Efficient light-to-electrical energy conversion with dithiocarbamate ruthenium polypyridyl sensitizers

New Ru(dcbH)(dcbH(2)(L) sensitizers, where L is diethyldithiocarbamate, dibenzyldithiocarbamate, or pyrrolidinedithiocarbamate, dcbH is 4-(COOH)-4'-(COO-)-2,2'-bipyridine, and dcbH(2) is 4,4'-(COOH)(2)-2,2'-bipyridine, have been synthesized, characterized, and anchored to nanocrystalline TiO2 films for light to electrical energy conversion in regenerative photoelectrochemical cells with I-/I-2 acetonitrile electrolyte. The sensitizers have intense metal-to-ligand charge-transfer (MLCT) bands centered similar to 380 and 535 nm that sensitize TiO2 over a notably broad spectral range. The photophysical and photoelectrochemical studies of these materials are contrasted with cis-Ru(dcbH(2))(2)(NCS)(2), which is one of the most efficient sensitizers reported to date. Photophysical measurements show that the high photocurrent observed for cis-Ru(dcb)(2)(NCS)(2)/TiO2 is due to efficient and rapid iodide oxidation.