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AMPHIPHILIC COPOLYMERS AS MEDIA FOR LIGHT‐INDUCED ELECTRON TRANSFER‐II. ELECTROSTATIC EFFECT ON THE BACK ELECTRON TRANSFER
Author(s) -
Itoh Yoshihiro,
Morishima Yotaro,
Nozakura Shunichi
Publication year - 1984
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1984.tb03897.x
Subject(s) - photosensitizer , triethanolamine , electron transfer , chemistry , photochemistry , monomer , viologen , copolymer , redox , electrochemistry , aqueous solution , polymer , electrode , inorganic chemistry , organic chemistry , analytical chemistry (journal)
— Photosensitized reduction of zwitterionic viologen (SPV) and methyl viologen (MV 2+ ) was investigated using an amphiliphilic copolymer having phenanthryl and sulfonate groups (APh) as photosensitizer in aqueous solutions. In the presence of triethanolamine the accumulation of SPV * (photoproduct) was found to be faster than that of MV + . This attributed to the electrostatic repulsion between SPV. and anionic segments of APh. Such difference between SPV and MV 2+ was minimized in the case of the related monomer model. Retardation of the back reaction for the APh‐SPV system was also demonstrated by laser photolysis, k b = 8.7 × 10 7 M ‐1 s ‐1 for the polymer system as compared to k b = 2.8 × 10 9 M ‐1 s ‐1 for the monomer model system. Strong salt‐effects on the yield of the photoreduction and the rate of back reaction confirm the strong electrostatic interaction between the photoproducts and polyanions. This remarkable electrostatic effect of the polyanions was simulated by electrochemical redox reactions by using a graphite electrode coated with APh.