Charge separation and charge recombination photophysical studies in a series of perylene-C60 linear and cyclic dyads.

A new donor­acceptor doubly bridged perylenediimide­fullerene dyad (PDI­C60, DB-3), where the perylenediimide (PDI) acts as a donor, has been synthesized and studied by time-resolved absorption spectroscopy. The DB-3 undergoes an electron transfer (ET) in both polar and non-polar media under photo-excitation. Structurally the DB-3 dyad resembles four other recently studied dyads (R. K. Dubey et al., Chem. Eur. J., 2013, 19, 6791­6806). Analysis of the ET reactions in this series of dyads was carried out in frame of both classic and semi-quantum ET theories. The result of the analysis for DB-3 suggests that the electronic coupling for the ET reaction is roughly 0.005 eV, internal reorganization energy is 0.16 eV, and outer sphere or solvent reorganization energy is 0.5 and 0.3 eV in benzonitrile and toluene, respectively.