Competition between superexchange-mediated and sequential electron transfer in a bridged donor-acceptor system

被引：50

作者：

Winters, MU ^{[1
]}

Pettersson, K ^{[1
]}

Mårtensson, J ^{[1
]}

Albinsson, B ^{[1
]}

机构：

[1] Chalmers Univ Technol, Dept Chem & Biosci, S-41296 Gothenburg, Sweden

来源：

CHEMISTRY-A EUROPEAN JOURNAL | 2005年 / 11卷 / 02期

关键词：

electron transfer; porphyrin; sequential electron transfer; solvent effects; superexchange;

D O I：

10.1002/chem.200400755

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

The temperature- and solvent-dependence of photoinduced electron-transfer reactions in a porphyrin-based donor-bridge-acceptor (DBA) system is studied by fluorescence and transient absorption spectroscopy. Two competing processes occur: sequential and direct superexchange-mediated electron transfer. In a weakly polar solvent (2-methyltetrahydrofuran), only direct electron transfer from the excited donor to the appended acceptor is observed, and this process has weak temperature dependence. In polar solvents (butyronitrile and dimethyf-formamide), both processes are observed and the sequential electron transfer shows strong temperature dependence. In systems where both electron transfer processes are observed, the long-range superexchange-mediated process is more than two times faster than the sequential process, even though the donor-acceptor distance is significantly larger in the former case.

引用

页码：562 / 573

页数：12

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