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

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