Photoinduced electron transfer from 3,3′,5,5′-tetramethylbenzidine (TMB) to C60 in polar and non-polar solvents has been investigated by nanosecond (ns) laser photolysis in the visible and near-IR regions. The transient absorption bands of triplet C60 (TC60*), the C60 radical anion (C60.-) and the TMB radical cation (TMB.+) were observed in both non-polar and polar solvents. The rate constants of electron transfer from TC60* to TMB, which were evaluated from the decay of TC60* and growths of TMB.+ and C60.-, decrease with increasing solvent polarity. In non-polar solvents, TMB.+ and C60.- seem to be produced immediately after the ns laser excitation at the same time as the formation of TC60*, suggesting a weak interaction between C60 and TMB, before electron transfer. On decreasing the solvent polarity, the kinetics of the back-electron-transfer reaction from C60.- to TMB.+ change from second-order to first-order, indicating that C60.- and TMB.+ exist as ion pairs in non-polar and less-polar solvents. The back-electron-transfer rates also tend to decrease with the solvent polarity.
|Number of pages||4|
|Journal||Journal of the Chemical Society, Faraday Transactions|
|Publication status||Published - 1995 Dec 1|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry