PHOTOELECTRODES BASED ON ELECTROPOLYMERIZED MOLECULAR RUTHENIUM AND OSMIUM DIADS

Ruthenium(II) and osmium(II) complexes with modified terpy ligands (terpy = 2,2':6',2"-terpyridine) have been prepared. The systems consist of two different ligands bonded to the metal center, one bearing an electron acceptor (viologen) and the other being end-linked to a pyrrole ring via its N atom. Electropolymerization of the ruthenium compound affords an electrically conductive film on the surface of a platinum electrode. The polypyrrole backbone is linked to pendent groups containing a photoactive component (ruthenium complex core) and an electron acceptor subunit (viologen). The modified electrode thus obtained acts as a photoelectrode. Visible light irradiation of the material in the presence of an organic electron donor (triethanolamine) in CH3CN leads to a significant photocurrent when the electrode is potentiostated at 0 V. The light energy conversion of the present integrated system is much more efficient than for the analogous material prepared by copolymerization of the two separate components, electron acceptor-pyrrole and ruthenium complex-pyrrole.