Visible Region Photooxidation on TiO_2 with a Chromophore−Catalyst Molecular Assembly

Nanocrystalline films of TiO_2 derivatized by adsorption of polypyridyl complexes of RuII have provided a basis for a family of solution photoelectrochemical devices. At the molecular level, a key feature in these devices is irreversible photoinjection into the TiO_2 conduction band following metal-to-ligand charge-transfer (MLCT) excitation giving Ru^(III). Reduction of Ru^(III) by I^- followed by I_3^- reduction at the anode completes the cell. It should be possible to exploit this basic scheme for the photoproduction of high-energy chemicals, and we report preliminary results on such an example based on an adsorbed chromophore−oxidant molecular assembly