EXCITED-STATE ELECTRON-TRANSFER OF FULLERENES - SINGLET-STATES VERSUSTRIPLET-STATES

We report that the quenching rate constants of the triplet states of f ullerenes (C-70 and C-60) by aromatic amines such as N,N-diethylanilin e and N-ethylcarbazole are at least four orders of magnitude smaller t han those of the singlet states in methylcyclohexane. Such dramatic di fferences between the singlet and triplet electron transfer rate const ants from a single species, in spite of the states' apparently similar energetics, are unprecedented. Several possible mechanisms are discus sed. The data can be rationalized by the presence of structural distor tion and biradical character in the triplet state.