1995 Fiscal Year Final Research Report Summary
Photoinduced hydrogen evolution with highly functional photocatalyst
| Project/Area Number |
06453100
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
触媒・化学プロセス
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
OKURA Ichiro Tokyo Institute of Technology, Department of Bioengineering, Professor, 生命理工学部, 教授 (90089821)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Intramolecular electron transfer / Porphyrin / Viologen / Laser flash photolysis / Photoinduced hydrogen evolution / Hydrogenase |
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| Research Abstract |
Various viologen linked porphyrins have been synthesized, which provide photosensitizer and electron carrier in the same molecule.Porphyrin containing viologen with different numbers of methylene groups were synthesized and used for photoinduced intramolecular electron transfer.
The fluorescence decay profiles consist of the sum of two first order decays with two lifetimes. The long fluorescence lifetimes of the viologen linked porphyrins are almost the same as the lifetime of the porphyrin without viologen. It is reasonable to assume that the fluorescence decay of the component with a long lifetime is spontaneous and is therefore independent of the distance between the viologen and the porphyrin ring. In contrast, the shorter lifetime strongly depends on the length of the methylene chain and the value increases with longer chain lengths. Therefore the fluorescence decay of the component with the short lifetime may arise from the direct quenching of the photoexcited singlet state of the porphyrin by the linked viologen.
The intramolecular electron transfer rate constant strongly depends on the methylene chain length and it decreases with increasing methylene chain length. In the intramolecular electron transfer process, the electron transfers from the photoexcited porphyrin to the viologen along the methylene chain. Photoinduced hydrogen evolution was accomplished with the viologen-linked porphyrin by the irradiation of visible light.
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