Synthesis and photoelectric studies of Ru(II) polypyridyl sensitizers

New cis-Ru(3,3′-dcbpy)2(NCS)2 photosensitizer (where 3,3′-dcbpy is 3,3′-dicarboxy-2,2′-bipyridine) was synthesized using Ru(DMSO)4Cl2 as a starting material and characterized. Its photophysical and redox properties were compared with those of cis-Ru(4,4′-dcbpy)2(NCS)2 and cis-Ru(5,5′-dcbpy)2(NCS)2.The photoelectrochemical properties of the three dyes adsorbed on the surface of the nanocrystalline TiO2 electrodes as well as on self-assembly monolayers (SAMs) were investigated. The photocurrents generated by sensitized TiO2 electrodes were much higher than those by SAMs. And cis-Ru(4,4′-dcbpy)2 showed a most efficient photosensitizer in both systems. The mechanism is discussed in the paper.