Photophysical and Electron Transfer Properties of C₆₀(C₆H₅)₅OH and C₆₀(C₆H₄F)₅OH: A Laser Flash Photolysis and Pulse Radiolysis Study

Photophysical properties of the excited singlet and triplet states of pentaphenylfulleren-2-ol (C 60 (C 6 H 5 ) 5 OH, PPF) and penta-4-fluorophenylfulleren-2-ol [C 60 (C 6 H 4 F) 5 OH, PFPF], two derivatives of buckminsterfullerene, C 60, have been investigated in benzene and benzonitrile solutions using two complementary transient absorption techniques, namely, laser flash photolysis and pulse radiolysis. Singlet−singlet and triplet−triplet absorption spectra have been characterized. Quantum yields for formation of the triplet states by intersystem crossing from the singlet states, and also the intrinsic lifetimes of the singlet and triplet states, have been determined. In addition to the intrinsic decay of the triplet state, the evidences have been obtained for the contribution of the other two processes, namely, the self-quenching by the ground state and the T−T annihilation reaction, toward the decay of the triplet state, and the rate constants for these processes have been determined. The formation of charge transfer (CT) complexes with two aromatic amines, diphenylamine (DPA) and triphenylamine (TPA), in benzonitrile and the electron transfer reactions in the excited singlet and CT complexes have been studied.