Photoinduced Electron Transfer from Phthalocyanines to Fullerenes (C60 and C70)

Photoinduced electron transfer between fullerenes (C 60 and C 70 ) and phthalocyanines such as tetra- tert -butylphthalocyanine (H 2 TBPc) and its zinc derivative (ZnTBPc) in solution has been investigated with nanosecond laser photolysis method by observing the transient absorption bands in the visible/near-IR regions. By the predominant excitation of fullerenes with 532 nm laser light, slow rises of the transient absorption bands of phthalocyanine cation radicals and fullerene anion radicals were observed instead of the decays of the excited triplet states of fullerenes ( T C 60 * and T C 70 *) in polar solvents. Electron-transfer from the phthalocyanines to T C 60 * or T C 70 * was confirmed. The quantum yield of the electron transfer via T C 70 * is higher than that via T C 60 *; ZnTBPc acts as stronger electron donor than H 2 TBPc. In nonpolar solvent, energy transfer from T C 60 * (and T C 70 *) to the phthalocyanines occurs predominantly as confirmed by the consecutive appearance of the triplet states of the phthalocyanines.