Theoretical investigation on two derivatives of [Ru(bpy)n-C60]2＋ (bpy: 2,2-bipyridine; n＝2, 3) has been performed by density functional theory. At TZP level, the compositions of frontier orbitals have been calculated in order to discuss the influence on C60 by metal and ligands. Taking into account solvent effects, the absorption spectra were investigated by time-dependent density functional theory (TDDFT) with LB94 and SAOP functional to correct local density approximation. The results show that inclusion of the solvent leads to important change of absorption spectra, and solvation induces a blue shift to some extent. The spectra calculated in the presence of the solvent are in good agreement with the experiment. Low energy transitions were found to originate mainly from the mixed transitions containing the metal, whereas the higher energy band arises from C60 and ligand charge transfer transitions.

Key words: fullerene, polypyridyl ruthenium, TDDFT, electronic absorption spectra, charge transfer