Photophysical and electron transfer properties of C-60(C6H5)(5)OH and C-60(C6H4F)(5)OH: A laser flash photolysis and pulse radiolysis study

Photophysical. properties of the excited singlet and triplet states of pent aphenylfulleren-2-ol (C-60(C6H5)(5)OH, PPF) and penta-4-fluorophenylfullere n-2-ol [C-60(C6H4F)(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 photolys is and pulse radiolysis. Singlet-singlet and triplet-triplet absorption spe ctra have been characterized. Quantum yields for formation of the triplet s tates by intersystem crossing from the singlet states, and also the intrins ic lifetimes of the singlet and triplet states, have been determined. In ad dition 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 th e decay of the triplet state, and the rate constants for these processes ha ve been determined. The formation of charge transfer (CT) complexes with tw o aromatic amines, diphenylamine (DPA) and triphenylamine (TPA), in benzoni trile and the electron transfer reactions in the excited singlet and CT com plexes have been studied.