Design of antenna-sensitizer polynuclear complexes. Sensitization of titanium dioxide with [Ru(bpy)2(CN)2]2Ru(bpy(COO)2)22-

The use of antenna-sensitizer molecular devices is proposed as a possible strategy to increase the light harvesting of sensitized semiconductors. To illustrate this approach, the cyano-bridged trinuclear complex [ Ru(bpy)2(CN)2]2Ru(bpy(COO)2)2- has been synthesized and studied. The complex adsorbs on TiO2 via the negativity charged-Ru(bpy(COO)2)2- central unit. The photophysical behavior in solution and the photoelectrochemical behavior on TiO2 have studied. Emission and excitation spectra show that in this complex the light energy absorbed by the terminal Ru(bpy)2(CN)2 (antenna) groups is efficiently funneled to the central -Ru(bpy(COO)2)2- (sensitizer) fragment. Photochemical spectra on TiO2 demonstrate that the light absorbed by the antenna fragments is efficiently used for sensitization of the semiconductor.