Photoinduced electron transfer between fullerenes (C60/C70) and disubstituted naphthalenes using laser flash photolysis

Photoinduced electron-transfer processes between fullerenes C-60/C-70 and disubstituted-naphthalenes have been studied by laser flash photolysis. Quantum yields (phi (T)(et)) and rate constants (k(et)) of electron transfer from naphthalenes to the excited triplet states of C-60 (C-3*(60)) and C-70 (C-3*(70)) have been determined by observing the transient absorption bands in the wide wavelength VIS/NIR regions. The observed phi (T)(et) and k(et) values depend significantly on the nature and position of the substituents. The k(et) values are seen to correlate well with the free energy changes (DeltaG(et)) for the electron transfer reactions on the basis of Rehm-Weller relation. Addition of pyridine (Py) enhanced significantly the rates and efficiencies of photoinduced electron transfer process of dihydroxy-naphthalenes (DHN). However, the effect of Py in the dimethoxy-naphthalenes (DMN) is far less than that of DHN. In the presence of octylviologen (OV2+), electron-mediation occurs from C-60(.-) to OV2+ to generate OV.+. (C) 2001 Elsevier Science B.V. All rights reserved.