Photoinduced electron transfer of the triplet states of C60 and C70 from oxotitanium(IV) tetra-t-butyl-phthalocyanine as an electron-donor in polar solvent

Excited triplet state properties of oxotitanium(IV) tetra-t-butyl-phthalocyanine (OTiPc) were investigated by the laser flash photolysis observing the transient absorption bands in the near-IR region. Photoinduced energy and electron transfer processes of the excited triplet states of C60 and C70 in the presence of OTiPc take place depending on the solvent polarity. In PhCN, slower formations of the ion radicals after the rapid decays of the triplet excited states of C60 and C70 were observed, suggesting the presence of the intermediates (i.e. triplet exciplex) for electron transfer. In longer time-scale, freely solvated radical ions show second-order back electron transfer.