1995 Fiscal Year Final Research Report Summary
Elucidation of Dynamics of Electron Transfer Process in Condensed Phases
| Project/Area Number |
06640654
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
NOZAKI Koichi Fac.of Sci., Dep.of Chem., Assistant, 理学部, 助手 (20212128)
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| Project Period (FY) |
1994 – 1995
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| Keywords | ELECTRON TRANSFER / RUTHENIUM COMPLEX / PORPHYRIN / CHARGE RECOMBINATION / RHODIUM COMPLEX / ZINC CHLORIN / ENERGY TRANSFER / DISTANCE DEPENDENCE |
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| Research Abstract |
To elucidate the effects of both intramolecular nuclear displacement and solvent dynamics on ET rates, intramolecular ET processes have been studied in the following donor-acceptor linked compounds.
(1) The dependencies of distance, solvent, temperature, and energy gap on the photoinduced and back ET rates in M (II) -Rh (III) (M=Ru and Os) dinuclear complexes have been examined. It is concluded that the large nuclear displacement in the rhodium complexes dominantly affected the ET rates.
(2) The high-density laser excitation of a Ru (II) dinuclear complex was used to produce a doubly excited state. A triplet-triplet annihilation between two MLCT states occurred to form a charge-separated state, [Ru (I) -Ru (III)], with 40% in a production yield. The distance dependence of the charge-separation and charge recombination have been examined.
(3) Rapid quenching of an Ru-MLCT excited state in the mixed-valent complexes, Ru (II) -M (III) (M=Ru and Os), was observed. The resulting product was the mixed-valence isomer state, Ru (III) -Os (II), which underwent back ET process to reproduce the ground state. Energy gap and temperature dependence of these ET rates have been studied.
(4) On the excitation of MMCT bands in mixed-valent complexes, Ru (II) -M (III) (M=Ru and Os), with a near-IR laser pulse, a back ET process from an optically generated mixed-valence isomer state was observed. However, the low quantum yield (-0.2) of the isomer state suggests that most of Franck-Condon states decayd to the ground state before they relaxd.
(5) The charge-separation and charge-recombination rates in Zinc chlorin-porphrin dyads have been measured in a variety of solvent. The variation of the charge-recombination rates with solvent was well understood in terms of current nonadiabatic ET theory. The intramolecular reorganization energy was estimated 0.175eV and the electronic interaction energy was 14meV.
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