Photoinduced electron transfer between C 60 and electroactive units

Abstract

A summary of our recent works on fulleropyrrolidines and fullerotriazolines covalently attached to the strong electron-donor tetrathiafulvalene (TTF) is presented. Absorption of light in C 60-based TTF-containing dyads leads to the formation of the fullerene excited singlet state, which undergoes an intramolecular electron transfer to give the charge-separated (CS) state. A further stabilization of the CS state takes place by gaining aromaticity upon oxidation of the donor (TTF) fragment. Back electron transfer proceeds mainly via formation of the fullerene triplet excited state due to the strong second-order vibronic spin–orbit coupling induced by the sulfur nucleus. Two C 60-acceptor systems have been also studied in the search for a possible electron transfer from the photoexcited fullerene to the covalently linked electron-acceptor. Formation of the fullerene triplet excited state rather than an intramolecular electron-transfer was observed in both cases.