The small reorganization energy of C 60 in electron transfer

Abstract

Porphyrin-linked fullerene 1 and porphyrin-linked quinone 2 have been designed and synthesized to evaluate the size and shape effect of fullerene in electron transfer. For evaluation of such an effect C 60 and benzoquinone with comparable reduction potentials have been chosen and linked with a porphyrin, where a relatively rigid spacer ensures similar separation distance and nature of the inteervening bonds between the redox pair. Accelerated charge separation and deceleratd charge recombination were observed in 1 compared with 2 by picosecond fluorescence lifetime measurements and time-resolved transient absorption spectroscopy. They may be explained by the smaller reorganization energy in C 60 compared with those in small acceptors.