Efficient osmium sensitizers containing 2,2′-bipyridine-4,4′-bisphosphonic acid ligand

The synthesis of a series of four complexes of the type Os(bpy-4,4′PO3H2)2L2 (bpy-4,4′PO3H2 = 2,2′-bipyridine-4,4′-bisphosphonic acid and L2 = Cl2, (CN)2, 2,2′-bipyridine-4,4′-bisphosphonic acid or 2,2′-bipyridine-4,4′-dimethoxy) is reported and the spectroscopic, photophysical, and photoelectrochemical properties are presented and compared to the cis-Ru(H2dcb)2(NCS)2 (H2dcb = 2,2′-bipyridine-4,4′-dicarboxylic acid).