Charge separation, charge recombination and electron transfer reactions in solutions of fullerene-C60 and phenothiazines

C60 forms weak charge transfer complexes with phenothiazine and methyl phenothiazine. Charge separation, charge recombination and ion dissociation reactions were investigated in the solution phase following excitation of the charge transfer band of the complexes with picosecond laser pulses. The formation of the triplet state of C60 on charge recombination, and electron transfer reactions of the singlet and triplet states of C60 with phenothiazine to give C60−· and cation radicals have been investigated. On longer timescales (> 1 μs) back electron transfer between C60−· and cation radical takes place. The effect of solvent polarity was studied on the charge recombination and back electron transfer reactions.