Photoinduced Electron Transfer from Cyclic Organogermanium Compounds to C₆₀ Studied by Laser Flash Photolysis

The electron transfer from cyclic organogermanium compounds to photo-excited C₆₀ in benzonitrile solution has been investigated by the 532 nm-laser flash photolysis with observation of the transient absorption bands in the near-IR region. The transient absorption band of the C₆₀ triplet state (^TC₆₀*) appeared at 730 nm immediately after nanosecond laser exposure. With the decay of ^TC₆₀*, the absorption bands of the radical anion of C₆₀ appeared at 1070 nm, showing that the electron transfer takes place from organogermanium compounds to ^TC₆₀*. The efficiencies and rates of the electron-transfer reactions vary with ring size of the germanium compounds.