Photoinduced electron transfer between C60/C70 and zinc tetraphenylporphyrin in polar solvents

Photoinduced electron transfer between C-60/C-70 and zinc tetraphenylporphyrin (ZnTPP) in a polar solvent has been investigated with a nanosecond laser photolysis method by observing the transient absorption bands in the near-IR region. The transient absorption bands of the C60C70 radical anion (C-60(.-)/C-70(.-)) in the near-IR region gave evidence of electron transfer for the system ZnTPP and C60/C70 In ZnTPP solution where C-60 and C-70 were photoexcited predominantly, electron transfer takes place from the ground state of ZnTPP to the triplet states of C-60/C-70 (C-3(60)*/C-3(70)*). In the concentrated ZnTPP solution where ZnTPP was predominantly photoexcited, the triplet state of ZnTPP donates the electron to the ground state of C-60/C-70, producing C-60(.-)/ C-70(.-) The efficiency of electron transfer via the C-3(60)*/C-3(70)* route is higher than that via (ZnTPP)-Zn-3*.