Photoinduced energy and electron transfer in phenylethynyl-bridged zinc porphyrin-oligothienylenevinylene-C 60 ensembles

Abstract

Donor-bridge-acceptor triad (Por-2TV-C 60) and tetrad molecules ((Por) 2-2TV-C 60), which incorporated C 60 and one or two porphyrin molecules that were covalently linked through a phenylethynyl-oligothienylenevinylene bridge, were synthesized. Their photodynamics were investigated by fluorescence measurements, and by femto- and nanosecond laser flash photolysis. First, photoinduced energy transfer from the porphyrin to the C 60 moiety occurred rather than electron transfer, followed by electron transfer from the oligothienylenevinylene to the singlet excited state of the C 60 moiety to produce the radical cation of oligothienylenevinylene and the radical anion of C 60. Then, back-electron transfer occurred to afford the triplet excited state of the oligothienylenevinylene moiety rather than the ground state. Thus, the porphyrin units in (Por)-2TV-C 60 and (Por) 2-2TV-C 60 acted as efficient photosensitizers for the charge separation between oligothienylenevinylene and C 60. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.