| Project/Area Number |
13640554
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ASANO Motoko S. Tokyo Institute of Technology, Department of Chemistry, Research Associate, 大学院・理工学研究科, 助手 (80201888)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Photodynamics / long-range相互作用 / Time-resolved fluorescence / Time-resolved EPR / exchange interaction / through-bond mechanism / porphyrin dimer / 常磁性種 / 光励起状態 / ケイ光 / ポルフイリンダイマー / ポリフィリンダイマー / 不対電子 |
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| Research Abstract |
A paramagnetic centers perturbs reaction dynamics and photophysical properties of molecular system even via a long distance. Thus by utilizing the paramagnetic species attached in a remote site, it will be possible to control the local dynamics of the molecular system with a long-range interaction.
Intersystem crossing is one of the simple photophysical processes, and it is suitable to study effect on the photodynamics by the long-range interaction with unpaired electron. In paramagnetic-metalloporphyrin - free base (diamagnetic) porphyin heterodimers such as a copper-free base porphyrin, the free base half undergoes enhanced intersystem crossing by interaction with the unpaired electron in the other half. Recently we have reported that in a series of copper(II)-free base porphyrin dimer linked via an aromatic spacer, the EISC rate exponentially decreases with the number of bonds of the spacer. In addition, the porphyrin HOMO affects EISC rates itself but does not influence the spacer dependence. This feature is in good agreement with an expression for EISC, derived theoretically.
In this project, we examined dependence of the EISC on the paramagnetic species in linearly-linked porphyrin dimers. The paramagnetic porphyrin halves we studied are V(IV)O porphyrins and a radical coordinated zinc(II) porphyrins. Difference of the EISC rate of the free base half between different paramagnetic species does not simply depends on the species itself. The EISC rate depends on the interaction between the unpaired electron and pai system, which is directly connected to the paramagnetic species. Long-range interaction with a remote electron is summarized in terms of three different factors, i.e., spacer, terminal HOMO and interaction between the unpaired electron and direct connecting site.
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