The photoinduced electron transfer between C60 and N,N,N′,N′-tetramethylbenzidine (NTMB) in polar and nonpolar solvents and their mixtures has been investigated by nanosecond laser flash photolysis/transient absorption spectroscopy in the visible and near-IR regions. The transient absorption bands of the C60 triplet state (TC60*) and the NTMB radical cation were observed in both nonpolar and polar solvents. In polar solvents such as benzonitrile, the reaction rate constants were determined from the decay of TC60* at 740 nm, which were consistent with the rate constants evaluated from the growth of the NTMB radical cation, suggesting that direct electron transfer occurs from ground-state NTMB to TC60*. In nonpolar solvents such as benzene, the NTMB radical cation and C60 radical anion were produced immediately after the nanosecond laser pulse, simultaneous with the formation of TC60*, indicating that a different electron transfer mechanism exists in nonpolar solvents. In the solvent mixtures, two simultaneous reaction routes are present for both forward and back electron transfer reactions. Pronounced solvent effects found for electron transfer reaction kinetics and rates are characteristic of the photoinduced electron transfer reactions between C60 and some kinds of aromatic amines.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry