1986 Fiscal Year Final Research Report Summary
Design on Photoredox Reaction Systems by Use of Functional Polymers
| Project/Area Number |
59430019
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
高分子合成
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| Research Institution | Osaka University |
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Principal Investigator |
NOZAKURA Shun-ichi Faculty of Science, Osaka University, 理学部, 教授 (90028085)
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| Co-Investigator(Kenkyū-buntansha) |
FURUE Masaoki Faculty of Science, Osaka University, 理学部, 助手 (30028245)
MORISHIMA Yotaro Faculty of Science, Osaka University, 理学部, 講師 (70028249)
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| Project Period (FY) |
1984 – 1986
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| Keywords | Amphiphilic polyelectrolyte / Photo-induced electron transfer / Charge separation / Local electric Potential / Hydrophobic interaction / Organized structure / Collisionless electron transfer / 電子移動理論 |
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| Research Abstract |
Amphiphilic polyelectrolytes consisting of hydrophobic chromophores(polycyclic aromatics or organic dyes) and charged groups create an organized structure in aqueous solution as a result of microphase separation. Laser photolysis studies revealed that a strong electrostatic potential around the hydrophobic microdomain resulted in an efficient charge separation in photo-induced electron transfer reaction. It was also revealed that the hydrophobic microdomains effectively associated with reaction partners, electron donors or acceptors to or from the excited chromophores within the microdomains, in the aqueous system, and thus the forward electron transfer reaction could be largely enhanced.
The structural organization of the amphiphilic polyelectrolytes occurs due to a hydrophobic association. Hydrophobic groups with <pi> -electron systems in the amphiphilic polyelectrolytes were found to be easier to self-aggregate than those with <sigma> -electron systems. A thermodynamical study suggested that the planar structure of the hydrophobic groups with the <pi> -system would fit tightly to each other in the hydrophobic interaction to release a large amount of free water, thus leading to a large positive entropy as compared with those with the <sigma> -system.
Chromophores covalently linked to a polyelectrolyte were "compartmentalized" in the hydrophobic aggregates of pendant photo-inactive hydrophobic groups. A collisionless long-range electron transfer that occurs in this system showed that the back electron transfer was slower than the forward reaction by a factor of several orders of magnitude. This is interpreted to be due to the "inverted region" of electron transfer theory.
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