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Time‐Resolved Spectroscopic Study on Photoinduced Electron‐Transfer Processes in Zn( II )porphyrin–Zn( II )chlorin–Fullerene Triad
Author(s) -
Ha JeongHyon,
Cho Hyun Sun,
Kim Dongho,
Lee JongCheol,
Kim TaeYoung,
Shim Young Key
Publication year - 2003
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200300695
Subject(s) - photochemistry , chlorin , chemistry , fullerene , electron transfer , porphyrin , triad (sociology) , ultrafast laser spectroscopy , photoinduced electron transfer , photoexcitation , excited state , spectroscopy , organic chemistry , psychology , physics , quantum mechanics , nuclear physics , psychoanalysis
Femtosecond time‐resolved transient absorption studies have been performed to investigate the photoinduced energy and electron‐transfer processes in Zn( II )porphyrin–Zn( II )chlorin–fullerene triad in which energy and oxidation potential gradients are directed along the donor–acceptor‐linked arrays. Fast energy transfer (≈450 fs) from photoexcited Zn( II )porphyrin to Zn( II )chlorin was observed upon selective photoexcitation of Zn( II )porphyrin unit in the triad. In a nonpolar solvent such as toluene, the energy transfer from the excited singlet state of Zn( II )chlorin to fullerene occurs and is followed by the formation of an intermediate state with a time constant of nanoseconds, which was attributed to the intramolecular exciplex between Zn( II )chlorin and fullerene. In benzonitrile, on the other hand, the photoexcitation of the triad results in the fast electron transfer (<1 ps) from photoexcited Zn( II )chlorin to fullerene. The generated charge‐separated species recombine with a time constant of ≈12 ps. The relatively fast charge separation and charge recombination rates imply that the strong electronic coupling between Zn( II )chlorin and fullerene moieties is probably induced by the folded conformation between Zn( II )chlorin and fullerene moieties which enhances direct through‐space interaction between the proximately contacted π systems.