Premium
Competition between Superexchange‐Mediated and Sequential Electron Transfer in a Bridged Donor–Acceptor System
Author(s) -
Winters Mikael U.,
Pettersson Karin,
Mårtensson Jerker,
Albinsson Bo
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400755
Subject(s) - superexchange , chemistry , acceptor , electron transfer , photochemistry , electron acceptor , solvent , excited state , photoinduced electron transfer , ultrafast laser spectroscopy , electron donor , chemical physics , spectroscopy , atomic physics , ion , organic chemistry , catalysis , physics , quantum mechanics , condensed matter physics
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 dimethylformamide), 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.