Photoinduced intermolecular electron transfer process of fullerene (C60) and amine-substituted fluorenes studied by laser flash photolysis

Photoinduced intermolecular electron transfer process of fullerene (C-60) with 9,9-bis(4-triphenylamino)fluorene (BTAF) and 9,9-dimethoxyethyl-2-diphenylaminofluorene (DAF) in toluene and benzonitrile has been investigated by nanosecond laser photolysis technique in the visible/near-IR regions. By the selective excitation of C-60 Using 532 laser light, it has been proved that the electron transfer takes place from the ground states BTAF and DAF to the triplet excited state of C-60 (C-3(60)*) by observing the radical anion of C-60 and radical cation of BTAF and DAF It was observed that the electron transfer of BTAF/C-3(60)* is more efficient than DAF/C-3(60)* reflecting the effect of amine-substitutents of the fluorene moiety on the efficiency of the electron transfer process. On addition of a viologen dication (OV2+), the electron of the anion radical of C-60 mediates to OV2+ yielding the OV center dot+. These results proved that the photosensitized electron-transfer/electron-mediating processes have been confirmed by the transient absorption spectral method. (c) 2006 Elsevier B.V. All rights reserved.