Time-resolved EPR investigation of intramolecular photoinduced electron transfer in spin-labeled fullerene/ferrocene dyads

Intramolecular photoinduced electron transfer from ferrocene-linked TEMPO-labeled fulleropyrrolidines has been studied by time-resolved EPR using laser excitation. The EPR signal of the quartet excited state of 2 and 3, which corresponds to triplet fullerene/doublet nitroxide, was substantially quenched relative to model compound 1 without ferrocene. Kinetic parameters of the electron transfer process have been obtained by simulating the time evolution of the EPR signal of both the ground electronic state and the excited quartet state that become spin polarized during the excitation and decay paths. The distance between donor and acceptor, when the photoinduced electron transfer occurs, has been estimated for both dyads on the basis of the Marcus electron transfer theory.