Photoinduced electron transfer from triplet states of phthalocyanines to fullerenes studied by transient absorption spectroscopies in visible and near-IR regions

Photoinduced electron transfer processes between C-60/C-70 and phthalocyanines such as tetra-tert-butylphthalocyanine (H2TBPc) and its zinc derivative (ZnTBPc) in polar solvents have been studied by observing the transient absorption spectra in the visible and near-IR regions. Upon predominant excitation of TBPcs with a 670 nm laser pulse in polar solvents, growth of the transient absorption bands of C-60(-) and C-70(-) was observed, accompanied by a concurrent decay of the tripler states of TBPcs ((TBPc)-T-3*). Thus it is confirmed that electron transfer occurs via (TBPc)-T-3* in polar solvents. The electron transfer rate constants and efficiencies of electron transfer via (ZnTBPc)-Zn-3* are greater than those via (H2TBPc)-H-3* owing to the electron ejection ability of (ZnTBPc)-Zn-3*. Solvent effects on the forward and backward electron transfer processes have been evaluated. Copyright (C) 2000 John Wiley & Sons, Ltd.