) by simply warming at 100 °C with an iridium catalyst. A high population of fluorenol units in the polymer accomplishes a large formula-weight-based theoretical hydrogen density (1.0 wt%). The dehydrogenated ketone derivative, poly(vinylfluorenone), exhibits reversible negative-charge storage with a high density of 260 mAh g . The electrolytically reduced poly(vinylfluorenone) is momentarily hydrogenated in the presence of an electrolyte with water as the hydrogen source to be converted to the original poly(vinylfluorenol). The formed poly(vinylfluorenol) almost quantitatively evolves hydrogen gas similar to the starting poly(vinylfluorenol). Both hydrogen and charge storage with the organic fluorenol/fluorenone polymer suggest a new type of energy-storage configuration. −1

    DOI PubMed

  • Characterization of PEDOT-quinone Conducting Redox Polymers in Water-in-salt Electrolytes for Safe and High-Energy Li-Ion Batteries

    K. Oka, C. Strietzel, R. Emanuelsson, H. Nishide, K. Oyaizu, M. Strømme, M. Sjödin

    Electrochem. Commun.   105   106489  2019  [Refereed]

     View Summary

    Li-ion batteries (LIBs) raise safety and environmental concerns, which mostly arise from their toxic and flammable electrolytes and the extraction of limited material resources by mining. Recently, water-in-salt electrolytes (WiSEs), in which a large amount of lithium salt is dissolved in water, have been proposed to allow for assembling safe and high-voltage (>3.0 V) aqueous LIBs. In addition, organic materials derived from abundant building blocks and their tunable properties could provide safe and sustainable replacements for inorganic cathode materials. In the current work, the electrochemical properties of a conducting redox polymer based on poly(3,4-ethylenedioxythiophene) (PEDOT) with hydroquinone (HQ) pendant groups have been characterized in WiSEs. The quinone redox reaction occurs within the potential region where the polymer is conducting, and fast redox conversion that involves lithium cycling during pendant group redox conversion was observed. These properties make conducting redox polymers promising candidates as cathode-active materials for safe and high-energy aqueous LIBs. An organic-based aqueous LIB, with a HQ-PEDOT as a cathode, Li Ti O (LTO) as an anode, and ca. 15 m lithium bis(trifluoromethanesulfonyl)imide water/dimethyl carbonate (DMC) as electrolyte, yielded an output voltage of 1.35 V and high rate capabilities up to 500C. 4 5 12

    DOI

  • Oxygen Scavenging and Oxygen Barrier Poly(1,2-butadiene) Films Containing an Iron-complex Catalyst

    Y. Wang, M. Shoda, A. Hisama, K. Oyaizu, H. Nishide

    Macromol. Chem. Phys.   2019   1900294  2019  [Refereed]

    DOI

  • Non-conjugated Redox-active Polymer Mediators for Rapid Electrocatalytic Charging of Lithium Metal Oxides

    K. Hatakeyama-Sato, T. Masui, T. Serikawa, Y. Sasaki, W. Choi, S. -G. Doo, H. Nishide, K. Oyaizu

    ACS Appl. Energy Mater.   2 ( 9 ) 6375 - 6382  2019  [Refereed]

    DOI

  • An Ultrahigh Output Rechargeable Electrode of a Hydrophilic Radical Polymer/Nanocarbon Hybrid with an Exceptionally Large Current Density beyond 1 A cm−2

    Kan Hatakeyama-Sato, Hisato Wakamatsu, Ryu Katagiri, Kenichi Oyaizu, Hiroyuki Nishide

    Advanced Materials   30 ( 26 ) 1800900  2018.06  [Refereed]

     View Summary

    Facile charge transport by a hydrophilic organic radical-substituted polymer and the 3D current collection by a self-assembled mesh of single-walled carbon nanotube bundles lead to the operation of an ultrahigh-output rechargeable electrode. Exceptionally large current density beyond 1 A cm−2 and high areal capacity around 3 mAh cm−2 are achieved, which are 101−2 times larger than those of the previously reported so-called “ultrafast electrodes.” A sub-millimeter-thick, flexible, highly safe organic redox polymer-based rechargeable device with an aqueous sodium chloride electrolyte is fabricated to demonstrate the superior performance.

    DOI

  • Arylamine polymers prepared via facile paraldehyde addition condensation: an effective hole-transporting material for perovskite solar cells

    Koki Suwa, Suguru Tanaka, Kenichi Oyaizu, Hiroyuki Nishide

    Polymer International   67 ( 6 ) 670 - 674  2018.06  [Refereed]

     View Summary

    Arylamine polymers were prepared via the facile one-step addition condensation of N,N′-diphenyl-N,N′-bis(4-methylphenyl)-1,4-phenylenediamine and 4-methoxytriphenylamine with paraldehyde. The polymers were highly soluble in common organic solvents. The non-conjugated arylamine polymer structure was characterized and found to form tough, homogeneous, amorphous layers with a glass transition temperature above 200 °C on a substrate by a simple spin-coating process. The polymer layers exhibited a hole mobility of the order of 10−5 cm2 V−1 s−1, which was comparable with those of previously reported arylamine polymers, and a highest occupied molecular orbital level of −5.38 eV appropriate for the hole-transporting layer of perovskite solar cells. The perovskite cells fabricated with the polymers gave a photovoltaic conversion efficiency of 16.0%. © 2018 Society of Chemical Industry.

    DOI

  • Polymer-Based White-Light-Emitting Electrochemical Cells with Very High Color-Rendering Index Based on Blue-Green Fluorescent Polyfluorenes and Red-Phosphorescent Iridium Complexes

    Yoshinori Nishikitani, Tetsuyuki Cho, Soichi Uchida, Suzushi Nishimura, Kenichi Oyaizu, Hiroyuki Nishide

    ChemPlusChem   83 ( 5 ) 463 - 469  2018.05  [Refereed]

     View Summary

    Application of the concept of three-color (red (R), green (G), and blue (B)) light-mixing to obtain white light is the most suitable way to realize white-light-emitting devices with very high color-rendering indices (CRI). White-light-emitting devices based on the three-color-mixing method could be used to create lighting and display technologies. Here, white-light-emitting electrochemical cells (LECs) with very high CRIs are reported, which were fabricated by using blend films composed of a fluorescent π-conjugated polymer (FCP), poly(9,9-dioctylfluorene-co-benzothiadiazole) (PFBT), and a phosphorescent iridium complex, [Ir(ppy)2(biq)]+(PF6)− (where (ppy)−=2-phenylpyridinate and biq=2,2′-biquinoline). The LECs fabricated with PFBT, the benzothiadiazole content of which is 0.01 mol %, showed blue electroluminescence (EL) emission originating from the fluorene segments and green EL emission from the benzothiadiazole units simultaneously. White LECs were then realized by adding red-emitting Ir complexes as guest molecules to the blue-green-emitting PFBT. By optimizing the proportions of the PFBT and Ir complexes in the active layers (PFBT/[Ir(ppy)2(biq)]+(PF6)−=1:0.2 (mass ratio)), white-light emission with Commission Internationale de l′Eclairage (CIE) coordinates of (0.29, 0.34) and a very high CRI value of 91.5 was achieved through RGB color-mixing. It was noted that the emission mechanism was based on Förster resonance energy transfer and Dexter energy transfer from excited PFBT to [Ir(ppy)2(biq)]+(PF6)−. The utilization of LECs based on blue-green FCPs and red Ir complexes looks very promising for the prospect of realizing white-light-emitting devices with very high CRIs.

    DOI

  • Oxoammonium cation of 2,2,6,6-tetramethylpiperidin-1-oxyl: A very efficient dopant for hole-transporting triaryl amines in a perovskite solar cell

    H. Maruo, S. Tanaka, M. Takamura, K. Oyaizu, H. Segawa, H. Nishide

    MRS Communications   8 ( 1 ) 122 - 126  2018.03  [Refereed]

     View Summary

    Oxoammonium cation of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) was used as an oxidizing dopant of triaryl amines to efficiently and almost quantitatively generate radical cations of the amines or a hole carrier. The doped-triaryl amines yielded an amorphous and homogeneous layer without any residual oxidant or neutral TEMPO molecule through its sublimination or warming the layer. The TEMPO cation-doped spiro-OMeTAD [tetrakis(dimethoxyphenylamine)spirobifluorene] produced a high hole mobility of 2 × 10-4 cm2/Vs. The perovskite solar cell fabricated with the TEMPO cation-doped or residual dopant-free spiro-OMeTAD as the hole-transporting layer displayed a photo-conversion efficiency of 20.1% with durability.

    DOI

  • Diffusion-Cooperative Model for Charge Transport by Redox-Active Nonconjugated Polymers

    Kan Sato, Rieka Ichinoi, Ryusuke Mizukami, Takuma Serikawa, Yusuke Sasaki, Jodie Lutkenhaus, Hiroyuki Nishide, Kenichi Oyaizu

    Journal of the American Chemical Society   140 ( 3 ) 1049 - 1056  2018.01  [Refereed]

     View Summary

    Charge transport processes in nonconjugated redox-active polymers with electrolytes were studied using a diffusion-cooperative model. For the first time, we quantitatively rationalized that the limited Brownian motion of the redox centers bound to the polymers resulted in the 103-4-fold decline of the bimolecular and heterogeneous charge transfer rate constants, which had been unexplained for half a century. As a next-generation design, a redox-active supramolecular system with high physical mobility was proposed to achieve the rate constant as high as in free solution system (&gt
    107 M-1 s-1) and populated site density (&gt
    1 mol/L).

    DOI

  • Poly(diphenanthrenequinone-substituted norbornene) for long life and efficient lithium battery cathodes

    Takuma Kawai, Satoshi Nakao, Hiroyuki Nishide, Kenichi Oyaizu

    Bulletin of the Chemical Society of Japan   91 ( 5 ) 721 - 727  2018  [Refereed]

     View Summary

    Poly(diphenanthrenequinone-substituted norbornene) (PQN) as a novel class of organic electrode-active material was reported. A Li coin cell composed of the PQN/carbon composite electrode as the cathode exhibited 2.8V and great cycle performance maintaining a capacity higher than 100mAh/g for more than 100 cycles at 60C. Among many types of o-quinonecontaining polymers for Li-ion batteries reported so far, the present research provides the first example of introducing phenanthrenequinone as the pendant group per repeating unit of polymers, which proved to be especially advantageous in terms of robustness and cyclability by virtue of the fused-ring structure to protect the reactive positions of the o-benzoquinone. The functional group tolerance against many types of redox-active groups, which we have established for the initiator and the propagating end of norbornene derivatives, apply for the phenanthrenequinone-substituted monomer, giving rise to a reversible redox activity.

    DOI

  • 酸化還元活性な高分子による集合組織の動的制御

    佐藤歓, 小柳津研一

    化学   73   70 - 71  2018

  • 有機材料でいかに電荷を貯蔵するか: 単一分子のレドックス反応から有機蓄電材料への展開

    小柳津研一, 西出宏之

    化学と工業   71   462 - 464  2018

  • Poly(vinyldibenzothiophenesulfone): Its Redox Capability at Very Negative Potential Toward an All-organic Rechargeable Device with High-energy Density

    K. Oka, R. Kato, K. Oyaizu, H. Nishide

    Adv. Funct. Mater.   28 ( 50 ) 1805858  2018  [Refereed]

     View Summary

    Dibenzothiophenesulfone undergoes a two-electron reduction in a single step at a very negative potential of -1.8 V (versus Ag/AgCl) in organic electrolytes, due to the electron-withdrawing sulfone group and the stability of the resulting dianion. The heterogeneous electron-transfer rate constant for the reduction is approximately 10 cm s , which is significantly faster than most redox-active species. The results presented herein suggest that dibenzothiophenesulfone is a potential candidate for use as an anode-active material with high-energy density. In addition, radical polymerization of vinyldibenzothiophenesulfone yielded poly(vinyldibenzothiophenesulfone) with a high molecular weight. A rechargeable device is fabricated with only organic compounds; poly(vinyldibenzothiophenesulfone) as the anode, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-substituted poly(methacrylate) as the cathode, and tetraethylammonium salt and organic solvent as the electrolyte. This device yields a maximum output voltage of 2.6 V in these organic devices, and the active component of the anode displays a very high-energy density of >500 mWh g . -1 -1 -1

    DOI

  • High-color-rendering-index white polymer light-emitting electrochemical cells based on ionic host-guest systems: Utilization of blend films of blue-fluorescent cationic polyfluorenes and red-phosphorescent cationic iridium complexes

    Yoshinori Nishikitani, Kotaro Suga, Soichi Uchida, Suzushi Nishimura, Kenichi Oyaizu, Hiroyuki Nishide

    ORGANIC ELECTRONICS   51   168 - 172  2017.12  [Refereed]

     View Summary

    The authors present high-color-rendering-index (CRI) white polymer light-emitting electrochemical cells (PLECs) based on ionic host-guest systems. PLECs were fabricated with blend films composed of a blue fluorescent cationic pi-conjugated polymer, poly(9,9-bis[60-(N, N, N,-trimethylammonium) hexyl] fluorineco- alt-1,4-phenylene) bromide (PFN+Br-), used as a host, and a red phosphorescent cationic iridium complex, [ Ir(ppy)(2)(biq)](+)(PF6)(-) (where (ppy)(-) = 2-phenylpyridinate and biq = 2,2'-biquinoline), used as a guest. By optimizing the composition of PFN+Br- and [Ir(ppy)(2)(biq)](+)(PF6)(-) in the active layers, white light emission with Commission Internationale de l'Eclairage (CIE) coordinates of (x = 0.28, y = 0.31) and a very high CRI of 95.8 was achieved through mixing of blue and red light at an applied voltage of 4.0 V. The white light emissions were obtained at a low [Ir(ppy)(2)(biq)](+)(PF6)(-) concentration (PFN+Br- :[Ir(ppy)(2)(biq)](+)(PF6)(-) = 1: 0.01 (mass ratio)), showing that [Ir(ppy)(2)(biq)](+)(PF6)(-) acts as a suitable energy acceptor. The emission mechanism of the ionic host-guest PLECs can be explained by Forster resonance energy transfer (FRET) and Dexter energy transfer (DET) from the excited PFN+Br- to [Ir(ppy)(2)(biq)](+)(PF6)(-). Utilization of ionic host-guest PLECs is a very promising method for realizing white light-emitting devices with very high CRI. (C) 2017 Elsevier B.V. All rights reserved.

    DOI

  • Ag nanocluster-based color converters for white organic light-emitting devices

    Yoshinori Nishikitani, Daisuke Takizawa, Soichi Uchida, Yue Lu, Suzushi Nishimura, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF APPLIED PHYSICS   122 ( 18 ) 184302  2017.11  [Refereed]

     View Summary

    The authors present Ag nanocluster-based color converters (Ag NC color converters), which convert part of the blue light from a light source to yellow light so as to create white organic light-emitting devices that could be suitable for lighting systems. Ag NCs synthesized by poly(methacrylic acid) template methods have a statistical size distribution with a mean diameter of around 4.5 nm, which is larger than the Fermi wavelength of around 2 nm. Hence, like free electrons in metals, the Ag NC electrons are thought to form a continuous energy band, leading to the formation of surface plasmons by photoexcitation. As for the fluorescence emission mechanism, the fact that the photoluminescence is excitation wavelength dependent suggests that the fluorescence originates from surface plasmons in Ag NCs of different sizes. By using Ag NC color converters and suitable blue light sources, white organic light-emitting devices can be fabricated based on the concept of light-mixing. For our blue light sources, we used polymer light-emitting electrochemical cells (PLECs), which, like organic light-emitting diodes, are area light sources. The PLECs were fabricated with a blue fluorescent p-conjugated polymer, poly[(9,9-dihexylfluoren-2,7-diyl)-co-(anthracen- 9,10-diyl)] (PDHFA), and a polymeric solid electrolyte composed of poly(ethylene oxide) and KCF3SO3. In this device structure, the Ag NC color converter absorbs blue light from the PDHFA-based PLEC (PDHFA-PLEC) and then emits yellow light. When the PDHFA-PLEC is turned on by applying an external voltage, pure white light emission can be produced with Commission Internationale de l'Eclairage coordinates of (x = 0.32, y = 0.33) and a color rendering index of 93.6. This study shows that utilization of Ag NC color converters and blue PLECs is a very promising and highly effective method for realizing white organic light-emitting devices. Published by AIP Publishing.

    DOI

  • Grafted radical polymer brush for surface-driven switching of chiral nematic liquid crystals

    Kan Sato, Takaaki Yamasaki, Hiroyuki Nishide, Kenichi Oyaizu

    POLYMER JOURNAL   49 ( 10 ) 691 - 693  2017.10  [Refereed]

    DOI

  • Command Surface of Self-Organizing Structures by Radical Polymers with Cooperative Redox Reactivity

    Kan Sato, Takahiro Mizuma, Hiroyuki Nishide, Kenichi Oyaizu

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   139 ( 39 ) 13600 - 13603  2017.10  [Refereed]

     View Summary

    Robust radical-substituted polymers with ideal redox capability were used as "command surfaces" for liquid crystal orientation. The alignment of the smectic liquid crystal electrolytes with low-dimensional ion conduction pathways was reversible and readily switched hi response to the redox states of the polymers. In one example, a charge storage device with a cooperative redox effect was fabricated. The bulk ionic conductivity of the cell was significantly decreased only after the electrode was fully charged, due to the anisotropic ionic conductivity of the electrolytes (ratio &gt;10(3)). The switching enabled both a rapid cell response and long charge retention. Such a cooperative Command surface of-self-assembled structures Will give rise to new highly energy efficient supramolecular-based devices including batteries, charge carriers, and actuators.

    DOI

  • Synthesis of Highly Crystallized Poly(1,4-phenylene sulfide) via Oxygen-Oxidative Polymerization of Diphenyl Disulfide

    Fuyuki Aida, Naoto Takasu, Yohei Takatori, Hiroyuki Nishide, Kenichi Oyaizu

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   90 ( 7 ) 843 - 846  2017.07  [Refereed]

     View Summary

    In the presence of diphenyl sulfide, oxygen-oxidative polymerization of diphenyl disulfide gave highly crystalized poly( 1,4-phenylene sulfide) (PPS) using a vanadyl-strong acid catalytic system. Effect of the sulfide, which was inactive to the vanadyl catalyst, was ascribed to the enhancement of the electrophilic substitution with a sulfonium cation onto a thiophenyl end. The finally purified PPS showed high crystallinity (X-c = 44%), which was even higher than that of the reagent grade PPS produced by the conventional polycondensation process.

    DOI

  • Supramolecular Organic Radical Gels Formed with 2,2,6,6-Tetramethylpiperidin-1-oxyl-Substituted Cyclohexanediamines: A Very Efficient Charge-Transporting and -Storable Soft Material

    Yoshito Sasada, Rieka Ichinoi, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY OF MATERIALS   29 ( 14 ) 5942 - 5947  2017.07  [Refereed]

     View Summary

    A supramolecular gelator, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-substituted cyclohexanediamine derivative, was synthesized, and its excellent charge-transporting capability was explored. The gels with organic solvents and electrolytes, or with ionic liquids, were formed via reversible sol-gel phase transition at ca. 50 degrees C. The organogels displayed electrochemical redox responses at E-1/2 = 0.72 V (vs Ag/AgCl) ascribed to the TEMPO moiety. Charge diffusion coefficient of the gel reached 3.3 x 10(-7) cm(2)/s even in the quasi-solid state, which was comparable to those of the homogeneous solution (ca. 10(-6)). The high charge-transporting capability led to the tremendously large current density (a diffusion limited one) of ca. 1.0 mA/cm(2) on a current collector and long distance for the charge-transporting beyond the organogel thickness of 50 mu m. A half-cell of the organogel performed a plateau output voltage at the E-1/2, very high rate, and almost quantitative charging-discharging, and it had cydability without any additives such as conductive carbons and binder polymers.

    DOI

  • Redox Mediation through TEMPO-substituted Polymer with Nanogap Electrodes for Electrochemical Amplification

    Hiroshi Tokue, Keita Kakitani, Hiroyuki Nishide, Kenichi Oyaizu

    CHEMISTRY LETTERS   46 ( 5 ) 647 - 650  2017.05  [Refereed]

     View Summary

    A thin layer of a polymer containing densely populated redox-active nitroxide radicals, photocrosslinked poly[2,3-bis(2',2',6',6'-tetramethylpiperidin-1'-oxyl-4'-oxycarbonyl)-5-norbornene] (PTNB), was employed to demonstrate an electrochemical transistor-like behavior in the form of a polymer-sandwiched nanogap device. A significant and sensitive change in the current in response to the applied electrode potential was produced, owing to the fast formation of the steep redox gradient of the electroactive species through the polymer layer. A current response to an alternating voltage obtained from the polymer-sandwiched nanogap device exhibited the electrochemical amplification effect based on the facile redox conduction.

    DOI

  • Totally Organic-based Bendable Rechargeable Devices Composed of Hydrophilic Redox Polymers and Aqueous Electrolyte

    Kan Sato, Ryu Katagiri, Natsuru Chikushi, Subin Lee, Kenichi Oyaizu, Jae-Suk Lee, Hiroyuki Nishide

    CHEMISTRY LETTERS   46 ( 5 ) 693 - 694  2017.05  [Refereed]

     View Summary

    Totally organic polymer-based, submillimeter-thick, bendable rechargeable devices were fabricated using hydrophilic polymers as electrode-active materials and brine as the electrolyte. The rapid and reversible electrochemical reactions of the polymers enabled quick charging within minutes, long life, and a moderate operation voltage of more than 1V. Quantitative discharge was achieved even when the devices were in a bent state with a radius of curvature of 1 mm.

    DOI

  • Low-Cost, Organic Light-Emitting Electrochemical Cells with Mass-Producible Nanoimprinted Substrates Made Using Roll-to-Roll Methods

    Kan Sato, Soichi Uchida, Shigetaka Toriyama, Suzushi Nishimura, Kenichi Oyaizu, Hiroyuki Nishide, Yoshinori Nishikitani

    ADVANCED MATERIALS TECHNOLOGIES   2 ( 5 ) 1600293  2017.05  [Refereed]

     View Summary

    Next-generation, power-efficient organic lighting systems, which ideally would be low-cost and mass-producible, are urgently needed because more than 20% of total electricity use goes to lighting. This study presents polymer light-emitting electrochemical cells (PLECs) made using mass-producible nanoimprinted corrugated substrates, which effectively improve light extraction efficiency. The corrugated substrates are fabricated using roll-to-roll methods, using self-assembled block copolymers on glass and film substrates (glass: 0.45 m x 0.55 m, film: 0.6 m wide). Using the glass-type corrugated substrates, two PLECs based on (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene]) and (super-yellow poly(p-phenylene vinylene)) (SY-PPV) are fabricated by solution-based spin-coating methods, which can in practice be replaced by roll-to-roll methods. The corrugated PLECs with SY-PPV show high brightness of 1740 cd cm(-2) and 2.1 times greater efficiency without changing the original spectrum or angular dependence. This successful combination of corrugated substrates and PLECs is one of the best examples of a promising cost-effective, high-performance lighting technology.

    DOI

  • A hydrogen-storing quinaldine polymer: nickel-electrodeposition-assisted hydrogenation and subsequent hydrogen evolution

    Ryo Kato, Takahiro Oya, Yuma Shimazaki, Kenichi Oyaizu, Hiroyuki Nishide

    POLYMER INTERNATIONAL   66 ( 5 ) 647 - 652  2017.05  [Refereed]

     View Summary

    Quinaldine-substituted poly(acrylic acid) (PQD) and its hydrogenated 1,2,3,4-tetrahydroquinaldine derivative (PHQD) were prepared, and a cycle of hydrogen fixing and hydrogen evolution in and from the polymer, respectively, is described. A PQD layer coated on a carbon substrate was electrochemically reduced or hydrogenated using water as a hydrogen source, accompanied by the electrodeposition of nickel microparticles in the polymer layer, to convert PQD to PHQD. The conversion efficiency was enhanced by coating PQD on the substrate as a scaffold of nickel electrodeposition, in comparison with that of quinaldine and PQD dissolved in the electrolyte. The formed PHQD evolved hydrogen by simply warming it in water containing an iridium complex catalyst. Hydrogen fixing and evolution under mild conditions could suggest a new system of hydrogen carriers. (c) 2017 Society of Chemical Industry

    DOI

  • Charge Discharge with Rocking-Chair-Type Li+ Migration Characteristics in a Zwitterionic Radical Copolymer Composed of TEMPO and Trifluoromethanesulfonylimide with Carbonate Electrolytes for a High-Rate Li-Ion Battery

    Hiroshi Tokue, Tomoaki Murata, Haruka Agatsuma, Hiroyuki Nishide, Kenichi Oyaizu

    MACROMOLECULES   50 ( 5 ) 1950 - 1958  2017.03  [Refereed]

     View Summary

    Redox-active copolymer containing organic robust radical, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), and charge neutralizing anion, trifluoromethanesulfonylimide (TFSI-) was synthesized as a cathode material of a Li-ion battery. The copolymer, poly(2,2,6,6-tetramethylpiperidin-1-oxy-4-yl methacrylate-co-styrenesulfonyl(trifluoromethanesulfonyl)imide) (1)(TMA-co-TFSI)), was designed to give rise to the Li+ migration during its charge-discharge process, based on the self charge compensation of TEMPO with TFSI- bound to the polymer chain in a widely used electrolyte system for Li-ion battery, organic carbonate mixtures. Copolymerization was performed to achieve efficient self-charge compensation with uniformly distributed TFSI- units. The P(TMA-co-TFSI) layer electrode exhibited reversible redox reaction at 0.73 V vs Ag/AgCl. Electrochemical measurements combined with quartz crystal microbalance analysis evidenced that the redox reaction involved the Li+ migration in binary system of ethylene carbonate and diethyl carbonate. A test cell fabricated with the P(TMA-co-TFSI) cathode exhibited high discharging voltage of 3.7 V and high -rate charge -discharge capability at 30 C (i.e., full charging in 2 min).

    DOI

  • Synthesis of Dimethyl-Substituted Polyviologen and Control of Charge Transport in Electrodes for High-Resolution Electrochromic Displays

    Kan Sato, Ryusuke Mizukami, Takahiro Mizuma, Hiroyuki Nishide, Kenichi Oyaizu

    POLYMERS   9 ( 3 ) 86  2017.03  [Refereed]

     View Summary

    Electrochromic (EC) polymers such as polyviologens have been attracting considerable attention as wet-processable electrodes for EC displays, thanks to their brilliant color change accompanied with reversible redox reactions. To establish wider usage, achieving multicolor and high-resolution characteristics is indispensable. In this paper, we demonstrated that the introduction of substituents such as methyl groups into bipyridine units changed the stereostructure of the cation radicals, and thus shifted the color (e.g., ordinary purple to blue). Also, by relaxing excessive pi-stacking between the viologen moieties, the response rate was improved by a factor of more than 10. The controlled charge transport throughout the polyviologen layer gave rise to the fabrication of EC displays which are potentially suitable for the thin film transistor (TFT) substrate as the counter electrodes with submillimeter pixels. The findings can be versatilely used for the new design of polyviologens with enhanced electrochemical properties and high-resolution, multicolor EC displays.

    DOI

  • 高純度ポリフェニレンスルフィドの合成化学

    小柳津研一

    ENEOS Technical Review   59   11 - 14  2017

  • A ketone/alcohol polymer for cycle of electrolytic hydrogen-fixing with water and releasing under mild conditions

    Ryo Kato, Keisuke Yoshimasa, Tatsuya Egashira, Takahiro Oya, Kenichi Oyaizu, Hiroyuki Nishide

    NATURE COMMUNICATIONS   7   13032  2016.09  [Refereed]

     View Summary

    Finding a safe and efficient carrier of hydrogen is a major challenge. Recently, hydrogenated organic compounds have been studied as hydrogen storage materials because of their ability to stably and reversibly store hydrogen by forming chemical bonds; however, these compounds often suffer from safety issues and are usually hydrogenated with hydrogen at high pressure and/or temperature. Here we present a ketone (fluorenone) polymer that can be moulded as a plastic sheet and fixes hydrogen via a simple electrolytic hydrogenation at -1.5V (versus Ag/AgCl) in water at room temperature. The hydrogenated alcohol derivative (the fluorenol polymer) reversibly releases hydrogen by heating (80 degrees C) in the presence of an aqueous iridium catalyst. Both the use of a ketone polymer and the efficient hydrogen fixing with water as a proton source are completely different from other (de) hydrogenated compounds and hydrogenation processes. The easy handling and mouldable polymers could suggest a pocketable hydrogen carrier.

    DOI

  • Metallopolyyne polymers with ferrocenyl pendant ligands as cathode active materials for organic battery application

    Zhengong Meng, Kan Sato, Takashi Sukegawa, Kenichi Oyaizu, Cheuk-Lam Ho, Jing Xiang, Ying-Hsuan Feng, Yih Hsing Lo, Hiroyuki Nishide, Wai-Yeung Wong

    JOURNAL OF ORGANOMETALLIC CHEMISTRY   812   51 - 55  2016.06  [Refereed]

     View Summary

    Two bis(acetylide)-functionalized platinum(II) polymers containing ferrocenyl pendant ligands, trans[(-Pt(PBu3n)(2)-C CRC C-)(n) P1 (R = 9-ferrocenylmethylene-2,7-diethynylfluorene) and P2 (R = ferrocenylmethylene-2,5-diethynylbenzene), were prepared in good yields and were characterized by NMR spectroscopy and GPC. Electrochemical characteristics with copolymers P1 and P2 as the cathode active materials for rechargeable lithium batteries showed chemical and electrochemical reversibility. The thin layer polymer electrodes of P1 and P2 exhibited reversible redox peaks at the potentials of 0.54 and 0.64 V (vs. Ag/AgCl), respectively. The P1 or P2/carbon composites are also used as cathode-active materials to enhance the conductivity and durability. The electrodes exhibited good cycle life of over 50 charging/discharging cycles and no reversible n-type redox abilities seemed to be available. (C) 2015 Elsevier B.V. All rights reserved.

    DOI

  • A Quasi-Solid State DSSC with 10.1% Efficiency through Molecular Design of the Charge-Separation and -Transport

    Michio Suzuka, Naoki Hayashi, Takashi Sekiguchi, Kouichi Sumioka, Masakazu Takata, Noriko Hayo, Hiroki Ikeda, Kenichi Oyaizu, Hiroyuki Nishide

    SCIENTIFIC REPORTS   6   28022  2016.06  [Refereed]

     View Summary

    Organic-based solar cells potentially offer a photovoltaic module with low production costs and low hazard risk of the components. We report organic dye-sensitized solar cells, fabricated with molecular designed indoline dyes in conjunction with highly reactive but robust nitroxide radical molecules as redox mediator in a quasi-solid gel form of the electrolyte. The cells achieve conversion efficiencies of 10.1% at 1 sun, and maintain the output performance even under interior lighting. The indoline dyes, customized by introducing long alkyl chains, specifically interact with the radical mediator to suppress a charge-recombination process at the dye interface. The radical mediator also facilitates the charge-transport with remarkably high electron self-exchange rate even in the quasi-solid state electrolyte to lead to a high fill factor.

    DOI

  • Synthesis and Charge-Discharge Properties of Organometallic Copolymers of Ferrocene and Triphenylamine as Cathode Active Materials for Organic-Battery Applications

    Jing Xiang, Kan Sato, Hiroshi Tokue, Kenichi Oyaizu, Cheuk-Lam Ho, Hiroyuki Nishide, Wai-Yeung Wong, Mingdeng Wei

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY   ( 7 ) 1030 - 1035  2016.03  [Refereed]

     View Summary

    Two new organometallic copolymers (PVFVM1 and PVFVM1-1) bearing different molar ratios of ferrocene and triphenylamine pendants were successfully designed and synthesized as cathode active materials for organic-battery applications. Their structural and thermal characteristics were determined by H-1 NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, size exclusion chromatography (SEC), and thermogravimetric analysis (TGA). Cyclic voltammograms of the as-prepared polymers show that the electrochemical reactions of the ferrocene and triphenylamine moieties are reversible after the first cycle. A composite electrode based on copolymer PVFVM1 exhibits an initial specific discharge capacity of 102 mAhg(-1), which corresponds to 98% of its theoretical capacity (104 mAhg(-1)). The cycle endurances for both polymers have been evaluated for over 50 cycles. Our results show that both copolymers are good candidates as a new class of cathode active materials and charge-storage materials for rechargeable batteries.

    DOI

  • Emerging Organosulfonium Electrophiles as Unique Reagents for Carbon Sulfur Bond Formation: Prospects in Synthetic Chemistry of Organosulfur Compounds

    Fuyuki Aida, Kenichi Oyaizu

    CHEMISTRY LETTERS   45 ( 2 ) 102 - 109  2016.02  [Refereed]

     View Summary

    Carbon-sulfur (C-S) bond formation is one of the important synthetic routes in organic chemistry. Among sulfur sources for C-S bond formation, organosulfur cations (RS+) and their synthetic equivalents are unique reagents. These cationic sulfur species are easily prepared as compared with the oxonium analogues, because of their low ionization potentials. This review describes various synthetic methods for C-S bond formation, mainly focusing on electrophilic reactions, addition to olefins, and substitution to aromatic rings. A breakthrough has been anticipated for RS+ electrophiles, based on their versatile utility in aromatic polymer synthesis.

    DOI

  • Dynamic switching of ionic conductivity by cooperative interaction of polyviologen and liquid crystals for efficient charge storage

    Kan Sato, Takaaki Yamasaki, Takahiro Mizuma, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF MATERIALS CHEMISTRY A   4 ( 9 ) 3249 - 3252  2016  [Refereed]

     View Summary

    The ionic conductivity of a liquid crystal electrolyte was switched along with redox reactions of polyviologen. The surface charge of the polymer determined the alignment and the bulk conductivity of the electrolyte. The cooperative switching firstly enabled the suppression of self-discharging and quick-response, giving rise to facile and persistent charge storage.

    DOI

  • Enhanced catalytic activity of oxovanadium complexes in oxidative polymerization of diphenyl disulfide

    Fuyuki Aida, Yohei Takatori, Daichi Kiyokawa, Kentaro Nagamatsu, Kenichi Oyaizu, Hiroyuki Nishide

    POLYMER CHEMISTRY   7 ( 11 ) 2087 - 2091  2016  [Refereed]

     View Summary

    Oxygen-oxidative polymerization of diphenyl disulfide gives poly(1,4-phenylene sulfide) (PPS), catalyzed by a vanadyl complex and a protic acid. N,N'-Ethylenebis(salicylideneaminato)oxovanadium(IV) (VO(salen)) which has been reported to be catalytically inactive at ambient temperature because of the insufficient reactivity of its oxidized state, an oxovanadium(V) complex, for the oxidation of the monomer turned out to exhibit an excellent catalytic activity on raising the reaction temperature above 100 degrees C. The enhanced reactivity of VO(salen)-acid or bis(2,4-pentanedionato)oxovanadium(IV) (VO(acac)(2))-acid catalytic systems at elevated temperatures gave insight into the catalytic mechanism where oxidation of the monomer with the oxovanadium(V) complex dominated the reactivity, which was also accelerated by a second redox shuttle molecule, such as quinones with a potential near that of the [VO(salen)](0/+) couple.

    DOI

  • Poly(norbornyl-NDIs) as a potential cathode-active material in rechargeable charge storage devices

    Y. Sasada, S. J. Langford, K. Oyaizu, H. Nishide

    RSC ADVANCES   6 ( 49 ) 42911 - 42916  2016  [Refereed]

     View Summary

    Two pendant-type naphthalene diimide (NDI) polymers bearing a polynorbornene backbone were prepared and their electrochemical properties explored. The NDI-based polymers displayed reversible redox responses in 1 M LiClO4 gamma-butyrolactone electrolyte. Polymer 1, bearing a N-methyl group, exhibited remarkable charge-storage capabilities which demonstrated its potential usefulness as an organic cathode-active material in rechargeable devices with excellent performances such as large charge capacity, high rate capability, and charge-discharge cyclability.

    DOI

  • Electrochemical current rectification with cross reaction at a TEMPO/viologen-substituted polymer thin-layer heterojunction

    H. Tokue, K. Kakitani, H. Nishide, K. Oyaizu

    RSC ADVANCES   6 ( 101 ) 99195 - 99201  2016  [Refereed]

     View Summary

    Totally reversible redox-active polymers, 4-amino-2,2,6,6-tetramethylpiperidin-1-oxyl functionalized polyacrylic acid (PTAm-A) and poly(tripyridiniomesitylene) (PTPM), both of which possessed rapid charge transport properties in an aqueous electrolyte, were applied to a polymer-sandwiched device to offer an electrochemical current rectification functionality. Single-layer and bilayer devices were fabricated employing the PTAm-A and/or PTPM thin layer(s) as charge transport media. Single-layer devices with a 1 cm(2) electrode area demonstrated large currents in the order of several milliamperes, which were established by redox mediation based on a fast electron self-exchange reaction between adjacent redox sites in the polymer layers. A current-voltage response obtained from the bilayer device exhibited a rectification effect due to thermodynamically favoured cross reaction at the polymer/polymer interface, retaining the large current densities. The observed currents were comparable to those predicted from the diffusion-controlled charge transport kinetics. Potentiostatic measurements revealed that the rectified current readily achieved a steady state in response to the applied voltage. These results demonstrate that the PTAm-A/PTPM thin-layer heterojunction enabled a large current rectification based on the redox mediation process, providing insight into ideal charge flow systems in various electrochemical devices.

    DOI

  • Vanadyl-TrBR4-Catalyzed Oxidative Polymerization of Diphenyl Disulfide

    Fuyuki Aida, Souske Yamaguchi, Yohei Takatori, Kentaro Nagamatsu, Daichi Kiyokawa, Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULAR CHEMISTRY AND PHYSICS   216 ( 18 ) 1850 - 1855  2015.09  [Refereed]

     View Summary

    A newly established catalyst system for oxygen-oxidative polymerization of diphenyl disulfide is reported. Combination of vanadyl compounds (e.g., VO(acac)(2)) and triphenylmethylium tetrakis(pentafluorophenyl) borate (TrB(C6F5)(4)) proceeds the polymerization to give poly(1,4-phenylene sulfide) (PPS) at 100 degrees C. When triphenylmethylium tetrafluoroborate (TrBF4) is applied with vanadyl tetraphenylporphyrin (VO(TPP)) or N,N'-(ethylenebis(salicylideneaminato)) oxovanadium (VO(salen)), PPS is also given via polymerization under conditions near 160 degrees C. Combination of the vanadyl complex and the borate affords the first protic-acid-free catalytic system for the polymerization of the disulfide, suggesting the overall reaction to produce PPS and H2O from O-2 and protons that are eliminated from the monomer.

    DOI

  • Poly(1,4-phenylene sulfide) (PPS) Synthesis via Oxidative Polymerization of Diphenyl Disulfide: Mechanistic Insight into the Selective Formation of 1,4-Thiophenylene Chain

    Fuyuki Aida, Yohei Takatori, Daichi Kiyokawa, Kentaro Nagamatsu, Hiroyuki Nishide, Kenichi Oyaizu

    CHEMISTRY LETTERS   44 ( 6 ) 767 - 769  2015.06  [Refereed]

     View Summary

    Oxidative polymerization of diphenyl disulfide under molten conditions at moderately elevated temperatures gave poly(1,4-phenylene sulfide) (PPS), using a vanadyl complex strong acid catalyst with oxygen as the ultimate oxidant. Origin of the selectivity of the sulfonium electrophile for the formation of the 1,4-thiophenylene chain, characterized by the presence of a disulfide bond at the chain end, was determined by the behavior of polymerization and structural analysis of the product together with a computational calculation, which revealed a unique chain growth-type polycondensation process.

    DOI

  • Facile grafting-onto-preparation of block copolymers of TEMPO and glycidyl methacrylates on an oxide substrate as an electrode-active layer

    Katsuyuki Takahashi, Konstantine Korolev, Kazumasa Tsuji, Kenichi Oyaizu, Hiroyuki Nishide, Evgeny Bryuzgin, Alexander Navrotskiy, Ivan Novakov

    POLYMER   68   310 - 314  2015.06  [Refereed]

     View Summary

    Block copolymers of 2,2,6,6-tetramethyl-4-piperidyl methaaylate and glycidyl methactylate were prepared by atom transfer radical polymerization. The block copolymer was immobilized on an indium-doped tin oxide substrate by simply coating the copolymer solution and annealing. The copolymer layers were efficiently converted to those of the corresponding 2,2,6,6-tetramethylpiperidin-1-oxy (TEMPO) polymer. The TEMPO layers were swelled with but not eluted into common electrolyte solutions such as acetonitrile and ethylene carbonate, and showed excellent electrochemically reversible redox cycling at 0.81 V vs. Ag/AgCl. The layer with the thickness of micron meters exhibited both a sufficient charge diffusivity (10(-10) cm(2) s(-1)) and a very large storage capacity (beyond 120 mC cm(-2)), which was applicable to a cathode of organic-based rechargeable devices. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

  • Polyviologen as the charge-storage electrode of an aqueous electrolyte- and organic-based dye-sensitized solar cell

    Michio Suzuka, Shu Hara, Takashi Sekiguchi, Kenichi Oyaizu, Hiroyuki Nishide

    POLYMER   68   353 - 357  2015.06  [Refereed]

     View Summary

    A dye-sensitized solar cell (DSSC) was fabricated with a viologen polymer as a charge-storable electrode and an aqueous electrolyte. The polyviologen was prepared via electrolytic polymerization of the 4-cyanopyridine moiety: It displayed reversible two-electron redox reactions at -0.48 and -0.86 V vs. Ag/AgCl in the aqueous electrolyte, which were appropriate for the acceptance of an electron from the photo-anode or TiO2 conduction band by the charge-storable electrode. The DSSC using the polyviologen electrode achieved both photo-current generation with a high open-circuit voltage of ca. 0.8 V upon light irradiation, and a charge-supply after irradiation at a constant voltage of ca. 0.4 V with a discharging capacity of ca. 75% of the polyviologen electrode. The potential tuning of the organic-based polyviologen electrode was described. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

  • Synthesis of Poly(TEMPO-Substituted Glycidyl Ether) by Utilizing t-BuOK/18-Crown-6 for an Organic Cathode-Active Material

    Kan Sato, Takashi Sukegawa, Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULAR SYMPOSIA   351 ( 1 ) 90 - 96  2015.05  [Refereed]

     View Summary

    A nitroxide radical-substituted polyether, poly(TEMPO-substituted glycidyl ether) (PTGE), was synthesized using a potassium tert-butoxide/18-crown-6 initiator. The presence of 18-crown-6 effected significant improvement in the reactivity of the chain end, thus allowing the polymerization to proceed at moderate temperatures to suppress the deactivation of the pendant nitroxide group. A high molecular-weight polyether with a theoretical radical concentration was first obtained in high yield. Charging and discharging cyclability was much improved by cross-linking, which helped the electrode-active material stay on a current collector during the electrolysis. The polymer/vapor-grown carbon nanofiber composite electrode exhibited a redox capacity comparable to the formula weight-based theoretical density over 10(3) cycles and fast charging/discharging capability up to a rate of 60C which corresponded to full charging and discharging in 60s. The redox capacity was almost maintained for a composite layer with a remarkably high polymer ratio of 90%, which demonstrated the presence of effective percolation network of the carbon nanofiber due likely to the affinity of the polyether to the carbon material.

    DOI

  • High-Density and Robust Charge Storage with Poly(anthraquinone-substituted norbornene) for Organic Electrode-Active Materials in Polymer-Air Secondary Batteries

    Takuma Kawai, Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULES   48 ( 8 ) 2429 - 2434  2015.04  [Refereed]

     View Summary

    An excellent functional group tolerance of ruthenium complex catalysts for olefin metathesis gave rise to ring-opening polymerization of norbornene functionalized with redox-active anthraquinone (AQ) pendants, yielding a high-molecular-weight and processable polynorbornene with large redox capacity. A thin layer of the polymer cast on current collectors showed reversible redox reaction at -0.85 V vs Ag/AgCl when immersed in basic aqueous electrolyte solutions. Good cycle performance was observed with a capacity comparable to the formula weight-based theoretical density of 212 mAh/g, which was the largest among those for the previously reported redox-active polynorbornenes. This suggested that all of the AQ units in the layer were redox-active, that electroneutralization was accomplished by successive compensation of counterions throughout the layer, and that the mechanical strength of the polymer layer prevented dissolution or exfoliation from the current collector surface. A robust polymer-air secondary battery with the high capacity was fabricated by using the polymer layer as the anode-active material. The battery showed a discharge voltage of 0.68 V and long life of over 300 cycles of charging/discharging, maintaining the moderate energy density of 143 mWh/g.

    DOI

  • Electrochemical Formation of a Polyviologen-ZnO Composite with an Efficient Charging Capability

    Hirofumi Maruo, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   44 ( 3 ) 393 - 395  2015.03  [Refereed]

     View Summary

    Concurrent and cathodic electrolysis of tris(cyanopyridinio)mesitylene and zinc chloride gave redox-active polyviologen, densely formed around the zinc oxide nanorod, on a substrate, which displayed a large charging discharging capacity and an excellent rate performance based on a large diffusivity of charge, and was useful as an anode-active material.

    DOI

  • Facile charge transport and storage by a TEMPO-populated redox mediating polymer integrated with polyaniline as electrical conducting path

    Kenichi Oyaizu, Hanae Tatsuhira, Hiroyuki Nishide

    POLYMER JOURNAL   47 ( 2 ) 212 - 219  2015.02  [Refereed]

     View Summary

    A copolymer of TEMPO-and aniline-substituted norbornene was prepared by ring-opening metathesis polymerization of the corresponding monomers. Electropolymerization of the pendant aniline groups in the copolymer gave a layer of polynorbornene populated with the redox-active TEMPO pendants, in which polyaniline chain was incorporated. Electroactivity of the TEMPO pendants throughout the layer and its excellent charging/discharging cyclability, in addition to the amorphous nature of the layer, suggested that the polyaniline chain was homogeneously dispersed in the layer and that each chain served as crosslinking moiety. The effect of the polyaniline chains was further enhanced when they were formed by in-situ electropolymerization of the aniline group in the preformed layer of the copolymer/polyaniline composite. The polyaniline chain served as a conducting path to reduce the charge-transfer resistance for redox mediation, which gave rise to an excellent rate performance for the charging/discharging process of the layer, compared with those for the composite layers of TEMPO-substituted polymers with polyaniline and other conductive additives prepared by the conventional grinding methods.

    DOI

  • Kinetic Control of Electron Transfer at Doped Zinc Oxide/Redox-active Molecule Interface for Photocurrent Rectification

    Michio Suzuka, Shu Hara, Takashi Sekiguchi, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   44 ( 1 ) 41 - 43  2015.01  [Refereed]

     View Summary

    Reactivity of redox-active molecules for heterogeneous electron-transfer processes at the surface of doped zinc oxide substrates depended on their energy levels. The redox-active molecules with negative redox potentials displayed a reversible electrochemical response but those with positive redox potentials were characterized by slow electrode kinetics, which was attributed to more than three times larger heterogeneous electron-transfer rate constant for the former redox-active molecules. A photovoltaic cell using methyl viologen as an acceptor molecule, TEMPOL as a donor molecule, and the doped ZnO as the transparent conducting substrate gave high photovoltage, which was ascribed to the reactivity of the redox-active molecules at the doped ZnO surface.

    DOI

  • Efficient charge transport of a radical polyether/SWCNT composite electrode for an organic radical battery with high charge-storage density

    Takashi Sukegawa, Kan Sato, Kenichi Oyaizu, Hiroyuki Nishide

    RSC ADVANCES   5 ( 20 ) 15448 - 15452  2015  [Refereed]

     View Summary

    A crosslinked poly(4-glycidyloxy TEMPO) was synthesized via anionic ring-opening copolymerization of 4-glycidyloxy TEMPO and a diglycidyl ether using a pentaerythritol/phosphazene base initiator. A fast and reversible charge storage capability was established for the polyether/SWCNT composite layer with a large layer thickness of several tens of micrometres, despite the low SWCNT content of 10% which was much closer to the percolation limit than the amount required for the previously reported TEMPO-substituted polymethacrylate.

    DOI

  • Oxygen-enriched electrolytes based on perfluorochemicals for high-capacity lithium-oxygen batteries

    Yuki Nishikami, Toshihiro Konishi, Ryo Omoda, Yuichi Aihara, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF MATERIALS CHEMISTRY A   3 ( 20 ) 10845 - 10850  2015  [Refereed]

     View Summary

    Electrolytes highly enriched with oxygen for lithium-oxygen (Li-O-2) batteries were prepared by combining perfluorohexyl bromide as an oxygen-uptake perfluorochemical (PFC) medium with lithium perfluorooctane sulfonate (LiPFOS) as a perfluoro-surfactant and a supporting electrolyte, which allowed an exceptionally high miscibility of PFCs with tetraethylene glycol dimethyl ether (TEGDME). The electrochemical reduction current of oxygen was enhanced three times in the LiPFOS-TEGDME electrolyte with ca. 60 wt% PFC content in comparison with that of a conventional Li-O-2 battery electrolyte, which was ascribed to the high oxygen solubility of the electrolyte. A Li-O-2 cell fabricated with the PFC-based electrolyte exhibited an excellent discharging capacity of 6500 mA h g(-1) which was approximately 1.5 times higher than that obtained with the conventional electrolyte.

    DOI

  • 導電性高分子, ポリアニリンをつくる

    小柳津研一

    高分子   64   445 - 447  2015

  • Expanding the Dimensionality of Polymers Populated with Organic Robust Radicals toward Flow Cell Application: Synthesis of TEMPO-Crowded Bottlebrush Polymers Using Anionic Polymerization and ROMP

    Takashi Sukegawa, Issei Masuko, Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULES   47 ( 24 ) 8611 - 8617  2014.12  [Refereed]

     View Summary

    Poly(norbornene)-g-poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl) (PNB-g-PTMA) was prepared by a grafting-through approach based on anionic polymerization of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl using a norbornene-substituted diphenylhexyllithium to yield a norbornene-functionalized macromonomer (NB-PTMA) and subsequent ring-opening metathesis polymerization of NB-PTMA using a Grubbs third-generation catalyst, which avoided critical side reactions involving the nitroxide radical of TEMPO moiety. The anionic polymerization resulted in high yields (&gt;94%), narrow polydispersity indices (&lt;1.20), and radical concentrations (0.95 radicals per monomer unit). The ROMP also resulted in high yields (&gt;98%) and high radical concentrations (0.95 radicals per monomer unit), by virtue of the functional group tolerance of these reactions. Single molecular dimension of PNB-g-PTMA was measured by dynamic light scattering and by atomic force microscopy (AFM), which precisely reflected the bottlebrush structure to reveal the presence of the TEMPO group crowded at the periphery of the molecule. The lengths of PNB-g-PTMA along the macromolecular side chains and the polynorbornene main chain were both approximately equal to the theoretical lengths estimated by the degree of polymerization for each chain. The number-average diameter of PNB-g-PTMA in THF increased with initial NB-PTMA ratio to the Grubbs catalyst. Photo-cross-linked thin layer electrodes of PNB-g-PTMA demonstrated the reversible redox reaction at 0.80 V vs Ag/AgCl corresponding to the TEMPO/TEMPO+ couple and quantitative charging/discharging processes even at 120 C rate (i.e., full charging in 30 s). As a novel application of redox-active polymers, PNB-g-PTMA exhibited 95% efficiency of the theoretical charge capacity in a flow cell system, based on the unique properties of bottlebrush polymers such as the defined molecular dimension and relatively low solution viscosity in comparison with corresponding linear polymers.

    DOI

  • Ionic Liquid-inspired Redox Shuttles: Properties of a Ferrocenylimidazolium Salt as an Efficient Mediator for Dye-sensitized Solar Cells

    Kenichi Oyaizu, Hiroki Ikeda, Noriko Hayo, Fumiaki Kato, Hiroyuki Nishide

    CHEMISTRY LETTERS   43 ( 7 ) 1134 - 1136  2014.07  [Refereed]

     View Summary

    A ferrocenylimidazolium salt was found to be an efficient iodine/iodide-free redox mediator for a dye-sensitized solar cell (DSSC), giving rise to a photoconversion efficiency of 4% under optimized electrolyte conditions. The excellent redox mediation process was ascribed not only to the electrochemically reversible nature of the molecule with a large heterogeneous electron-transfer rate constant in the order of 10(-2) cm s(-1) at electrodes, but also to an exceptionally high solubility up to 2.7 M to produce a large redox gradient in the mediation layer, thus allowing the increase of diffusion-limited current. The high solubility originating from the imidazolium group in the mediator molecule was reminiscent of ionic liquids, which are typically characterized by small absorption coefficients in a visible region. These properties provided a mass-transfer-based concept of molecular design for organic redox mediators in DSSCs.

    DOI

  • Redox-active Hydroxy-TEMPO Radical Immobilized in Nafion Layer for an Aqueous Electrolyte-based and Dye-sensitized Solar Cell

    Ryo Kato, Fumiaki Kato, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   43 ( 4 ) 480 - 482  2014.04  [Refereed]

     View Summary

    A hydrophilic nitroxide radical molecule, 4-hydroxy-2,2,6,6-tetramethylpiperidinoxyl (TEMPOL), was immobilized in a Nafion layer yielding a redox-active modified electrode which enhanced the reduction peak current: The modified electrode and the TEMPOL aqueous electrolyte were applied in a dye-sensitized solar cell to achieve a 2.1% conversion efficiency.

    DOI

  • Anionic Polymerization of 4-Methacryloyloxy-TEMPO Using an MMA-Capped Initiator

    Takashi Sukegawa, Hajime Omata, Issei Masuko, Kenichi Oyaizu, Hiroyuki Nishide

    ACS MACRO LETTERS   3 ( 3 ) 240 - 243  2014.03  [Refereed]

     View Summary

    Anionic polymerization of 4-methacryloyloxy-TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidin-1-oxyl) was successfully carried out using methyl methacrylate-capped 1,1-diphenylhexyllithium (DPHLi/MMA), of which nucleophilicity is moderate enough to suppress the side reaction between the nitroxide radical of TEMPO moiety and the carbanion of DPHLi, to yield the radical polymer with well-controlled molecular weight, narrow polydispersity index (PDI &lt; 1.10), high yield (&gt;95%), and almost 1.0 radicals per monomer unit.

    DOI

  • TEMPO/Viologen Electrochemical Heterojunction for Diffusion-Controlled Redox Mediation: A Highly Rectifying Bilayer-Sandwiched Device Based on Cross-Reaction at the Interface between Dissimilar Redox Polymers

    Hiroshi Tokue, Kenichi Oyaizu, Takashi Sukegawa, Hiroyuki Nishide

    ACS APPLIED MATERIALS & INTERFACES   6 ( 6 ) 4043 - 4049  2014.03  [Refereed]

     View Summary

    A couple of totally reversible redox-active molecules, which are different in redox potentials, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and viologen (V2+), were employed to give rise to a rectified redox conduction effect. Single-layer and bilayer devices were fabricated using polymers containing these sites as pendant groups per repeating unit. The devices were obtained by sandwiching the redox polymer layer(s) with indium tin oxide (ITO)/glass and Pt foil electrodes. Electrochemical measurements of the single-layer device composed of poly-norbornene-bearing TEMPO (PTNB) exhibited a diffusion-limited current-voltage response based on the TEMPO+/TEMPO exchange reaction, which was almost equivalent to a redox gradient through the PTNB layer depending upon the thickness. The bilayer device gave rise to the current rectification because of the thermodynamically favored cross-reaction between TEMPO+ and V+ at the polymer/polymer interface. A current-voltage response obtained for the bilayer device demonstrated a two-step diffusion-limited current behavior as a result of the concurrent V2+/V+ and V+/V-0 exchange reactions according to the voltage and suggested that the charge transport process through the device was most likely to be rate-determined by a redox gradient in the polymer layer. Current collection experiments revealed a charge transport balance throughout the device, as a result of the electrochemical stability and robustness of the polymers in both redox states.

    DOI

  • In-situ Polymerization of Thiophene Derivatives Using a Gas-phase Oxidant to Form a Hole-transporting Layer in Dye-sensitized Solar Cell

    Yoshito Sasada, Fumiaki Kato, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY   27 ( 3 ) 347 - 350  2014  [Refereed]

     View Summary

    Poly(3,4-ethylenedioxythiophene) (PEDOT), for use as a hole-transporting layer in dye-sensitized solar cells (DSSCs), was synthesized via in-situ polymerization using a gas-phase oxidant. Highly volatile iodine was used as the gas-phase oxidant to fill up a porous TiO2 substrate. The conductivity of PEDOT increased to 0.9 S/cm upon the addition of a base, 4-tert-butylpyridine, to the monomer solution. A solid-state DSSC was fabricated using PEDOT as the hole-transporting layer, which displayed photo-electric conversion.

    DOI

  • 高密度レドックス分子を用いた有機電池

    小柳津研一

    応用物理学会有機分子・バイオエレクトロニクス分科会誌   25   281 - 287  2014

  • Polyviologen Hydrogel with High-Rate Capability for Anodes toward an Aqueous Electrolyte-Type and Organic-Based Rechargeable Device

    Naoki Sano, Wataru Tomita, Shu Hara, Cheong-Min Min, Jae-Suk Lee, Kenichi Oyaizu, Hiroyuki Nishide

    ACS APPLIED MATERIALS & INTERFACES   5 ( 4 ) 1355 - 1361  2013.02  [Refereed]

     View Summary

    A highly cross-linked polyviologen hydrogel, poly(tripyridiniomesitylene) (PTPM), has been designed as an anode-active material. It displays a reversible two-electron redox capability at -0.4 and -0.8 V vs Ag/AgCl in an aqueous electrolyte. The PTPM layer coated on a current collector by electropolymerization via a 4-cyanopyridinium electro-coupling reaction demonstrates a rapid charging-discharging reaction with a redox capacity comparable to that obtainable using the formula weight-based theoretical density, because of the combination of the redox-active viologen moieties built into the hydrogel. A test cell that has been fabricated using the developed PTPM anode, a poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) (PTAm)-based cathode, and an aqueous electrolyte exhibits a discharging voltage of 1.1 and 1.5 V, and has proven its ability to be recharged more than 2000 times.

    DOI

  • Synthesis of Pendant Nitronyl Nitroxide Radical-Containing Poly(norbornene)s as Ambipolar Electrode-Active Materials

    Takashi Sukegawa, Ayumi Kai, Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULES   46 ( 4 ) 1361 - 1367  2013.02  [Refereed]

     View Summary

    Ambipolar redox-active polymers with a reversible charging and discharging capability were synthesized via ring-opening metathesis polymerization (ROMP) of nitronyl nitroxide radical (NN) mono- and disubstituted norbornenes which exhibited p- and n-type redox processes (i.e., one-electron oxidation and reduction per NN group, respectively), using Grubbs catalyst to N avoid side reactions of the radical moiety allowing over 95% of radicals to survive after ROMP. ROMP of the NN monomers was accomplished with well-controlled molecular weights of the resulting NN polymers which were coincident with theoretical values in the ratio of [monomer]/[catalyst] = 25-200, narrow polydispersity index (ca. 1.2), and high yields even with [monomer]/[catalyst] &gt; 600. The living character for the ROMP of the NN monomers also allowed block copolymerization. NN-containing block copolymers were synthesized through sequential ROMP with benzyl ether-containing norbornene in high yields. The NN polymer/carbon composite electrode exhibited both p- and n-type charging/discharging with plateau potentials near the redox potentials of the polymer at 0.78 and -0.80 V vs Ag/AgCl, respectively. The spin-coated layer electrode of the NN polymer immobilized on a current collector also demonstrated a fast charging/discharging performance in the range of 10-100 C rates and a cycle stability especially for the p-type reaction. These results made the NN polymer accessible as ambipolar electrode-active materials and also encouraged other organic radicals to be candidates for electroactive polymers.

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  • Self-doping inspired zwitterionic pendant design of radical polymers toward a rocking-chair-type organic cathode-active material

    Il Seok Chae, Masafumi Koyano, Kenichi Oyaizu, Hiroyuki Nishide

    Journal of Materials Chemistry A   1 ( 4 ) 1326 - 1333  2013.01  [Refereed]

     View Summary

    'Self-doping' inspired high-density redox copolymers were designed and prepared via free radical copolymerization of 2,2,6,6-tetramethyl-4-piperidyl methacrylate and vinylsulfonic acid (VSA) with a view to preventing a change in salt concentration during the one-electron oxidation of the nitroxide radicals to N-oxoammonium cations in a polymer layer. A copolymer composition of TEMPO-sulfonate anionic group = 1/1 for density-maximized charge neutralization was achieved by controlling the feed ratio of the copolymerization. The formation of copolymers was evidenced by 2D nuclear Overhauser enhanced spectroscopy (NOESY) and diffusion ordered spectroscopy (DOSY) NMR. Poly(TEMPO methacrylate-stat-VSA) was considered to have the alternating tendency due to the acid-base interaction in the comonomers, which were supported not only by the single crystal structure of the 2,2,6,6-tetramethyl-4-piperidyl methacrylate and VSA complex, but also by the 1H-1H correlation in NOE signals. In an aqueous electrolyte with 0.5 M NaCl, the copolymer electrode showed a redox response near 0.66 V (vs. Ag/AgCl), and the excellent cycle performance during 1000 cycles. During the one-electron oxidation of the nitroxide radical, anionic sulfonate groups led to charge compensation of the N-oxoammonium cation. Consequently, the copolymer electrode exhibited the cation migration, which was evidenced by mass-transfer analysis using an electrochemical quartz crystal microbalance (EQCM) technique. The copolymer could be applied as an aqueous electrolyte-type organic rechargeable device. Moreover, this design proposes the ultimate principle toward the strategy of maximizing energy density in organic charge storage devices. © The Royal Society of Chemistry 2013.

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  • BODIPY-Sensitized Photocharging of Anthraquinone-Populated Polymer Layers for Organic Photorechargeable Air Battery

    Kenichi Oyaizu, Yukina Niibori, Akinari Takahashi, Hiroyuki Nishide

    Journal of Inorganic and Organometallic Polymers and Materials   23 ( 1 ) 243 - 250  2013  [Refereed]

     View Summary

    Photocharging of anthraquinone (AQ)-populated polymers was accomplished by incorporating chromophores with redox potentials suitable for the 2e- reduction of the AQ pendants near -1 V versus Ag/AgCl in aqueous basic electrolytes. The photoactive polymers were designed to exhibit redox-isolated behaviors and reversible charge-discharge responses, either by employing a polyacetylene main chain with the π-π* absorption bands in a visible region, or with an aliphatic chain incorporating a BODIPY dye in the form of a multilayer. The charge storage density was maximized by minimizing the molecular weight of the compact repeating units, thus reducing the redox site-to-site distance to allow redox gradient-driven electron self-exchange reactions to proceed throughout the slab of the polymer layer. Homogeneous layers of poly(2-ethynylanthraquinone) and poly(2-vinylanthraquinone) were both sufficiently robust for charge storage application, swellable, and yet insoluble in aqueous basic electrolyte solutions. Such properties allowed the accommodation of external cations from the electrolyte to permeate through the layer for electroneutralization of the negative charge produced by the electroreduction, which led to the repeatable charging and discharging cycles of the photoanodes without degradation of the charge storage capabilities. By virtue of the swelling properties of the polymer layers in the basic aqueous electrolyte, exploration of the aqueous electrochemistry and photochemistry of AQ that had been inaccessible by the lack of the solubility in H2O became feasible. A striking feature of the photoanodes was the capability of employing a hydroxide ion (OH-) as the sacrificial reducing agent, which enabled the use of the O2/OH- redox couple for the cathode reaction during discharging. Combination of the photoanodes with the MnO2/carbon composite cathode, sandwiching the electrolyte layer of aqueous KOH, gave rise to photorechargeable battery effect under irradiation and repeatable discharging with the consumption of O2 at the cathode. © 2012 Springer Science+Business Media, LLC.

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  • Robust and efficient charge storage by uniform grafting of TEMPO radical polymer around multi-walled carbon nanotubes

    Wonsung Choi, Shogo Endo, Kenichi Oyaizu, Hiroyuki Nishide, Kurt E. Geckeler

    JOURNAL OF MATERIALS CHEMISTRY A   1 ( 9 ) 2999 - 3003  2013  [Refereed]

     View Summary

    The radical polymer of redox-active nitroxide was first terminally modified and then grafted onto multi-walled carbon nanotubes (MWNTs) by a facile terminating reaction. The radical polymer-grafted MWNTs allowed a high dispersibility in organic solvents and fadeless redox ability of nitroxide. The TEM images revealed that the radical polymer was successfully wrapped around a MWNT with nanometre thickness showing a core-shell nanotube structure homogeneously over the whole MWNTs. The radical polymer wrapping around the MWNT exhibited quantitative and high-rate redox properties of nitroxide suitable for a cathode-active material, which was prominent when compared with a radical polymer-grafted MWNT via a "grafting from" method. These results demonstrate that nano-scale homogeneous wrapping prevented the aggregation of the radical polymer and allowed the rapid counterion accommodation leading to quantitative and rapid charge propagation.

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  • Redox equilibrium of a zwitterionic radical polymer in a non-aqueous electrolyte as a novel Li+ host material in a Li-ion battery

    Il Seok Chae, Masafumi Koyano, Takashi Sukegawa, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF MATERIALS CHEMISTRY A   1 ( 34 ) 9608 - 9611  2013  [Refereed]

     View Summary

    Poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate-co-styrenesulfonate) was prepared and utilized as a Li+ host material for a cathode in a Li-ion battery. The polymer allowed high density incorporation of the Li+ ion per repeating unit at a positive redox potential near 0.6 V vs. Ag/AgCl. Redox equilibrium involving the Li+ migration was proved by the theoretical approach based on the Nernst equation as well as a microgravimetry analysis using an electrochemical quartz crystal microbalance technique. A cell fabricated with the polymer as the cathode-active material showed a high power rate capability with an average discharging potential near 3.9 V vs. the lithium metal anode.

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  • Enhanced bimolecular exchange reaction through programmed coordination of a five-coordinate oxovanadium complex for efficient redox mediation in dye-sensitized solar cells

    Kenichi Oyaizu, Noriko Hayo, Yoshito Sasada, Fumiaki Kato, Hiroyuki Nishide

    DALTON TRANSACTIONS   42 ( 45 ) 16090 - 16095  2013  [Refereed]

     View Summary

    Electrochemical reversibility and fast bimolecular exchange reaction found for VO(salen) gave rise to a highly efficient redox mediation to enhance the photocurrent of a dye-sensitized solar cell, leading to an excellent photovoltaic performance with a conversion efficiency of 5.4%. A heterogeneous electron-transfer rate constant at an electrode (k(0)) and a second-order rate constant for an electron self-exchange reaction (k(ex)) were proposed as key parameters that dominate the charge transport property, which afforded a novel design concept for the mediators based on their kinetic aspects.

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  • 空気電池: 有機負極を目指したポリマー膜の設計

    小柳津研一, 西出宏之

    膜   38   131 - 136  2013

  • Indoline dye-coupled polyviologen: Its electrochemical property and electropolymerization

    Naoki Sano, Miu Suzuki, Wataru Tomita, Kenichi Oyaizu, Hiroyuki Nishide

    Japanese Journal of Applied Physics   51 ( 10 ) 10NE17  2012.10  [Refereed]

     View Summary

    An indoline dye-coupled polyviologen was designed as a possible photoanode material for organic photovoltaic cells. A new donor-acceptor (D- A) coupled molecule (CVD131) was immobilized on a current collector by the reductive electropolymerization of its two cyanopyridinium moieties. The formed polyviologen could efficiently accept an excited electron from the indoline dye moiety. © 2012 The Japan Society of Applied Physics.

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  • Indoline Dye-Coupled Polyviologen: Its Electrochemical Property and Electropolymerization

    Naoki Sano, Miu Suzuki, Wataru Tomita, Kenichi Oyaizu, Hiroyuki Nishide

    JAPANESE JOURNAL OF APPLIED PHYSICS   51 ( 10 ) 10NE17  2012.10  [Refereed]

     View Summary

    An indoline dye-coupled polyviologen was designed as a possible photoanode material for organic photovoltaic cells. A new donor-acceptor (D-A) coupled molecule (CVD131) was immobilized on a current collector by the reductive electropolymerization of its two cyanopyridinium moieties. The formed polyviologen could efficiently accept an excited electron from the indoline dye moiety. (C) 2012 The Japan Society of Applied Physics

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  • Macromolecular Complexes Leading to High-Performance Energy Devices

    Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULAR SYMPOSIA   317 ( 1 ) 248 - 258  2012.08  [Refereed]

     View Summary

    Dynamic interactions and electronic processes in macromolecule-metal complexes established in 1970s provided conceptual basis for the development of a new class of functional polymers. Principles of soft/multiple interaction and multielectron processes have been pursued by exploring the macromolecule-metal complexes and polyion complexes, which gave rise to more generalized concept of macromolecular complexes. As one of the multiple interaction, reversible binding of O-2 in aqueous media and facilitated transport of O-2 were first accomplished by macromolecular metal complexes. The related oxygen technologies have led to the development of unprecedented materials to allow oxygen enrichment in cathodes of fuel cells and air batteries. Properties of electric/ionic conduction and electron transfer mediation in macromolecular complexes suggested our avenue toward the "radical batteries'' as entirely organic, rare metal-free, and rechargeable burst power sources. Combination of the photoelectrochemistry of macromolecular complexes and the methods for the precision control of charge separation, transport, and storage in polymers derived from the battery research have inspired design principles of novel photovoltaic polymers useful for organic solar cells. In this paper, recent developments of energy-related materials originated from the idea of the macromolecular complexes are focused.

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  • TEMPO-substituted polyacrylamide for an aqueous electrolyte-typed and organic-based rechargeable device

    Natsuru Chikushi, Hiroshi Yamada, Kenichi Oyaizu, Hiroyuki Nishide

    SCIENCE CHINA-CHEMISTRY   55 ( 5 ) 822 - 829  2012.05  [Refereed]

     View Summary

    A hydrophilic radical polymer, poly(2,2,6,6-teteramethylpiperidinyloxyl-4-yl acrylamide) (PTAm), was synthesized via oxidation of the corresponding precursor polymer, poly(2,2,6,6-teteramethylpiperidine-4-yl acrylamide). Electrochemical properties of the PTAm layer were characterized in three aqueous electrolytes of sodium chloride (NaCl), sodium tetrafluoroborate (NaBF4), and sodium hexafluorophosphate (NaPF6) to optimize its activity as an organic cathode. The counter anion species significantly affected the capacity and the cycle performance of the PTAm layer. The PTAm layer in the presence of BF4 (-1) displayed quantitative redox capacity beyond 1 mu m layer thickness and maintained the discharging capacity of 110 mAh g(-1) (97% vs. the calculated capacity) even after 1000 cycle charging/discharging, which could be ascribed to its appropriate affinity to the aqueous electrolyte without any dissolution into the electrolyte. A totally organic-based rechargeable cell was fabricated using PTAm and poly(N-4,4'-bipyridinium-N-decamethylene dibromide) as the cathode and the anode, respectively, and the aqueous electrolyte of NaBF4. The cell gave a plateau voltage at 1.2 V both on charging and discharging and an excellent charging/discharging cyclability of &gt; 2000 with high coulombic efficiency of &gt; 95%.

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  • Nitroxide Radicals as Highly Reactive Redox Mediators in Dye-Sensitized Solar Cells

    Fumiaki Kato, Akitomo Kikuchi, Takumi Okuyama, Kenichi Oyaizu, Hiroyuki Nishide

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   51 ( 40 ) 10177 - 10180  2012  [Refereed]

    DOI

  • Electrolyte anion-assisted charge transportation in poly(oxoammonium cation/nitroxyl radical) redox gels

    Kentaro Nakahara, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF MATERIALS CHEMISTRY   22 ( 27 ) 13669 - 13673  2012  [Refereed]

     View Summary

    Charge transport in poly(oxoammonium cation/nitroxyl radical) redox gels was investigated by chronoamperometry on the basis of an infinite-diffusion model without a volume change during the redox reaction and a limit of the diffusion distance by means of fabricating the bulk solid gels. Charge transportation in the redox gels was found to be dominated by the mobility of electrolyte anion rather than the concentration of redox centers. Furthermore, the ionic conductivity of the redox gel was estimated to be almost one third of that of the liquid electrolyte. The result indicates that larger ionic conductivity in the gel also brings faster charge transportation through the redox centers.

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  • Nitroxide Radical Molecules as Highly Reactive Redox Mediators in Dye-sensitized Solar Cells

    F. Kato, A. Kikuchi, T. Okuyama, K. Oyaizu, H. Nishide

    Angew. Chem. Int. Ed.   124   10324 - 10327  2012  [Refereed]

    DOI

  • Aqueous Electrochemistry of Poly(vinylanthraquinone) for Anode-Active Materials in High-Density and Rechargeable Polymer/Air Batteries

    Wonsung Choi, Daisuke Harada, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   133 ( 49 ) 19839 - 19843  2011.12  [Refereed]

     View Summary

    A layer of poly(2-vinylanthraquinone) on current collectors underwent reversible electrode reaction at 0.82 V vs Ag/AgCl in an aqueous electrolyte. A repeatable charging/discharging cycles with a redox capacity comparable to the formula weight-based theoretical density at the negative potential suggested that all of the anthraquinone pendants in the layer was redox-active, that electroneutralization by an electrolyte cation was accomplished throughout the polymer layer, and that the layer stayed on the current collector without exfoliation or dissolution into the electrolyte during the electrolysis. The charging/discharging behavior of the polymer layer in the aqueous electrolyte revealed the capability of undergoing electrochemistry even in the nonsolvent of the pendant group, which offered insight into the nature of the anthraquinone pendants populated on the aliphatic chain. Charging/discharging capability of air batteries was accomplished by using the polymer layer as an organic anode-active material. A test cell fabricated using the conventional MnO(2)/C cathode catalyst exhibited a discharging voltage at 0.63 V corresponding to their potential gap and a charging/discharging cycle of more than 500 cycles without loss of the capacity.

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  • Radical Polymer-Wrapped SWNTs at a Molecular Level: High-Rate Redox Mediation Through a Percolation Network for a Transparent Charge-Storage Material

    Wonsung Choi, Shota Ohtani, Kenichi Oyaizu, Hiroyuki Nishide, Kurt E. Geckeler

    ADVANCED MATERIALS   23 ( 38 ) 4440 - +  2011.10  [Refereed]

     View Summary

    A transparent nanocomposite of a radical polymer, the poly(2,2,6,6-tetramethylpiperidine-1-oxy-4-yl methacrylate) (PTMA), and single-walled carbon nanotubes (SWNTs) display a reversible charging and discharging, allowing full discharge in seconds. This is ascribed to the reversible electrochemical reaction of the pendant radical group in PTMA aided by both PTMA wrapping at a molecular level and the SWNT network for electrical conduction.

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  • Designing current collector/composite electrode interfacial structure of organic radical battery

    Sunao Yoshihara, Haruhiko Katsuta, Hiroshi Isozumi, Masanori Kasai, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF POWER SOURCES   196 ( 18 ) 7806 - 7811  2011.09  [Refereed]

     View Summary

    Charge/discharge processes of organic radical batteries based on the radical polymer&apos;s redox reaction should be largely influenced by the structure and the composition of the composite electrodes. AC impedance measurement of the composite electrodes reveals a strong correlation between the overall electron transfer resistance of the composite electrode and the material of the current collector, and suggests that the electric conduction to the current collector through the contact resistance should be crucial. We also find that the adhesion and the contact area between the composite electrode and the current collector strongly influence the contact resistance rather than the work functions and the volume resistivities of the composite electrode and the current collector. It is also confirmed that the charge/discharge performance of the composite electrode is related to the overall electron transfer resistance of the composite electrode. These results indicate that the charge/discharge performance of the radical battery is dominated by the interfacial electron transfer processes at the current collector/carbon fiber interface. In fact, the composite electrode which has a high adhesion to the current collector shows a small overall electron transfer resistance and an excellent charge/discharge performance. The rate performance would be much improved by suitably designing the interfacial structure including adhesion and contact area. (C) 2010 Elsevier B.V. All rights reserved.

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  • Functionalization of poly(4-chloromethylstyrene) with anthraquinone pendants for organic anode-active materials

    Kenichi Oyaizu, Wonsung Choi, Hiroyuki Nishide

    POLYMERS FOR ADVANCED TECHNOLOGIES   22 ( 8 ) 1242 - 1247  2011.08  [Refereed]

     View Summary

    Condensation of anthraquinone-2-carboxylic acid with poly(4-chloromethylstyrene) afforded a high-density redox polymer containing the anthraquinone pendants with reversible charge storage capability at negative potentials near -1V versus Ag/AgCl. Electrochemically reversible redox response of the polymer, which was ascribed to the reduction of the pendant group to the anion radical and the dianion, suggested that the polymer was sufficiently robust in these redox states for charge storage application. Immobilizing the anthraquinone groups on current collectors was accomplished by the use of the polymer which was swellable and yet insoluble in both aqueous and nonaqueous electrolyte solutions. Such properties allowed the accommodation of external cations from the electrolyte solution to permeate through the polymer layer for electroneutralization of the negative charge produced at the reduced state, which led to the repeatable charging and discharging cycles without degradation of the charge storage capacity. Exploration of the aqueous electrochemistry of anthraquinone, which had been inaccessible by the lack of the solubility of the conjugated and fused-ring molecule in H2O, became feasible by virtue of the swelling property of the polymer layer in the aqueous electrolyte. While negative charge was relatively difficult to be stored with redox polymers compared to the positive charge due to the enhanced reactivity in their reduced states and small varieties of the appropriate redox sites, the present polymer was characterized as the excellent organic electrode-active materials that operated at sufficiently negative potentials which was essential for the fabrication of entirely organic batteries. Copyright (C) 2011 John Wiley & Sons, Ltd.

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  • Organic Radical Battery Approaching Practical Use

    Kentaro Nakahara, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   40 ( 3 ) 222 - 227  2011.03  [Refereed]

     View Summary

    The electrochemical redox reactions of organic polymers bearing robust unpaired electrons were investigated to determine the applicability of these polymers to rechargeable batteries. Such an "organic radical battery" would be environmentally friendly and have high-power characteristics. This highlight review describes the performance of a battery using a nitroxyl radical polymer as the cathode active material. The electron-transfer mechanism and recent developments that should lead to the practical application of the organic radical battery are also described.

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  • Dual Dopable Poly(phenylacetylene) with Nitronyl Nitroxide Pendants for Reversible Ambipolar Charging and Discharging

    Kenichi Oyaizu, Takashi Sukegawa, Hiroyuki Nishide

    CHEMISTRY LETTERS   40 ( 2 ) 184 - 185  2011.02  [Refereed]

     View Summary

    An electrode-attached layer of poly(phenylacetylene) bearing a pendant nitronyl nitroxide group per repeating unit, obtained by the Rh-catalyzed polymerization of 2-(4-ethynylphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, underwent oxidation and reduction at 0.80 and 0.84 V vs. Ag/AgCl, respectively. The magnetically determined unpaired electron density of 92% was coulometrically reproduced, which supported the presumption that the radical survived during the course of the polymerization to allow both positive and negative charging of the pristine neutral polymer substantially per repeating unit. Galvanostatic Coulomb titration revealed the charge storage capability of the polymer, which demonstrated usefulness as organic electrode-active material with unprecedented ambipolar chargeability.

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  • p- and n-Type Bipolar Redox-Active Radical Polymer: Toward Totally Organic Polymer-Based Rechargeable Devices with Variable Configuration

    Takeo Suga, Shuhei Sugita, Hiroki Ohshiro, Kenichi Oyaizu, Hiroyuki Nishide

    ADVANCED MATERIALS   23 ( 6 ) 751 - +  2011.02  [Refereed]

     View Summary

    The p- and n-type bipolar redox-active radical polymer with a nitronylnitroxyl group, poly(nitronylnitroxylstyrene), expands its utilization as a cathode-or anode-active material in organic polymer-based rechargeable devices with two unprecedented configurations: a poleless battery and a "rocking-chair type" battery. These batteries exhibit a remarkably high power rate capability (chargeable within 20 s) and high cycle performance.
    [GRAPHICS]
    .

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  • POLYMERIZATION OF LACTIC O-CARBOXYLIC ANHYDRIDE USING ORGANOMETALLIC CATALYSTS

    Xiu-li Zhuang, Hai-yang Yu, Zhao-hui Tang, Kenichi Oyaizu, Hiroyuki Nishide, Xue-si Chen

    CHINESE JOURNAL OF POLYMER SCIENCE   29 ( 2 ) 197 - 202  2011.01  [Refereed]

     View Summary

    The ring-opening polymerization of 5-methyl-1,3-dioxolane-2,4-dione (lactic O-carboxylic anhydride, LacOCA) using organometallic complexes, including Co(III) complexes with Schiff base ligands, Tin(II) alphatates and Al(III) complexes with Schiff base ligands, was explored. The polymerization was carried out by treatment of the organometallic complexes with LacOCA in toluene under mild conditions. The corresponding poly(lactic acid) was characterized by spectroscopy and thermal analyses, which revealed insight into the structure of the effective catalyst for the polymerization of LacOCA.

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  • Synthesis of Amphiphilic Block Copolymers Bearing Stable Nitroxyl Radicals

    Xiuli Zhuang, Chunsheng Xiao, Kenichi Oyaizu, Natsuru Chikushi, Xuesi Chen, Hiroyuki Nishide

    JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY   48 ( 23 ) 5404 - 5410  2010.12  [Refereed]

     View Summary

    We present here the synthesis of two kinds of amphiphilic block copolymers, a diblock copolymer MPEG-b-PTAm and a triblock copolymer MPEG-b-PLA-b-PTAm, which can self-assemble into micelles with nitroxyl radicals-containing PTAm segment in the core. The structure of the block copolymers was characterized by H-1 NMR and GPC. Dynamic laser light scattering and transmission electron microscopy were used to study the micellar behavior of the two block copolymers in aqueous solution. The micelles carrying nitroxyl radicals in the core can generate electron paramagnetic resonance, which is stable for a period of time up to 8 min even in the presence of reducing reagent such as ascorbic acid. The enhanced stability against the reducing agent was ascribed to the inaccessibility of the nitroxyl radical core placed in the interior of the micelles. Combined with the biocompatibility, these micelles were promising to be used as the EPR probes for bioimaging in vivo. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5404-5410, 2010

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  • Synthesis and Charge Transport Properties of Redox-Active Nitroxide Polyethers with Large Site Density

    Kenichi Oyaizu, Takeshi Kawamoto, Takeo Suga, Hiroyuki Nishide

    MACROMOLECULES   43 ( 24 ) 10382 - 10389  2010.12  [Refereed]

     View Summary

    To maximize the theoretical redox capacity of polymers containing cyclic nitroxides as redox active pendant groups for high density charge storage application, a compact five membered ring with the smallest equivalent weight among the robust cyclic nitroxides was directly bound to a poly(ethylene oxide) chain 2,2,5,5 Tetramethyl 3 oxiranyl-3-pyrrolin 1 oxyl was synthesized and polymerized via anionic coordinated ring-opening polymerization utilizing diethyl zinc/H2O as an initiator The unpaired electron in the monomer survived during the polymerization giving rise to a high density redox polymer with a weight-specific theoretical capacity of 147 mA h/g Cyclic voltammetry of the polymer layer confined at the surface of an electrode revealed a large redox capacity comparable to the theoretical capacity which was ascribed to the efficient swelling and yet insoluble properties of the polyether in electrolyte solutions by virtue of the high molecular weight of &gt;10(5) and adhesive properties allowing immobilization of the layer on the electrode surface The redox capacity also indicated that the ionophoric polyether matrix accommodated electrolyte anions through the polymer/electrolyte interface to neutralize positive charges produced by the oxidation of the neutral radicals at the polymer/electrode interface The diffusion coefficient for the redox gradient driven charge hopping process corresponded to a large second order rate constant in the order of 10(7) M-1 s(-1), which suggested an efficient electron self-exchange reaction throughout the polymer layer due to the large redox site population and hence to the small intersite distance Test cells fabricated with a polymer/carbon fiber composite layer on an aluminum current collector as the cathode and a Li anode sandwiching an electrolyte layer were capable of charging and discharging as a secondary battery with an output voltage near 3 7 V and were durable for more than 10(3) charging discharging cycles without substantial degradation

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  • Biodegradable and Electroactive TEMPO-Substituted Acrylamide/Lactide Copolymers

    Xiuli Zhuang, Han Zhang, Natsuru Chikushi, Changwen Zhao, Kenichi Oyaizu, Xuesi Chen, Hiroyuki Nishide

    MACROMOLECULAR BIOSCIENCE   10 ( 10 ) 1203 - 1209  2010.10  [Refereed]

     View Summary

    Copolymers composed of PLA and PTAm were prepared by a macromonomer approach. The PLA bearing vinyl group at chain end was copolymerized with 2,2,6,6-tetrametylpiperidine-4-ylacrylamide. The resulted copolymers were oxidized by a peroxide to give PTAm-g-PLA. The structures of the copolymers were confirmed by NMR and FTIR spectroscopy. The comparison of (1)H NMR results and SQUID measurements demonstrated that the oxidation of the PTAm fragment proceeded almost to completion. An MTT assay, cell adhesion and spreading evaluation showed that the copolymers exhibited improved cytocompatibility as compared to the PTAm homopolymer due to the introduction of the biocompatible PLA moiety.

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  • Improving Charge/Discharge Properties of Radical Polymer Electrodes Influenced Strongly by Current Collector/Carbon Fiber Interface

    Sunao Yoshihara, Hiroshi Isozumi, Masanori Kasai, Hisatomo Yonehara, Yuko Ando, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF PHYSICAL CHEMISTRY B   114 ( 25 ) 8335 - 8340  2010.07  [Refereed]

     View Summary

    Charge/discharge processes of organic radical batteries based on the radical polymer's redox reaction are largely influenced by carbon fibers consisting in the composite electrodes to help electron transfer. To find the optimal structure of the composite electrodes, the dominant electron transfer processes were determined by ac impedance measurement of the composite electrodes. A strong correlation between the overall electron transfer resistance of the composite electrodes and the materials of the current collector suggests that the electric conduction to the current collector through the contact resistance should be crucial. It was also confirmed that the charge/discharge performance of the composite electrode was related to the overall electron transfer resistance of the composite electrode. These results indicated that the charge/discharge performance of the radical battery was dominated by the interfacial electron transfer processes at the current collector/carbon fiber interface and that the rate performance would be much improved by suitably designing the interfacial structure.

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  • Nitroxide Radicals for Highly Efficient Redox Mediation in Dye-sensitized Solar Cells

    Fumiaki Kato, Naoki Hayashi, Takaya Murakami, Chie Okumura, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   39 ( 5 ) 464 - 465  2010.05  [Refereed]

     View Summary

    A robust nitroxide radical, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its 4-subsituted derivatives (R-TEMPO) exhibit electrochemically reversible redox properties with tunable half-wave potentials (E-1/2) based on the substituent effect. Dye-sensitized solar cells using R-TEMPO as mediators with electron-withdrawing R groups showed significantly enhanced photovoltages compared with those obtained using iodides. The linearity between the open-circuit voltage (V-oc) and E-1/2 revealed that V-oc dominated by the energy gap between the Fermi level of TiO2 and the SOMO level of R-TEMPO.

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  • Electronic Communication in the Formation of a Quartet Molecule 2,6,10-Tris[bis(p-methoxyphenyl)aminium]triphenylene

    Takeshi Ibe, Shu Kaiho, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   39 ( 4 ) 356 - 357  2010.04  [Refereed]

     View Summary

    A quartet triradical molecule, 2,6,10-tris[bis(p-methoxyphenyl)aminium]triphenylene, was characterized by the electronic interaction among the three aminium sites based on the fused-aromatic, triphenylene-linked, and non-Kekule connectivity, which lead to the stable high-spin triradical formation.

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  • Synthesis and Electrochemistry of Schiff Base Cobalt(III) Complexes and Their Catalytic Activity for Copolymerization of Epoxide and Carbon Dioxide

    Xiuli Zhuang, Kenichi Oyaizu, Yongsheng Niu, Kenichiroh Koshika, Xuesi Chen, Hiroyuki Nishide

    MACROMOLECULAR CHEMISTRY AND PHYSICS   211 ( 6 ) 669 - 676  2010.03  [Refereed]

     View Summary

    A series of cobalt complexes with N,N,O,O-tetradentate Schiff base ligands were prepared. All the complexes were characterized by spectroscopy and electrochemical methods. An X-ray crystal structure analysis revealed that L-1-Co-III-dnp was monomeric with a six-coordinated central cobalt(III) atom in the solid state. The complexes were employed as catalysts for the alternating copolymerization of CO2 and racemic propylene oxide. End group analysis of the resulting polymer provided strong evidence for a monomer insertion mechanism for the propagation step. The catalytic activity was interpreted using the redox potential of cobalt(II/III) for the L-Co-III-dnp complexes, which offered a measure of the bond strength, or the degree of inertness of the axial ligand, to promote or suppress the monomer insertion.

    DOI

  • Mesoscale Radical Polymers: Bottom-Up Fabrication of Electrodes in Organic Polymer Batteries

    Kenichi Oyaizu, Hiroyuki Nishide

    Advanced Nanomaterials   1   319 - 332  2010.01  [Refereed]

    DOI

  • Radical Polymers with Ultimate Population of Unpaired Electrons

    K. Oyaizu

    高分子   59   390 - 390  2010

  • Redox-active polyimide/carbon nanocomposite electrodes for reversible charge storage at negative potentials: expanding the functional horizon of polyimides

    Kenichi Oyaizu, Akihiko Hatemata, Wonsung Choi, Hiroyuki Nishide

    JOURNAL OF MATERIALS CHEMISTRY   20 ( 26 ) 5404 - 5410  2010  [Refereed]

     View Summary

    The reversible n-type charge-storage capability of polyimides was significantly enhanced in a polyimide/carbon nanocomposite prepared by cyclodehydration of the corresponding polyamic acid which was solution-processed into a composite layer on an electrode surface with a vapor-grown carbon nanofiber. The stepwise preparation process gave the first polyimide-based electrode-active material with a sufficient dispersion of the polyimide particles at the carbon nanofiber surface, while a simple grinding of the polyimide and the carbon nanofiber gave mixtures without charge retention capability due to gradual dissolution in the reduced state. The polyimide/carbon nanocomposites were characterized by negative redox potentials at -1.36 and -0.76 V vs. Ag/AgCl for poly(4,4'-oxydiphthalimido-1,4-phenylene) (1) and poly(pyromellitimido-1,4-phenylene) (2), respectively, which corresponded to a charging per repeating unit of the neutral polymers to radical polyanions. The 2/carbon nanocomposite underwent further reduction at -1.34 V to produce a dianion per repeating unit, giving rise to a high-density charging with a redox capacity of 185 mAh g(-1) based on the formula weight of 2. The typical redox capacity of the electrolyzed nanocomposites amounted to ca. 60% of the formula weight-based capacity, which was still larger than those of typical redox polymers with negative potentials, such as viologen-based polyelectrolytes. Additional advantages originated from the robustness of the polyimide framework, which allowed excellent charging/discharging cyclability. The polyimide/carbon nanocomposite electrodes would be highly promising as anode-active materials in organic rechargeable devices, owing to these excellent redox properties.

    DOI

  • A TEMPO-substituted polyacrylamide as a new cathode material: an organic rechargeable device composed of polymer electrodes and aqueous electrolyte

    Kenichiroh Koshika, Natsuru Chikushi, Naoki Sano, Kenichi Oyaizu, Hiroyuki Nishide

    GREEN CHEMISTRY   12 ( 9 ) 1573 - 1575  2010  [Refereed]

     View Summary

    Poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) was designed and synthesized as an electrode-active polymer for an organic rechargeable device containing an aqueous electrolyte. The device demonstrated a 1.2 V output voltage, exceeded 2000 charging-discharging cycles, and had a high charging rate performance within 1 min.

    DOI

  • Porphyrin-Dye Sensitized Solar Cell Utilizing Nitroxide Radical Mediator

    Takaya Murakami, Fumiaki Kato, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY   23 ( 3 ) 353 - 355  2010  [Refereed]

  • Nanolithographic patterning via electrochemical oxidation of stable poly(nitroxide radical)s to poly(oxoammonium salt)s

    Tsuyoshi Hyakutake, Jin Young Park, Yasunori Yonekuta, Kenichi Oyaizu, Hiroyuki Nishide, Rigoberto Advincula

    JOURNAL OF MATERIALS CHEMISTRY   20 ( 43 ) 9616 - 9618  2010  [Refereed]

     View Summary

    Electrochemically oxidized patterns of stable poly(nitroxide radical)s at the nano-scale were demonstrated by controlling lithographic parameters, such as voltage, scan speed, and sweep duration.

    DOI

  • Synthesis of Poly(oxoammonium salt)s and Their Electrical Properties in the Organic Thin Film Device

    Takeo Suga, Shunya Takeuchi, Takanori Ozaki, Miki Sakata, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   38 ( 12 ) 1160 - 1161  2009.12  [Refereed]

     View Summary

    Two redox-active poly(oxoammonium salt)s were synthesized via chemical oxidation of a TEMPO-substituted polymer, or conventional radical polymerization of the oxoammonium monomer, respectively. The diode-structured thin film device composed of poly(oxoammonium salt) with radical conc. of 6-43% exhibited a resistive switching behavior (ON-OFF ratio &gt; 10(3)), in contrast to the radical-free poly(oxoammonium salt), which revealed that the coexistence of radical/oxoammonium salts contributed to a significant change in I-V characteristics.

    DOI

  • Environmentally benign batteries based on organic radical polymers

    Hiroyuki Nishide, Kenichiroh Koshika, Kenichi Oyaizu

    PURE AND APPLIED CHEMISTRY   81 ( 11 ) 1961 - 1970  2009.11  [Refereed]

     View Summary

    A radical polymer is an aliphatic organic polymer bearing densely populated unpaired electrons in the pendant robust radical groups per repeating unit. These radicals&apos; unpaired electrons are characterized by very fast electron-transfer reactivity, allowing reversible charging as the electrode-active materials for secondary batteries. Organic-based radical batteries have several advantages over conventional batteries, such as increased safety, adaptability to wet fabrication processes, easy disposability, and capability of fabrication from less-limited resources, which are described along the fashion of green chemistry.

    DOI

  • An Aqueous, Electrolyte-Type, Rechargeable Device Utilizing a Hydrophilic Radical Polymer-Cathode

    Kenichiroh Koshika, Naoki Sano, Kenichi Oyaizu, Hiroyuki Nishide

    MACROMOLECULAR CHEMISTRY AND PHYSICS   210 ( 22 ) 1989 - 1995  2009.11  [Refereed]

     View Summary

    A hydrophilic poly(vinyl ether)-backbone polymer bearing a pendant TEMPO radical, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl vinyl ether) (PTVE), was designed as a cathode-active material, which displays a reversible one-electron redox capability, even in an aqueous electrolyte. The PTVE layer coated on a current collector demonstrated a rapid charging-discharging rate based on the combination of the redox-active nitroxide radicals built into the hydrophilic polymer and the aqueous electrolyte that possessed a high electrical conductivity. A test cell fabricated with a PTVE cathode, a zinc anode, and an aqueous electrolyte gave an output voltage of 1.7 V and showed the ability to be recharged more than 500 times rechargeability.

    DOI

  • Radical Polymers for Organic Electronic Devices: A Radical Departure from Conjugated Polymers?

    Kenichi Oyaizu, Hiroyuki Nishide

    ADVANCED MATERIALS   21 ( 22 ) 2339 - 2344  2009.06  [Refereed]

     View Summary

    Radical polymers are aliphatic or nonconjugated polymers bearing organic robust radicals as pendant groups per repeating unit. A large population of the radical redox sites allows the efficient redox gradient-driven electron transport through the polymer layer by outer-sphere self-exchange reactions in electrolyte solutions. The radical polymers are emerging as a new class of electroactive materials useful for various kinds of wet-type energy storage, transport, and conversion devices. Electric-field-driven charge transport by hopping between the densely populated radical sites is also a remarkable aspect of the radical polymers in the solid state, which leads to many dry-type devices such as organic memories, diodes, and switches.

    DOI

  • Chiral alkylated poly(m-phenylene)s: Optical activity and thermal stability of helical structures

    Risa Sone, Ichiro Takemura, Kenichi Oyaizu, Hiroyuki Nishide

    SYNTHETIC METALS   159 ( 9-10 ) 925 - 930  2009.05  [Refereed]

     View Summary

    Chiral poly[4,6-bis(alkylthio)-1,3-phenylene-alt-2-methyl-1,3-phenylene] was synthesized from 1,3-dibromo-2,6-bis(3-dodecyl-2-methylthio)benzene and 2-methyl-1,3-phenylenebis(pinacol borate) as a precursor of chiral poly(thiaheterohelicene). Circular dichroism (CD) spectra that arise from the poly(1,3-phenylene) backbone inverted according to the chirality of the side chains, which indicated that a helical conformation of the polymer was induced by the interaction between the side chains. The CD intensity of the polymer increased in non-polar solvents such as hexane. The decrease in the molar CD intensity and the broadening of a fluorescence band at higher concentrations Suggested that the aggregation of the polymer Suppressed the formation of the helical structure. The conformational changes were monitored by the CD and the (1)H NMR spectra at different temperatures. In a good solvent Such as dichloromethane, the CD intensity increased, and the (1)H NMR signal of benzene protons shifted to lower fields at low temperatures. In hexane. the CD spectra and the I H NMR signals were less dependent on temperatures, as a result of the strong interaction between the chiral alkyl chains in the polymer to freeze the helical conformation. (C) 2009 Elsevier B.V. All rights reserved.

    DOI

  • Emerging N-Type Redox-Active Radical Polymer for a Totally Organic Polymer-Based Rechargeable Battery

    Takeo Suga, Hiroki Ohshiro, Shuhei Sugita, Kenichi Oyaizu, Hiroyuki Nishide

    ADVANCED MATERIALS   21 ( 16 ) 1627 - +  2009.04  [Refereed]

     View Summary

    A n-type and redox-active radical polymer bearing galvinoxyl radicals, poly (galvinoxylstyrene), is utilized as an anode-active material, which enabled, for the first time, the fabrication of a totally organic polymer-based rechargeable battery in conjunction with p-type redox-active radical polymer. This battery was characterized by its remarkably high power rate capability.

    DOI

  • An ultrafast chargeable polymer electrode based on the combination of nitroxide radical and aqueous electrolyte

    Kenichiroh Koshika, Naoki Sano, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMICAL COMMUNICATIONS   ( 7 ) 836 - 838  2009  [Refereed]

     View Summary

    A film of poly( 2,2,6,6-tetramethylpiperidinyloxy-4-yl vinylether) coated on a current collector displayed a rapid and reversible electrochemical response in aqueous electrolytes, and allowed an ultrafast full charging of 3 mC cm(-2) in as short as 3 seconds by virtue of the combination of the hydrophilic radical polymer and the aqueous electrolyte possessing a high electrical conductivity.

    DOI

  • A rechargeable battery based on hydrophilic radical polymer electrode and its green assessment

    K. Koshika, M. Kitajima, K. Oyaizu, H. Nishide

    GREEN CHEMISTRY LETTERS AND REVIEWS   2 ( 3 ) 169 - 174  2009  [Refereed]

     View Summary

    A hydrophilic radical polymer electrode-based rechargeable battery was designed along the concept of green chemistry. A hydrophilic radical polymer, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl vinylether), was synthesized as an electrode-active material; its battery demonstrated a high charging-discharging rate and long cycle life. The combination of the hydrophilic polymer electrode and an aqueous electrolyte for the battery fabrication was expected to provide safety improvements such as a low ignition risk besides the high battery performance. The green characteristics were studied using the "i-Messe," an evaluation method proposed by the committee of the Green Sustainable Chemistry Network, Japan. The electrode-active polymer was evaluated for substantial improvements in disaster safety and health safety.

    DOI

  • Facilitated oxygen transport through a Nafion membrane containing cobaltporphyrin as a fixed oxygen carrier

    Masami Shoji, Kenichi Oyaizu, Hiroyuki Nishide

    POLYMER   49 ( 26 ) 5659 - 5664  2008.12  [Refereed]

     View Summary

    A Nafion membrane containing a cobaltporphyrin (CoP) complex as a fixed oxygen carrier was prepared with a view to facilitate oxygen transport through the membrane. The design concept of the CoP-loaded Nafion membrane was based on the CoP&apos;s modification to place the CoP complex in a hydrophobic domain of the microphase-separated structure, in order to facilitate the oxygen transport and to maintain proton conductivity. The oxygen permeability through the CoP-loaded Nafion membrane was higher than the nitrogen permeability, and significantly enhanced at relatively-low oxygen pressures of the upstream, indicating that the fixed Col? complex acted as an oxygen hopping site to facilitate the oxygen transport. The oxygen/nitrogen permselectivity increased with the content of CoP in the Nafion membrane. Electrochemical reduction of oxygen at a glassy carbon electrode, modified with a Pt/C catalyst and the CoP-loaded Nafion membrane, provided additional support for the facilitated oxygen transport by the membrane. Increased current for the reduction of oxygen on the modified electrode by loading CoP indicated that the CoP offered the oxygen hopping site in the Nafion membrane. (c) 2008 Elsevier Ltd. All rights reserved.

    DOI

  • Preparation of pH-sensitive liposomes retaining SOD mimic and their anticancer effect

    Kazue Hiraka, Mayuko Kanehisa, Miho Tamai, Shoichiro Asayama, Shoji Nagaoka, Kenichi Oyaizu, Makoto Yuasa, Hiroyoshi Kawakami

    COLLOIDS AND SURFACES B-BIOINTERFACES   67 ( 1 ) 54 - 58  2008.11  [Refereed]

     View Summary

    We prepared an anticancer drug based on a pH-sensitive liposome retaining Fe-porphyrin as an SOD mimic. The liposomes contained cationic/anionic lipid combinations and were composed of Feporphyrin, 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine, dimethylditetradecylammonium bromide, sodium oleate, and Tween-80. The Fe-porphyrin was released from the liposome at low pH, and the cytotoxicity for cancer cells by the liposome depended on the acidic environments of the endosomes in the cells. Furthermore, although the liposome exhibited an excellent anticancer effect on a gastric cancer cell line, the SOD activity of Fe-porphyrin was shown to have a significant influence on the cytotoxicity toward cancer cells. These findings suggest that the pH-sensitive liposome retaining the Fe-porphyrin as an SOD mimic promises to be a novel anticancer drug for endosomal escape. (C) 2008 Elsevier B.V. All rights reserved

    DOI

  • Nernstian Adsorbate-like Bulk Layer of Organic Radical Polymers for High-Density Charge Storage Purposes

    Kenichi Oyaizu, Yuko Ando, Hiroaki Konishi, Hiroyuki Nishide

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   130 ( 44 ) 14459 - +  2008.11  [Refereed]

     View Summary

    Redox polymer layers with 2,2,6,6-tetramethylpiperidin-1-oxyl-4-yl(TEMPO) groups showed nernstian adsorbate-like electrochemical behaviors up to submicrometer thicknesses, based on a fast charge propagation within the bulk layer and persistency in electrolyte solutions.

    DOI

  • Synthesis and characterization of radical-bearing polyethers as an electrode-active material for organic secondary batteries

    Kenichi Oyaizu, Takeo Suga, Kentaro Yoshimura, Hiroyuki Nishide

    MACROMOLECULES   41 ( 18 ) 6646 - 6652  2008.09  [Refereed]

     View Summary

    In search of polymer backbones to bind organic radical pendant groups as redox centers for high-density charge storage application, polyether was employed as a flexible chain with a low glass transition temperature and affinity to electrolyte solutions. Cyclic ethers bearing nitroxide radicals were synthesized and polymerized via ring-opening polymerization utilizing various initiators. Polyethers bearing robust radical substituents such as 2,2,6,6-tetramethylpiperidin-l-oxyl-4-yl and 2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-l-oxyl-3-yl groups with high density, i.e., per repeating unit with small equivalent weights, were prepared by the anionic polymerization of the corresponding epoxides. Cyclic voltammetry of the radical polyethers, obtained for polymer/carbon composites confined at an aluminum current collector, revealed large redox capacities comparable to the formula weight-based theoretical values, which was ascribed to the efficient swelling and yet insoluble properties of the polyethers in electrolyte solutions by virtue of their high molecular weights and adhesive properties to be held on electrode surfaces. The redox capacity also indicated that the ionophoric polyether matrix accommodated electrolyte anions to compensate positive charges produced by the oxidation of the neutral radicals at the polymer/electrode interface, allowing charge propagation deep into the polymer layer by a site-hopping mechanism. Test cells fabricated with the polymer/carbon composite as the cathode and a Li anode, sandwiching an electrolyte layer, performed as a secondary battery at output voltages near 3.6 V without substantial degradation even after 100 charging-discharging cycles.

    DOI

  • Reduction of 2,3,5-triphenyl-2H-tetrazolium chloride in the presence of polyelectrolytes containing 4-styrenesulfonate moieties

    Ignacio Moreno-Villoslada, Marcos Soto, Felipe Gonzalez, Francisco Montero-Silva, Susan Hess, Ichiro Takemura, Kenichi Oyaizu, Hiroyuki Nishide

    JOURNAL OF PHYSICAL CHEMISTRY B   112 ( 17 ) 5350 - 5354  2008.05  [Refereed]

     View Summary

    The redox behavior of 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) in the presence of different polyelectrolytes such as poly(sodium 4-styrenesulfonate) (PSS), poly(sodium 4-styrenesulfonate-co-sodium maleate) at two different comonomer compositions (P(SS1-co-MA(1)) and P(SS3-co-MA(1))), poly(sodium acrylate-co-sodium maleate) (P(AA(1)-co-MA(1))), and poly(sodium acrylate) (PAA) is studied. Due to aromatic-aromatic interactions, the polyelectrolytes containing benzene sulfonate groups produce a decrease on the reduction rate of TTC in the presence of ascorbic acid (ASC) and a shift of the anodic and cathodic peaks to higher negative potentials for the electrochemical reaction of TTC. As an important conclusion, these effects are a function of the linear aromatic density of the polyelectrolytes.

    DOI

  • Materials science - Toward flexible batteries

    Hiroyuki Nishide, Kenichi Oyaizu

    SCIENCE   319 ( 5864 ) 737 - 738  2008.02  [Refereed]

    DOI

  • ラジカル電池: 有機ラジカルポリマーの電極反応に基づく二次電池

    小柳津研一

    化学と教育   56   118 - 119  2008

  • Synthesis and Properties of Poly(phenylene ether) Diblock Copolymers Bearing Acid Substituents

    Kenichi Oyaizu, Hidenori Murata, Daisuke Yoshi, Takehiro Ishikawa, Makoto Yuasa

    KOBUNSHI RONBUNSHU   65 ( 2 ) 145 - 149  2008  [Refereed]

     View Summary

    The oxidative polymerization of 2,6-dimethylphenol is a convenient engineering method to synthesize poly (2,6-dimethyl-1,4-phenylene ether) (PPE) as a high-performance engineering plastic in industrial fields. Recently, we reported the novel synthesis of PPE diblock copolymers based on the analysis of the polymerization mechanism. We report the preparation of PPE diblock copolymers bearing carboxylic or sulfonic acid as acid substituents. The resulting acid substituented PPE block copolymers, poly (2,6-dimethyl-1,4-phenylene etherblock-2-carboxy-6-methyl-1,4-phenylene ether) 3 and poly [2,6-dimethyl-1,4-phenylene ether-block-2-phenyl-6-(4-sulfophenyl)-1,4-phenylene ether] 5, were applied as polymer electrolyte membranes for fuel cells. 3 and 5 were soluble in polar organic solvents such as N,N-dimethylformamide, dimethylsulfoxide, and THF and gave tough membranes by casting. Sulfonated polymer 5 membrane showed high ion exchange capacity and high oxidative stability. The results suggested that the acid substituents attached onto the pendant phenyl groups were more stable than those on main chains.

  • Preparation of Novel Gold Nanoparticles Modofoed with Thiol-substituted Porphyrin and Their Derivatives

    H. Murata, K. Oyaizu, M. Komuro, R. Awa, H. Tsukioka, T. Saotome, M. Yuasa

    J. Jpn. Soc. Colour Mater.   81   37 - 42  2008  [Refereed]

  • Totally Organic Polymer-Based Electrochromic Cell Using TEMPO-Substituted Polynorbornene as a Counter Electrode-Active Material

    Yusuke Takahashi, Naoki Hayashi, Kenichi Oyaizu, Kenji Honda, Hiroyuki Nishide

    POLYMER JOURNAL   40 ( 8 ) 763 - 767  2008  [Refereed]

     View Summary

    An electrochromic (EC) cell using a viologen-based polymer as an EC material and a radical polymer bearing a redox-active 2,2,6,6-tetramethylpiperidin-N-oxyl (TEMPO) group per repeating unit as a counter electroactive material was fabricated. The radical polymer was spin-coated on an ITO/glass electrode as the counter electrode of the EC cell. The electrochromic material of the cell was a polyion complex consisted of poly(decyl viologen) and poly(styrene sulfonate) (PV 10-PSS), which was also spin-coated on the ITO/glass. An ion-conducting polymer gel Solution was sandwiched between the two electrodes. Electrochemical switching of the cell was monitored using the visible absorption of the PV 10-PSS complex (lambda(max) = 550 nm) that appeared in the reduced state, while the radical polymer was transparent in the visible region in both redox states. PV 10-PSS and the radical polymer were Concurrently reduced and oxidized, respectively, on each electrode during the charging process, which corresponded to the coloration of the cell. The decoloration of the polyion complex was effected by a discharging process under short circuit conditions. The electrochromic behavior of the cell was characterized by a remarkably low driving voltage, as a result of a small potential gap between PV 10-PSS and the radical polymer. The use of the organic redox polymers, not only for the low energy-driven electrochromic switching but also for the charge-storage purposes, allowed a universal design of a battery-like display device, with possible application to a flexible and totally organic electrochromic cell.

    DOI

  • Construction of Manganese Porphyrin Modified Hemoglobin Complex and Its Antioxidant Activities

    Hidenori Murata, Yuji Ito, Tomoyuki Shimpo, Kenichi Oyaizu, Makoto Yuasa

    KOBUNSHI RONBUNSHU   65 ( 4 ) 277 - 282  2008  [Refereed]

     View Summary

    Manganese 5,10,15,20-tetrakis(N-methyl-2-yl) porphyrin (MnT2MePyP) was introduced to hemoglobin to use it as a drug carrier. Reconstituted hemoglobin was reacted with pyridoxal-5-phosphate and borohydride to yield pyridoxalated reconstituted hemoglobin (PLPrHb). The reaction of PLPrHb with activated polyethyleneglycol gave pegylated reconstituted hemoglobin (PEGrHb). PEGrHb was polymerized using glutaraldehyde to yield cross-linked pegylated reconstituted hemoglobin (Cross-link PEGrHb). The number average moleculer weight of Cross-link PEGrHb was estimated to be 1.0 x 10(5) by GPC. The modification of hemoglobin was checked by using SDS-PAGE. Stopped flow analysis showed a high SOD activity of Cross-link PEGrHb. A pharmacokinetic study of I'll-labelled Cross-link PEGrHb that was infused into mice revealed a long-term blood circulation. The novel Manganese porphyrin modified hemoglobin complex was found to remain long-term in the blood circulation without being removed by excretion. These results showed that this complex can be used as a high performance antioxidant.

  • Synthesis of Six-coordination Proximal Base Conjugation Iron(III) porphyrin Complexes and Evaluation as a Superoxide Sensor

    Makoto Yuasa, Kenichi Oyaizu, Hidenori Murata, Yujiro Toyoda, Masahiro Namba, Masaki Shitara

    KOBUNSHI RONBUNSHU   65 ( 5 ) 349 - 354  2008  [Refereed]

     View Summary

    Reactive oxygen species (ROS) such as the superoxide anion radical (O-2(-)center dot) play an essential role on normal cellular growth and homeostasis. However, excess ROS generated by perturbing O-2(-)center dot homeostasis under various conditions of oxidative stress induce high radical toxicity, resulting in many diseases such as a cancer, brain and mitocondrial infarction, and inflammation. Therefore, quantitative measurement of O-2(-)center dot in vivo is important for clarifying their relationship under various conditions. However, in most cases, the biological significance and mechanism of the O-2(-)center dot generation are not well understood yet. We have developed a O-2(-)center dot sensor composed of a thin film of N-methylimidazole-coordinated iron meso-tetra(3-thienyl)porphyrin ((Im)(2)FeT3ThP) for the electrochemical detection of O-2(-)center dot. The microsensor displayed high selectivity and activity for the oxidation of O-2(-)center dot and showed a linear relationship between electric current and O-2(-)center dot concentration. In this study, we have designed and synthesized a novel hexa-coordinated iron (111) porphyrin compound, which is more stable than the meso-tetra(3-thienyl)porphyrin coordinating imidazoles. This compound was electropolymerized onto the electrode and used as a O-2(-)center dot sensor. The redox potential of the electrode suggests that the molecular structure in the electropolymerized film is maintained. This novel modified electrode displayed a high activity for the oxidation of O-2(-)center dot even in the presence of H2O2 and showed a linear relationship between the electric current and O-2(-)center dot concentration.

  • Synthesis of Poly(2,6-dimethyl-1,4-phenylene oxide) by Double-Step Polymerization in Supercritical Carbon Dioxide

    Hidenori Murata, Takuro Sato, Kenichi Oyaizu, Takeshi Furuya, Yoshihiro Takebayashi, Satoshi Yodai, Katsuto Otake, Makoto Yuasa

    KOBUNSHI RONBUNSHU   65 ( 11 ) 688 - 694  2008  [Refereed]

     View Summary

    Oxidative polymerization of 2,6-dimethylphenol (2,6-DMP) is a convenient method to prepare poly (2,6-dimethyl-1,4-phenyleneoxide) (PPO), an important plastic in engineering. The polymerization of 2,6-DMP is carried out in organic solvents under oxygen; thus, a solvent-recovery system and an anti-explosive reactor are required for the industrial application. The use Of scCO(2) instead of organic solvents is expected to make the polymerization of 2,6-DMP safer and environmentally more benign. We have studied the oxidative polymerization of 2,6-DMP in scCO(2). In this report, we have applied the &apos;double-step polymerization&apos; method in scCO(2) to synthesize PPO with better polymer properties, i.e., higher average molecular weight (M(w)) and narrower molecular weight distribution (M(w)/M(n)). In the first step, a prepolymer with a narrow molecular weight distribution (M(w)/M(n) = 1.4) was synthesized under a homogeneous-phase condition. The prepolymer was purified and dried to remove water. In the second step, the prepolymer was further polymerized to increase the molecular weight. The second-step polymerization was performed at 40 degrees C and 20 MPa. The M(w) was increased from 4.9 x 10(3) to 9.0 x 10(3), keeping the narrow molecular weight distribution (M(w)/M(n) = 1.4). We further optimized the polymerization condition in the second step to obtain higher molecular weight. The M(w) was increased to 3.4 x 10(4) (M(w)/M(n) = 2.3) at 80 degrees C and 15 MPa in the presence of CuBr (0.0004 mol) and pyridine (0.019 mol).

  • Synthesis of cobalt complex using pyrrole derivative with basic ligand and application to cathodic catalyst for oxygen reduction

    Hidenori Murata, Yuichi Iai, Takahisa Otake, Kenichi Oyaizu, Kozo Kozawa, Makoto Yuasa

    ELECTROCHEMISTRY   75 ( 12 ) 964 - 968  2007.12  [Refereed]

     View Summary

    A ligand compound with strong coordinating property, 2-(1H-pyrrole-3-yl) pyrazine (pz-Py), was synthesized to increase the density of active sites for oxygen reduction. The obtained compound was coordinated with cobalt (11) ions strongly. It was revealed that the metal complex could be used as a cathode catalyst in fuel cells. The potential for oxygen reduction was positive (E-p = 0.27 V vs SCE) for the catalyst prepared by refluxing the corresponding compound, cobalt acetate tetrahydrate, and the carbon particles. This activity was superior to CoPy/C which was synthesized by refluxing pyrrole, cobalt acetate tetrahydrate, and the carbon particles, and it was shown that nitrogen atoms of pyrazine type contribute accumulation of cobalt ions. The activity of the catalyst was improved after heat treatment under Ar gas. These results show the potential use of the present catalyst as a novel cathode catalyst in fuel cells.

  • Battery-inspired, nonvolatile, and rewritable memory architecture: a radical polymer-based organic device

    Yasunori Yonekuta, Kentaro Susuki, Kenichi Oyaizu, Kenji Honda, Hiroyuki Nishide

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   129 ( 46 ) 14128 - +  2007.11  [Refereed]

     View Summary

    A nonvolatile, bistable, and rewritable organic memory device based on radical polymers was prepared and tested. The excellent performance of a battery-inspired memory architecture with a configuration of p- and n-type charge-transporting radical polymers sandwiching a dielectric layer was characterized. The ON-OFF ratio was more than 4 orders of magnitude, and retention and endurance cycles of more than 10(4) and 10(3), respectively, were accomplished.

  • Electrocatalytic activities for the reduction of oxygen of carbon particles modified with polypyrrole including various metal ions as electrocatalytic sites

    Makoto Yuasa, Kenichi Oyaizu, Hidenori Murata, Ken Tanaka, Masakuni Yamamoto, Shinichi Sasaki

    ELECTROCHEMISTRY   75 ( 10 ) 800 - 806  2007.10  [Refereed]

     View Summary

    We reported that carbon black modified with cobalt and various transition metal ions (M) incorporated in a polypyrrole film (Co+MPPy/C) were good electrocatalysts for the reduction of oxygen (O-2). After heat treatment of the catalysts at 600 to 650 degrees C under argon atmosphere, which were prepared using with iron and iridium ions as M. the resulted catalysts gave rise to the reduction of O-2 at a remarkably positive potential (E-p &gt; 0.40 V vs SCE). Rotating ring disk voltammetry (RRDV) revealed that Co+IrPPy/C reduced O-2 completely with four electrons (n(av) = 4.0). X-ray photoelectron spectroscopy and X-ray diffraction indicated that the cobalt and M ions were coordinated with nitrogen as the donor atoms and the active sites were maintained even after the heat treatment under argon atmosphere without aggregation of metals and formation of alloys.

  • Structural implication of oxoammonium cations for reversible organic one-electron redox reaction to nitroxide radicals

    Yasunori Yonekuta, Kenichi Oyaizu, Hiroyuki Nishide

    CHEMISTRY LETTERS   36 ( 7 ) 866 - 867  2007.07  [Refereed]

     View Summary

    Structures and electrochemical behaviors of nitroxide radicals reveal that their rapid and reversible redox reactions are based not only on their chemical stability but also on the increased sp(2) character of nitrogens which is intermediate between the purely sp(2) and sp(3) nitrogens in oxoammonium cations and amines, respectively.

  • 金属錯体を用いた新しいカソード触媒の開発

    小柳津研一, 湯浅真

    ケミカルエンジニヤリング   52   175 - 180  2007

  • 非貴金属とポリピロールのコンポジットからなる燃料電池触媒

    小柳津研一, 湯浅真

    高分子   56   153 - 153  2007

  • Fabrication of Sensor for Reactive Oxygen Species Using Gold Electrodes Modified with Electropolymerized Porphyrins and Application for Detection of Stress of Plants

    M. Yuasa, K. Oyaizu, H. Murata, T. Kobayashi, C. Kobayashi

    J. Oleo Sci.   56   81 - 86  2007  [Refereed]

  • Antioxidant and Anticancer Properties of Metalloporphyrins Embedded in Liposomes

    M. Yuasa, K. Oyaizu, H. Murata, Y. Sahara, T. Hatsugai, A. Ogata

    J. Oleo Sci.   56   87 - 93  2007  [Refereed]

  • Synthesis of Cationic Manganese Porphyrin Bearing Alkylsulfonio Groups and Evaluation of Their Antioxidant Activities

    M. Yuasa, K. Oyaizu, H. Murata, M. Komuro, R. Awa, A. Ohkubo

    J. Oleo Sci.   56   95 - 101  2007  [Refereed]

  • Quantitative analysis of active oxygen species by potentiometry

    Makoto Yuasa, Kenichi Oyaizu, Hidenori Murata, Katsuya Eguchi, Yujiro Toyoda

    KOBUNSHI RONBUNSHU   64 ( 2 ) 90 - 95  2007  [Refereed]

     View Summary

    Reactive oxygen species (ROS) have many vital functions including sterilizing function of white blood cell, carcinostatic function, aging, cell death, inflammation, and DNA damage. Among various ROS, superoxide anion radical (O-2(-) center dot) has been attracting great attention as a cause of human disease. We have developed an O-2(-) center dot sensor composed of a thin film of 1-methylimidazole(1m) coordinatied Bromoiron(III) meso-tetrathienyleporphyrin ([FeBr(ttp)]) for the electro-chemical detection. In this study, highly sensitive measurements of O-2(-) center dot by potentiometry were conducted. The potentiometric response for O-2(-) center dot was monitored in 10 mM phosphate buffer. The O-2(-) center dot sensor displayed a high catalytic activity for oxidation of O-2(-) center dot and showed a linear relationship between the sensor response and the logarithm of O-2(-) center dot concentration. This O-2(-) center dot sensor showed low interferences due to the electrochemical interferents H2O2 and uric acid. Measurement of O-2(-) center dot by potentiometry was able to detect the low concentrations of O-2(-) center dot (7 x 10(-7) M) that measurements of O-2(-) center dot by amperometry could not easily detect.

  • pH-sensitive liposome retaining Fe-porphyrin as SOD mimic for novel anticancer drug delivery system

    Hiroyoshi Kawakami, Kazue Hiraka, Miho Tamai, Aiko Horiuchi, Akihiko Ogata, Tomomi Hatsugai, Aritomo Yamaguchi, Kenichi Oyaizu, Makoto Yuasa

    POLYMERS FOR ADVANCED TECHNOLOGIES   18 ( 1 ) 82 - 87  2007.01  [Refereed]

     View Summary

    In this article the novel design of an anticancer drug delivery system is reported based on a pH-sensitive liposome retaining the Fe-porphyrin as a superoxide dismutase(SOD) mimic. The liposomes contained cationic/anionic lipid combinations and were composed of Fe-porphyrin, L-ei-phosphatidylcholine (DMPC), dimethylditetradecylammonium bromide (DTDAB), sodispdum oleate (OA(Na)), and Tween-80. The size of the liposome was approximately 30 nm. The EC50 value (the effective concentration of compound required to produce a 50% lethal dose against cells) of the liposome was found to be significantly smaller than that of cisplatin as the control drug, suggesting that the liposome showed a high cytotoxicity toward the cancer cells. This is due to the fact that the pH-sensitive liposome rapidly corresponds to the acidic environments of the endosomes and is unstable, and the Fe-porphyrin is delivered into the cytosol. This result suggests that O-2 may be useful as a target molecule to induce the selective death of cancer cells and that a pH-sensitive liposome retaining Fe-porphyrin as an SOD mimic is a new class of anticancer agent. Copyright (c) 2006 John Wiley & Sons, Ltd.

    DOI

  • Low-energy driven electrochromic devices using radical polymer as transparent counter electroactive material

    Yusuke Takahashi, Kenichi Oyaizu, Kenji Honda, Hiroyuki Nishide

    JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY   20 ( 1 ) 29 - 34  2007  [Refereed]

     View Summary

    Electroactive and transparent organic radical polymers offered a novel design of materials for electrochromic (EC) devices. A radical polymer containing 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) groups as redox active sites per repeating unit was spin-coated on a counter ITO/glass electrode of the EC device which was also comprised of Prussian blue (PB) as an electrochromic material on ITO and ion-conducting polymer gel between the two electrodes. Electrochemical switching of the cell was monitored using the visible absorption of PB (lambda(max) = 700 nm) that appeared in the oxidized (mixed-valence) state, while the radical polymer was transparent in the visible region in both redox states. PB and the radical polymer were concurrently reduced and oxidized, respectively, on each electrode during the charging process, which corresponded to the decoloration of the cell. The coloration was effected by a discharging process. The electrochromic switching and stability of the cell was characterized by a low driving voltage AV and, consequently, a small driving energy integral Delta Vi(t)dt, as a result of a small potential gap between PB and the radical polymer. The optical switch was fast and fully reversible by virtue of the large heterogeneous electron transfer rate constant of the TEMPO center (k(0) approximate to 10(-1) cm/s). The polymeric counter electrode material, without dissolution into the electrolyte layer, led to a good open circuit memory that did not require refreshing charges to maintain the redox states of PB.

  • Evaluation of O2-・ Scavenging Activities of Antioxidant Compounds Using an Electrochemical Superoxide Sensor

    M. Yuasa, K. Oyaizu, H. Murata, S. Ohseki, T. Aoki

    Mater. Technol.   25   175 - 181  2007  [Refereed]

  • Electrochemical synthesis of polyaniline film in supercritical carbon dioxide as a solvent

    Hidenori Murata, Kenichi Oyaizu, Manabu Hoshino, Yasuhiro Yokota, Makoto Yuasa

    KOBUNSHI RONBUNSHU   64 ( 11 ) 812 - 816  2007  [Refereed]

     View Summary

    A conductive polyaniline (PAN) film was successfully synthesized in a homogeneous supercritical carbon dioxide (scCO(2))/acetonitrile (AN) system. The homogeneous supercritical state was confirmed by observations of the phase behavior of the system through a high-pressure cell with a viewing window. The flatness of the film in that system decreased with the further addition of CO2. This result suggests that the low Viscosity of ScCO2 plays an important role in improving the transfer rate of solvent. The roughness of the film prepared in the homogeneous ScCO2/AN system was reduced compared with that of the film prepared in dichloromethane itself as a solvent. The slow growth of the film and the high diffusion rate of the monomer seemed to account for the smooth and flat film formation.

  • Preparation of Cathodic Catalyst for Fuel Cell Using Cobalt-polypyrrole Complex Containing Basic Compound and Their Catalytic Activities for Oxygen Reduction

    M. Yuasa, K. Oyaizu, H. Murata, K. Ikkanda, K. Tanaka, T. Imai

    Mater. Technol.   25   313 - 319  2007  [Refereed]

  • Synthesis and characterization of a pi-conjugated hybrid of oligothiophene and porphyrin

    Kenichi Oyaizu, Mainabu Hoshino, Masuhide Ishikawa, Takuya Imai, Makoto Yuasa

    JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY   44 ( 18 ) 5403 - 5412  2006.09  [Refereed]

     View Summary

    5-(3-Thienyl)-10,15,20-triethyl-21H,23H-porphine (H-2(ttep)) was synthesized and characterized. Oxidative polymerization of H-2(ttep) gave a novel oligomeric porphyrin linked at the 2,5-positions of the thienyl group. Electric conductivity of 4 x 10(-1) S/cm after I-2 doping indicated that the oligomer had a pi-conjugated. structure with a delocalization of pi electrons over the thienylene backbone. PM3 calculations revealed a low HOCO-LUCO gap, which was consistent with the relatively high electric conductivity. Regioregular (head-to-tail) structure was inferred from spectroscopic and calculational results. The pendant porphyrin groups formed a regular J-type array along the thienylene backbone, which was indicated by a significant red shift of the Soret, band maximum. (c) 2006 Wiley Periodicals, Inc.

    DOI

  • Surface-modified mesoporous silicas as recyclable adsorbents of an endocrine disrupter, bisphenol A

    Aritomo Yamaguchi, Terumasa Awano, Kenichi Oyaizu, Makoto Yuasa

    Journal of Nanoscience and Nanotechnology   6 ( 6 ) 1689 - 1694  2006.06  [Refereed]

     View Summary

    Surface-modified mesoporous silicas (MSs) were investigated for recyclable adsorption of an endocrine disrupter, bisphenol A (BPA). Surface-modified MSs were prepared by (i) post-synthesis surface modification of MSs using surface hydroxyl groups and organosilanes (m-MS) and by (ii) co-condensation of tetraethoxysilane and the corresponding organosilanes (d-MS). Infrared measurements indicated that organic groups mainly existed on the surface of m-MS, which resulted in a surface characterized by high hydrophobicity. Both organic groups and isolated hydroxyl groups existed on the surface of d-MS, resulting in both hydrophobicity and hydrophilicity on the surface. The amount of BPA adsorbed on surface-modified MSs per organic group was similar for m-MS and d-MS, however, the d-MS established equilibrium for BPA adsorption faster than m-MS, as measured by UV-vis spectra. A larger amount of BPA per surface area could be adsorbed on carbon materials than on the surface-modified MSs, however, the regeneration of carbon materials by washing could not be done easily. The surface-modified MSs retain adsorption capacity for BPA after several regeneration cycles, demonstrating that the surface-modified MSs are effective recyclable adsorbents of the endocrine disrupter, bisphenol A. Copyright © 2006 American Scientific Publishers All rights reserved.

    DOI PubMed

  • Surface-modified mesoporous silicas as recyclable adsorbents of an endocrine disrupter, bisphenol A

    Aritomo Yamaguchi, Terumasa Awano, Kenichi Oyaizu, Makoto Yuasa

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   6 ( 6 ) 1689 - 1694  2006.06  [Refereed]

     View Summary

    Surface-modified mesoporous silicas (MSs) were investigated for recyclable adsorption of an endocrine disrupter, bisphenol A (BPA). Surface-modified MSs were prepared by (i) post-synthesis surface modification of MSs using surface hydroxyl groups and organosilanes (m-MS) and by (ii) co-condensation of tetraethoxysilane and the corresponding organosilanes (d-MS). Infrared measurements indicated that organic groups mainly existed on the surface of m-MS, which resulted in a surface characterized by high hydrophobicity. Both organic groups and isolated hydroxyl groups existed on the surface of d-MS, resulting in both hydrophobicity and hydrophilicity on the surface. The amount of BPA adsorbed on surface-modified MSs per organic group was similar for m-MS and d-MS, however, the d-MS established equilibrium for BPA adsorption faster than m-MS, as measured by UV-vis spectra. A larger amount of BPA per surface area could be adsorbed on carbon materials than on the surface-modified MSs, however, the regeneration of carbon materials by washing could not be done easily. The surface-modified MSs retain adsorption capacity for BPA after several regeneration cycles, demonstrating that the surface-modified MSs are effective recyclable adsorbents of the endocrine disrupter, bisphenol A.

    DOI

  • Highly stable polymerizable vesicles in anionic surfactant/ammonium salt mixtures in the presence of cross-linking monomers for convenient preparation of hollow nanospheres

    K Oyaizu, Y Shiba, Y Nakamura, M Yuasa

    LANGMUIR   22 ( 12 ) 5261 - 5265  2006.06  [Refereed]

     View Summary

    Spontaneous and stable vesicles are formed from vinylbenzyltrimethylammonium chloride (VBTAC) and sodium dodecyl sulfate (SDS) ranging in molar composition from 3: 7 to 7: 3 in the presence of 30 mol % divinylbenzene (DVB). Dynamic light scattering analysis and transmission electron microscope observations revealed that microparticles with diameters around 120 nm (30%) and 580 nm (70%) were formed. Trapping efficiency of the vesicles examined with D-(+)-glucose amounted to ca. 15%. These vesicles were capable of undergoing polymerization in the presence of water-soluble radical initiators such as 2,2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride to fix the vesicular structure. Retention of the vesicle size and bimodal size distribution characteristics during the polymerization indicated that intravesicular polymerization prevailed over the intervesicular process. SDS was stably retained in the cross-linked vesicle and was not removed from the vesicle by exhaustive dialysis or ultrafiltration, due to the electrostatic interaction within the cross-linked polymeric framework produced from VBTAC and DVB. The resulting hollow nanospheres are readily redispersed in water without the aid of additional surfactants.

    DOI

  • Stepwise direct synthesis of alumino-silicate mesoporous materials with high ion-exchange capacity

    A. Yamaguchi, R. Sano, K. Oyaizu, M. Yuasa

    Journal of the Japan Society of Colour Material (Shikizaki)   79 ( 2 ) 47 - 54  2006.02  [Refereed]

  • 対流ボルタンメトリー(2) (回転リング-ディスク電極系)

    小柳津研一, 湯浅真

    Electrochemistry   74   81 - 83  2006

  • スーパーオキシドジスムターゼミミックス: その分子設計とナノバイオ応用

    湯浅真, 小柳津研一, 村田英則

    オレオサイエンス   6   307 - 317  2006

  • 燃料電池開発の現状と将来

    小柳津研一, 湯浅真

    理大科学フォーラム   263   32 - 38  2006

  • 電子・スピン機能材料としてのπ共役系縮合環ポリマー

    小柳津研一

    日本化学会コロイドおよび界面化学部会ニュースレター   31 ( 2 ) 2 - 5  2006

  • 高分子錯体ナノ薄膜を活用した固体高分子形燃料電池系カソード触媒

    湯浅真, 小柳津研一, 村田英則

    ケミカルエンジニヤリング   51   353 - 356  2006

  • ポリチオフェニレンの新規合成法

    小柳津研一

    高分子   55   888 - 888  2006

  • Non-cyanide electroless gold plating using polyphenols as reducing agents

    Y Ohtani, A Horiuchi, A Yamaguchi, K Oyaizu, M Yuasa

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   153 ( 1 ) C63 - C66  2006  [Refereed]

     View Summary

    Polyphenol compounds were investigated as reducing agents for non-cyanide electroless gold plating for electronics assembly applications. The pH value and temperature were optimized to determine the conditions that lead to a high deposition rate without precipitation. The surface morphology was evaluated by scanning electron microscopy. Catechol, pyrogallol, and gallic acid yielded deposited films with good appearance and solderability under the optimized conditions. Among the tested reducing agents, catechol is the most suitable for use as a stable plating bath with a long life. It has a moderate reducing ability to stabilize the bath and deposit the film. The calculated values of the heat of formation and the highest occupied molecular orbital levels of the reducing agents supported the experimental results. (c) 2005 The Electrochemical Society.

  • Development of Method for Rapid Measurement of Blood Reactive Oxygen Species in Calves

    H. Takahashi, T. Miyamoto, Y. Takahashi, R. Horino, M. Fujino, K. Nakamura, M. Yamada, Y. Yamamoto, T. Oohashi, S. Tsutsui, M. Nanba, K. Oyaizu, M. Yuasa

    Bull. Natl. Inst. Anim. Health   112 ( 112 ) 25 - 31  2006  [Refereed]

     View Summary

    An electrochemical sensor for reactive oxygen species like the superoxide anion radical using polymeric iron porphyrin complexes was developed by Yuasa et al. of the Tokyo University of Science. The present experiment was designed to develop a method for rapid measurement of reactive oxygen species in calf blood by employing this technique. The needle-type sensor, including an integrated microelectrode, was dipped into calf blood in a test tube. After xanthine oxidase (O_2^- ・ -generating enzmyme), superoxide dismutase (O_2^- ・ -scavenging enzyme) and opsonized zymosan (phagocyte stimulant) were successively administered in the blood, the current value detected by the sensor in the blood was recorded. The current value increased, decreased and reincreased after the successive administrations of xanthine oxidase, superoxide dismutase and opsonized zymosan, respectively. The sensor was proven to detect the reactive oxygen species of blood. Change in the reactive oxygen species concentration of calf blood following castration was investigated, by dipping the needle-type sensor in the calf blood just after sampling. The reactive oxygen species concentration increased to a maximum at 3 hr, decreasing gradually thereafter following the castration. The fluctuation was almost linked to those of the blood chemiluminescence activity and leukocyte count. Thus, we succeeded in perfoming a rapid measurement of the reactive oxygen species concentration in the peripheral blood of calves.

    DOI CiNii

  • Controlled oxidation of dextran for evolution of polyether segment bearing pendant carboxyl groups for corrosion inhibition applications

    K Oyaizu, A Yamaguchi, T Hayashi, Y Nakamura, D Yoshii, Y Ito, M Yuasa

    POLYMER JOURNAL   38 ( 4 ) 343 - 348  2006  [Refereed]

     View Summary

    Partially oxidized dextran containing carboxyl a ups was prepared as an environmentally benign organic corrosion inhibitor for mild steel. Introduction of carboxyl groups was accomplished by oxidation of dextran using sodium hypochlorite under basic conditions. The structure of the product was confirmed by spectroscopic measurements. GPC analysis revealed that oxidation of dextran proceeded without significant molecular-weight degradation. H-1 NMR spectra revealed that up to 1.3 carboxyl groups per repeating unit were introduced into the polymer. The product showed moderate corrosion inhibition activity for mild steel. and biodegradability under conditions for cooling water systems.

    DOI

  • Stepwise Direct Synthesis of Aluminosilicate Mesoporous Materials for Catalyst Supports

    A. Yamaguchi, R. Sano, K. Oyaizu, M. Yuasa

    J. Jpn. Soc. Colour Mater.   2   47 - 54  2006  [Refereed]

  • Investigations of Bath Compositions and Operating Conditions of Gold Plating Using Hydantoin-gold Complex

    Y. Ohtani, K. Sugawara, K. Nemoto, A. Shiozawa, A. Yamaguchi, K. Oyaizu, M. Yuasa

    J. Sur. Finish. Soc. Jpn.   57   167 - 171  2006  [Refereed]

  • Novel electrocatalysts for oxygen reduction using cobaltporphyrins that undergo facile electropolymerization

    M Yuasa, K Oyaizu, A Yamaguchi, T Imai, M Kitao

    KOBUNSHI RONBUNSHU   63 ( 3 ) 182 - 188  2006  [Refereed]

     View Summary

    [Meso-tetra(thiophen-3-yl)porphinato]cobalt (II) (CoT3ThP) complex, which undergoes facile electropolymerization, was synthesized by the dehydro-condensation reaction of pyrrole and 3-thienylaldehyde. The electroconductive thin film of CoT3ThP interconnected by 2,5-thienylene chains, was produced at the glassy carbon electrode by electrolysis. The catalytic activity for oxygen reduction at the modified electrode was evaluated by cyclic voltammetry. The catalytic current for the O-2 reduction appeared near E-p=0.2 V vs. SCE. It was found that the electrode modified with CoT3ThP film has a higher stability than that modified with porphyrin by absorption. Next, we chose carbon black with a high surface-area as a catalyst support, and CoT3ThP was electropolymerized under the condition of suspension of carbon black in an electrolyte solution. We found that the polymerized CoT3ThP was produced on the surface of the carbon nanoparticle. The carbon nanoparticles modified with polymerized CoT3ThP (polyCoT3ThP/C) were suspended in a Nafion solution, and a pseudo MEA (Membrane Electrode Assembly) was made by casting polyCoT3ThP/C on an edge-plane pyrolytic graphite electrode. The polyCoT3ThP/C catalyst was found to reduce O-2 mainly with four electrons (the number of electrons transferred n=3.8) at a positive potential of E-p=0.44 V vs. SCE. The catalytic activity of polyCoT3ThP/C was improved by heat treatment under an inert gas atmosphere (E-p=0.47 V vs. SCE, n=3.8). The results show the possibility of a novel cathode catalyst for use in fuel cells.

  • Preparation of novel conductive polymer ligand-coated carbon particles by electropolymerization of pyridylthiophene and application as metal complex catalysts for oxygen reduction

    K Oyaizu, A Yamaguchi, Y Iai, K Tanaka, M Yuasa

    KOBUNSHI RONBUNSHU   63 ( 3 ) 189 - 195  2006  [Refereed]

     View Summary

    Conductive polymer ligand-coated carbon particles were prepared by a fluid-bed electrolysis of 2-(3-pyridyl)thiophene using carbon particles as a working electrode. The resulting particles were suspeneded in a DMF solution of cobalt acetate. The surface of carbon particles was successfully modified with the highly dispersed cobalt complex. The modified carbon particles were suspended in an alcoholic solution of Nafion, and a pseudo-MEA was prepared on an electrode by casting the solution. The electrocatalytic reduction of dissolved 02 was examined using the modified electrode. When the catalyst was prepared using a carbon black with a large surface area and pyrrole was added as a complementary ligand, the catalytic potential for the reduction of 02 appeared at E-p=0.37 V vs. SCE. The catalyst was found to reduce 02 mainly with four electrons (n=3.1). This activity was superior to that of the previously reported carbon nanoparticles modified with a cobalt polypyrrole complex. It was clearly shown that nitrogen atoms of the pyridine-type ligand contribute to accumulate cobalt ions on the surface of the catalyst. It was also revealed that the catalytic activity improved remarkably after heat treatment of the catalyst under argon. The catalyst revealed the possibility of its use as a cathode catalyst for platinum-free fuel cells.

  • Preparation of Hollow Fine Particles by Polymerization of Vesicles and Their Application to Functional Materials

    Y. Shiba, Y. Nakamura, K. Oyaizu, M. Yuasa

    J. Jpn. Soc. Colour Mater.   79   237 - 242  2006  [Refereed]

  • Improved activity of cathode catalysts for fuel cells by optimizing the conditions for preparation of carbon particles modified with cobalt-polypyrrole complex

    Makoto Yuasa, Kenichi Oyaizu, Hidenori Murata, Ken Tanaka, Masakuni Yamamoto

    KOBUNSHI RONBUNSHU   63 ( 9 ) 601 - 606  2006  [Refereed]

     View Summary

    Carbon nanoparticles modified with a cobalt-adsorbed polypyrrole film (Co/PPy/C) were found to be a good electrocatalyst for O-2 reduction. The Co/PPy/C catalyst was synthesized by a multiple modification method for the purpose of obtaining Co-N-4 structure in high density. The conventional Co/PPy/C catalyst was prepared by electropolymerization of pyrrole onto the surface of carbon particles dispersed in the electrolyte solution containing pyrrole, followed by complexation using cobalt acetate. The new Co/PPy/C catalyst was prepared by repeating the above operation. Compared with those of the conventional catalyst, the cobalt ions and nitrogen atoms constituting active centers increased remarkably. The carbon nanoparticles prepared by the multiple modification method was suspended in a Nafion solution, and pseudo MEA (Membrane Electrode Assembly) was made by casting the solution onto an edge-plane pyrolytic graphite electrode. It was revealed that the new catalyst reduced 02 mainly with four electrons, the number of electrons transferred n being 3.3 at a positive potential (E-p = 0.31 V vs. SCE). In addition, the catalytic activity of the catalyst was improved by optimizing the heat-treatment conditions (n = 3.8 at E-p = 0.42 V vs. SCE). These results show the potential use of the present catalyst as a novel cathode catalyst in the fuel cell.

  • Fabrication of electrodes for highly sensitive detection of a superoxide anion radical by electropolymerization of thienylporphyrins in the prescence of thiophene and application to active oxygen sensors

    M Yuasa, K Oyaizu, H Murata, M Ishikawa, S Tsutsui, M Namba

    KOBUNSHI RONBUNSHU   63 ( 6 ) 427 - 431  2006  [Refereed]

     View Summary

    The superoxide anion radical (O-2(-) center dot) has attracted much attention in many fields of biology since it was realized that superoxide anions are produced in significant quantities in various parts of biological systems, from microorganisms to mammals. Therefore, quantitative measurements of O-2(-) center dot in vivo are important for clarifying such relationships under various conditions. However, in most cases, the biological significance and the mechanism of the generation O-2(- center dot) are not yet well understood. We have developed an O-2(- center dot) sensor composed of a thin film of 1-methylimidazole-coordinated iron meso-tetra (3-thienyl) porphyrin ([Fe(im)(2)(ttp)]Br) for the electrochemical detection of O-2(-) center dot. The microsensor displayed high selectivity and activity for the oxidation of O-2(-) center dot and showed a linear relationship between the current and the O-2(-) center dot concentration. In this research, the improvement of the sensor sensitivity was accomplished by mixing polythiophene as the electroconductive polymer on the electrode surface. The sensors were prepared using various compositions of [Fe(im)(2)(ttp)]Br and thiophene as the monomers. During in vitro tests, O-2(-) (center dot) was generated as an intermediate during the oxidation of xanthine by xanthine oxidase (XOD), for detection using this sensor. The electric conductivity of the polymer increased, accompanied by the increase in the amount of the thiophene unit. The highest sensitivity was obtained at a monomer composition of [Fe(im)(2)(ttp)]Br : thiophene = 1 : 8.

  • Investigation of carbon materials as supports for metalloporphyrins used for cathode catalyst in fuel cells

    Makoto Yuasa, Kenichi Oyaizu, Hidenori Murata, Mizuki Kitao, Kenji Fujita

    KOBUNSHI RONBUNSHU   63 ( 9 ) 607 - 612  2006  [Refereed]

     View Summary

    meso-Substituted cobalt porphyrins adsorbed on carbon materials were prepared by using a homogenizer in mixing cobalt tetraethylporphyrin and various carbon materials. these electrocatalysts gave rise to electroreduction of O-2 at a remarkably positive potential (E-p = 0.44 V versus saturated calomel electrode (SCE)) and showed a high selectivity for the four-electron reduction (n = 3.9). The catalyst heat-treated at 600 degrees C showed higher potential (E-p = 0.44 V vs. SCE). Electrochemical study and X-ray photo spectroscopy (XPS) analysis revealed that the adsorbed amount of cobalt-porphyrin molecules caused highly effective catalysts for electroreduction of O-2.

  • Methods for Prediction of Gold Plating Characteristics by Numerical Analysis

    M. Yuasa, N. Momozawa, K. Oyaizu, Y. Ohtani, K. Sugawara

    J. Sur. Finish. Soc. Jpn.   57   789 - 792  2006  [Refereed]

  • Electrochemical synthesis of conducting polypyrrole film in a homogeneous supercritical CO2/acetonitrile system

    H. Yan, T. Sato, D. Komago, A. Yamaguchi, K. Oyaizu, M. Yuasa, K. Otake

    LANGMUIR   21 ( 26 ) 12303 - 12308  2005.12  [Refereed]

  • Electrochemical synthesis of a polypyrrole thin film with supercritical carbon dioxide as a solvent

    H Yan, T Sato, D Komago, A Yamaguchi, K Oyaizu, M Yuasa, K Otake

    LANGMUIR   21 ( 26 ) 12303 - 12308  2005.12  [Refereed]

     View Summary

    A conductive polypyrrole (PPy) film was successfully synthesized in a homogeneous supercritical carbon dioxide (scCO(2))/acetonitrile (AN) system. The occurrence of a homogeneous supercritical state was confirmed by observations of the phase behavior of the system through a high-pressure cell with a viewing window. The concentration of a supporting electrolyte, tetrabutylammonium hexafluorophosphate (TBAPF(6)), significantly changed the phase behavior of the scCO(2)/AN system. The polymerization rate of the film in that system decreased with further addition of CO2. This result suggested that the low Viscosity of scCO(2) did not play an important role in improving the growth rate of the PPy film. The low polymerization rate might have been due to the electron-transfer resistance arising from the low dielectric constant of scCO(2)/ AN mixture. The roughness of the film prepared in the homogeneous scCO(2)/AN system was 1/10 that synthesized in AN itself as a solvent. The slow growth of film and the high diffusion rate of the monomer seemed to account for the smooth flat film formation.

    DOI

  • Electrochemical detection and sensing of reactive oxygen species

    M Yuasa, K Oyaizu

    CURRENT ORGANIC CHEMISTRY   9 ( 16 ) 1685 - 1697  2005.11  [Refereed]

     View Summary

    Reactive oxygen species (ROS) such as superoxide anion radical (O-2(-.)) play an essential role on normal cellular growth and homeostasis. However, excess ROS generated by perturbing O-2(-.). homeostasis under various conditions of oxidative stress induce high radical toxicity, resulting in many diseases such as cancer, brain and myocardial infarction, and inflammation. Quantitative analysis Of O-2(-.) by a convenient method is a subject of intense research, since most of ROS are derived from O-2(-.). In situ real-time measurement Of O-2(-.) is very important to understand the relevance of ROS to many diseases. Recent progress in electrochemical sensors for the facile detection Of O-2(-.), including biosensors utilizing a variety of metalloproteins as sensing elements for O-2(-.) and very recently developed all-synthetic sensors with a high selectivity for O-2(-.) detection, is reviewed. Emphasis is placed on the possibility of the all-synthetic sensor for convenient in vivo measurement of ROS.

  • A water-soluble gold(III) comprex with a hydantoin ligand for gold plating

    K. Oyaizu, Y. Ohtani, A. Shiozawa, K. Sugawara, T. Saito, M. Yuasa

    INORGANIC CHEMISTRY   44 ( 20 ) 6915 - 6917  2005.10  [Refereed]

  • Highly stable Gold(III) complex with a hydantoin ligand in alkaline media

    K Oyaizu, Y Ohtani, A Shiozawa, K Sugawara, T Saito, M Yuasa

    INORGANIC CHEMISTRY   44 ( 20 ) 6915 - 6917  2005.10  [Refereed]

     View Summary

    A novel gold(III) complex with a monodentate 5,5-dimethylhydantoin ligand, [Au(dmh)(4)](-), is square planar in geometry, inert and highly stable in alkaline solutions because of soft acid-base interactions, and electrochemically reduced near -0.3 V vs Ag/AgCl to give a gold(0) film with a high current efficiency.

    DOI

  • Cobaltporphyrin-adsorbed carbon black: highly efficient electrocatalysts for oxygen reduction

    M Yuasa, A Yamaguchi, K Oyaizu, Y Fujito, M Kitao, T Sato

    POLYMERS FOR ADVANCED TECHNOLOGIES   16 ( 9 ) 702 - 705  2005.09  [Refereed]

     View Summary

    meso-Substituted cobalt porphyrins adsorbed on carbon black were prepared as catalysts for the electroreduction of O-2. The catalyst, which was prepared by using a homogenizer in mixing cobalt tetraethylporphyrin and carbon black, gave rise to electroreduction Of 02 at a remarkably positive potential (E-P = 0.45 V versus saturated calomel electrode (SCE)) and showed a high selectively for the four-electron reduction (n = 3.8). Electrochemical study and extended X-ray absorption fine structure (EXAFS) analysis revealed that the adsorbed face-to-face dimeric aggregates of cobalt porphyrin molecules were highly efficient catalysts for electroreduction of O-2. Copyright (c) 2005 John Wiley & Sons, Ltd.

    DOI

  • Structure and redox properties of electropolymerized film obtained from iron meso-tetrakis(3-thienyl)porphyrin

    M Yuasa, K Oyaizu, A Yamaguchi, M Ishikawa, K Eguchi, T Kobayashi, Y Toyoda, S Tsutsui

    POLYMERS FOR ADVANCED TECHNOLOGIES   16 ( 8 ) 616 - 621  2005.08  [Refereed]

     View Summary

    Oxidative polymerization of bromoiron(III) meso-tetrakis(3-thienyl)porphyrin gave a novel polymeric porphyrin complex randomly crosslinked at the 2,5-positions of the peripheral thienyl groups. The electrical semiconductivity of ca. 10(-5) S/cm after 12 doping indicated that the polymer had a pi-conjugated structure with a moderate delocalization of pi electrons over the thienylporphyrin units. PM3 calculations for free-base models revealed that HOCO (the highest occupied crystal orbital) band width was reduced by introduction of the porphyrin moieties into the thienylene backbone and yet low HOCO-LUCO (the lowest unoccupied crystal orbital) gap was maintained, which accounted for the relatively low electrical conductivity of the porphyrin polymer. The modified electrode prepared by electropolymerization was redox-active due to the presence of iron(II/III) couple and the semiconductivity of the film, which served as a novel non-enzymatic electrochemical sensor for superoxide anion radical based on the facile electrocatalytic oxidation of the superoxide. Copyright (c) 2005 John Wiley & Sons, Ltd.

    DOI

  • Modifying carbon particles with polypyrrole for adsorption of cobalt ions as electrocatatytic site for oxygen reduction

    M Yuasa, A Yamaguchi, H Itsuki, K Tanaka, M Yamamoto, K Oyaizu

    CHEMISTRY OF MATERIALS   17 ( 17 ) 4278 - 4281  2005.08  [Refereed]

    DOI

  • Electrochemical sensor for superoxide anion radical using polymeric iron porphyrin complexes containing axial 1-methylimidazole ligand as cytochrome c mimics

    M Yuasa, K Oyaizu, A Yamaguchi, M Ishikawa, K Eguchi, T Kobayashi, Y Toyoda, S Tsutsui

    POLYMERS FOR ADVANCED TECHNOLOGIES   16 ( 4 ) 287 - 292  2005.04  [Refereed]

     View Summary

    A needle-type electrochemical sensor for the facile detection of superoxide anion radical (O-2(-)) was devised using an electrodeposited film of a polymeric porphyrin complex attached to a carbon microelectrode which was placed in a stainless steel 18G needle tube as an auxiliary electrode. The sensing element was prepared by means of electropolymerization of bromoiron(III) mesotetra(3-thienyl)porphyrin in the presence of 1-methylimidazole in CH2Cl2 containing 100 mM tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte, which gave a smooth film of the corresponding polymer. The film was electrochemically active to give a redox response near -0.05 V versus Ag/AgCl due to the iron(II/III) couple. The microsensor was applied to detect O-2(-). produced by xanthine oxidation catalyzed by xanthine oxidase. The amperometric response for O-2(-) was monitored at an electrode potential of 0.5 V versus the auxiliary electrode in a 10 mM phosphate buffer. The microsensor displayed a high catalytic activity for the oxidation of O-2(-) and showed a linear relationship between the current and the O-2(-) concentration. Axial coordination of an imidazole ligand to the iron porphyrin center enhanced selectivity for O-2(-) by impeding the undesired coordination of H2O2 that resulted from the dismutation of O-2(-). Copyright (c) 2005 John Wiley A Sons, Ltd.

    DOI

  • Novel approach for the preparation of metal containing mesoporous silica using solubilization of fatty acid salt

    A Yamaguchi, M Yokoyama, T Ogura, K Oyaizu, M Yuasa, T Ohkubo, H Sakai, M Abe

    CHEMISTRY LETTERS   34 ( 3 ) 346 - 347  2005.03  [Refereed]

     View Summary

    We have prepared copper-containing mesoporous silica (Cu/MS) using solubilization of copper oleate in nonionic surfactant aggregates. The amount of copper loading in calcined Cu/MS corresponded to the amount of copper oleate solubilized in surfactant aggregates of the mixed solution.

    DOI

  • Synthesis of Polymeric Reconstituted Hemoglobins as Superoxide Dismutase Mimics Designed for Long-term Circulation Maintenance

    Makoto Yuasa, Kenichi Oyaizu, Takamitsu Hayashi, Aritomo Yamaguchi

    Journal of Oleo Science   54 ( 7 ) 413 - 418  2005  [Refereed]

     View Summary

    Superoxide dismutase (SOD), catalase and glutathione peroxidase catalize the elimination of reactive oxygen species (ROS) such as a superoxide anion radical (O2 -·). But enzyme activity decreases in diseases in which ROS attacks DNA, lipid and blood vessels. Recent studies on SOD mimics indicate that manganese porphyrin (MnT2MePyP) express high SOD activity. But the half-life of MnT2MePyP in the blood is usually very short. In the present study, a novel reconstituted polymerized hemoglobin containing manganese porphyrins (MnT2MePyP-PolyHb) was synthesized. SOD activity of MnT2MePyP-PolyHb (IC50 = 1.1 μM, kc at = 7.3 × 106 M-1s-1) was found to be somewhat less than that of MnT2MePyP (IC50 = 0.23 μM, kcat = 60 × 106 M-1s-1). MnT2MePyP-PolyHb half-life in H2O2 (t1/2 = 1070 s) was found to be as much as four times that of MnT2MePyP (t1/2 = 250 s). MnT2MePyP-PolyHb may thus be a valid SOD model for effectively maintaining and prolonging blood circulation. © 2005, Japan Oil Chemists' Society. All rights reserved.

    DOI

  • 金属ポルフィリンの分子集合系および多核錯体系を用いた酸素還元触媒

    小柳津研一, 湯浅真

    高分子加工   54   88 - 93  2005

  • In vivo活性酸素種センサーの研究開発

    湯浅真, 小柳津研一

    化学と教育   53   128 - 131  2005

  • サイクリックボルタンメトリー(4) (電極吸着系および電極触媒系の特徴と観測例)

    小柳津研一, 湯浅真

    Electrochemistry   73   460 - 463  2005

  • 高分子錯体を用いた燃料電池用酸素還元触媒

    小柳津研一, 湯浅真

    膜   30   254 - 259  2005

  • 電解重合性ポルフィリン錯体の設計と活性酸素センサーへの応用

    小柳津研一, 湯浅真

    表面   43   1 - 6  2005

  • 対流ボルタンメトリー(1) (概要および回転ディスク電極系)

    小柳津研一, 湯浅真

    Electrochemistry   73   1060 - 1063  2005

  • Surface Modification of Reconstituted Hemoglobins Containing SOD-active Metalloporphyrins

    M. Yuasa, K.Oyaizu, A. Yamaguchi, T. Hayashi, U. Midorikawa

    J. Oleo Sci.   54   115 - 123  2005  [Refereed]

  • Formation of active sites for the NO plus CO reaction over palladium catalysts supported on mesoporous silica

    A Yamaguchi, T Hayashi, K Oyaizu, M Yuasa

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   78 ( 1 ) 192 - 194  2005.01  [Refereed]

     View Summary

    The catalytic activities and structural changes of Pd containing mesoporous silica (Pd/MCM-41) catalysts for the NO + CO reaction were investigated. Pd/MCM-41 after calcination in air showed a very high catalytic activity for the NO + CO reaction because Pd metal particles with an appropriate size for the reaction were formed by the reaction gases.

  • Preparation of Liposomes Surface-Loaded with Cationic Manganese Porphyrins as SOD Mimics

    Makoto Yuasa, Kenichi Oyaizu, Akihiko Ogata, Noriyoshi Matsukura, Aritomo Yamaguchi

    Journal of Oleo Science   54 ( 4 ) 233 - 239  2005  [Refereed]

     View Summary

    A water-soluble cationic 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphinatomanganese(III) ion (MnT4MPyP) and water-insoluble 5,10,15,20-tetrakis(N-3-furyl)porphinatomanganese(III) ion (MnT3FuP) were prepared and ion-complexed with an anionic phospholipid membrane to enhance the circulation persistence of the porphyrin complexes in vivo. Fluorescence spectra and fluorescence depolarization experiments indicated MnT3FuP to be situated within the hydrophobic interior of the vesicle composed of the phospholipid membrane, while MnT4MPyP was anchored to the membrane by lipophilic tails with the metalloporphyrin head-group located on the interface between the membrance and aqueous solvent. SOD activity was determined by stopped-flow analysis and cytochrome c assay, which allowed the determination of IC50 and kcat values for the reaction of the metalloporphyrins with superoxide anion radical (O2 -·). Sodium stearate-linked MnT4MPyP was the most effective catalyst as an SOD mimic to decompose O2 -· at a second-order rate constant of 1.9 × 107 M-1s-1 in dimyristoylphosphatidylcholine (DMPC) liposomes. SOD activity of MnT3FuP was less than that of MnT4MPyP. © 2005, Japan Oil Chemists' Society. All rights reserved.

    DOI

  • Synthesis of Polymeric Reconstituted Hemoglobins as Superoxide Dismutase Mimics Designed for Long-term Circulation Maintenance

    Makoto Yuasa, Kenichi Oyaizu, Takamitsu Hayashi, Aritomo Yamaguchi

    Journal of Oleo Science   54 ( 7 ) 413 - 418  2005  [Refereed]

     View Summary

    Superoxide dismutase (SOD), catalase and glutathione peroxidase catalize the elimination of reactive oxygen species (ROS) such as a superoxide anion radical (O2 -·). But enzyme activity decreases in diseases in which ROS attacks DNA, lipid and blood vessels. Recent studies on SOD mimics indicate that manganese porphyrin (MnT2MePyP) express high SOD activity. But the half-life of MnT2MePyP in the blood is usually very short. In the present study, a novel reconstituted polymerized hemoglobin containing manganese porphyrins (MnT2MePyP-PolyHb) was synthesized. SOD activity of MnT2MePyP-PolyHb (IC50 = 1.1 μM, kc at = 7.3 × 106 M-1s-1) was found to be somewhat less than that of MnT2MePyP (IC50 = 0.23 μM, kcat = 60 × 106 M-1s-1). MnT2MePyP-PolyHb half-life in H2O2 (t1/2 = 1070 s) was found to be as much as four times that of MnT2MePyP (t1/2 = 250 s). MnT2MePyP-PolyHb may thus be a valid SOD model for effectively maintaining and prolonging blood circulation. © 2005, Japan Oil Chemists' Society. All rights reserved.

    DOI

  • Novel Functional Nano-size Nonionic Surfactant Particles on Which Cationic Metalloporphyrins are Absorbed; Preparation, Characterization, and Anti-oxidant Properties

    Makoto Yuasa, Kenichi Oyaizu, Yukihiro Hanyuu, Kazunori Kasahara, Aritomo Yamaguchi

    Journal of Oleo Science   54 ( 8 ) 465 - 471  2005  [Refereed]

     View Summary

    Cationic manganese (III) 5,10,15,20-tetrakis(N-methylpyridinium-2-yl) porphyrin (MnT2MPyP) and manganese (III) 5,10,15,20-tetrakis(N-methylpyridinium-4-yl) porphyrin (MnT4MPyP) complexes were synthesized as superoxide dismutase (SOD) mimics which were introduced into niosomes so as to examine this effects on the capacity of drug delivery system (DDS) to maintain and perpetuate blood circulation. All the niosomes were prepared from polyoxyethylene solbitan monostearate (Tween 61) by the conventional sonication method. SOD activity was measured by the stopped-flow analysis and the cytochrome c method. Sodium stearate-linked MnT2MPyP was found to be the most effective catalyst along with SOD activity for decomposing O2 - • at a second-order rate constant of 2.0 × 107 M-1s-1 in Tween 61 niosomes. Rate constants of metalloporphyrin-embedded niosomes for reaction with hydrogen peroxide (H2O2) and half-life times in H2O2 were also determined. Metalloporphyrin-embedded niosomes were found to have greater half-life times compared to metalloporphyrin without niosomes. The present findings clearly indicate that metalloporphyrin-embedded niosomes are highly effective for bringing about O2 -• decomposition and should thus find application as DDS in antioxidant drugs. © 2005, Japan Oil Chemists' Society. All rights reserved.

    DOI

  • Synthesis of Hexameric Manganese Porphyrin as an SOD Mimic and SOD Activity

    Makoto Yuasa, Kenichi Oyaizu, Yukihiro Hanyuu, Takamitsu Hayashi, Aritomo Yamaguchi

    Journal of Oleo Science   54 ( 9 ) 513 - 518  2005  [Refereed]

     View Summary

    Free radicals and related species derived from O2 such as superoxide anion radical (O2 -·), hydrogen peroxide (H2O2), hydroxyl radical (·OH) and peroxynitrite ion (ONOO-) are often generated in organisms with possibly consequent diseases. The enzyme, superoxide dismutase (SOD), catalyzes the reaction which eliminates O2 -· As models of SOD, manganese porphyrins such as [meso-tetrakis(N-methylpyridinium-4-yl)porphyrinato] manganese(III) (MnT4MPyP) have been investigated. However, the half-life of any one of these in the blood is usually quite short. We undertook the design of a novel hexameric manganese porphyrin (HexMnP) capable of remaining for a prolonged period in the blood. The SOD activity of HexMnP (IC50 = 2.1±0.7 μM) was found to be somewhat less than that of MnT4MPyP (IC50 = 0.71 μM), but to exceed that of reconstituted hemoglobin (MnT4MPyP-Hb) (IC50 = 2.0 μM) prepared in a previous study. HexMnP proved to be an effective SOD model in which HexMnP had the capacity to remain over a long period of time in the blood, owing to its molecular diameter of more than 80Å. © 2005, Japan Oil Chemists' Society. All rights reserved.

    DOI

  • Coordination Equilibria of Hydantoin Derivatives with Gold Ions

    Y. Ohtani, T. Saito, K. Sugawara, A. Shiozawa, A. Yamaguchi, K. Oyaizu, M. Yuasa

    J. Sur. Finish. Soc. Jpn.   56   479 - 480  2005  [Refereed]

  • Preparation, Characterization, and Catalytic Properties of Pd Metal Particles Supported on Mesoporous Silicas

    A. Yamaguchi, K. Iwaoka, K. Oyaizu, M. Yuasa

    Mater. Technol.   23   272 - 278  2005  [Refereed]

  • Water-soluble poly(phenylene ether) derivatives as environmentally benign and heat-resistant coating materials for paper

    Y Shiba, D Yoshii, K Oyaizu, M Yuasa

    KOBUNSHI RONBUNSHU   62 ( 12 ) 591 - 597  2005  [Refereed]

     View Summary

    Functional and environmentally benign water-soluble polymers which have characteristic heat-resistant properties, mechanical strength values, and depolymerization capabilities were designed by introducing ionic groups as side chains to poly (phenylene ether) s (PPE). Two water-soluble PPE polymers were prepared by oxidation of 3-methylsalicylic acid and 5-methylsalicylic acid. They were evaluated as functional coating materials for paper production. The compounds showed important characteristics as paper coating materials: high solubility in alkaline water, low viscosity values of polymer solutions and mixtures with inorganic pigments at high shear rates, and adhesion to pulp fiber and inorganic pigments. High glass transition temperature values of the compound provided stiffness and strong resistance against heat blocking of sheet media when a thin layer of compound was applied to a surface of a paper sheet. Additionally, the compounds were found to depolymerize into oligomers by oxidation in the presence of methylsalicylic acid monomers. Such properties of the water-soluble PPE polymers allowed applications to advanced strong and recyclable coating materials.

  • Electron-transfer kinetics of nitroxide radicals as an electrode-active material

    T Suga, YJ Pu, K Oyaizu, H Nishide

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   77 ( 12 ) 2203 - 2204  2004.12  [Refereed]

     View Summary

    The electron-transfer rate constants of nitroxide derivatives, 4-(N-t-butyl-N-oxylamino)-t-butylbenzene, 4-(N-t-butyl-N-oxylamino)methoxybenzene, and 2,2,6,6-tetramethylpiperidinyl-N-oxyl, were investigated by electrochemical methods, which demonstrated that these radicals can potentially be used as a high power-rate electrode-active material due to their fast electron-transfer process.

    DOI

  • Liposomal surface-loading of water-soluble cationic iron(III) porphyrins as anticancer drugs

    Makoto Yuasa, Kenichi Oyaizu, Aiko Horiuchi, Akihiko Ogata, Tomomi Hatsugai, Aritomo Yamaguchi, Hiroyoshi Kawakami

    MOLECULAR PHARMACEUTICS   1 ( 5 ) 387 - 389  2004.09  [Refereed]

     View Summary

    A novel design of anticancer drug delivery system, based on an electrostatic binding of negatively charged liposomes and cationic metalloporphyrins under physiological conditions, is reported. A lack of cytotoxicity of the iron(III) porphyrin-loaded liposomes and an efficient generation of a toxic hydroxyl radical (OH center dot) from a superoxide anion radical (O-2(-center dot)) through the iron(III)-catalyzed dismutation and the Fenton-like reaction allow for a targeted necrosis of tumor cells where the concentration of O-2(-center dot) is locally increased as a result of the reduced activity of superoxide dismutase and catalase in these cells.

    DOI

  • Micellar cobaltporphyrin nanorods in alcohols

    M Yuasa, K Oyaizu, A Yamaguchi, M Kuwakado

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   126 ( 36 ) 11128 - 11129  2004.09  [Refereed]

    DOI

  • Electrocatalysis for dioxygen reduction by a mu-oxo decavanadium complex in alkaline medium and its application to a cathode catalyst in air batteries

    EL Dewi, K Oyaizu, H Nishide, E Tsuchida

    JOURNAL OF POWER SOURCES   130 ( 1-2 ) 286 - 290  2004.05  [Refereed]

     View Summary

    The redox behavior of a decavanadium complex [(V=O)(10)(mu(2)-O)(9)(mu(3)-O)(3)(C5H7O2)(6)] (1) was studied using cyclic voltammetry under acidic and basic conditions. The reduction potential of V(V) was found at less positive potentials for higher pH electrolyte solutions. The oxygen reduction at complex I immobilized on a modified electrode was examined using cyclic voltammetry and rotating ring-disk electrode techniques in the I M KOH solutions. On the basis of measurements using a rotating disk electrode (RDE), the complex I was found to be highly active for the direct four-electron reduction of dioxygen at -0.2 V versus saturated calomel electrode (SCE). The complex I as a reduction catalyst of O-2 with a high selectivity was demonstrated using rotating ring-disk voltammograms in alkaline solutions. The application of complex I as an oxygen reduction catalyst at the cathode of zinc-air cell was also examined. The zinc-air cell with the modified electrode showed a stable discharge potential at approximately I V with discharge capacity of 80 mAh g(-1) which was about five times larger than that obtained with the commonly used manganese dioxide catalyst. (C) 2004 Published by Elsevier B.V.

    DOI

  • New pi-conjugated polyelectrolyte composed of alkylphenoxathiinium-type repeating units

    K Oyaizu, T Mikami, E Tsuchida

    MACROMOLECULES   37 ( 6 ) 2325 - 2327  2004.03  [Refereed]

    DOI

  • Electroreduction of oxygen at a Pt/C-modified electrode with a cobaltporphyrin complex

    B Shentu, K Oyaizu, H Nishide

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   77 ( 2 ) 401 - 405  2004.02  [Refereed]

     View Summary

    Cobalt complexes that reversibly bind and release O-2 functioned as O-2 carriers, or O-2-enriching media, at the surface of a cathode to enhance the current for the reduction of O-2. The effect of the cobalt complex to accumulate O-2 was evidenced by the higher open-circuit potential, which reflected the equilibrated concentration of O-2 at the electrode surface. The combination of the cobalt complex and the conventional Pt/C catalyst resulted in a significant increase in the steady-state Current for the four-electron reduction of O-2, particularly at small overpotentials where typical fuel cells operate, based on the facilitated transport of O-2 from the atmosphere to the catalyst at the electrode Surface.

    DOI

  • Linear ladder-type pi-conjugated polymers composed of fused thiophene ring systems

    K Oyaizu, T Iwasaki, Y Tsukahara, E Tsuchida

    MACROMOLECULES   37 ( 4 ) 1257 - 1270  2004.02  [Refereed]

     View Summary

    A novel carbon-sulfur (C2S) analogue of polyacene has been synthesized and characterized. The polymer is composed of a nondegenerate trans-cisoid polyacetylene backbone in which all hydrogen atoms are replaced with sulfur atoms to form thiophene rings that are fused into a linear cross-conjugated ladder-type structure. The newly developed synthetic route of the ladder-type polymer is based on an intramolecular condensation of a prepolymer consisting of 3-(alkane-1-sulfinyl)thiophen-2,5-diyl units in triflic acid. The geometric and band electronic structure of the ladder-type polymer were calculated and analyzed at the PM5 level of theory. The fused ring structure imposes strong quinonoid-type character to the originally benzenoid polyene backbone, which destabilizes the HOMO and stabilizes the LUMO and thus reduces the band gap. The shift of absorption and emission maxima to longer wavelengths responding to lower pi-pi* transition energies than those of polythiophene and the smaller gap between electrochemical p- and n-doping potentials are consistent with the reduction of the band gap. The microstructure of the isolated oligomers in their neutral, singly oixidzed, and doubly oxidized states were computed for short and intermediate chain length. Various energetic and structural aspects of the convergence behavior from the properties of small cations or dications to those of an isolated polaronic or bipolaronic defects on a sufficiently long chain were monitored and are discussed. The geometric structures of the p-doped ladder-type polymer in the form of either polaron or bipolaron were calculated by adopting suitable boundary conditions to represent charged unit cells. The geometry relaxation process for the charged ladder-type backbone induces the appearance of a stronger quinonoidic character than that in the case of polythiophene, which suggests that the fused rings more easily adopt quinonoid forms than thiophene rings. Calculated energetic aspects of the doping behavior and the paramagnetic resonance spectra of p-doped polymers revealed that the ladder-type polymer possesses polaron as the prevailing charged species, in contrast to many other pi-conjugated polymers where bipolaron is the lowest-energy charge storage configuration.

    DOI

  • 協奏的多電子移動系の構築とその機能開拓

    小柳津研一, 湯浅真

    表面   41   22 - 33  2004

  • 鉄系材料の防食塗料としてのポリアニリン含有塗料

    湯浅真, 小柳津研一

    色材協会誌   77   26 - 33  2004

  • Preparation of a tetraphenylporphyrinatocobalt(II)-poly(3,4azopyridylene) complex and its oxygen enrichment effect at an oxygen electrode

    B Shentu, K Oyaizu, H Nishide

    JOURNAL OF MATERIALS CHEMISTRY   14 ( 22 ) 3308 - 3311  2004  [Refereed]

     View Summary

    The reversible oxygen-binding properties of tetraphenylporphyrinatocobalt(II) (CoTPP) complexed with poly(3,4-azopyridylene) ( PAP) were established. The CoTPP complexes functioned as oxygen carriers at the surface of a cathode to enhance the current for the reduction of oxygen. PAP was synthesized by the oxidative polymerization of 3,4-diaminopyridine in a DMF solution at 25degreesC using a Cu/pyridine catalyst. The combination of the CoTPP complex and the conventional Pt/C catalyst resulted in a significant increase in the steady-state current for the four-electron reduction of O-2, particularly at small overpotentials where typical fuel cells operate, based on the facilitated transport of O-2 from the atmosphere to the catalyst at the electrode surface.

    DOI

  • Investigation of Hydantoin Derivatives as Complexing Agent for Gold Plating

    Y. Ohtani, K. Sugawara, K. Nemoto, A. Shiozawa, A. Yamaguchi, K. Oyaizu, M. Yuasa

    J. Sur. Finish. Soc. Jpn.   55   933 - 936  2004  [Refereed]

  • Crystal structure and reactivity of a five-coordinate chloroiron(III) complex with a bulky tetradentate Schiff base ligand

    K Oyaizu, E Tsuchida

    INORGANICA CHIMICA ACTA   355   414 - 419  2003.11  [Refereed]

     View Summary

    Crystal structure of [Fe(salphen)Cl] (H(2)salphen = N,N'-(1R,2R)-1,2-diphenylethylenebis(salicylideneimine)) reveals that a steric effect induced by the bulky substituent on the Schiff base ligand brings about drastic changes in the reactivity of the complex; the typical dimerization of the chloroiron(III) complex upon basification to yield mu-oxo complexes are suppressed, resulting in the high-yielding conversion to a hydroxide salt. (C) 2003 Published by Elsevier Science B.V.

    DOI

  • Polythiophenylene synthesis through multi-electron transfer process

    K Oyaizu, E Tsuchida

    MACROMOLECULAR SYMPOSIA   204   19 - 25  2003.11  [Refereed]

     View Summary

    Superacidification of aromatic sulfoxides effects the electrophilic substitution reaction of the resulting hydroxysulfonium ions onto aromatic rings with the elimination of H2O at room temperature. The product, the alkyldiarylsulfonium ion, allows the synthesis of alkylsulfonio-bridged (lambda(4)-alkylsulfanyliumdiyl) aromatic polymers. High molecular-weight poly(alkylsulfonioarylene) salts have been made accessible by the regioselective condensation of aryl sulfoxides. Polymers having a wide variety of structural dimensionalities such as linear, hyper-branched and ladder-type structures can be prepared by this method, which possess interesting properties such as good solubility in polar organic solvents and sometimes even in H2O, susceptibility to nucleophiles to provide thioarylene derivatives, photo-degradability, and electric semiconductivity based on a 3d-2p interaction in aryl sulfonium ion.

  • Depolymerization of poly(2,6-dimethyl-1,4-phenylene oxide) under oxidative conditions

    K Saito, T Masuyama, K Oyaizu, H Nishide

    CHEMISTRY-A EUROPEAN JOURNAL   9 ( 17 ) 4240 - 4246  2003.09  [Refereed]

     View Summary

    Depolymerization of an engineering plastic, poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), was accomplished by using 2,6-dimethylphenol (DMP) under oxidative conditions. The addition of an excess amount of DMP to a solution of PPO in the presence of a CuCl/pyridine catalyst yielded oligomeric products. When PPO (M-n = 1.0 X 10(4), M-w/M-n = 1.2) was allowed to react with a sufficient amount of DMP, the molecular weight of the product decreased to M-n = 4.9 X 10(2) (M-w/M-n = 1.5). By a pro-longed reaction with the oxidant, the oligomeric product was repolymerized to produce PPO essentially identical to the starting material, making the oligomer useful as a reusable resource. During the depolymerization reaction, an intermediate phenoxyl radical was observed by ESR spectroscopy. Kinetic analysis showed that the rate of the oxidation of PPO was about 10 times higher than that of DMP. These results show that a monomeric phenoxyl radical attacks the polymeric phenoxyl to induce the redistribution via a quinone ketal intermediate, leading to the substantial decrease in the molecular weight of PPO, which is much faster than the chain growth.

    DOI

  • Oxovanadium(V) hydroxide with a tetradentate Schiff base ligand resulting from oxidation of oxovanadium(IV) with O-2

    K Oyaizu, E Tsuchida

    INORGANICA CHIMICA ACTA   353   332 - 335  2003.09  [Refereed]

     View Summary

    Unlike common oxovanadium(IV) complexes with tetradentate Schiff base ligands, [N,N'-(2,2-dimethyl-1,3-propylene)bis(salicylideneiminato)]oxovanadium(IV) ([VO(salptn)]) was easily oxidized by dioxygen in aqueous CH3CN. The [VO(salptn)]-O-2 stoichiometry was 4:1. This particular reactivity comes from the preference of [VO(salptn)] to be six-coordinate rather than five, that drives the formation of an O-2-complex. The structure of the oxidized product, [VO(salptn)]OH, was characterized by single-crystal X-ray diffraction. The results are consistent with a mechanism involving an attack of O-2 at the vanadium(IV) center, followed by the formation of the mu-dioxo dimmer as a transient species and the subsequent splitting of the O-O bond by hydrolysis to yield [VO(salptn)]OH. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • The first oxovanadium ring in [{O=V(salen)}(2)(mu-F)][VO(salen)][BF4]center dot(CH2Cl2)(x) crystals

    K Oyaizu, E Tsuchida

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   125 ( 19 ) 5630 - 5631  2003.05  [Refereed]

    DOI

  • Cationic polysulfonium membrane as separator in zinc-air cell

    EL Dewi, K Oyaizu, H Nishide, E Tsuchida

    JOURNAL OF POWER SOURCES   115 ( 1 ) 149 - 152  2003.03  [Refereed]

     View Summary

    A polyelectrolyte containing a sulfonium cation, poly(methylsulfonio-1,4-phenylenethio-1,4-phenylene trifluoromethanesulfonate) (1) was tested as a separator in a zinc-air cell. In comparison with the commercially available separators such as polypropylene, polysulfonium 1 was highly effective to prevent cation permeation from the anode to cathode and effectively increased the capacity six-fold greater than that of polypropylene during discharge. This phenomenon was explained by the ion-exchange process of the membrane 1, which showed an anion-permselectivity toward OH- at low KOH aqueous solution concentrations (&lt;1 M). (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • Oxovanadium(III-V) mononuclear complexes and their linear assemblies bearing tetradentate Schiff base ligands: structure and reactivity as multielectron redox catalysts

    E Tsuchida, K Oyaizu

    COORDINATION CHEMISTRY REVIEWS   237 ( 1-2 ) 213 - 228  2003.02  [Refereed]

     View Summary

    This review summarizes the recent advances in the chemistry of oxovanadium(III-V) mononuclear complexes and their linear assemblies bearing tetradentate Schiff base ligands. Structural parameters of the oxovanadium assemblies are compiled, which reveal the preference of specific coordination geometries around vanadium atoms according to the valence state. Emphasis is placed on the catalysis of multielectron redox reactions by oxovanadium(IV) complexes which disproportionate to vanadium(III) and oxovanadium(V) complexes under suitable conditions. Their biological implications and synthetic applications are described. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Coordination of BF4- to oxovanadium(V) complexes, evidenced by the redox potential of oxovanadium(IV/V) couples in CH2Cl2

    K Oyaizu, EL Dewi, E Tsuchida

    INORGANIC CHEMISTRY   42 ( 4 ) 1070 - 1075  2003.02  [Refereed]

     View Summary

    The oxidation of oxovanadium(IV) complexes [(LVO)-O-IV] (L = tetradentate Schiff-base ligands such as N,N'-ethylenebis(salicylideneaminate)(2-) (salen) and N,N'-2,2-dimethylpropylenebis(salicylideneaminate)(2-) (salpn)) to [(LVO)-O-v](+), believed to be responsible for the voltammetric response near 0.6 V vs Ag/AgCl in CH2Cl2 in the presence of tetrabutylammonium tetrafluoroborate as a supporting electrolyte, is in fact coupled to a homogeneous process where [LVO](+) coordinates BF4- to form a neutral complex formulated as [LVOBF4]. The formation constants for [VO(salen)BF4] and [VO(salpn)BF4] are evaluated to be K-salen(-1) = 1.1 X 10(2) M-1 and K-saipn(-1) = 1.4 x 10 M-1, respectively. Crystal structure of [VO(salen)BF4] reveals that one of the fluorine atoms in BF4- is so close to the vanadium(V) atom as to be practically bound in the solid state.

    DOI

  • Alkylsulfonioarylene and thioarylene polymers derived from sulfonium electrophiles

    E Tsuchida, K Oyaizu

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   76 ( 1 ) 15 - 47  2003.01  [Refereed]

     View Summary

    Superacidification of sulfoxides and sulfinates effects the electrophilic substitution reaction of the resulting hydroxy-sulfonium ions onto aromatic rings with the elimination of H2O at room temperature. The present account emphasizes the utility of the reaction for use as an elementary step in organic synthesis. The product, the alkyldiarylsulfonium ion, often quantitatively obtained, allows the synthesis of alkylsulfonio-bridged (lambda(4)-alkylsulfanyliumdiyl) aromatic polymers. High molecular-weight poly(alkylsulfonioarylene) salts with a wide range of structural dimensionalities from linear to network architectures have been made accessible by the regioselective condensation of aryl sulfoxides. The polymers possess interesting properties such as good solubility in polar organic solvents and sometimes even in H2O, susceptibility to nucleophiles to provide thioarylene derivatives, photo-degradability, and electric semiconductivity, according to the dimensionality of the molecule. The synthetic chemistry of the alkylsulfonioarylene polymers as well as their possible applications in high molecular-weight poly(thioarylene) synthesis, photochemical recycling processes of an engineering plastic poly(thio-1,4-phenylene), and photo-resist technologies, are reviewed.

  • Four-electron reduction of dioxygen catalyzed by a decavanadium complex

    EL Dewi, K Oyaizu, E Tsuchida

    INORGANICA CHIMICA ACTA   342   316 - 318  2003.01  [Refereed]

     View Summary

    The electroreduction of O-2 in acidic aqueous solutions at an electrode modified with a decavanadium cluster [(V=O)(10)(mu(2)-O)(9)(mu(3)-O)(3)(C5H7O2)(6)] (1) revealed that it produces H2O with four electrons per O-2 molecule near 0.5 V versus SCE. The usefulness of the complex as a reduction catalyst of O-2 with a high selectivity was demonstrated. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Ion-exchange and apparent diffusion coefficients within cationic polysulfonium coatings containing ferricyanide

    EL Dewi, H Nakano, K Oyaizu, H Nishide, E Tsuchida

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   A40 ( 1 ) 37 - 47  2003  [Refereed]

     View Summary

    A cationic polyelectrolyte of various poly(arylenesulfonium salt)s were coated on the surface of glassy carbon electrodes with an incorporated ferricyanide anion from the electrolyte solutions. The apparent diffusion coefficients of Fe(CN)(6)(3-), that are electrostatically bound were determined by chronoamperometry, chronocoulometry and mediated electron transfer from the rotating disk voltammetry. The complex incorporated by the S-cationic polyelectrolyte shows a high diffusion coefficient for the polyelectrolyte of poly(methylsufonio-1,4-phenylenethio-1,4-phenylene trifluoromethanesulfonate). The diffusion of poly(arylenesulfonio triflate) depended on the ionic exchange of the S-cation which has an alkyl bond and the crystalline structure that influenced the electrostatic motion of the anion within the polyelectrolyte modified electrode.

    DOI

  • Convenient syntheses of methylsulfonioarylene and thioarylene polymers from 1,4-bis(methylsulfinyl)benzene

    K Oyaizu, H Yonemaru, T Iwasaki, R Matsubara, E Tsuchida

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   A40 ( 4 ) 415 - 423  2003  [Refereed]

    DOI

  • Heteropolyacene with thianthrenimn ring systems proving pi electron delocalization over S atoms

    K Oyaizu, R Matsubara, T Iwasaki, E Tsuchida

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   A40 ( 7 ) 655 - 670  2003  [Refereed]

     View Summary

    The superacid-induced condensation of o-methylsulfinylated thiophenyl(ene) compounds under dilute conditions induces an intramolecular electrophilic ring-closing reaction of a hydroxysulfonium cation onto the adjacent benzene ring to yield the thianthrenium ring systems, which disclose pi electron delocalization over sulfonio linkages demonstrating the efficacy of planarization of the benzene rings for the p-pi/d-pi interaction in arylsulfonium moieties. Crystal structure of the thianthrenium salt reveals that the S+-C(phenyl) bond is significantly shortened upon the ring closing as a result of the increased bond order by the resonance effect.

    DOI

  • Palladium-catalyzed synthesis of oligo(methylthio)aniline and conversion to polyacene-type electrolytes bearing phenothiazinium repeating units

    K Oyaizu, F Mitsuhashi, E Tsuchida

    MACROMOLECULAR CHEMISTRY AND PHYSICS   203 ( 10-11 ) 1328 - 1336  2002.07  [Refereed]

     View Summary

    The synthetic routes to ladder polymers which consist of benzenetetrayl subunits with imino and methylsulfonio linkages are described. As the key intermediate, oligo- and polyaniline derivatives having pendant methylthio groups are prepared by the Pd-catalyzed aryl amination from various monomers. The oxidation of the polymers with H2O2 the presence of CH3COOH effects the high yielding conversion of methylthio to methylsulfinyl groups without the formation of the undesired methylsulfonyl groups. The superacid-induced condensation of the resulting polymers under dilution conditions induced the polymer-analogous intramolecular electrophilic ring closure reaction of the hydroxy(methyl)(phenyl)sulfonium cation onto the adjacent benzene ring to yield the required ladder polymers which have proved to be semiconductors with intrinsic electric conductivides of ca. 10(-5) S (.) cm(-1).

  • Reduction of oxygen at an electrode modified by cobaltporphyrin liquid membrane

    BQ Shentu, K Oyaizu, H Nishide

    CHEMISTRY LETTERS   ( 7 ) 712 - 713  2002.07  [Refereed]

     View Summary

    The picket-fence cobaltporphyrin (Col?) having rapid and reversible oxygen-binding properties was employed to accumulate oxygen from a bulk solution to a diffusion layer at an electrode surface. Modification of a carbon electrode with a thin CoP liquid membrane resulted in a significant increase in the reduction current of oxygen, which proved to be a new type of modified electrode to reduce the diffusion resistance of oxygen from the bulk solution onto the electrode surface.

  • 磁極で操る電極反応—界面電子移動における磁気効果

    小柳津研一

    化学   57   56 - 57  2002

  • ヘテロポリアセンの合成と機能

    小柳津研一

    高分子加工   51   548 - 553  2002

  • Synthetic routes to polyheteroacenes: Characterization of a heterocyclic ladder polymer containing phenoxathiinium-type building blocks

    K Oyaizu, T Mikami, F Mitsuhashi, E Tsuchida

    MACROMOLECULES   35 ( 1 ) 67 - 78  2002.01  [Refereed]

     View Summary

    The synthetic routes to ladder polymers that consist of benzenetetrayl subunits with oxo and methylsulfonio linkages are described. As the key intermediate, poly(phenylene oxide)s having pendant methylsulfenyl groups are prepared by copper-catalyzed oxidative polymerization of the corresponding phenols with O-2. The oxidation of the polymer with an equimolar amount of H2O2 in the presence of acetic acid effects the high-yielding conversion of methylsulfenyl to methylsulfinyl groups without the formation of the undesired methylsulfonyl groups. The superacidified condensation of the resulting polymer (Swern reaction of aryl sulfoxides) under dilution conditions induces the polymer-analogous intramolecular electrophilic ring-closing reaction of the hydroxymethylphenylsulfonium cation onto the adjacent benzene ring to yield the required ladder polymer, which has proved to be a semiconductor with an intrinsic electric conductivity of 2 x 10(-5) S/cm. A comparison of the spectroscopic properties of the ladder polymer with those of the model compounds such as 5-methylphenoxathiinium triflate and phenoxathiin discloses pi -electron delocalization over the methylsulfonio linkages, demonstrating the efficacy of the ladderization for p-pi /d-pi interactions in arylsulfonium moieties. This synthetic approach permits the thio and alkylsulfonio ladder linkages for a variety of phenyl ethers to form in high yields.

    DOI

  • Electroreduction of oxygen enriched in a [poly(ethyleneiminato)]cobalt(II) layer

    K Oyaizu, H Nakano, B Shentu, H Nishide

    JOURNAL OF MATERIALS CHEMISTRY   12 ( 10 ) 3162 - 3166  2002  [Refereed]

     View Summary

    An aqueous solution of a [poly(ethyleneiminato)]cobalt(II) complex that reversibly binds and releases O-2 functions as an O-2-enriching medium for an O-2 electrode to enhance the current for the uncatalyzed reduction of O-2. The effect of the electrochemically inactive cobalt complex is to supply reducible O-2 to the solution within the diffusion layer near the electrode by releasing the bound O-2 from the O-2 adduct, which contributes to a decrease in the diffusion layer thickness of O-2. Based on the rapid release of O-2 from the O-2 adduct, a diffusion-limited current is obtained for the reduction of O-2. The hypothetical concentration of the enriched O-2 supplied under pure diffusion control (i.e. unperturbed by the kinetics of the O-2 binding) is several times larger than that of the actual concentration of O-2 due to the higher solubility of the O-2 adduct than the physical solubility of O-2 in H2O at room temperature under an atmosphere of air. An insoluble membrane of a cobalt( II) complex with a cross-linked poly( ethyleneimine) ligand that has the ability to swell serves as an O-2-enriching material to concentrate O-2 from aqueous electrolyte solutions. A new type of O-2-diffusion electrodes for metal/air batteries and fuel cells is proposed using the O-2-enriching material immobilized at the electrode surface.

    DOI

  • A mu-oxo diiron(III) complex with a short Fe-Fe distance: crystal structure of (mu-oxo)bis[N,N '-o -phenylenebis(salicylideneiminato)iron(III)]

    K Oyaizu, EL Dewi, E Tsuchida

    INORGANICA CHIMICA ACTA   321 ( 1-2 ) 205 - 208  2001.09  [Refereed]

     View Summary

    The crystal structure of (mu -oxo)bis[N,N'-o-phenylenebis(salicylideneiminato)iron(III)] ([{Fe(salpn)}(2)(mu -O)]) revealed the shortest intermetallic distance among the crystallo graphically characterized mu -oxo diiron(III) complexes bearing macrocyclic ligands. X-ray data indicate that the Fe-Fe distances are mainly controlled by the steric effect of the ligand. Arrangement of the two Fe(salpn) moieties in close proximity with a fairly bent Fe-O-Fe bond is allowed by the reduced steric crowding of the salpn ligand. (C) 2001 Elsevier Science BN. All rights reserved.

  • Oxidative polymerization of pyrrole promoted by four-electron transfer to O-2: Catalysis of O-2-oxidation by mu-oxo dinuclear complexes with macrocyclic ligands

    K Oyaizu, A Haryono, H Shinoda, E Tsuchida

    MACROMOLECULAR CHEMISTRY AND PHYSICS   202 ( 7 ) 1273 - 1279  2001.05  [Refereed]

  • Copper(II) complexes resulting from the oxygenation of (2,9-dimethyl-1,10-phenanthroline)copper(I) chloride in the presence of dimethylformamide

    K Oyaizu, M Ueno, H Li, E Tsuchida

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   74 ( 5 ) 869 - 870  2001.05  [Refereed]

     View Summary

    The oxygenation of (2,9-dimethyl-1,10-phenanthroline)copper(I) chloride in THF, followed by a treatment with DMF and acidification with HCl, afforded dichloro[2-(dimethylamino) (hydroxy)methyl-9-methyl-1,10-phenanthroline] copper(LI) and (aqua)dichloro(2,9-dimethyl-1,10-phenanroline)copper(II) quantitatively.

  • Electrochemical and ferromagnetic couplings in 4,4 ',4 ''-( 1,3,5-benzenetriyl)tris(phenoxyl) radical formation

    H Nishide, R Doi, K Oyaizu, E Tsuchida

    JOURNAL OF ORGANIC CHEMISTRY   66 ( 5 ) 1680 - 1685  2001.03  [Refereed]

     View Summary

    4,4',4"-(1,3,5-Benzenetriyl)tris(2,g-di-tert-butylphenol) was prepared by the cross-coupling of 1,3,5-tribromobenzene and [4-(trimethylsiloxy)phenyl]magnesium bromide. X-ray analysis of the single crystal showed a propeller-like structure with a mean dihedral angle of 39 degrees between the hydroxyphenyl and the core benzene. The phenoxyl mono-, di-, and triradicals were generated by the electrochemical oxidation of the trianion. A stepwise radical formation was revealed by a differential pulse voltammogram, electrolytic ESR spectroscopy, and a comproportionation reaction between the radicals, which was discussed as an effect of the pi -conjugated but non-Kekule-type coupler. The quartet and triplet ground state for the tri- and diradical, respectively, were confirmed by a SQUID measurement.

  • Synthesis and properties of novel sulfonated arylene ether/fluorinated alkane copolymers

    K Miyatake, K Oyaizu, E Tsuchida, AS Hay

    MACROMOLECULES   34 ( 7 ) 2065 - 2071  2001.03  [Refereed]

     View Summary

    The polymerization of 2,3,5,6-tetraphenylhydroquinone (or 2,2 ' ,3,3 ' ,5,5 ' -hexaphenyl-4,4 ' -dihydroxybiphenyl) with alpha ,w-tetrahydroperfluoroalkanediol and decafluorobiphenyl was carried out to synthesize a series of copolymers III (M-w = 49 100-80 900). The copolymers III are composed of arylene ether (10-30 mol %) and fluorinated alkane (90-70 mol %) moieties. The reaction of III with chlorosulfonic acid gave sulfonated polymers IV, which are soluble in polar organic solvents and form flexible and transparent films by casting from solution. The polymers TV have glass transition temperatures of 109-155 degreesC and decomposition temperatures of ca. 300 degreesC. The hydrated polymers show protonic conductivity (3.4 x 10(-3) S cm(-1)), which does not decrease at temperatures up to 170 degreesC.

    DOI

  • Structure and redox properties of a novel decavanadium cluster [(V=O)(10)(mu(2)-O)(9)(mu(3)-O)(3)(C5H7O2)(6)] in dichloromethane

    K Oyaizu, EL Dewi, E Tsuchida

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   498 ( 1-2 ) 136 - 141  2001.02  [Refereed]

     View Summary

    A novel decavanadium cluster [(V=O)(10)(mu (2)-O)(3)(C-5-O)(3)(C5H7O2)(6)] bearing ten oxovanadium(V) centers linked with bridging oxygen atoms was prepared. In contrast to the well known decavanadate ion V10O286-, the molecule was soluble in organic solvents such as dichloromethane and 1,1,2,2-tetrachloroethane due to the peripheral acetylacetone ligands. X-ray crystallographic analysis revealed a molecular Framework formed by nine square-pyramidal VO5 polyhedra surrounding one VO4 tetrahedron linked through the corners. The molecule consists of approximate three-fold rotational symmetry, allowing the classification of ten vanadium atoms into four chemically equivalent categories. The unique metal core geometry persists in solution, which was demonstrated by the four peaks in the V-51-NMR spectrum. However, the four types of vanadium atom could not be distinguished by electrochemical measurements; consequently, the molecule was a multielectron reservoir which showed a broad cathodic wave near 0.6 V vs. Ag / AgCl due to the reduction of the vanadium(V) centers to vanadium(IV). (C) 2001 Elsevier Science B.V. All rights reserved.

  • Polysulfonium as a new electrode-modifying polyelectrolyte

    K Oyaizu, H Nakano, J Natori, E Tsuchida

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   498 ( 1-2 ) 232 - 236  2001.02  [Refereed]

     View Summary

    A new type of cationic polyelectrolyte, poly(methylsulfonio-1,4-phenylenethio-1,4-phenylene trifluoromethanesulfonate)? that adheres to a glassy carbon electrode surface has been employed to bind a ferricyanide anion to the electrode surface from electrolyte solutions. The complex incorporated by the polyelectrolyte shows significant shifts in formal potential to less positive values due to the stronger binding of ferricyanide by the polycation coating than that of ferrocyanide. The apparent formal potential for the incorporated ferricyanide/ferrocyanide redox couple changes as the concentration of supporting electrolyte is varied. The polycation coating is anion-permselective when a methanesulfonate is used as a supporting electrolyte. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Polymerization of methyl phenyl sulfoxide under acidic conditions: Synthesis and X-ray structure analysis of a phenylene sulfonium polymer

    K Miyatake, K Oyaizu, Y Nishimura, E Tsuchida

    MACROMOLECULES   34 ( 5 ) 1172 - 1179  2001.02  [Refereed]

     View Summary

    Methyl phenyl sulfoxide was found to undergo self-polycondensation in triflic acid in the presence of diphenylamine to produce poly(methylsulfonio-1,4-phenylene triflate). Diphenylamine formed a charge-transfer (CT) complex with the hydroxy methyl phenyl sulfonium cation produced by the protonation of the sulfoxide, facilitating the electrophilic substitution reaction of the sulfonium cation onto the carbon atom of the terminal phenyl ring. The obtained polymer is a highly crystalline material whose structure was determined by X-ray analysis using the typical geometric parameters of the sulfoniophenylene dimer and trimer model compounds. The orthorhombic unit cell of the polymer (a = 10.875 Angstrom, b = 10.449 Angstrom, and c = 18.629 Angstrom) contains eight monomeric units. The space group is Pbcn (#60). Two molecular chains along the c axis pass through the unit cell, one through the corner and the other through the center. The crystal structure of the polymer not only revealed a structural relevance to those of oxy- and thiophenylene polymers but also provided support for CT complex formation between the polymer and diphenylamine.

    DOI

  • Synthesis and thermal properties of a polysulfonium salt with a comb-like structure

    K Miyatake, A Haryono, K Oyaizu, E Tsuchida

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   38 ( 8 ) 851 - 859  2001  [Refereed]

  • A new synthetic route to poly(seleno-1,4-phenylene) from selenoanisole

    K Oyaizu, Y Ikai, E Tsuchida

    JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY   38 ( 10 ) 1049 - 1057  2001  [Refereed]

  • Copper-catalyzed oxidative coupling of 2,4,6-trimethylphenol with oxygen

    K Oyaizu, K Saito, E Tsuchida

    CHEMISTRY LETTERS   ( 11 ) 1318 - 1319  2000.11  [Refereed]

     View Summary

    2,4,6-Trimethylphenol was oxidized with oxygen in the presence of (1,4,7-tribenzyl-1,4,7-triazacyclononane)copper(II) chloride as a catalyst to produce exclusively a coupled product stilbenequinone, without the formation of oxygenated products.

  • First synthesis of high molecular weight poly(2,6-difluoro-1,4-phenylene oxide) by oxidative polymerization

    K Oyaizu, Y Kumaki, K Saito, E Tsuchida

    MACROMOLECULES   33 ( 16 ) 5766 - 5769  2000.08  [Refereed]

  • Crystal structures of dimeric manganese(III) complexes of tetradentate Schiff-base ligands with ancillary axial donors

    K Oyaizu, T Nakagawa, E Tsuchida

    INORGANICA CHIMICA ACTA   305 ( 2 ) 184 - 188  2000.07  [Refereed]

     View Summary

    [N,N'-Ethylenebis(salicylideneaminato)]manganese(III) benzoate ([Mn(salen)(O2CC6H5)] crystallized to form a solid-state dimer in which the Mn(salen) moiety is linked to its neighbor by two shared phenolate oxygen atoms, in striking contrast to the linear polymeric structure formed with bridging acetate ligands. A substantial cavity between the two manganese atoms was then produced by the weak coordination of the phenolate oxygen to the neighboring manganese bearing benzoate in a monodentate mode. (C) 2000 Elsevier Science S.A. All rights reserved.

  • Electroreduction of mu-oxo iron(III) porphyrins adsorbed on an electrode leading to a cofacial geometry for the iron(II) complex: Unexpected active site for the catalytic reduction of O-2 to H2O

    K Oyaizu, A Haryono, J Natori, H Shinoda, E Tsuchida

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   73 ( 5 ) 1153 - 1163  2000.05  [Refereed]

     View Summary

    Acidification of a solution of (mu-oxo)bis[(5,10,15,20-tetraphenylporphyrinato)iron(III)] ([{Fe(tpp)}(2)O], II) in CH2Cl2 produced equimolar amounts of a hydroxoiron(III) complex [(tpp)Fe-III(OH)] (III) and an iron(III) complex [(tpp)Fe-III(ClO4)] (TV). The complex IV was isolated as a perchlorate salt, which crystallyzed in the triclinic space group P (1) over bar (#2); a = 11.909(3), b = 19.603(4), c = 10.494(3) Angstrom, alpha = 95.74(2)degrees, beta = 107.91(2)degrees, gamma = 89.14(2)degrees, V = 2319.1(9) Angstrom(3), Z = 2, D-calc = 1.328 g cm(-3), mu(Mo K alpha) = 4.35 cm(-1), final R = 0.055 and R-w = 0.050. The crystal structure of IV revealed that ClO4- is coordinated to the iron atom, which may be driven by the preference of iron(III) to be five coordinate rather than four coordinate. Reduction of the complex II in the presence of acid by electrolysis and/or by a reducing agent, such as sodium dithionite, under argon produced [Fe-II(tpp)]. The addition of O-2 to a solution of [Fe(tpp)] in acidic CH2Cl2 in the presence of an equimolar amount of the reducing agent produced the complex III. When the complex II was adsorbed on an electrode surface and placed in aqueous acidic electrolyte solutions, electroreduction of the adsorbate proceeded according to the half-reaction:
    [{Fe(tpp)}(2)O] +2H(+) +2e(-) --&gt; 2[Fe(tpp)] + H2O, at 0.031-0.059 pH V (vs. SCE, pH &gt; 1.0). Based on these results, ore-bridged iron(III) porphyrin dimers were used as electrocatalysts for the reduction of O-2. The catalytic reduction of O-2 proceeded at potentials in the vicinity of those for II. As a whole, the proportion of H2O as the product increased from 50% for adsorbed [(tpp)(FeCl)-Cl-III] to &gt; 90% for the adsorbed dimer. Thus, electroreduction of the dimer adsorbed on a carbon electrode immersed in aqueous acid produced two solid state, cofacially fixed iron(II) porphyrin molecules:
    [(PFeOFeP)-O-III-P-III](ad) + 2H(+) + 2e(-) --&gt; [pFe(II) Fe(II)p](ad) + H2O (P = porphyrin dianion). Coordination of molecular oxygen to the adjacent two iron(II) centers under acidic conditions allowed formation of O-2-bridged iron(III) porphyrin [PFeIII(O-2) (FeP)-P-III](ad) at the electrode surface. Electroreduction of the adsorbate under acidic conditions produced H2O and allowed the reformation of [PFeII (FeP)-P-II](ad). The implication is that the electroreduction of the adsorbed ore-bridged dimer gives a cofacial geometry for PFeII on the electrode, facilitating the coordination and subsequent splitting of O-2.

  • Synthesis and characterization of nickel dithiocarbamate complexes bearing ferrocenyl subunits

    K Oyaizu, K Yamamoto, Y Ishii, E Tsuchida

    CHEMISTRY-A EUROPEAN JOURNAL   5 ( 11 ) 3193 - 3201  1999.11  [Refereed]

     View Summary

    Syntheses of a unique molecule, nickel(II) dithiocarbamate bearing two ferrocenyl groups (3), and its oxidized product, nickel(IV) dithiocarbamate bearing three ferrocenyl groups (4(+)), are reported. Spectroelectrochemical investigations have shown that the complex 4(+) undergoes a three-electron oxidation process, according to two quasireversible steps ([Ni(IV)(Fe(II))(3)](+) reversible arrow [Ni(IV)(Fe(II))(2)Fe(III)](2+)+e(-), [Ni(IV)(Fe(II)),Fe(III)](2+) reversible arrow [Ni(IV)(Fe(III))(3)](4+)+2e(-)), whose redox potentials are separated by Delta E= 250 mV. The value Delta E is related to the comproportionation equilibrium ( [Ni(IV)(Fe(II))3](+)+[Ni(IV)(FeIII)(2)Fe(II)](3+) reversible arrow [Ni(IV)Fe(III)(Fe(II))(2)](2+)) and results fi-om the combination of a statistical contribution and a term which reflects the electrostatic repulsive interaction between the metal centers. In spite of the chemical equivalence of the three ferrocenyl groups, the mixed-valence state [Ni(IV) Fe(III)(Fe(II))(2)](2+) (4(2+)) substantially persists in solution. Model studies with ethylene-bridged bis(ferrocenylimine) (6) have revealed that the electrostatic term is much lower in the absence of the nickel(IV) center. Preliminary force-field simulations on 4(+) have shown that enhanced electrostatic repulsion caused by the oxidation of the ferrocenyl subunits affects the conformation of the molecule, which results in a significant dimensional increment. Stereochemical features of the molecules are related to the electrostatic interaction and Delta G(0) associated with the comproportionation process is affected by such strong deformation that a decrease in electrostatic repulsion results.

  • High-spin polyphenoxyl based on poly(1,4-phenyleneethynylene)

    H Nishide, T Maeda, K Oyaizu, E Tsuchida

    JOURNAL OF ORGANIC CHEMISTRY   64 ( 19 ) 7129 - 7134  1999.09  [Refereed]

     View Summary

    Rodlike poly(1,4-phenyleneethynylene) fl-substituted with multiple pendant phenoxyls 1 was synthesized by polymerizing 4-bromo-2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethynylbenzene 10a using the catalyst of a palladium-triphenylphosphine complex and cuprous iodide and subsequent heterogeneous oxidation. The corresponding dimer 2 was also synthesized; X-ray analysis of its precursor 4 indicated a linear phenyleneethynylene backbone and twisted dihedral angles of 50 and 77 degrees for the pendant phenol groups, ESR spectra suggested a delocalized spin distribution from the pendant phenoxyl to the backbone. The diphenoxyl 2 had a triplet (S = 2/2) ground state. The spin concentration of the polyphenoxyl 1 could not be increased beyond 0.7 spin/unit due to its low solvent solubility; 1 with a spin concentration of 0.62 had an average S of 3/2.

  • Catalysis of the electroreduction of O-2 to H2O by vanadium-salen complexes in acidified dichloromethane

    E Tsuchida, K Oyaizu, EL Dewi, T Imai, FC Anson

    INORGANIC CHEMISTRY   38 ( 16 ) 3704 - 3708  1999.08  [Refereed]

     View Summary

    Addition of stoichiometric quantities of trifluoromethanesulfonic (triflic) acid to solutions of (VO)-O-IV(salen) (H-2-salen = N,N'-ethylenebis(salicylideneamine)) in dichloromethane produces the mu-oxo dinuclear vanadium(IV) complex [(salen)(VOVIV)-O-IV(salen)](2+) ([(VOVIV)-O-IV](2+)). Addition of significant excesses of triflic acid converts the dimer into [V-IV(salen)](2+). In dichloromethane solutions containing 0.1 M tetrabutylammonium tetrafluoroborate, the [(VOVIV)-O-IV]2+ complex undergoes disproportionation and dissociation reactions to produce a solution containing an equimolar mixture of (VO)-O-IV(salen), [V-III(salen)](+), and [(VOVV)-O-IV](3+). The oxophilic [V-III(salen)](+) complex reacts with O-2 to accomplish a four-electron reduction of O-2: 2[V-III(salen)](+) + O-2 --&gt; 2[(VO)-O-V(salen)](+). These reactions can be exploited to carry out catalytic electroreductions of O-2 to H2O in acidified dichloromethane solutions of (VO)-O-IV(salen) at unusually positive potentials.

  • Molecular structure of a mu-oxo chromium-iron complex: Rare example of a crystallographically characterized mu-oxo heterometallic porphyrin

    K Oyaizu, A Haryono, Y Nishimura, K Yamamoto, E Tsuchida

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   72 ( 8 ) 1781 - 1784  1999.08  [Refereed]

     View Summary

    The crystal structure of a mu-oxo heterometallic porphyrin [(pip)(tpp)(CrOFeIII)-O-III(tpp)] (pip = piperidine) not only confirmed the proposed oxidation state of chromium and iron atoms, but also revealed a unique coordination environment around chromium(III), which is substantially protruded from the porphyrin plane.

  • (mu-peroxo)bis[pyridine(phthalocyaninato)iron(III)] as a convenient catalyst for the four-electron reduction of dioxygen

    K Oyaizu, A Haryono, J Natori, E Tsuchida

    JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS   94 ( 24 ) 3737 - 3742  1998.12  [Refereed]

     View Summary

    A remarkable increase in the selectivity of four-electron reduction of O-2 at an iron phthalocyanine complex adsorbed on a carbon electrode is accomplished by the use of a peroxo-bridged pyFe(III)Pc-O-2-PcFe(III)py (py = pyridine, Pc = phthalocyanine dianion). Electroreduction of the dimer adsorbed on an electrode produced two solid state, cofacially fixed iron(II) phthalocyanine molecules under acidic conditions. Raman studies on the adsorbate revealed the restricted dynamics of the phthalocyanine rings adsorbed on a solid support that was responsible for the facile accommodation of an O-2 molecule between the adjacent two iron(II) atoms. The contrast with the catalytic behavior of a mononuclear iron(II) stems from the formation of a mu-peroxo bond upon the reaction with O-2, which subsequently cleaves under acidic conditions to produce two molecules of H2O.

  • Catalytic behavior of a mu-oxo dimanganese(III) octaethylporphyrin in O-2 reduction

    K Oyaizu, A Haryono, H Yonemaru, E Tsuchida

    JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS   94 ( 22 ) 3393 - 3399  1998.11  [Refereed]

     View Summary

    The electrochemistry of a mu-oxo dimanganese(III) octaethylporphyrin (II) and those of the corresponding mononuclear complexes Mn-III(OEP)Cl (I), Mn-III(OEP)ClO4 (III) and Mn-III(OEP)OH (IV) (where OEP represents octaethylporphyrin) were studied. When complex II was adsorbed on an electrode and placed in aqueous acidic electrolyte solutions, efficient catalysis of the four-electron reduction of O-2 to H2O was accomplished. A control experiment using an electrode modified with the mononuclear manganese(III) complex I resulted in a significant decrease in the selectivity for the four-electron reduction. The hydroxomanganese(III) complex IV was produced in the course of the oxidation of Mn-II(OEP) to Mn-III(OEP)(+) with O-2 under acidic conditions. Complex I was isolated as single crystals and characterized by X-ray crystallography. Although complex II was not isolated as single crystals, the long manganese-axial ligand distance (2.385 Angstrom) in I provided an estimate that a similar geometry would be true for a allowing accommodation of an O-2 molecule between the two manganese atoms in the adsorbed cofacial porphyrins.

  • A novel decavanadium(V) cluster with a chiral framework: [(O = V)(10)(mu(2)-O)9(mu(3)-O)(3)(C5H7O2)(6)] having an approximate C-3 symmetry

    K Oyaizu, E Tsuchida

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   120 ( 1 ) 237 - 238  1998.01  [Refereed]

  • Electrocatalytic reduction of dioxygen to water by a carbon electrode coated with (eta-oxo)bis[(meso-tetraphenylporphyrinato)iron(III)]: a convenient template for cofacially oriented iron(II) porphyrins

    A Haryono, K Oyaizu, K Yamamoto, J Natori, E Tsuchida

    CHEMISTRY LETTERS   ( 3 ) 233 - 234  1998  [Refereed]

     View Summary

    Electroreduction of an ore-bridged iron(III) porphyrin dimer adsorbed on an electrode surface produced solid state, cofacially fixed two iron(II) porphyrin molecules when immersed in aqueous acid, allowing an efficient catalysis of the four-electron reduction of O-2 to H2O.

  • Oxidative polymerization of pyrrole with a vanadium dinuclear complex as a two-electron redox catalyst

    E Tsuchida, K Yamamoto, K Oyaizu

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   438 ( 1-2 ) 167 - 171  1997.11  [Refereed]

     View Summary

    The catalytic oxidation of pyrrole by the [(salen)(VOVV)-O-IV(salen)](3+) cation, which is formed on an electrode surface by the oxidation of [(salen)(VOVIV)-O-IV(salen)](2+), was examined by hydrodynamic voltammetry at a rotating glassy carbon disk electrode. The electron transfer rate constant for the cross-reaction [(salen)VOV(salen)](3+)/pyrrole was estimated to be 4 x 10(4) mol(-1) cm(3) s(-1). O-2-oxidation of the [(salen)VOV(salen)](+) cation gives rise to the catalysis for the O-2-oxidative polymerization of pyrrole. The polymerization was rate-determined by the reoxidation step of the catalyst by O-2. (C) 1997 Elsevier Science S.A.

  • Highly selective oxygen transport through a cobalt porphyrin liquid membrane

    XS Chen, H Nishide, K Oyaizu, E Tsuchida

    JOURNAL OF PHYSICAL CHEMISTRY B   101 ( 29 ) 5725 - 5729  1997.07  [Refereed]

     View Summary

    The facilitated transport of oxygen in a liquid membrane containing [meso-alpha,alpha,alpha,alpha-tetrakis(o-pivalamidophenyl)porphyrinatocobalt(II)]-laurylimidazole (CoP) as an oxygen carrier leads to high permeability and permselectivity of oxygen against nitrogen. The oxygen permeation was properly analyzed by a dual-mode model and using the oxygen-binding constants spectroscopically determined, to give permeation parameters of the membrane such as the diffusion coefficient (D-CoP) of the CoP mobile carrier and the physical diffusion coefficient of oxygen. D-CoP was in accordance with that electrochemically determined. The facilitated permeation was represented by the product of the Cop concentration and D-CoP in the membrane solution. D-CoP decreased with solution viscosity and increased with the measured temperature. High oxygen permeability (10(-7) cm(3)(STP) cm cm(-2) s(-1) cmHg(-1)) was observed, e.g. for the membrane of the 31 wt % CoP methylanisole solution at 10 degrees C, where the facilitation factor and the oxygen/nitrogen permselectivity were over 20 and 40, respectively.

  • Oxidation of disulfides by 4-electron transfer to O-2: A Ru(bpy)(3)(2+)-catalyzed photo-oxidation system for selective formation of polythioethers

    K Yamamoto, K Oyaizu, S Kobayashi, E Tsuchida

    PHOSPHORUS SULFUR AND SILICON AND THE RELATED ELEMENTS   120   407 - 408  1997  [Refereed]

     View Summary

    Tris(2,2'-bipyridine)ruthenium(II) chloride catalyzed the photo oxidative polymerization of diaryl disulfides by O-2, by which poly(thioarylene)s were efficiently produced. The polymerization proceeded through the electrophilic reaction of the sulfonium cation which was produced selectively by the photo-redox system.

  • Role of Multinuclear Complexes in Coordination and 4-Electron Reduction of Dioxygen

    K. Yamamoto, K. Oyaizu, E. Tsuchida

    J. Inorg. Biochem.   67   390 - 390  1997  [Refereed]

  • Catalytic cycle of a divanadium complex with salen ligands in O-2 reduction: Two-electron redox process of the dinuclear center (salen equals N,N'-ethylenebis(salicylideneamine))

    K Yamamoto, K Oyaizu, E Tsuchida

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   118 ( 50 ) 12665 - 12672  1996.12  [Refereed]

     View Summary

    In an attempt to provide confirmation for the postulated mechanism of O-2 reduction in vanadium-mediated oxidative polymerization of diphenyl disulfide, a series of divanadium complexes containing salen ligand (salen = N,N'ethylenebis(salicylideneamine)) were prepared, characterized, and subjected to reactivity studies toward dioxygen. A divanadium(III, IV) complex, [(salen)VOV(salen)][I-3] (II), was yielded both by treatments of solutions of [(salen)-VOV(salen)][BF4](2) (I) in acetonitrile with excess tetrabutylammonium iodide and by electroreduction of I followed by anion exchange with tetrabutylammonium triiodide. The complex II was characterized by a near-infrared absorption at 7.2 x 10(3) cm(-1) (epsilon = 60.1 M(-1) cm(-1) in acetonitrile) assigned to an intervalence transfer band. A crystallographically determined V(III)-V(IV) distance of 3.569(4) Angstrom is consonant with the classification of II as a weakly coupled Type II mixed-valence vandium (alpha = 3.0 x 10(-2)). Oxidation of the cation [(salen)VOV(salen)](+) with O-2 in dichloromethane yielded spontaneously the deep blue, mixed valent, divanadium(IV, V) species [(salen)VOVO-(salen)](+) which was structurally characterized both as its triiodide (III) and perchlorate (IV) sales. Crystal data for III: triclinic space group P (1) over bar (no. 2), a = 14.973(2) Angstrom, b = 19.481(2) Angstrom, c 14.168(2) Angstrom, alpha = 107.00 (1)degrees, beta = 115.56(1)degrees, gamma = 80.35(1)degrees, V = 3561.3(9) Angstrom(3), Z = 4, D-calc = 1.953 g/cm(3), mu (MoK alpha) = 31.74 cm(-1), final R = 0.057 and R(w) = 0.065. Crystal data for IV: triclinic space group P (1) over bar (no. 2), a = 11.923(3) Angstrom, b = 14.25(1) Angstrom, c = 11.368(7) Angstrom, alpha = 112.92(5)degrees, beta = 92.76(4)degrees, gamma = 99.13(4)degrees, V = 1743(1) Angstrom(3), Z = 2, D-calc = 1.537 g/cm(3), mu (CuK alpha) = 57.69 cm(-1), final R = 0.042 and R(w) = 0.061. The complexes III and IV were deoxygenated in strongly acidic nonaqueous media to produce [(salen)VOV(salen)](3+) as a high-valent complex whose reversible two-electron redox couple (VOV3+/VOV+) at 0.44 V vs Ag/AgCl has been confirmed. Its ability to serve as a two-electron oxidant provided a unique model of a multielectron redox cycle in oxidative polymerization.

  • Multielectron redox process of vanadium complexes in oxidation of low-coordinate vanadium(III) to oxovanadium(V) with dioxygen

    K Oyaizu, K Yamamoto, K Yoneda, E Tsuchida

    INORGANIC CHEMISTRY   35 ( 23 ) 6634 - &  1996.11  [Refereed]

     View Summary

    Electroreduction of a vanadium dinuclear complex [(salen)V-IV-O-V-IV(salen)](2+) in the presence of Or resulted in the stoichiometric formation of a [(salen)V-IV-O-V-V-(salen)=O](+) complex. The process provided not only evidence for the interconversion of vanadium(III)/oxovanadium(V) in the action of vanadium complexes operating as redox catalysts, but also possibilities for the use of the vanadium complex as electrocatalysts for the 4-electron reduction of O-2.

  • Multi-electron transfer process of a vanadium dinuclear complex for molecular conversions

    E Tsuchida, K Yamamoto, K Oyaizu

    METAL-CONTAINING POLYMERIC MATERIALS     139 - 149  1996  [Refereed]

  • SYNTHESIS OF REACTIVE FUNCTIONALIZED OLIGO(P-PHENYLENE SULFIDE)S

    E TSUCHIDA, K YAMAMOTO, K OYAIZU, F SUZUKI, AS HAY, ZY WANG

    MACROMOLECULES   28 ( 2 ) 409 - 416  1995.01  [Refereed]

     View Summary

    Modification of the oligo(phenylene sulfide) chain at the ends with reactive groups such as chloro, bromo, iodo, and carboxyl to enhance its reactivtiy was performed. alpha,omega-Dihalooligo(p-phenylene sulfide) was synthesized through the oxidative polymerization of diphenyl disulfide in the presence of bis(4-halophenyl)disulfide. Linear oligo(p-phenylene sulfide) (OPS) terminated by Cl or Br with a high degree of functionality was obtained by a one-pot process. alpha-Carboxy-OPS was synthesized by the thermolysis of the disulfide-bond of the OPS in the presence of an aromatic iodide having a carboxyl group. The carboxy-terminated OPS was used for the synthesis of polyamide-graft-OPS copolymers.

  • Multi‐electron transfer process of vanadyl complexes for oxidative polymerization of diphenyl disulfide

    Kimihisa Yamamoto, Kenichi Oyaizu, Eishun Tsuchida

    Polymers for Advanced Technologies   6 ( 3 ) 155 - 158  1995  [Refereed]

     View Summary

    Oligo(p‐phenylene sulfide) is synthesized by oxidative polymerization of diphenyl disulfide with oxygen catalyzed by vanadyl acetylacetonate under strongly acidic conditions. The mechanistic studies reveal that the redox cycles of the vanadyl complexes give rise to catalysis through a two‐electron transfer between diphenyl disulfide and molecular oxygen. The VO catalysts act as an excellent electron mediator to bridge a 1.0 V potential gap between the oxidation potential of disulfides and the reduction potential of oxygen. The VO‐catalyzed oxygen‐oxidative polymerization provides pure oligo(pphenylene sulfide)s containing an S–S bond. The polymeric product is of low molecular weight due to the insolubility under these conditions. (N,N′‐ethylenebis(salicylideneaminato))oxovanadium‐(IV), VO(salen), was used as an inert model compound to elucidate the redox chemistry of the vanadium complex. VO(salen) reacts with trifluoromethanesulfonic acid (CF3SO3H) or triphenylmethyl tetrafluoroborate (ϕ3C(BF4)) to form a deoxygenated complex, VIV(salen)2+, and a μ‐oxodinuclear complex, [(salen)VOV(salen)]X2, (X = CF3SO3− or BF4−). The dimerization of VO(salen) is initiated by deoxygenation to produce V(salen)2+ which enters into an equilibrium with a second VO(salen) complex to produce the μ‐oxo dimer. The two‐electron transfer of the μ‐oxo dinuclear vanadium complex is elucidated. Copyright © 1995 John Wiley &amp
    Sons, Ltd.

    DOI

  • Preparation of poly(1,4‐phenylene)s by electro‐oxidative polymerization

    Kenichi Oyaizu, Kimihisa Yamamoto, Toshio Asada, Hiroyuki Nishide, Eishun Tsuchida

    Polymers for Advanced Technologies   6 ( 4 ) 254 - 257  1995  [Refereed]

     View Summary

    The effect of substituents on the electropolymerization of benzene derivatives and the redox properrties of the corresponding polymers were determined using Brown's substituent constants (σ+). Electron‐donating groups lower the oxidation potential by which increase in the current efficiency was observed. However, stabilization of the produced cation radicals by the electron‐donating groups resulted in a decrease in the polymerization efficiency. The appropriate values of σ+ for the efficient polymerization ranged near −1.5. Copyright © 1995 John Wiley &amp
    Sons, Ltd.

    DOI

  • SYNTHESIS OF POLY(2,6-DIMETHYLPHENYLENE SULFIDE) BY PHOTOOXIDATIVE POLYMERIZATION

    K YAMAMOTO, K OYAIZU, E TSUCHIDA

    MACROMOLECULAR CHEMISTRY AND PHYSICS   195 ( 9 ) 3087 - 3094  1994.09  [Refereed]

     View Summary

    Photo-oxidation of bis(3,5-dimethylphenyl) disulfide proceeds in the presence of aromatic nitriles as sensitizers. Catalytic amounts of 9,10-dicyanoanthracene act as an electron mediator of the transfer from the disulfide to oxygen in the presence of biphenyl as a co-sensitizer. The photo-redox system enabled an efficient formation of poly(thio-2,6-dimethyl-1,4-phenylene) through electrophilic reaction of the sulfonium cation produced in the photo-oxidation.

  • ACID-PROMOTED ELECTRON-TRANSFER TO FACILITATE OXIDATIVE POLYMERIZATION OF DIARYL DISULFIDES

    K OYAIZU, N IWASAKI, K YAMAMOTO, H NISHIDE, E TSUCHIDA

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   67 ( 5 ) 1456 - 1461  1994.05  [Refereed]

     View Summary

    A catalytic amount of Lewis acids ([Lewis acid]/[Disulfide]=1/200) facilitated electron transfer from diaryl disulfides to a stoichiometric amount of another oxidizing agent by which linear poly[thio(1,4-arylene)] was produced. Such Lewis acids as SbCl5 and FeCl3 facilitated oxidation of diphenyl disulfide by quinones more efficiently than protic acids such as CF3COOH, where the Lewis acid showed more than 200-fold more activity than the protic acid. Oxovanadium complex-catalyzed oxygen-oxidation of disulfides was also facilitated by these Lewis acids. The catalysis of these Lewis acids includes not only the activation of quinones or the oxovanadium complex, but also the lowering of the oxidation potential of the monomers.

  • ELECTROCHEMICAL INVESTIGATIONS OF THE COMPLEXES RESULTING FROM THE ACID-PROMOTED DEOXYGENATION AND DIMERIZATION OF (N,N'-ETHYLENEBIS(SALICYLIDENEAMINATO))OXOVANADIUM(IV)

    E TSUCHIDA, K YAMAMOTO, K OYAIZU, N IWASAKI, FC ANSON

    INORGANIC CHEMISTRY   33 ( 6 ) 1056 - 1063  1994.03  [Refereed]

     View Summary

    Electrochemical confirmation that (N,N'-ethylenebis(salicylidenoaminato))oxovanadium(IV), VO(salen), reacts with trifluoromethanesulfonic acid (CF3SO3H) or triphenylmethyl tetrafluoroborate (Ph3C(BF4)) to form a deoxygenated complex, V(IV)(salen)2+, and a mu-oxodinuclear complex, [(salen)VOV(salen)]X2, (X = CF3SO3- or BF4-) is presented. Cyclic voltammograms of VO(salen) in the presence of CF3SO3H or Ph3C(BF4) exhibit reversible waves with formal potentials near 0.5 and 0.8 V (vs Ag/AgCl). The cathodic wave at 0.5 V is argued to arise from the combined reduction of V(salen)2+ and the mu-oxo dimeric complex and the wave at 0.8 V from the oxidation of the V(salen)2+ complex. The diffusion coefficients of these three complexes in acetonitrile were determined. The dimerization of VO(salen) is initiated by deoxygenation of the V=O center by H+ or Ph3C+ to produce V(salen)2+ which enters into an equilibrium with a second VO(salen) complex to produce the mu-oxo dimer. The kinetics of the second order dimerization reaction were monitored, and the equilibrium contant for the formation of the mu-oxo dimer in acetonitrile was evaluated as 0.7 mM-1.

  • PREPARATION OF POLY(1,4-PHENYLENE) BY OXIDATIVE POLYMERIZATION OF BENZENE WITH 2,3-DICHLORO-5,6-DICYANO-P-BENZOQUINONE

    K YAMAMOTO, K OYAIZU, T ASADA, H NISHIDE, E TSUCHIDA

    CHEMISTRY LETTERS   ( 2 ) 363 - 366  1994.02  [Refereed]

     View Summary

    Oxidative polymerization of benzene with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) under strongly acidic conditions produced structure-defined poly(1,4-phenylene) (PP). Addition of CF3SO3H prior to the stoichiometric oxidation enabled the efficient formation of the protonated sigma-complex of benzene through which linear PP (degree of the polymerization was ca. 30) was produced by the subsequent addition of DDQ.

  • Multielectron Transfer Process and Molecular Conversion

    E. Tsuchida, K. Yamamoto, K. Oyaizu

    Kagaku   49   74 - 75  1994

  • PREPARATION OF POLY(THIO-1,4-PHENYLENE)S BY OXYGEN-OXIDATIVE POLYMERIZATION OF DIARYL DISULFIDES

    K YAMAMOTO, M JIKEI, K OYAIZU, F SUZUKI, H NISHIDE, E TSUCHIDA

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   67 ( 1 ) 251 - 256  1994.01  [Refereed]

     View Summary

    Oxygen-oxidative polymerization of diphenyl disulfides with vanadyl acetylacetonate (VO(acac)(2)) was studied by the kinetics based on oxygen uptake. Lineweaver-Burk plots reveal that the oxidation of diphenyl disulfide is a rate-determining step for the VO-catalyzed oxidative polymerization of diphenyl disulfide. K-m (Michaelis constant) and V-max were determined to be 1.6x10(-2) moldm(-3) and 1.5x10(-4) moldm(-3) min(-1), respectively. The polymerization rate is influenced by the oxidation potential of disulfides. The reoxidation step of the catalyst by oxygen is the rate determining step in case of the polymerization of alkyl-substituted disulfides such as bis(3-methylphenyl)disulfide, bis(2,5-dimethylphenyl) disulfide, and bis (3,5-dimethylphenyl) disulfide because the oxidation step of the disulfides is facilitated due to their lower oxidation potentials.

  • PHOTOOXIDATIVE POLYMERIZATION OF BIS(3,5-DIMETHYLPHENYL) DISULFIDE FOR SYNTHESIS OF POLY(THIOARYLENE)

    K YAMAMOTO, K OYAIZU, E TSUCHIDA

    CHEMISTRY LETTERS   ( 7 ) 1101 - 1104  1993.07  [Refereed]

     View Summary

    Bis(3,5-dimethylphenyl) disulfide was subject to photo-oxidation in the presence of 2,3-dicyanonaphthalene as a sensitizer. The photo-redox system enabled efficient formation of poly(thio-2,6-dimethyl-1,4-phenylene) non-contaminated with metal salt at room temperature through the electrophilic reaction of the sulfonium cation produced by the photo-oxidation.

  • ELECTROCHEMICAL CONFIRMATION OF DISPROPORTIONATION OF MU-OXO-BIS[(N,N'-ETHYLENEBIS(SALICYLIDENEAMINATO))VANADIUM(IV)] TETRAFLUOROBORATE

    K YAMAMOTO, K OYAIZU, N IWASAKI, E TSUCHIDA

    CHEMISTRY LETTERS   ( 7 ) 1223 - 1226  1993.07  [Refereed]

     View Summary

    Mu-Oxo-bis[(N,N'-ethylenebis(salicylideneaminato))vanadium(IV)] tetrafluoroborate is prepared from (N,N'-ethylenebis(salicylideneaminato)) oxovanadium(IV) (VO(salen)) through an electrophilic reaction by triphenylmethyl tetrafluoroborate (Ph3CBF4) in dichloromethane. The voltammetric analysis of the binuclear complex in dichloromethane revealed a one-step two-electron transfer at 0.58V (vs Ag/AgCl) based on the disproportionation (2V(IV)OV(IV) reversible V(III)OV(IV) + V(IV)OV(V)).

  • OXOVANADIUM-CATALYZED OXIDATIVE POLYMERIZATION OF DIPHENYL DISULFIDES WITH OXYGEN

    K YAMAMOTO, E TSUCHIDA, H NISHIDE, M JIKEI, K OYAIZU

    MACROMOLECULES   26 ( 13 ) 3432 - 3437  1993.06  [Refereed]

     View Summary

    Oligo(p-phenylene sulfide) is synthesized through oxygen oxidative polymerization of diphenyl disulfide catalyzed by vanadyl acetylacetonate. The mechanistic studies reveal that two redox cycles [V(M)/V(IV) and V(IV)/V(V)] give rise to catalysis through a 2-electron transfer between diphenyl disulfide and molecular oxygen. The VO catalysts act as an excellent electron mediator to bridge a 1.0-V potential gap between the oxidation potential of disulfides and the reduction potential of oxygen. The VO-catalyzed oxygen oxidative polymerization provides pure oligo(p-phenylene sulfide)s containing an S-S bond. The polymeric product is of low molecular weight due to the insolubility of poly(p-phenylene sulfide) under these experimental conditions.

  • Thermolysis of reactive oligo(p‐phenylene sulfide) containing disulfide bond

    Kenichi Oyaizu, Junya Katoh, Fumiaki Suzuki, Mitsutoshi Jikei, Kimihisa Yamamoto, Hiroyuki Nishide, Eishun Tsuchida

    Polymers for Advanced Technologies   2 ( 3 ) 155 - 159  1991  [Refereed]

     View Summary

    Oligo(phenylene sulfide) (OPS) containing one disulfide bond at the end of the chain, which was obtained by the oxidative polymerization of diphenyl disulfide, had a relatively low Td10%(temperature for 10% weight loss) of 412 °C because of degradation of the disulfide bond. But this thermal cleavage of the disulfide bond promoted the curing reaction through thiophenoxy radical formation. OPS was allowed to react with diiodobenzene at 220 °C. The thermal stability of OPS was improved through the consumption of the disulfide bond and the coupling of the chain. Copyright © 1991 John Wiley &amp
    Sons, Ltd.

    DOI

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Books and Other Publications

  • ハイドロジェノミクス : “水素"を使いこなすためのサイエンス

    折茂, 慎一, 福谷, 克之, 藤田, 健一( Part: Contributor, リチャージャブル燃料電池)

    共立出版  2022.01 ISBN: 9784320044982

  • “Redox-active Polymers as an Organic Energy Storage Material”, Handbook of Conducting Polymers

    K. Oyaizu, H. Nishide

    CRC Press/Taylor & Francis  2019

  • “レドックスポリマー微粒子を活物質として用いたレドックスフロー電池” 『レドックスフロー電池の開発動向』

    小柳津研一

    シーエムシー出版  2017 ISBN: 9784781312620

  • “高分子ラジカル電池”, 『スピン化学が拓く分子磁性の新展開』, CSJカレントレビュー

    西出宏之, 小柳津研一

    化学同人  2014 ISBN: 9784759813760

  • “Organic Batteries”, Encyclopedia of Sustainable Science and Technology, ed by R. A. Meyers

    H. Nishide, K. Oyaizu

    Springer  2012 ISBN: 9780387894690

  • “Polyradicals in Batteries”, Encyclopedia of Radicals in Chemistry, Biology and Materials, ed by C. Chatgilialoglu, A. Studer

    K. Oyaizu, H. Nishide

    Wiley  2012 ISBN: 9780470971253

  • “有機ラジカル電池” 『最先端電池と材料』, 最先端材料システムワンポイントシリーズ

    小柳津研一, 西出宏之

    共立出版  2012 ISBN: 9784320044296

  • “Molecular Catalysis for Fuel Cells”, Energy Production and Storage: Inorganic Chemical Strategies for a Warming World, ed by R. H. Crabtree

    K. Oyaizu

    Wiley  2011 ISBN: 9780470749869

  • “Mesoscale Radical Polymers: Bottom-up Fabrication of Electrodes in Organic Polymer Batteries”, Advanced Nanomaterials, ed by K. Geckeler, H. Nishide

    K. Oyaizu, H. Nishide

    Wiley  2010 ISBN: 9783527317943

  • “芳香族化合物の酸化的ラジカル重合”, 『ラジカル重合ハンドブック』

    西出宏之, 小柳津研一

    エヌ・ティー・エス  2010 ISBN: 9784860432744

  • “Macrocycles for Fuel Cell Cathodes”, Molecular Catalysis for Energy Conversion, ed by T. Okada

    K. Oyaizu, H. Murata, M. Yuasa

    Springer  2009 ISBN: 9783540707301

  • “チエニルポルフィリン類を用いた共役ポリマーの拡張と新機能の開拓” 『次世代共役ポリマーの超階層制御と革新機能』, 赤木和夫監修

    小柳津研一

    シーエムシー  2009 ISBN: 9784781300733

  • “有機ラジカル電池の展望” 『高性能蓄電池』

    小柳津研一, 西出宏之

    エヌ・ティー・エス  2009 ISBN: 9784860432638

  • “フレキシブルラジカルポリマー電池” 『次世代二次電池材料の開発』

    小柳津研一, 西出宏之

    シーエムシー  2009 ISBN: 9784781301792

  • “Heteroacenes and Heterohelicenes: Bottom-up Strategies for Syntheses of Molecular Solenoids and Springs”, Bottom-up Nanofabrication: Supramolecules, Self-assemblies, and Organized Films, ed by K. Ariga, H. S. Nalwa

    K. Oyaizu, M. Yuasa

    American Scientific Publishers  2007 ISBN: 1588830799

  • “錯体系電極触媒”『燃料電池と高分子』, 先端高分子材料ワンポイントシリーズ, 高分子学会燃料電池材料研究会編

    小柳津研一, 西出宏之

    共立出版  2005 ISBN: 4320043693

  • “Multi-electron Transfer and Catalytic Mechanisms in Oxidative Polymerization”, Bioinorganic Catalysis Second Edition, Revised and Expanded, ed by J. Reedijk E. Bouwman

    E. Tsuchida, K. Yamamoto, K. Oyaizu

    Marcel Dekker  1999 ISBN: 0824702417

  • “Multi-electron Transfer Process of a Vanadium Dinuclear Complex for Molecular Conversions”, Metal Containing Polymeric Materials, ed by C. U. Pittman, C. E. Carraher, B. M. Culberston, M. Zeldin, J. E. Sheets

    E. Tsuchida, K. Yamamoto, K. Oyaizu

    Plenum Press  1996 ISBN: 9780306452956

  • “Molecular Conversion Based on Multi-electron Transfer System”, Novel Trends in Electroorganic Synthesis

    E. Tsuchida, K. Yamamoto, K. Oyaizu

    Kodansha, VCH  1995 ISBN: 9784062075039

▼display all

Misc

  • PMSE 433-Radical polymers for organic-based rechargeable device

    Hiroyuki Nishide, Kenichi Oyaizu

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   236  2008.08

    Research paper, summary (international conference)  

  • Involvement of reactive oxygen species in ovulation

    NARIAI Koichi, TSUBOTA Akihito, NAMIKI Yoshihisa, FUJISE Kiyotaka, MURATA Hidenori, OYAIZU Kenichi, YUASA Makoto

      25 ( 2 ) S22  2008.04

    CiNii

  • Microelectrode Studies of Electrochemical Reaction using Supercritical Carbon Dioxide as the Solvent

    D. Komago, H. Yan, T. Sato, A. Yamaguchi, K. Oyaizu, M. Yuasa

    Proceedings of 7th International Symposium on Supercritical Fluids (ISSF2005)    2005.05

  • Copper(II) complexes resulting from the oxygenation of (2,9-dimethyl-1,10-phenanthroline)copper(I) chloride in the presence of dimethylformamide (vol 74, pg 869, 2001)

    K Oyaizu, M Ueno, H Li, E Tsuchida

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   74 ( 12 ) 2463 - 2463  2001.12

    Other  

  • Multielectron transfer of a decanuclear oxovanadium cluster and application to oxygen batteries.

    K Oyaizu, EL Dewi, E Tsuchida

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   220   U467 - U467  2000.08

    Research paper, summary (international conference)  

  • Electroreduction of oxygen to water by vanadium complexes.

    K Oyaizu, EL Dewi, FC Anson, E Tsuchida

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   217   U970 - U971  1999.03

    Research paper, summary (international conference)  

▼display all

Industrial Property Rights

  • 正極材および蓄電デバイス

    小柳津 研一, 西出 宏之, 畠山 歓

    Patent

  • 樹脂組成物

    小柳津 研一, 松島 貫太, 渡辺 青瑚, 高山 央

    Patent

  • 硫黄含有重合体、その製造方法、及び、硫黄含有重合体組成物

    小柳津 研一, 渡辺 青瑚, 松島 貫太, 高山 央

    Patent

  • ポリマー、電極活物質及び二次電池

    小柳津 研一, 西出 宏之, 畠山 歓, 鈴木 美結, 赤羽 智紀

    Patent

  • 燃料電池セル

    小柳津 研一

    Patent

  • 電極材料

    小柳津 研一, 畠山 歓, 赤羽 智紀, 呉 朝逸

    Patent

  • 塩基性主鎖を有する縮環キノン修飾架橋ポリマー、電極活物質、及び二次電池

    小柳津 研一, 西出 宏之, 川井 拓真, 鈴木 美結

    Patent

  • 熱可塑性高分子材料、その製造方法、及び熱可塑性組成物

    小柳津 研一, 平井 元康, 孫 雨舜, 松島 貫太

    Patent

  • レドックスフロー電池システム

    小柳津 研一, 畠山 歓, 菅井 陽太

    Patent

  • 酸素除去用樹脂組成物及び食品保存用フィルム

    西出 宏之, 小柳津 研一, 西上 由紀

    Patent

  • 成形材料及びそれを用いた光学部材、並びに、成形材料の製造方法

    6241881

    西出 宏之, 小柳津 研一, 清川 大地, 永松 健太郎, 四宮 圭亮

    Patent

  • ポリアリーレンスルフィドの製造方法

    6286773

    西出 宏之, 小柳津 研一, 清川 大地, 永松 健太郎, 谷 翔太

    Patent

  • ポリアリーレンスルフィドの製造方法

    6179945

    西出 宏之, 清川 大地, 小柳津 研一, 鷹取 洋平, 永松 健太郎

    Patent

  • ポリアリーレンスルフィドの製造方法

    6179946

    西出 宏之, 小柳津 研一, 鷹取 洋平

    Patent

  • 光電気素子

    5649716

    西出 宏之, 小柳津 研一, 加藤 文昭, 佐野 直樹

    Patent

  • ベンゾジチオフェンキノンポリマー、電荷貯蔵材料、電極活物質、電極、及び電池

    6069787

    原 美代子, 西出 宏之, 小柳津 研一, 向井 拓史

    Patent

  • 電極複合体、及びこれを備える光電気素子

    5947688

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 光電変換素子

    小柳津 研一, 佐野 直樹, 西出 宏之

    Patent

  • ポリアリーレンスルフィドの製造方法

    6052631

    西出 宏之, 小柳津 研一

    Patent

  • ポリアリーレンスルフィドの製造方法

    6052630

    西出 宏之, 小柳津 研一

    Patent

  • 空気電池

    西出 宏之, 崔 源成, 小柳津 研一, 原田 大輔

    Patent

  • 光電気素子

    5957012

    加藤 文昭, 西出 宏之, 小柳津 研一

    Patent

  • 光電気素子及びその製造方法

    6010549

    西出 宏之, 小柳津 研一, 加藤 文昭, 佐野 直樹

    Patent

  • 光吸収材料及び光電変換素子

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 光電気素子

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 光電変換素子

    5639510

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • ジシアノアントラキノンジイミンポリマー、電荷貯蔵材料、電極活物質、電極及び電池

    5700371

    西出 宏之, 小柳津 研一

    Patent

  • 光電気素子、及び光電気素子の製造方法

    5894372

    西出 宏之, 小柳津 研一, 加藤 文昭, 佐野 直樹

    Patent

  • ラジカルを有する化合物、重合体、およびその重合体を用いた蓄電デバイス

    5625151

    西出 宏之, 小柳津 研一

    Patent

  • 光電気素子

    5584447

    小柳津 研一, 西出 宏之, 加藤 文昭

    Patent

  • 光電気素子

    5480552

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 光電気素子

    5400180

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 光電気素子

    5654779

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 光吸収材料及び光電変換素子

    5711470

    西出 宏之, 小柳津 研一, 加藤 文昭

    Patent

  • 平版印刷版の画線部形成用材料、この画線部形成用材料が使用された平版印刷版、この平版印刷版の画線部形成方法及びこの平版印刷版の書換え方法

    5263518

    西出 宏之, 小柳津 研一

    Patent

  • ピロリン系ニトロキシド重合体およびそれを用いた電池

    5527667

    西出 宏之, 小柳津 研一, 川本 健

    Patent

  • メモリ素子

    西出 宏之, 小柳津 研一, 米久田 康智, 尾崎 貴則

    Patent

  • キノンポリマー電極、電荷貯蔵材料、及び電池

    西出 宏之, 小柳津 研一, 崔 源成

    Patent

  • 光電気素子

    5204848

    西出 宏之, 小柳津 研一, 加藤 文昭, 高橋 央

    Patent

  • 蓄電材料およびそれを用いた二次電池

    西出 宏之, 小柳津 研一, 小鹿 健一郎

    Patent

  • 導電性含水ゲル

    西出 宏之, 小柳津 研一, 小鹿 健一郎

    Patent

  • ピロリン系ニトロキシド重合体およびそれを用いた電池

    5424402

    西出 宏之, 小柳津 研一

    Patent

  • 歩行パターン作成装置、2足歩行ロボット装置、歩行パターン作成方法、2足歩行ロボット装置の制御方法、プログラムおよび記録媒体

    高西 淳夫, 石井 裕之, 小柳津 研一, 菅原 雄介, 小鹿 健一郎, 川北 泉, 田中 智明

    Patent

▼display all

Awards

  • Prizes for Science and Technology, The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology

    2013.04  

  • Oleo Science Award

    2007.06   Japan Oil Chemists' Society  

  • Chemical Society of Japqan Award for Young Chemists

    2002.03  

  • Award for Encouragement of Research in Polymer Science; The Society of Polymer Science, Japan

    2001.05  

  • Mizuno Award

    1995.03   Waseda University  

Research Projects

  • 高速移動水素による次世代創蓄電デバイスの設計

    Project Year :

    2018.06
    -
    2023.03
     

     View Summary

    プラスチックフィルム中でプロトンを高速移動させるための構造要件を検討した、スルホフェニレンを側鎖に複数連結してスルホン酸基を高密度導入することにより、バルクのイオン交換容量がほぼ同じであるプラスチックフィルムに比べて親水性が1.4倍、プロトン導電率が4.5倍増大することを見出した。コンパクトな分子構造で密度高いポリビニルフルオレノンを設計・合成し、その電荷および水素の交換反応と水素発生を明らかにした。数wt%の高質量水素密度を期待し、水素付加・脱離体をフルオレノンから窒素複素環式化合物へと拡張したポリビニルキノキサリンを設計・合成し、常圧、80~120℃の温和な条件下で可逆的に水素化・水素発生が起こることを確認した。酸性水溶液を用いたリチャージャブル燃料電池のモデルデバイスとして、電子/プロトン交換反応に基づく有機レドックスポリマーを負極に用いた有機空気二次電池を作製し、予備的な検討ではあるものの500回を超える高いサイクル特性を実証した。界面から移動するプロトンの移動速度をその場で計測する新手法として、遠紫外域の界面選択的分光(Far-UV-ATR)法の確立に取り組み、水素の貯蔵・放出する高分子膜を第一の対象として計測を進めた。水素を付加・脱離した化学状態の違いにより250nm付近に顕著な吸収違いが見られ、この電子遷移を時間依存密度汎関数法で帰属した。さらにIr錯体共存下での加熱による水素発生過程(酸化)、電極からの電子移動と水の付加によるアルコールへの還元過程の観測に成功した。親水性ポリビニルフルオレノンを水素貯蔵性高分子シートとしてアノード側に内蔵することにより、発電と充電を繰り返して行うことができるリチャージャブル燃料電池の原理を計画を前倒して実証した。水素高速移動機能の高度化を推進し、プラスチックフィルム中におけるプロトンの挙動を制御する分子設計および高次構造形成技術を確立し、従来の有機材料に比べて著しく高いプロトン導電率を示す薄膜を達成した。また、これらの成果を他計画研究と融合させることにより発展させ、リチャージャブル燃料電池の原理を計画を前倒して実証することができた。本計画研究では5年間の間に、水素高速移動機能の高度化(ステージⅠ)、学問分野の枠を超えた水素機能の融合(ステージⅡ)、領域全体での多彩な高次水素機能の誘起(ステージⅢ)に順次取り組む。2020年度はステージIIでの研究を進めながら、他計画研究との連携を一層深めながらステージIIIへ移行していく。プラスチック薄膜中におけるプロトン高密度化と高速移動:スルホン酸化ポリフェニレン系高分子において、フェニレン環の置換位置や配列規則性がプラスチックフィルムとしての物性に及ぼす効果を明らかにする。A05-1と連携しながらフィルム中における水の分布を詳細に解析し、高プロトン導電性を示す構造要件を整理する。高分子双安定性を利用した水素の貯蔵・放出の高速・高密度化:水素供与体と受容体が同程度に安定である「双安定性(を有する)高分子」を利用して、水素の貯蔵と放出を高速化・高密度化させることを目指す。A04と連携しながら、例えば二級アルコールとこれから2プロトンが脱離したジアニオンが共に安定構造となるような有機化合物を高分子化して、プロトンの交換反応速度を著しく増加させることを目指す。新規深紫外界面分光(Far-UV-ATR)法による水素貯蔵高分子の構造解析:分担者が開発したFar-UV-ATR法を用いて、電位や雰囲気を厳密に制御した条件下でポリビニルフルオレノンなどの水素貯蔵高分子の構造変化を解明する。電極界面から深さ方向の官能基を定量的に解析し、水素貯蔵・放出過程のその場観察を行う。これらの課題に関して、公募研究との連携も開始して、多様な高次水素機能の発現を加速する

  • Development of Energy Conversion Materials Based on Bistability of Polymers

    Project Year :

    2017.04
    -
    2022.03
     

  • Development of High-density Redox Fluid for Charge Storage

    Project Year :

    2018.06
    -
    2021.03
     

  • Synthesis of Pure and High Molecular-weight Poly(phenylene sulfide) Derivatives and Development of Their Functionality

    Project Year :

    2016.04
    -
    2018.03
     

     View Summary

    Polymerization of diphenyl disulfide (PhSSPh) proceeded in the presence of vanadyl complexes to catalyze the oxidation of PhSSPh with oxygen. Because water decomposed the active form of the catalyst, pricy strong acid anhydrides have been regarded as essential. We solved this problem using molten PhSSPh as the monomer, where the eliminated water was removed by evaporation. This led to the establishment of the process to yield highly pure and high molecular-weight PPS. Calculation results suggested the terminal disulfide functionality, based on the comparison of the HOMO levels and the shapes of their lobes. The reaction was expanded to those with many kinds of diaryl disulfides to yield poly(1,4-arylene sulfide)s (PAS), typically for those containing methyl groups at the phenyl ring. The PAS, derived from bis(3,5-dimethylphenyl) disulfide, showed a high glass transition temperature with the capability of wet processing by virtue of the enhanced solubility in common organic solvents

  • Aromatic Ketone Polymers for A Hydrogen Career

    Project Year :

    2015.04
    -
    2017.03
     

     View Summary

    We have proposed aromatic ketone polymers as a new class of hydrogen careers and elucidated their hydrogen storage property. The fluorenone polymers were synthesized, and highly efficient hydrogenation of the polymers was examined through the electrolytic reduction and successive protonation with water. Quantitative hydrogen evolution from the hydrogenated polymers was measured by heating in the solution containing catalyst, to characterize the aromatic ketone polymers as a hydrogen career

  • Development of Organic Gel Junction Devices for Electrochemical Transistors

    Project Year :

    2014.04
    -
    2016.03
     

     View Summary

    High-density redox polymers with excellent charge-transport properties, based on electron self-exchange reactions in polymer layers, were employed to develop characteristic electrochemical devices for large flux charge transport and rectification at interfaces of dissimilar polymers. Capability of modulating the charge-transport properties as a function of equilibrated potentials gave rise to redox conduction properties determined by applied voltage of a gate electrode, which allowed fabrication of redox transistors. AC current amplification was accomplished with electrochemical circuits containing the redox transistor, by tuning diffusion currents based on rate constants for the exchange reaction and thickness of diffusion layers, potential gaps that dominated cross reaction at polymer/polymer heterojunctions, and molecular design of the electrochemical interfaces

  • Development of Organic Anode-active Polymers for High-density Energy Storage

    Project Year :

    2013.04
    -
    2016.03
     

     View Summary

    Electron-transfer processes of quinones characterized by their electrochemical reversibility and rapid reaction rates were employed to develop organic anode-active materials for energy storage, based on electron self-exchange reactions in the polymer layer. Polymers bearing anthraquinones as pendant group per repeating unit gave rise to highly efficient charge transport properties to allow fabrication of organic rechargeable air battery, giving insight into the nature of n-type charge storage with the polymers. The polymers were developed according to (i) design of novel n-type redox-active groups, (ii) analyses of electron- and ion-transport processes, (iii) precise control of these processes for rectification at heterojunctions, and (iv) establishment of charge storage with polymers characterized by rocking-chair-type migration of electroneutralizing ions and bipolar charging capabilities, which led to (v) rational design of a series of high-density energy-storable polymers

  • 有機ラジカルのSOMO制御による新しい光・電子機能性ポリマーの開拓

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(S))

    Project Year :

    2012
    -
    2016
     

     View Summary

    本研究は、当初計画に基づき、有機安定ラジカル種の可逆的かつ速い電子授受に着目し世界に先駆け合成してきたラジカルポリマーによる高速電荷輸送と高密度電荷貯蔵の発見とその解釈を起点とした、π共役物性に支配される従来の導電性ポリマーから脱却した電子交換反応に基く導電・蓄電物質の基礎科学確立を目指して推進した。計画書記載の研究方針である ①大流束電荷輸送系の創出と ②ヘテロ接合を用いた流束制御 を基軸とした現象の普遍化による学問的深化と、③有機ラジカル種の拡充による超高速化やpnバイポーラ性など新規物性も活用した ④SOMO (Singly Occupied MO)π共役複合系へと一般化する道筋での有機物性化学の新領域開拓を着実に推進した。新型太陽電池や次世代蓄電池など実デバイスに波及する、実践的学術として確立しつつある。本年度の成果を以下に記す。
    1. 電子交換に基づく導電現象の物理化学 (1) 非共役系での導電現象の確立と深化:薄層化(界面積増大)により膜厚を精密制御する方法を、高い交換反応性を有するラジカル種とも組合せ、電荷・イオン伝播の大流束輸送系を構築した。(2) 大流束輸送系の解析:大流束輸送の非平衡熱力学を解明するため、電荷輸送の素過程を様々な解析法により定量的に捉えた。
    2. ラジカルポリマーの合成有機化学 (1) ラジカルポリマーを与える反応有機化学の確立:これまでに確立した重合法を駆使して、分子量、分散度に加え不対電子密度を制御したポリマーを精密合成した。(2) ラジカル不対電子の合成化学による特性制御:従来明らかにして来た安定ラジカル種に加え、pnバイポーラ性を有するフェルダジルやニトロニルニトロキシド、不均一電子移動速度定数が極めて大きいアダマンタン骨格などに拡張し、レドックス電位、電解質膨潤度、対イオンや溶媒の物質移動量と速度の実測より電荷輸送特性を解明した。

  • π共役レドックス融合型エネルギー貯蔵マテリアルの創出

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

    Project Year :

    2013.04
    -
    2015.03
     

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    (1) 律速過程と充放電性能の相関解明:複合電極における電荷の移動抵抗への寄与が推測される素過程として、ポリマー内の自己電子交換、ポリマー/π共役界面での交差電子交換、π共役固体ネットワークの電子移動、π共役固体集電体間の電子移動に分類し、各過程の寄与について電極組成・構造を変えたπ共役/凝縮レドックス融合物質の電気化学応答をもとに解明した。π共役固体の組成を調整した電極の電荷移動抵抗と固体/ポリマー間の接触面積の相関、膜厚の異なる電極における電荷移動抵抗を明らかにした。材質の異なる集電体上に形成された複合電極における電荷移動抵抗の支配因子を明確にした。電荷移動抵抗が充放電特性と直接相関をもつことを実証し、充放電特性向上に向けた活物質の設計指針の一つを導出した。(2) 律速段階における電荷移動の効率向上と高密度エネルギー貯蔵物質としての実証:π共役/凝縮レドックス融合物質に電荷補償系を共存させ、電荷保持力を確かめた。予備知見として明らかにしている高密度レドックスポリマー単独による可逆的エネルギー貯蔵能を、π共役系との分子レベルでの融合により向上させ、従来性能を超えた有機電池を実現した。具体的には、定電流下での平衡電位を参照電極基準で測定し、ポリマーに蓄積される電荷密度を求めた。また、減衰挙動から電荷保持力を含めた速度パラメータを見積もり、電荷貯蔵効率を把握した。電解質中での平衡膨潤度、対イオンや溶媒の物質移動量と速度を実測し、対イオン種や溶媒因子との相関を明確にすることにより、レドックス凝縮系としての特性を解明した。レドックス席の速い外圏的電子移動が、膨潤ゲル中でも大きな速度定数を与えることを実証し、高速電荷輸送可能な機能性界面を分子レベルで創出した。以上を総合し、π共役/凝縮レドックス融合物質を斬新なエネルギー貯蔵材料の一つとして確立した。26年度が最終年度であるため、記入しない。26年度が最終年度であるため、記入しない

  • π共役レドックス融合型エネルギー貯蔵マテリアルの創出

    Project Year :

    2013.04
    -
    2015.03
     

     View Summary

    (1) 律速過程と充放電性能の相関解明:複合電極における電荷の移動抵抗への寄与が推測される素過程として、ポリマー内の自己電子交換、ポリマー/π共役界面での交差電子交換、π共役固体ネットワークの電子移動、π共役固体集電体間の電子移動に分類し、各過程の寄与について電極組成・構造を変えたπ共役/凝縮レドックス融合物質の電気化学応答をもとに解明した。π共役固体の組成を調整した電極の電荷移動抵抗と固体/ポリマー間の接触面積の相関、膜厚の異なる電極における電荷移動抵抗を明らかにした。材質の異なる集電体上に形成された複合電極における電荷移動抵抗の支配因子を明確にした。電荷移動抵抗が充放電特性と直接相関をもつことを実証し、充放電特性向上に向けた活物質の設計指針の一つを導出した。(2) 律速段階における電荷移動の効率向上と高密度エネルギー貯蔵物質としての実証:π共役/凝縮レドックス融合物質に電荷補償系を共存させ、電荷保持力を確かめた。予備知見として明らかにしている高密度レドックスポリマー単独による可逆的エネルギー貯蔵能を、π共役系との分子レベルでの融合により向上させ、従来性能を超えた有機電池を実現した。具体的には、定電流下での平衡電位を参照電極基準で測定し、ポリマーに蓄積される電荷密度を求めた。また、減衰挙動から電荷保持力を含めた速度パラメータを見積もり、電荷貯蔵効率を把握した。電解質中での平衡膨潤度、対イオンや溶媒の物質移動量と速度を実測し、対イオン種や溶媒因子との相関を明確にすることにより、レドックス凝縮系としての特性を解明した。レドックス席の速い外圏的電子移動が、膨潤ゲル中でも大きな速度定数を与えることを実証し、高速電荷輸送可能な機能性界面を分子レベルで創出した。以上を総合し、π共役/凝縮レドックス融合物質を斬新なエネルギー貯蔵材料の一つとして確立した。26年度が最終年度であるため、記入しない。26年度が最終年度であるため、記入しない

  • 非晶質凝縮相を形成する高分子錯体の創出とエネルギー変換・貯蔵素子への応用

    Project Year :

    2012.04
    -
    2014.03
     

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    前年度の研究成果に基づき、高密度レドックスポリマー複合膜における電子移動と、それに伴うイオン輸送の全容解明により、有機光電変換に不可欠な革新的ポリマー・金属錯体複合素子を創出するとともに、金属錯体の光誘起電子・エネルギー移動を組み込んだ電荷分離・輸送系へ拡張し、光電変換能を引き出すことを目的として研究展開した。本年度の成果内容は以下の通りである。(1) n型レドックス席への拡張:n型酸化還元電位と電極反応の速度定数を把握し、酸化チタンのフェルミレベルに近い準位で可逆的な1電子移動を示すn型レドックス席を絞り込んだ。次いでこれらをペンダント置換基として導入した高密度レドックスポリマーを分子量高く合成し、電極修飾膜でn型容量を実測した。(2) n型電荷輸送の確立:酸化チタンのフェルミレベル近傍で可逆的1電子レドックス席を高密度に含有するレドックスポリマーは、励起色素から受け渡された電子を高エネルギー準位を保ったまま輸送でき、自己電子交換により電荷分離距離が顕著に増加するため、逆電子移動による電荷再結合を抑制できることを明らかにした。光電荷分離による起電力発生を実証し、従来にない全有機湿式太陽電池の実現に向けたn型輸送材料として確立した。初年度に得られたn型ポリマー膜に色素として働く金属錯体と電荷補償系を共存させ、光起電力の発生を確かめた。(3) n型ポリマーを用いた光電変換系の確立:透明電極上に形成させたn型ポリマー膜に、金属錯体(色素)を擬不均一系での高密度担持や、それをペンダント基とする高分子錯体の積層により複合した。光照射下での開回路電圧を測定し、蓄積される電荷密度を求めた。また、減衰挙動から逆電子移動を含めた速度パラメータを見積もった。選定されたn型電荷輸送層とp型電荷補償系を共存させたセルを構成し、開放電圧、短絡電流、フィルファクター、光電変換効率を把握し、高い開放電圧を引出した。25年度が最終年度であるため、記入しない。25年度が最終年度であるため、記入しない

  • π共役レドックス融合型エネルギー貯蔵マテリアルの創出

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

    Project Year :

    2013
    -
    2014
     

     View Summary

    本研究は、レドックス活性基を含有する有機ポリマーを活物質とした有機二次電池に関する研究において、物質移動の促進が効率高い電荷拡散に繋がることに基づき、伝導性と蓄電特性を両立しうる斬新な融合物質を創出することを目的とする。一般に蓄電能を有するポリマーは電子伝導性が乏しく、単独で電池容量を確保することは困難であり、有機二次電池を実用可能なレベルに到達させるには、導電助剤の添加による活物質の電気抵抗低減が必要となっている。従来の研究ではポリマー設計に力点が置かれ、分散状態や界面構造、集電体との相互作用など、本質的な構造因子は十分に研究されていなかった。これに対し本研究は、導電助剤であるπ共役有機固体とレドックスポリマーの融合による新材料創製を目指して、界面構造や分散状態などスケールを俯瞰した構造設計によりポリマーの性質を最大限引き出すことを目的とした。電気伝導と電荷輸送を融合させ、材料設計のスケール性を分子レベルからナノ寸法へ拡張し、斬新なエネルギー貯蔵マテリアルを創出するのが狙いである。本年度の具体的な成果を以下に記す。
    (1) 斬新なπ共役/凝縮レドックス融合物質の創出:π-πスタックによりバンドル形成するSWNTを、高密度レドックスポリマーの一つであるポリ(ニトロキシド置換メタクリレート)(PTMA)により分子ラッピングし、導電性を維持しながら高分散体を得た。PTMA被覆したSWNTをPTMA中に均一配置することにより、微量な炭素含有量で導電性ポリマー電極を形成させた。得られた電極が透明性と高速な充放電特性を示すことを明確にし、光電極としての可能性も含め応用範囲を拡大した。(2) π共役/凝縮レドックス融合物質における律速過程の解明:電子授受効率を高める導電助剤として炭素繊維との複合系を含め、集電体上に形成した多様な組成・膜厚のπ共役/凝縮レドックス融合物質における電荷移動を解析した。

  • Development of Organic Memory Devices Using Radical Polymers

    Project Year :

    2009
    -
    2011
     

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    Organic aliphatic polymers bearing a redox-active robust radical pendant per repeating unit have been applied as key materials for organic polymer memo-ries that are viewed as next-generation memory devices. Synthesis of the so-called radical polymers with designed SOMO levels and elucidation of charge injection mechanisms at polymer/metal interfaces allowed fabrication of nonvolatile memories with ON/OFF ratio of more than 10^5, high cycle durability, and excellent bistability. Factors that dominate the electric bistability in response to the applied voltage have been determined, which offered insight into the design principles of entirely organic organic memories. Thin devices made of the radical polymer layers sandwiched by two metal electrodes demonstrated the mem-ory properties at low applied voltages, which were based on the characteristic charge in-jection and transport behaviors found for the radical polymers.

  • ラジカルポリマーゲルを用いた超高速電荷輸送ソフト界面の構築

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

    Project Year :

    2009
    -
    2010
     

     View Summary

    本研究は、有機安定ラジカル種がモノマー単位当たり置換した非共役系ポリマーである「ラジカルポリマー」を用いて、高速かつ高密度の電荷輸送・貯蔵機能をもつ電解質膨潤ゲル膜を創出し、膜の内部における電子移動とそれにともなうイオン輸送現象の全容解明により、革新的電極活物質を創出することを目的とする。特に、これらの支配因子と考えられる膜/電解液界面における物質移動を、ポリマーゲル表面への規則的・階層的構造の導入を手段として効率化する切り口から、大容量の電荷貯蔵に関わるソフト界面の化学を確立する。酸化還元活性なラジカル席が密集した電解液膨潤ゲルを、外部からの電気刺激により酸化状態やDonnan平衡が素早くダイナミックに変化する機能性ソフト界面と捉え、エネルギー分野を志向した材料開拓の切り口から、ソフト界面の分子科学創出の一例として貢献する。
    (1)界面構造制御による炭素フリーの活物質設計
    メソスコピックレベルの規則・階層的構造をポリマーゲル/電解液界面に形成させ、電極面積当たりのレドックス容量と充放電のレート特性を両立させた斬新な機能性ゲルを創出した。光架橋ラジカル膜へのパターニングや相分離を利用したイオン移動チャンネルの導入により、電荷や対イオンの正味の拡散距離を低減させた構造を構築し、ポリマー膜への電荷注入が対イオンによる電荷補償に律速されず、あたかも溶存レドックス種のように素早く応答するソフト界面として確立した。
    (2)電子・イオン輸送現象の解明と制御
    ポリマーのキャスト膜における低次元イオン輸送チャンネルを形成するイオノフォア機能を期待して、ラジカル置換ポリエーテル類へと展開、ラジカル部位の電荷補償カチオン種について、ポリエーテル相互作用に基づく拡散経路を形成させた。有効レドックス層として働くポリマー膜厚を把握し、対イオンの拡散性向上が不活性層低減に繋がることを実証した。

  • ラジカルポリマーゲルを用いた超高速電荷輸送ソフト界面の構築

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

    Project Year :

    2009
    -
    2010
     

     View Summary

    本研究は、有機安定ラジカル種がモノマー単位当たり置換した非共役系ポリマーである「ラジカルポリマー」を用いて、高速かつ高密度の電荷輸送・貯蔵機能をもつ電解質膨潤ゲル膜を創出し、膜の内部における電子移動とそれにともなうイオン輸送現象の全容解明により、革新的電極活物質を創出することを目的とする。特に、これらの支配因子と考えられる膜/電解液界面における物質移動を、ポリマーゲル表面への規則的・階層的構造の導入を手段として効率化する切り口から、大容量の電荷貯蔵に関わるソフト界面の化学を確立する。酸化還元活性なラジカル席が密集した電解液膨潤ゲルを、外部からの電気刺激により酸化状態やDonnan平衡が素早くダイナミックに変化する機能性ソフト界面と捉え、エネルギー分野を志向した材料開拓の切り口から、ソフト界面の分子科学創出の一例として貢献する。(1)界面構造制御による炭素フリーの活物質設計メソスコピックレベルの規則・階層的構造をポリマーゲル/電解液界面に形成させ、電極面積当たりのレドックス容量と充放電のレート特性を両立させた斬新な機能性ゲルを創出した。光架橋ラジカル膜へのパターニングや相分離を利用したイオン移動チャンネルの導入により、電荷や対イオンの正味の拡散距離を低減させた構造を構築し、ポリマー膜への電荷注入が対イオンによる電荷補償に律速されず、あたかも溶存レドックス種のように素早く応答するソフト界面として確立した。(2)電子・イオン輸送現象の解明と制御ポリマーのキャスト膜における低次元イオン輸送チャンネルを形成するイオノフォア機能を期待して、ラジカル置換ポリエーテル類へと展開、ラジカル部位の電荷補償カチオン種について、ポリエーテル相互作用に基づく拡散経路を形成させた。有効レドックス層として働くポリマー膜厚を把握し、対イオンの拡散性向上が不活性層低減に繋がることを実証した

  • エネルギーデバイスを目指した高密度電子輸送材料の創製

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(萌芽研究)

    Project Year :

    2007
    -
    2008
     

     View Summary

    本研究では、負極活物質として電極反応速度が大きく、還元ドープにより高容量が期待できる新規なn型活性ポリマーを設計・合成することを目的とする。具体的には、還元電位と電子移動速度を制御して、n型活性なポリマーを探索した。n型ドープ状態の安定化に働く各種因子を解明し、卑な電位で安定度高く電子貯蔵できるポリマーを合成した。さらに、安定ラジカル種に関する申請者の従来知見を活用し、ニトロニルニトロキシド、フェノキシル、ガルビノキシルおよびセミキノンラジカルへと拡張し、斬新なn型活性物質群として確立した。
    (1)n型ポリマーの合成
    前年度に選定されたn型活性なレドックス席を有するメタ(ア)クリレード、スチレン誘導体などを合成し、対応するポリマーを得た。カルボニル基が隣接位に置換したアシルニトロキシドモノマーは、対応するヒドロキシルアミンを出発物として、酸クロ法により保護基、ビニル基を導入して得た。重合後、ベンゾイル基の脱保護、酸化を経てニトロキシドポリマーを得た。
    (2)n型ラジカルポリマーの拡張
    ガルビノキシルおよびフェノキシルとの関連から、キノン/セミキノンラジカルをレドックス席に有するポリマーを合成した。セミキノンラジカルの安定度の向上と、キンヒドロン生成の抑制が期待できる主鎖型および剛直なペンダント構造を有するポリマーを合成した。
    (3)全有機二次電池の試作
    ポリマー膜内の電子・イオンの拡散過程を解析し、負極活物質と導電性部材との複合化について検討した。

  • Synthesis of Novel Functional Conductive Polymers in Supercritical Carbon Dioxide and their Properties

    Project Year :

    2004
    -
    2006
     

     View Summary

    In this work, we have investigated the electrochemical synthesis of conductive polymers in homogenous supercritical condition. The effects of several factors such as pressure, phase behavior and mass transfer process for the obtained polymer film were examined.
    Thiophene was chosen as a model monomer to electropolymerize in supercritical carbon dioxide (scCO_2). The homogeneous supercritical state was confirmed by the observation of the phase behavior through a high-pressure cell with a viewing window. The conductive polymer film of thiophene synthesized in scCO_2 was characterized with cyclic voltammetry, SEM, Laser microscopy, AFM and four-point probe conductivity. The roughness of the film in that system was decreased with the further addition of CO_2. This result suggested that the low viscosity of scCO_2 play an important role in improving the transfer rate of solvent. The roughness of the film prepared in the homogeneous scCO_2/ acetonitrile (AN) system was reduced compared with that prepared in dichloromethane. The slow growth of the film and the high diffusion rate of the monomer seemed to account for the smooth and flat film formation. Other conductive polymers, polyaniline and polypyrrole, were successfully synthesized in a homogeneous scCO_2/ AN system.
    This electropolymerization system was extended to the polymerization of thienylporphyrin (H23ThTEtP) for the application as a superoxide sensor. The resulting film of H23ThTEtP was characterized using SEM, laser microscopy and AFM. It was revealed that the electropolymerized film in scCO_2 provided flatter, smoother and higher densified active sites than the one electropolymerized in organic solvent.
    The polymerized film as an electrocatalyst was applied to a superoxide sensor. The catalyst displayed selectivity and activity for the oxidation of 02・and showed a linear relationship between current and 02・concentration, which revealed the possibility of quantitative analysis of 02・in vivo. The catalyst showed higher sensitivity than the one electropolymerized in organic solvent.

  • Synthesis of Novel Functional Conductive Polymers in Supercritical Carbon Dioxide and their Properties

    Project Year :

    2004
    -
    2006
     

     View Summary

    In this work, we have investigated the electrochemical synthesis of conductive polymers in homogenous supercritical condition. The effects of several factors such as pressure, phase behavior and mass transfer process for the obtained polymer film were examined.
    Thiophene was chosen as a model monomer to electropolymerize in supercritical carbon dioxide (scCO_2). The homogeneous supercritical state was confirmed by the observation of the phase behavior through a high-pressure cell with a viewing window. The conductive polymer film of thiophene synthesized in scCO_2 was characterized with cyclic voltammetry, SEM, Laser microscopy, AFM and four-point probe conductivity. The roughness of the film in that system was decreased with the further addition of CO_2. This result suggested that the low viscosity of scCO_2 play an important role in improving the transfer rate of solvent. The roughness of the film prepared in the homogeneous scCO_2/ acetonitrile (AN) system was reduced compared with that prepared in dichloromethane. The slow growth of the film and the high diffusion rate of the monomer seemed to account for the smooth and flat film formation. Other conductive polymers, polyaniline and polypyrrole, were successfully synthesized in a homogeneous scCO_2/ AN system.
    This electropolymerization system was extended to the polymerization of thienylporphyrin (H23ThTEtP) for the application as a superoxide sensor. The resulting film of H23ThTEtP was characterized using SEM, laser microscopy and AFM. It was revealed that the electropolymerized film in scCO_2 provided flatter, smoother and higher densified active sites than the one electropolymerized in organic solvent.
    The polymerized film as an electrocatalyst was applied to a superoxide sensor. The catalyst displayed selectivity and activity for the oxidation of 02・and showed a linear relationship between current and 02・concentration, which revealed the possibility of quantitative analysis of 02・in vivo. The catalyst showed higher sensitivity than the one electropolymerized in organic solvent.

  • π共役系剛直鎖ポリヘテロアセン類におけるナノ構造制御と量子秩序

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(若手研究(A))

    Project Year :

    2002
    -
    2003
     

     View Summary

    本研究は、芳香族スルホニウム塩類の親電子置換反応を擬二次元型π共役系高分子の新合成法として確立すると共に、その電子・光電子物性を詳細に解明することを目的とする。特に、歪みの無いπ共役系構造におけるドーピング構造の安定化を、計算と実験の両面から明らかにする。本年度の研究実績は以下の通りである。1.擬二次元π共役系連鎖の基礎物性解析合成されたヘテロポリアセン類(フェノチアジニウム型、チアントレニウム型、フェノキサチイニウム型およびチオフェンラダー型)の吸収スペクトルにおけるπ-π^*遷移吸収波長、吸光係数、薄膜の屈折率、CVにおける酸化還元電位、熱安定度(Tg,Tm,Td)などの基礎物性を正確に測定、これらを構造と相関させて整理した。酸化還元電位は置換基の導入や対アニオンにより調節可能であった。分子軌道計算を援用して、3d-2p共鳴効果、励起エネルギーおよびドーピング構造などを算出、実験結果を反映させながら高伝導体を実現させる有効な分子骨格を決定した。併せて構造明確な低重合度閉環体の性質を計算予測し、ポリマーと共に合成した。2.電子・光電子機能の解明溶液キャスト法により上記4種類のポリスルホニオアセンの成膜試料を作成、4端子法によりバルク電子伝導度を測定、酸化ドーピングによる伝導度向上を実証すると共に、還元ドーピングも可能であることを酸化還元電位から実証した。紫外可視およびESRスペクトルからポーラロン、バイポーラロン生成を確認すると共に、ラジカル濃度の定量からポーラロン状態の安定度を正確に把握した。伝導度の温度依存性から伝導機構を明らかにすると共に、対イオンを変化させて配向試料を作成、YAGレーザを用いて二次非線形感受率を予備的に測定することにより、偏光方向や波長依存性を明らかにした。以上を総合して、新しい物質系である長鎖共役型ポリスルホニオアセンについて、光電子機能に関する基礎的な性質を解明した

  • π共役系剛直鎖ポリヘテロアセン類におけるナノ構造制御と量子秩序

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(若手研究(A))

    Project Year :

    2002
    -
    2003
     

     View Summary

    本研究は、芳香族スルホニウム塩類の親電子置換反応を擬二次元型π共役系高分子の新合成法として確立すると共に、その電子・光電子物性を詳細に解明することを目的とする。特に、歪みの無いπ共役系構造におけるドーピング構造の安定化を、計算と実験の両面から明らかにする。本年度の研究実績は以下の通りである。1.擬二次元π共役系連鎖の基礎物性解析合成されたヘテロポリアセン類(フェノチアジニウム型、チアントレニウム型、フェノキサチイニウム型およびチオフェンラダー型)の吸収スペクトルにおけるπ-π^*遷移吸収波長、吸光係数、薄膜の屈折率、CVにおける酸化還元電位、熱安定度(Tg,Tm,Td)などの基礎物性を正確に測定、これらを構造と相関させて整理した。酸化還元電位は置換基の導入や対アニオンにより調節可能であった。分子軌道計算を援用して、3d-2p共鳴効果、励起エネルギーおよびドーピング構造などを算出、実験結果を反映させながら高伝導体を実現させる有効な分子骨格を決定した。併せて構造明確な低重合度閉環体の性質を計算予測し、ポリマーと共に合成した。2.電子・光電子機能の解明溶液キャスト法により上記4種類のポリスルホニオアセンの成膜試料を作成、4端子法によりバルク電子伝導度を測定、酸化ドーピングによる伝導度向上を実証すると共に、還元ドーピングも可能であることを酸化還元電位から実証した。紫外可視およびESRスペクトルからポーラロン、バイポーラロン生成を確認すると共に、ラジカル濃度の定量からポーラロン状態の安定度を正確に把握した。伝導度の温度依存性から伝導機構を明らかにすると共に、対イオンを変化させて配向試料を作成、YAGレーザを用いて二次非線形感受率を予備的に測定することにより、偏光方向や波長依存性を明らかにした。以上を総合して、新しい物質系である長鎖共役型ポリスルホニオアセンについて、光電子機能に関する基礎的な性質を解明した

  • Precision Synthesis of Poly(thiophene)s by oxidative polymerization

    Project Year :

    2001
    -
    2002
     

     View Summary

    Alkyl-sulfinyl substituted poly(l,2-phenyleneoxide) and poly(1,3-phenylene) are prepared by oxidative polymerization under air to lead them the double-stranded structure via oxidation and superacid-induced intraraolecular condensation. The extended π-conjugation system of the result polymers is also discussed. Additionally, a depolymerization of the polymers consisted of alkylsulfinyl phenols are revealed and applied to the control of molecular weight.
    (1) Synthesis of the helical polymer consisted of condensed thiophene rings. A oxidative polymerization of 4-methoxy-2-methylsulfinylphenol afforded the precursor poly(1,2-phenyleneoxide) with pendant methylsulfinyl groips. The following intramolecular condensation gave the phenoxathiinium-type helical ladder polymer. The absorption maximum and tail in the UV-vis spectrum of the ladder polymer showed bathochromicalfy shift comprable with those of the precursor polymer to suggest the extended π-conjugated planarity even in the helical structure. A Pd catalyzed polymerization of 1,3-benzene bis(boronate) and methylthio substituted 1,3-dibromobenzene provided the corresponding poly(1,3-phenylene). The oxidation and the intramolecular condensation of the pendant groups were carried out to yield the helical ladder polymer. The stricture was characterized by NMR, IR and Elemental analysis, the absorption spectrun revealed the delocalization of the π-electron.
    (2) Study of the polymerization and depolymerization kinetics. In order to control the nolecular weight of the poly (alkylsulfinyl-phenyleneoxide), the condition of depolymerization of poly (2,6-dimethyl-1,4-phenyleneoxide) (PPO) was studied. An addition of 2,6-dimethylphenol and evaluated phenoxy-radicals in the oxidative condition shifted the equilibrium to the depolymerization of the polymer. The molecular weight after the depolymerization depended on the concentration of the terminal OH groups and agreed with the theoretical calculated molecular weight. A presence of the intermediate phenoxy-radical in the ESR and the rate constants from UV-vis spetra indicated the depolymerization of polyfphenyleneoxide) was occurred by the repetitive redistribution.

  • Synthesis of Nitrogen-containing Polymers Using Dinitrogen Splitting

    Project Year :

    1999
    -
    2000
     

     View Summary

    The present research aims at making a catalytic system to allow molecular splitting of nitrogen for molecular conversion of organic molecules. One-step multi-electron transfer complexes were applied for the multi-electron reduction of nitrogen via a μ-dinitrido type complex.
    The four-electron reduction of oxygen catalyzed by a μ-oxo divanadium complex were expanded to the μ-dinitrido complex for the reduction of nitrogen. An effective complex, Nb diethyldithiocarbamate complex was found which formed the desired μ-dinitrido complex upon the reaction with nitrogen. Electrocatalytic reduction of nitrogen was established using the complex.
    The N-N bond splitting reaction was investigated using MO calculations and in-situ electrochemical Raman spectroscopy, which revealed that the multi-electron transfer is fostered by the catalytic system.

  • One-Step Multi-electron Transfer for Molecular Conversion

    Project Year :

    1996
    -
    1998
     

     View Summary

    The research project aims at elucidating the multi-electron transfer process of oxygen molecules incorporated into the macromolecule-metal complexes, in order to establish novel molecular conversion processes which are promoted by the four-electron reduction of oxygen.
    Followings have been established : Detailed analysis of the oxygen splitting reaction by one-step four-electron transfer, establishment of oxidative polymerization facilitated by multi-electron transfer process, elucidation of multi-electron transfer process in molecular assemblies. Based on these results, a general strategy to allow molecular conversions to proceed efficiently by multi-electron transfer process has been provided.
    1. Multi-nuclear metal complexes that show one-step multi-electron transfer processes were synthesized and their structure was determined. A general method to provide a one-step multi-electron transfer was provided.
    2. Oxygen splitting reaction by way of a μ-dioxo intermediate MOM-OO-MOM was established.
    3. Synthesis of novel compounds, polysulfoniums and polythioethers, were established, and their properties were determined in detail.
    4. Structure and properties of molecular assembly systems were elucidated, in terms of photoelectron transfer process.
    5. Synthesis of high molecular-weight polyheteroacenes were established, and their physicochemical properties were determined.

  • Development of Functional Liposomes Modified with Hydrophilic Porphyrins Based on Electrostatic Force

     View Summary

    The present study aimed at development of functionality of liposomes by surface modification with metal complexes using electrostatic interaction, thereby employing the functional liposomes to a variety of catalytic reactions that proceed at the surface of the liposome surface. Hydrophilic metal complexes such as cationic porphyrins substituted with pyridinium, sulfonium, and thophenium groups were synthesized. The metal complexes of these porphyrins with Fe and Mn were immobilized at the surface of the anionic liposomes by electrostatic interaction. The porphyrin complexes were exposed at the surface of the liposomes, in contrast to those reported for many types of porphyrin-bearing liposomes which typically employed hydrophobic complexes to accommodate the porphyrins in the lipid bilayers. The proposed porphyrin-modified liposomes proved to be a new type of functional nanoparticles. For example, the Fe-porphyrin modified liposome underwent catalytic disproportionation reaction of superoide anion radical according to 2O_2+2H^+→H_2O_2+O_2, and also catalyzed the Fenton reation of hydrogen peroxide according to H_2O_2→2OH・. The liposome was sufficientluy small in diameter to be delivered to cells, where it underwent the catalytic reaction related to the active oxygen species, producing the hydroxyl radical HO・to effectively induce apoptosis of the targeted cell. The porphyrin-modified liposome based on the electrostatic effect was shown to be an effective antitumor agent with high tumor cell selectivity

  • チエニルポルフィリン類を用いた共役ポリマーの合成と機能開拓

     View Summary

    本研究は、メソ位3-チエニル基置換されたポルフィリンを用いてポルフィリンとポリチオフェンからなる全共役系の高分子錯体を合成し、連鎖に沿ったポルフィリン環の配向が無秩序から共面配列まで階層的に制御された一連のp共役連鎖を創出することを目的とする。物質移動が顕著に促進される超臨界二酸化炭素中での電解重合により、精密な積層膜を構築する。これを用いて、ポリチオフェン鎖がポルフィリン部位の酸化還元における電子移動経路を提供することを実証し、高効率な電子移動触媒およびエネルギー変換系としての可能性を明らかにする。本研究の結果、類例のない全共役系ポルフィリンーポリチオフェン複合体を提供することに成功し、ポリチオフェンに沿ったポルフィリン環の配列制御や人工格子の構築に展開すると共に、ポリチオフェンを電子伝達経路に用いてポルフィリンのレドックス活性を向上させた。具体的成果を以下に述べる。(1)チエニルポルフィリン類の設計と合成 ポルフィリンーポリチオフェン複合体の単量体としてチエニルポルフィリンを合成し、中心金属を導入した。チエニル基の置換位置の違いに基く生成ポリマーの高次構造の多様性により薄膜物性に差異が生じることを明らかにした。(2)化学酸化重合によるポリマー合成 チエニルポルフィリン類を化学酸化重合し、ポルフィリン配向度の高いHT-HT型ポリマーを得た。ポルフィリン環の立体障害が緩和された共重合体を合成し、立体規則性を保ちながらポルフィリン環の配向度が制御された一連の誘導体に展開した。各種スペクトルからポルフィリンの整列度を解析し、成膜性と導電性を有する配向ポルフィリン集積体として確立した。(3)電解重合による薄膜化 常温常圧下におけるチエニルポルフィリン類の電解重合を経て、超臨界二酸化炭素環境下における電解重合へ展開し、膜厚や配向度が精密制御された高密度ポルフィリン集積膜を作製した。ナノレベルの超構造薄膜を形成しうる材料としての性質を、構造と相関させてまとめた。(4)多重積層膜の構築と機能開拓 超臨界二酸化炭素中で得られる平滑・高密度の導電性薄膜を用いて、膜厚がナノメータレベルで制御された積層構造を構築した。ポルフィリン環に局在するHOMOの高いエネルギーレベルにより極めて高いエネルギーレベルにより極めてp-ドーブ容易なポルフィリン-ポリチオフェン複合体として確立した

  • チエニルポルフィリン類を用いた共役ポリマーの拡張と新機能の開拓

     View Summary

    本研究は、ポリマーのレドックス特性とバルク構造の相関を明らかにし、高効率な電荷貯蔵材料として確立することを目的とする。具体的には、ポルフィリンをレドックスサイトに有する共役系高分子錯体に関する従来知見を拡張し、迅速・可逆なレドックス反応を特徴とする有機レドックス中心に着目、主鎖にペンダント結合させたレドックスポリマーを合成する。機能ユニットの配向が無秩序から規則配列まで階層的に制御された一連の高分子を創出し、高次構造がレドックス部位の活性における電荷補償を支配していることを明確にし、高効率な電荷貯蔵材料として確立する。(1) チエニルポルフィリン類の拡張チエニルポルフィリン類の合成を縦続し、種々の中心金属を導入した。立体規制されたポリマーを得る反応条件を把握し、ポルフィリン配向度を決定した。(2) レドックスポリマーのキャラクタリゼーション可逆な-電子還元を示す有機置換基を探索した。縮合環のレドックスにより可逆な電極反応が期待できるポリマーを創出し、これらの成膜性、導電性等の基礎物性を把握した。(3) 超構造構築と新機能の開拓平滑で高密度の導電性ポリマー薄膜を用いて、膜厚制御された薄膜を基板電極上に形成させ、膜を介した電位・電流応答を解明した。膜内電子移動に由来する触媒機能についても明らかにした。(4) レドックス機能の拡張と電子貯蔵材料への応用レドックス活性が、導電経路に働く主鎖共役系により顕著に向上するとの知見を基に、電極触媒へと応用した。鉄ポルフィリンがスーパーオキシドの酸化触媒となりうることに着目し、不安定ラジカル種の高感度検出について検討した。これらを電子貯蔵部位として用い、電荷貯蔵材料としての性質を解明した。ユニット当り可逆的に1電子移動し、安定度高く高レベルドープ可能であることを実証した

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Presentations

  • 有機ラジカル型色素増感太陽電池の高機能化

    日本化学会第94春季年会 

    Presentation date: 2014.03

  • 創電・エネルギー貯蔵分野における高分子未来技術

    ゴム技術フォーラム, ゴム・エラストマーと資源・エネルギー, 第3回調査委員会 

    Presentation date: 2014.02

  • ラジカルイオン電池の最新動向

    高分子学会第22回ポリマー材料フォーラム 

    Presentation date: 2013.11

  • 有機ラジカル型色素増感太陽電池-電荷輸送の基礎と応用

    光化学協会370-01光化学応用講座, 次世代光電変換技術への応用 

    Presentation date: 2013.10

  • 創電・エネルギー貯蔵分野における高分子未来材料

    第58回高分子夏季大学 

    Presentation date: 2013.07

  • ラジカルメディエータを用いた有機太陽電池

    光機能材料研究会第43回講演会 

    Presentation date: 2013.04

  • 有機ラジカル型色素増感太陽電池

    日本化学会第93春季年会 

    Presentation date: 2013.03

  • Polymers for Energy Storage

    POLYCHAR 21, World Forum on Advanced Materials 

    Presentation date: 2013.03

  • 有機空気二次電池: 蓄電・導電ポリマーとデバイス設計

    平成24年度化学系学協会東北大会, 高分子コロキウム 

    Presentation date: 2012.09

  • 蓄電ポリマーの設計と有機ラジカル電池・空気二次電池への応用

    高分子学会12-3ポリマーフロンティア21 

    Presentation date: 2012.09

  • Radical Molecules as Highly Reactive Mediators for Dye-Sensitized Solar Cell

    The Third International Organic Excitonic Solar Cell Conference (IOESC2012) 

    Presentation date: 2012.09

  • Polymers for Energy Storage Ecomaterials

    The 1st International Symposium on Polymer Ecomaterials (PEM 2012) 

    Presentation date: 2012.08

  • 有機蓄電・創電ポリマーとデバイス設計

    日本化学会第92春季年会 

    Presentation date: 2012.03

  • Polymers for Energy Storage Materials

    HPI-APA International Conference on Innovation in Polymer Science and Technology (IPST 2011) 

    Presentation date: 2011.11

  • 有機空気二次電池: 電気を貯める高分子の設計

    第77回高分子若手研究会 [関西] 

    Presentation date: 2011.11

  • 光空気電池: エネルギーを貯める有機分子の設計

    日本化学会第1回CSJ化学フェスタ (2011世界化学年記念大会) 

    Presentation date: 2011.11

  • High-Density Redox Polymers for Energy Conversion and Storage

    XIX Mendeleev Congress on General and Applied Chemistry 

    Presentation date: 2011.09

  • Radical Block Copolymers for Application to Electro-active Biomaterials

    The 10th China-Japan-Korea Foresight Joint Symposium on Gene Delivery and International Symposium on Biomaterials 

    Presentation date: 2011.05

  • 高密度レドックスポリマーによるエネルギー変換: 有機ラジカル電池と太陽電池

    静岡大学薄膜基板研究懇話会第14回研究発表会 

    Presentation date: 2011.01

  • 有機ラジカル電池

    第41回繊維学会夏季セミナー 

    Presentation date: 2010.08

  • Redox Polymers with Ultimate Site Densities: Soft Electronic Interfaces for Flexible Rechargeable Devices

    Presentation date: 2010.02

  • ラジカルポリマー電池

    第18回ポリマー材料フォーラム 

    Presentation date: 2009.11

  • 有機ラジカル電池: ラジカルポリマーによる電荷の輸送と貯蔵

    第71回武蔵野地区高分子懇話会 

    Presentation date: 2009.11

  • New Material Development in Fuel Cell Technology

    International Conference on Fuel Cell &amp; Hydrogen Technology (CFCHT 2009) 

    Presentation date: 2009.10

  • 有機ラジカル電池:フレキシブルでプリンタブルな有機二次電池

    2008年度印刷・情報記録・表示研究会講座 

    Presentation date: 2009.02

  • Vanadyl Complex Catalysts for New Polymer Syntheses

    Polymer Science Lecture Series, State Key Laboratory of Polymer Physics and Chemistry, Chinese Academy of Sciences 

    Presentation date: 2008.01

  • Organic Radical Batteries with High Power Density

    3rd Global Plastic Electronics Conference and Showcase 

    Presentation date: 2007.10

  • Novel Functionalization of Polythiophene Derivatives

    The Second International Symposium on Polymer Chemistry (PC2006) 

    Presentation date: 2006.06

  • 高分子錯体を用いた燃料電池用酸素還元触媒

    日本膜学会第27年会 

    Presentation date: 2005.05

  • Polythiophenylene Synthesis through Multi-electron Transfer Processes

    IUPAC 10th International Symposium on Macromolecule-metal Complexes (MMC X) 

    Presentation date: 2003.05

  • Polythiophenylene Synthesis through Multi-electron Transfer Processes

    International Symposium on Biotechnology, Metal Complexes and Catalysis (BMC) 

    Presentation date: 2002.11

  • ポリヘテロアセンの合成と機能

    第51回高分子年次大会 

    Presentation date: 2002.05

  • μ-オキソ不均化錯体系の多電子過程を利用した新機能物質合成法の確立

    日本化学会第81春季年会 

    Presentation date: 2002.03

  • Electroreduction of mu-Oxo Dinuclear Porphyrins Adsorbed on an Electrode Leading to a Cofacial Geometry: Active Site for the Reduction of O2

    Materials Science &amp; Technology Cooperation Workshop (MATEC Bremen) 

    Presentation date: 2000.06

▼display all

Specific Research

  • 高耐熱・結晶性エンプラの精密3D造形を目指した革新的相溶化法の開拓

    2019  

     View Summary

    本研究は,ポリフェニレンスルフィド(PPS)の機能展開を目指し, PPSの三次元(3D)プリンティング造形の鍵になりうる新しい高分子物質を開拓することを目的とした。モノマーであるジフェニルジスルフィドにメチル基,エチル基,メトキシ基,アルケニル基を導入し,対応するポリマーを直鎖かつ成形加工可能な高分子量体として得た。2,6-位にアルキル基を有する場合,PPSは完全非晶質になりポリスチレンとの相溶性を獲得することを明らかにしている。今回得られたPPS誘導体も同様の相溶性を示した。アルケニル基の反応性により無機酸化物との親和性が向上し,コンポジット材料として展開できることも明確にした。

  • 低環境負荷型合成プロセスによる超高屈折率ポリマーの創出

    2018  

     View Summary

    本研究は,申請者らが見出した芳香族ジスルフィド類の酸化重合をさらに追究し,ポリフェニレンスルフィド誘導体をはじめとしたポリチオエーテル高分子の革新的合成法として幅広く確立するとともに,低環境負荷かつ省エネプロセスでの芳香族系耐熱性高分子材料の合成法として定着させることを目的として展開した。特に,従来にない透明かつ高屈折率の機能性光学樹脂を創出することを目指した。この結果,従来の芳香族求核置換反応機構に基づく重縮合では困難とされたアルキル置換基を有する新規PPS誘導体が酸化重合で簡単に合成できることを確立した。これらが完全非晶質の耐熱性固体を与えることを明らかにし,熱特性を兼ね備えた透明光学樹脂としての展開と合わせ,関連する無定形高分子固体における電荷・イオン輸送の解明にも役立つ知見を得た。

  • 電極活物質に用いる高度機能性バインダーの研究開発

    2016  

     View Summary

     本申請は、ラジカルポリマーに関するこれまでの研究で見出された有機系活物質の酸化還元に伴う制御可能な膨潤・収縮過程を、全く新しいバインダー材料として応用する着想で、活物質の充放電に伴う体積変化を補償する高度機能性バインダーを創出することを目的とした。特に、酸化・還元と膨潤・収縮の両状態を自在かつ可逆的にコントロールできる新規バインダー材料として、スルホン酸基を含有させたニトロキシドラジカルポリマーが従来のp型とは異なる電解質カチオンによる電荷補償過程(n型過程)を示すことの発見に基づき、その具体例を展開した。 &nbsp; &nbsp;

  • 電荷分離・輸送制御による人工光合成システムの構築

    2015  

     View Summary

    本研究は、可逆的な酸化還元を示すレドックス席を密度高く有するレドックスポリマー、すなわち高密度レドックスポリマーが形成する膜における電子移動と、それに伴うイオン輸送の解明により、水の光分解に資する電荷輸送物質を創出するとともに、レドックス/色素複合分子による光電荷分離系へ拡張し、人工光合成モデルとしての可能性を明確にすることを目的とした。このような分子組織体を電荷輸送層に利用したセルを予備的に試作した。さらに、光電荷分離・輸送性を高めた新しい高密度ポリマーの設計により、光反応系としての効率を向上させる因子を明確にした。これらの知見を総合し、人工光合成モデルを構成する光電荷分離・輸送材料としての具体化の可能性を明らかにした。

  • 電荷分離・輸送分子の組織化による新しい光電変換系の構築

    2015  

     View Summary

    本研究は、有機二次電池の具体化に不可欠な高特性の電極活物質を創出するとともに、色素分子の複合化により、光電変換能を引き出すことを目的とした。特に、これらの支配因子と考えられる膜/電解液界面における物質移動を、レドックス基と化学結合させた色素分子を用いて効率化する切り口から、光電荷分離に関わる基本的な性質を引き出すことを試みた。その結果、これらと電解質の界面に配置させた色素部位の増感反応を活用し、効率高い有機太陽電池を試作・動作実証することが可能となった。さらに、光電荷分離・輸送性を高めた新しいポリマーの設計 (例えば色素準位とマッチさせたポテンシャル勾配の形成など) により、光電変換系としての変換効率を向上させた。これら基礎的追究から得られる知見を総合し、有機太陽電池を構成しうる斬新な光電荷分離・輸送材料としての可能性を明確にした。

  • 電荷分離・輸送分子の組織化による新しい光電変換系の構築

    2014  

     View Summary

    本研究は、有機二次電池の具体化に不可欠な革新的電極活物質を創出するとともに、色素複合分子の組織化による効率高い光電変換能を引き出すことを目的として研究展開した。具体的には、これらの支配因子と考えられる膜/電解液界面における物質移動を、規則的・階層的な集合組織の構築を手段として効率化する切り口から、光電荷分離に関わる協働機能を引き出した。次いで、この複合組織体と電解質の界面に配置させた色素部位の増感反応を活用し、有機太陽電池を試作して動作実証した。さらに、光電荷分離・輸送性を高めた新しいポリマーの設計により、光電変換系としての変換効率を向上させた。

  • 光蓄電デバイスの遍在性向上に資する大流束電荷輸送レドックス系の創発

    2014  

     View Summary

    本研究は、高密度レドックスポリマーによる電荷輸送の概念を拡張し、新たに有機色素を組み込んだ複合系を対象として、遍在型電源の例示である有機光・空気二次電池の実現に必須となる革新的電荷分離・輸送・貯蔵ポリマーを創出することを目的とした。光反応の支配因子と考えられる界面における電荷分離効率を、分子レベルでの色素複合体形成を手段として高める切り口から、有効な光化学系の構築に関する基礎知見を集積した。高密度レドックスポリマー内の電子移動機構に立脚した分子設計により、高い電荷分離・輸送効率で蓄電にも対応できる色素複合レドックスポリマーの実例を拡張し、斬新な光機能負極を有機系新物質として確立した。

  • キノイド系有機負極を用いた超高密度エネルギー変換系の創発

    2012  

     View Summary

    キノン類の速い電子授受に着目し、アントラキノン置換ポリマーによるn型電荷輸送の実現とこれを負極とする有機空気二次電池の実証を起点として、卑な電位での電子交換反応に立脚した導電・蓄電現象に関わる基礎科学を確立することを目的とする。具体的には、有機負極として働くポリマーの拡充を斬新なn型レドックス席の創出と電荷輸送・貯蔵過程における電子・イオン輸送の解明を基軸とした普遍化により計り、ヘテロ接合面のボトムアップ集積に立脚した高速輸送性および界面での交差反応に基く整流性発現を、ロッキングチェア型電荷補償やpnバイポーラ性を持たせた多様な電荷貯蔵形態の実証を経て超高密度蓄電物質の創出へと繋げ、化学・電気エネルギー変換に関連した有機物性化学の新領域を開拓することを目指して研究展開した。この結果、負電荷の高密度蓄積すなわちn型ヘビードーピングが可能な斬新なn型レドックス席と主鎖構造を絞り込み、形成されるレドックス勾配から電荷輸送の駆動力を引き出すための方法論を導出できた。また、レドックス席間の電荷・物質移動過程を解析し、電子交換をポリマー内で連続的に生起させ、可逆的・高速かつ高密度な電荷貯蔵の要件を明確にした。さらに、レドックス凝縮相による電荷輸送の概念を拡張し、分子細線としての共役鎖を組込んだ複合系に踏み込むための手掛かりを明確にした。以上を組み合わせて、n型ポリマーをLi負極と組合せたロッキングチェア型電荷補償による高エネルギー密度化、pnバイポーラ性に基づく極性フリーの電荷貯蔵形式、酸素極と組合せた空気二次電池、光負極を導入した光空気二次電池など、多様な蓄積形態が可能な電荷貯蔵物質としてのアイデアを確立した。このような非共役キノイドポリマーを活物質とする概念自体は新規性が高く、有機空気電池の実証を成功例として展開し成果集積の道筋をつけた。電極反応や光反応の多くが一電子移動に基づき不安定なラジカル種を経由する点に着目し、電荷保持力や化学安定度を高める観点から2電子反応に焦点を絞る発想に学術的意義を期待している。有機ポリマー合成を手段とすることにより、無機材料にない光・電気応答の実現、高密度・高速化を具体化するとともに、ポリマー内の迅速かつ可逆的な電荷・物質移動を制御し、高密度エネルギー変換をソフトマテリアルの応用の一つとして位置づけることが可能となってきている。

  • ラジカルポリマーを用いた電荷分離・輸送ソフト界面の構造制御と光電変換系の構築

    2011  

     View Summary

    ニトロキシド、ニトロニルニトロキシド、ガルビノキシル、フェルダジル、トリアリールアミニウム、2,6-ジ-tert-ブチルフェノキシルラジカルなどの有機安定ラジカル種を繰返し構造単位当たりにペンダント置換基として有する非共役ポリマーであるラジカルポリマーを、電荷輸送および貯蔵材料に利用し、色素と組合せた分子レベルの光電荷分離界面を構築することによって、効率高い光電変換系の構築に取り組んだ。ラジカルポリマー膜における電子移動と、それに伴うイオン輸送現象の全容解明により、有機二次電池の具体化に不可欠な革新的電極活物質を創出するとともに、色素を組み込んだ光電荷分離・輸送系へ拡張し、光電変換能に基づく新型有機太陽電池を試作、動作実証することにより、その効果を明らかにした。特に、これらの支配因子と考えられる膜/電解液界面における物質移動を、ラジカルポリマーゲル表面への規則的・階層的構造の導入を手段として極限まで効率化する切り口から、光電荷分離に関わるソフト界面の化学として一般性高い知見を確立した。研究期間内に、安定ラジカル種の電気化学・磁気的性質、ラジカルポリマーでの蓄電に関わる諸現象の解明、ラジカルポリマーゲル/電解質界面に配置させた色素の増感反応の実証に焦点を絞り、新規ポリマー合成を中心とした具体的成果を集積した。この結果、インドリン系有機色素、ルテニウム錯体色素を単一分子レベルで制御しながらポリマー界面に配置させた電荷分離界面で、吸収波長と吸光度、内部変換効率、太陽電池セルでの開放電圧、短絡電流密度、フィルファクターとの相関を詳細に解明し、色素の励起電子受容とメディエータ分子による連続的再生が全体の光電変換効率を支配していることを明らかにすると共に、密集したラジカル分子が光電荷分離の頻度因子を増加させ、効率高い光電変換系を可能とすることを明らかにした。メディエータ分子およびラジカルポリマーのエネルギー準位は化学構造により自在設計可能であり、従来の湿式太陽電池と比べて一層の効率向上を可能とする有機分子ならではの自由度を有することを、これら全有機太陽電池の優位性の一つとして確立した。

  • 高密度電荷分離・輸送ポリマーの創製

    2009  

     View Summary

    レドックス活性なポリマー膜への電荷注入は、濃度勾配に基づく拡散による電荷輸送と、電荷補償する対イオンの注入・放出を伴う。膜内輸送現象の包括的な制御により、固体膜本来のレドックス活性を引き出すことが、界面での電荷分離とバルク相への輸送を可能とするための課題となっている。本研究は、レドックス席を高密度で含有するポリマーのメソスコピックレベルの超構造構築とその分子レベルでの精密制御を手段とする輸送現象の全容解明により、斬新なエネルギー変換・貯蔵材料としての具体化を目指している。ポリマー膜の電荷輸送性を向上させるには、対イオンの構造制御や膨潤性の調節によりその拡散性を高めると同時に、レドックス席当りの当重量を抑え、レドックス席間の二次反応である自己電子交換を速くする必要がある。この指針に沿って、ニトロキシラジカル/オキソアンモニウムカチオンのレドックス対が、安定な高速レドックス応答を示すと共に当重量を極限まで小さくできることを明らかにした。以下に具体的に述べる。(1) ニトロキシラジカルポリマーをはじめとするレドックスポリマー内の輸送現象を解明した。有限厚み層への電荷注入、拡散による電荷輸送、低振動数域での電荷飽和 (レドックスキャパシタンスの発生) を解析し、構造や基礎物性との相関を明らかにした。(2) イオン種の溶媒和半径、ポリマー/溶液界面における (脱) 溶媒和とDonnan平衡に関する検討から迅速応答する電荷補償イオン種を選定し、電荷輸送の見かけの拡散定数を用いて移動度を定量的に把握した。(3) 有機レドックス席を高密度に導入したポリマーを合成し、溶媒和状態の制御によりイオン輸送チャンネルを形成できることを見出した。これを元に、ポリマー膜への電荷注入が対イオンによる電荷補償に律速されず、あたかも溶存レドックス種のように応答する物質系として確立した。(4) 膜内レドックス席の高密度化と自己電子交換の高速化により輸送性が顕著に向上することを実証した。

  • 電子濃縮キノイドポリマーの創製と電極活物質への応用

    2008  

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    n型レドックス活性な酸化還元席であるイミドやアントラキノンから誘導されるアニオンラジカルの化学安定度を増加させ、斬新なレドックス活性種として確立することにより、卑な電位で電気化学的に可逆応答を示す新しいレドックスポリマーを創出した。イミド類は、-1 V vs. Ag/AgCl 付近で一電子還元され、アニオンラジカルの後続反応抑制に効く非プロトン性条件下において、可逆性高いレドックス応答が電気化学計測により実証された。一方、キノン類の二電子移動は、同条件下-0.8~-1.2 Vにおいて段階的に (異なる酸化還元電位で二段階にて) 生起し、セミキノンラジカルQ-・への第一還元波 (Q + e- = Q-・)に続きジアニオンを与える第二波 (Q-・ + e- = Q2-) が観測された。これらの有機電極反応を可逆性高く生起させるには、キノン酸素原子との水素結合形成が有効な手段であることを一般性高い知見として確立した。電荷貯蔵材料すなわち二次電池の電極活物質として長期使用に耐えうる化学安定性を具えた骨格として、イミド骨格に加えキノン類の中で突出した化学安定度を示すアントラキノン骨格に着目し、水素結合を安定度高く分子内で形成させるため、酸素原子の隣接位にアシルアミノ基などのプロトンドナー性置換基を導入したモデル化合物を合成した。分子内水素結合を構造データ (各種NMR、単結晶X線構造解析など) から実証すると共に、アニオンラジカルの安定化に寄与していることを結合次数の解析から実証した。電極反応速度に相当する不均一系電子移動速度を幅広く実測し、溶媒因子などとの相関を明確にした。電子移動速度は、サイクリックボルタンメトリーを用いたNicolson法、Tafelプロットによる交換電流密度i0, ACインピーダンス測定によるナイキストプロットなどから定量し、電極表面の微細構造、吸着種の有無も含め詳細に解明した。

  • レドックスポリマーの相分離制御に基づく高速・大容量エネルギー貯蔵材料の創製

    2007  

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    ポリビニルフェロセン膜やレドックス活性な対イオンを導入したNafion膜などにおいて、膜内電荷輸送はイオン移動に律速されることが知られている。Ansonらは拡散輸送の高速化に取り組み、親水・疎水型ブロックコポリマーをマトリクスとするナノ相分離系で、拡散係数の3桁上昇を達成している。低次元イオン伝導を可能とする規則的なイオンチャンネルの構築など、ポリマーの特性向上につながる方法論が進歩している一方、導電性ポリマーはエネルギー容量が小さく、レドックス反応の遅いジスルフィド類はレート特性に劣るため、電極活物質としての高速・大容量化に向けて新しい設計コンセプトが待望されている。代表者らは、ニトロキシラジカル/オキソアンモニウムカチオンのレドックス対が、安定な高速レドックス応答を示すと共に当重量を小さくできる点に着目し、イオン拡散チャンネルを精密設計することによって、レドックス容量を極限まで引き出せると着想した。本研究は、ニトロキシラジカルポリマーをはじめレドックスポリマー内の輸送現象を詳細解明すること、有限厚み層への電荷注入、拡散による電荷輸送、低振動数域での電荷飽和現象を分離して解析し、構造や基礎物性との相関を明確にすること、イオン種の溶媒和半径、ポリマー/溶液界面における溶媒和に関する検討から迅速応答する電荷補償イオン種を選定、電荷輸送の見かけの拡散定数を用いて移動度を定量的に把握することを目的として推進した。以下に成果概要を記す。(1) 膜内輸送現象の解明レドックスポリマー膜内の電荷の拡散輸送過程を交流インピーダンス法により解析し、電荷移動に支配される高振動数域、膜の有限厚みによるレドックス容量が観測される低振動数域と分けて定量化した。等価回路を用いた解析から電荷移動抵抗を求め、様々な材質の電極基板を用いて表面構造がポリマーとの接触界面に与える影響を明らかにした。ポリマー膜中の電荷移動を支配する抵抗成分を、高振動数域の複素インピーダンスから求め、ポリマーの一次構造や膨潤度との相関を解明した。等重量が小さく電極反応の可逆性が高いポリマーを代表例として、物質移動パラメータを電極界面における平衡状態の関数として求め、高速パルスアンペロメトリーの解析とあわせ、膜内輸送現象の全容を解明した。次に、膜内を拡散するイオン種の溶媒和半径、溶液との界面における溶媒和エネルギーに関する基礎的検討から、対イオンの拡散が電荷輸送と直接関連していることを実証した。セルフドープ型ポリマーの設計と合成も含め、幅広いイオン種の拡散挙動を電荷輸送の見かけの拡散定数を用いて定量的に把握した。(2) イオン拡散過程の制御法の確立さまざまな主鎖構造のポリマーを合成し、一次構造と膨潤度の相関を追究し、レドックスサイト間距離を考慮して膜内における効率高い自己電子交換反応の存在を明確にした。イオンの拡散性を十分高めることにより、ニトロキシラジカルなどのレドックス席への電荷注入が対イオンの追随にほとんど律速されず、自己電子交換による電荷の拡散輸送が溶液中と同様に効率よく進行する物質系として確立した。

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Syllabus

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Committee Memberships

  • 2022.02
    -
    2023.02

    日本化学会第12回化学フェスタ実行委員会  実行委員

  • 2020.06
    -
    2022.05

    高分子学会国際交流委員会  第35期委員

  • 2020.06
    -
    2022.05

    高分子学会関東支部  第35期常任幹事

  • 2020.04
    -
    2022.03

    高分子学会水素•燃料電池材料研究会  第35期運営委員

  • 2020.04
    -
    2022.03

    高分子学会超分子研究会  第35期運営委員

  • 2021.01
    -
    2022.02

    日本化学会第11回化学フェスタ実行委員会  実行委員

  • 2018.08
    -
    2021.07

    MRS Communications  Advisory Board

  • 2019.05
    -
    2021.05

    日本化学会  理事

  • 2020.01
    -
    2021.02

    日本化学会第10回化学フェスタ実行委員会  実行委員

  • 2018.06
    -
    2020.05

    高分子学会  理事

  • 2018.06
    -
    2020.05

    高分子学会関東支部,  第34期常任幹事

  • 2018.04
    -
    2020.03

    高分子学会超分子研究会  第34期運営委員

  • 2018.04
    -
    2020.03

    高分子学会水素•燃料電池材料研究会  第34期運営委員

  • 2019.02
    -
    2020.01

    日本化学会第9回化学フェスタ実行委員会  実行委員

  • 2018.02
    -
    2019.01

    日本化学会第8回化学フェスタ実行委員会  実行委員

  • 2016.11
    -
    2018.05

    高分子学会関東支部23区懇話会  世話人

  • 2016.06
    -
    2018.05

    高分子学会関東支部  第33期常任幹事

  • 2016.04
    -
    2018.03

    高分子学会超分子研究会  運営委員長

  • 2016.04
    -
    2018.03

    高分子学会水素•燃料電池材料研究会  第33期運営委員

  • 2016.04
    -
    2018.03

    高分子学会超分子研究会  第33期運営委員長

  • 2017.03
    -
    2018.02

    日本化学会関東支部  支部長

  • 2017.03
    -
    2018.02

    日本化学会第7回化学フェスタ実行委員会  実行委員

  • 2015.03
    -
    2018.02

    日本化学会高分子ディビジョン  幹事

  • 2015.06
    -
    2017.05

    高分子学会  第32期 (後期) 行事委員

  • 2016.03
    -
    2017.02

    日本化学会関東支部  副支部長

  • 2016.03
    -
    2017.02

    日本化学会第6回化学フェスタ実行委員会  実行委員

  • 2014.08
    -
    2016.05

    日本化学連合企画委員会  企画委員

  • 2014.06
    -
    2016.05

    高分子学会関東支部  第32期常任幹事

  • 2014.04
    -
    2016.03

    高分子学会燃料電池材料研究会  第32期運営委員

  • 2014.04
    -
    2016.03

    高分子学会超分子研究会  第32期運営副委員長

  • 2015.03
    -
    2016.02

    日本化学会関東支部,  幹事・事業企画委員会委員長

  • 2015.02
    -
    2016.02

    日本化学会第5回化学フェスタ実行委員会  実行委員

  • 2014.03
    -
    2015.02

    日本化学会関東支部  幹事・事業企画委員会副委員長

  • 2014.02
    -
    2015.02

    日本化学会第4回化学フェスタ実行委員会  実行委員

  • 2012.06
    -
    2014.05

    高分子学会関東支部,  第31期常任幹事

  • 2012.04
    -
    2014.03

    高分子学会燃料電池材料研究会  第31期運営委員

  • 2012.04
    -
    2014.03

    高分子学会超分子研究会  第31期運営委員

  • 2013.02
    -
    2014.02

    日本化学会第3回化学フェスタ実行委員会  実行委員

  • 2010.04
    -
    2012.03

    高分子学会超分子研究会  第30期運営委員

  • 2009.04
    -
    2011.03

    高分子学会燃料電池材料研究会  第30期運営委員

  • 2007.04
    -
    2009.03

    高分子学会燃料電池材料研究会  第29期運営委員

  • 2006.06
    -
    2008.05

    高分子学会  第28期行事委員

  • 2006.04
    -
    2008.02

    電気化学会関東支部  幹事

  • 2005.04
    -
    2008.02

    日本化学会コロイドおよび界面化学部会  事業企画委員

  • 2005.02
    -
    2007.02

    Electrochemistry  Editorial Board Member

  • 2004.03
    -
    2005.02

    日本化学会コロイドおよび界面化学部会  幹事・事業企画委員

  • 2000.08
     
     

    Polymers for Advanced Technologies (John Wiley & Sons)  Editor, Special Issue for The 5th International Symposium on Polymers for Advanced Technologies

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