Syntheses, Characterization, and Photo-Hydrogen-Evolving Properties of Tris(2,2'-bipyridine)ruthenium(II) Derivatives Tethered to an H2-Evolving (2-phenylpyridinato)platinum(II) Unit

Abstract

With the aim of developing new molecular devices having higher photo-hydrogen-evolving activity, Pt(ppy)ClX units (ppy = 2-phenylpyridinate, X = Cl- or DMSO; DMSO = dimethylsulfoxide) have been employed as an H2-evolving site, as the catalytic activity of [Pt(ppy)Cl2]- was confirmed to be higher than those of other mononuclear platinum(II) complexes. In the present study, two new heterodinuclear Ru(II)Pt(II) complexes, produced by condensation of [Ru(bpy)2(5-amino-phen)]2+ (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) with [Pt(cppy)Cl2]- and Pt(cppy)(DMSO)Cl (cppy = 9-carboxy-phenylpyridinate), respectively, have been prepared and their photo-hydrogen-evolving activities have been evaluated in detail. The ineffectiveness of these systems as photo-hydrogen-evolving molecular devices are interpreted in terms of their negative driving forces for the photoinduced electron transfer from the triplet MLCT excited state of the Ru chromophore to the p*(ppy) orbital of the catalyst moiety.

Keywords

• solar energy conversion and storage
• hydrogen energy
• photocatalysis
• platinum(II) catalysts
• ruthenium complexes
• molecular devices