Photo-hydrogen-evolving molecular devices driving visible-light-induced water reduction into molecular hydrogen: structure-activity relationship and reaction mechanism

This article summarizes the ongoing studies on the photo-hydrogen-evolving molecular devices (PHEMDs) made up of polypyridyl Ru(II) photosensitizers and Pt(II)-based molecular catalysts, carried out in the authors' group in the last two decades. The H-2-evolving activities of Pt(II)-based molecular catalysts demonstrated by various experimental evidences are first described. Then the structure-activity relationship, some important factors required for the higher catalytic activity, and several important insights into the mechanism of photochemical H-2 evolution catalyzed by the Ru(II) Pt(II)-based PHEMDs will be discussed in detail.