Synthesis and photophysics of new types of fullerene–porphyrin dyads

The synthesis and photophysical properties of three types of porphyrin–fullerene (P-C60) dyads are presented: (a) conformationally flexible dyads with polyether linkers, (b) rigid dyads with steroid linkers, and (c) a parachute-shaped dyad in which the flat porphyrin and spherical fullerene chromophores are in very close proximity. The course of events following photoexcitation of these dyads and (in some cases) corresponding porphyrin–zinc complexes has been probed through studies of fluorescence quenching, measurements of fluorescence lifetimes and quantum yields for singlet molecular oxygen formation, and transient absorption spectroscopy. These data provide insight into the dynamic competition between intramolecular energy transfer and electron transfer in these dyads, and, for the case of the parachute-shaped dyad, the kinetics of back-electron transfer.