Photochemical reactions between the excited triplet state of C60 and the ion-pair charge-transfer complex which consists of electron-acceptor cation (methyl viologen (MV2)) and electron-donor anion (organo borates (~BPh3R, where R = Ph or Bu)) have been investigated by both steady-state and laser-flash photolysis. By photoirradiation of CM in the presence of MV2(-BPh3R)2 in organic solvents, the amount of MV+ increases with irradiation time, and persists for a long time even in the dark. From the laser-flash photolysis, it is found that electron transfer proceeds via 3C60 from -BPh3R in the complex, yielding ·BPh3R and C60-. Although generated Cr does not decay in the absence of MV2+ because of the rapid dissociation of BPh3R, in the presence of MV2+, C60- decays quickly by transferring an electron to MV2+ yielding MV+. Thus, it is proved that Ceo acts as a photosensitizer for pumping up an electron from -BPh3R as well as an electron mediator to MV2+. In these systems, MV+ persists even in air-saturated solution for more than an hour, suggesting that the electron transfer from MV+ to O2 is retarded.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry