| Project/Area Number |
07044148
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Osaka University |
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Principal Investigator |
YANAGIDA Shozo Osaka University, 工学部, 教授 (10029126)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITA Etsuko Brook Haven Notional Laboratory, 化学部門, 研究員
BRUNSCHWIG Bruce Brook Haven Notional Laboratory, 化学部門, 研究員
CRUETZ Carol Brook Haven Notional Laboratory, 化学部門・部門長, 主任研究員
SUTIN Norman Brook Haven Notional Laboratory, 化学部門, 主任研究員
FUJIWARA Hiroaki Osaka University, 工学部, 博士課程後期日本学術
HOSOKAWA Hiroji Osaka University, 工学部, 博士課程後期日本学術
SUENOBU Tomoyoshi Osaka University, 工学部, 助手 (90271030)
MURAKOSHI Kei Osaka University, 工学部, 助手 (40241301)
ITOH Shinobu Osaka University, 工学部, 助教授 (30184659)
WADA Yuji Osaka University, 工学部, 助教授 (40182985)
FUKUZUMI Shun-ichi Osaka University, 工学部, 教授 (40144430)
緒方 朋行 大阪大学, 工学部, 博士課程後期日本学術
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥8,100,000 (Direct Cost: ¥8,100,000)
Fiscal Year 1996: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1995: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | carbon dioxide / photochemistry / metal complex / artificial photosynthesis / linear aromatic compound / electron transfer / semiconductor / nanoparticles / 還元 / 半導体超微粒子 / 錯体 |
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| Research Abstract |
Cobalt macrocycles mediate electron transfer in the photoreduction of CO_2 with p-terphenyl as the photosensitizer and a tertiary amine as the sacrificial electron donor. Mechanistic investigation was carried out using Co^1HMD (HMD=5,7,7,12,14,14-hexamethyl-1,4,8,11-tetrazacyclotetradeca-4,11-diene) by means of laser flash photolysis. The rate constant for electron transfer from the radical anion of p-terphenyl was determined. It was elucidated that not the electron transfer rate but coordination of CO_2 to the complex was controlled by the structure of the complex, which is reflected in the photocatalytic actibity of CO_2 reduction.
Nickel cyclam or other saturated 14-membered tetraazamacrocycles are used as catalysts instead of cobalt complexes, the above system does not produce CO.Instead a small amount of H_2 is fromed. Flash photolysis studies indicate that the Ni (I) species including NiL (CO_2)^+ form even in the absence of p-terphenyl upon irradiation at 313 nm under CO_2. Our studies indicate that Ni^<11>L^<2+> interacts with CO_2 in CH_3CN solution containing TEA (triethylamine) to from the Ni^<11>L (TEA) (CO_2)^<2+> adduct. NiL(CO_2)^+ seems to be produced by photoinduced electron transfer from the bound TEA.In addition to the nature of the Ni^<11>L (TEA) (CO_2)^<2+> adduct, differences between Co and Ni macrocycles (i.e., CO_2 binding constants, CO_2 binding rate constants, the pK_a of the hydrides, and redox properties) will be discussed.
Electron transfer rates for three coumarine dyes (Coumarins 343, D-1421, and D-126) adsorbed on TiO_2 and ZnO nanocrystallites were directly obtained from the ultra fast fluorescence dynamics, measured using the femtosecond upconversion technique. Observed ultra fast electron transfer injection should be due to not only the strong electronic couplong, but also large overlapping of the conduction band states of semiconductor and the donor states of excited molecules.
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