Photoinduced electron transfer and long lived charge separation in a donor-bridge-acceptor supramolecular ‘diad’ consisting of ruthenium(II) tris(bipyridine) functionalized C60

Evidence for photoinduced electron transfer from the excited state of ruthenium(II) tris(bipyridine) to buckminister-fullerene, C60, in a covalently bound donor-bridge-acceptor supramolecule is reported. Photoinduced optical absorption (PIA) studies clearly show an excitation spectrum with a long lived PIA band at 688 nm assigned to the absorption band of the ruthenium(III) tris(bipyridine). A photoinduced electron spin resonance signal exhibits signatures of both the ruthenium(III) tris(bipyridine) and the C60 radical anion. From the quenching of the photoluminescence a rate constant of 6.4 × 106 s−1 is estimated for the photoinduced electron transfer in acetonitrile solutions at 296 K.