Electron Accumulation on Naphthalene Diimide Photosensitized by [Ru(2,2'-Bipyridine)].

In a molecular triad comprised of a central naphthalene diimide (NDI) unit flanked by two [Ru(bpy)] (bpy = 2,2'-bipyridine) sensitizers, NDI is formed after irradiation with visible light in deaerated CHCN in the presence of excess triethylamine. The mechanism for this electron accumulation involves a combination of photoinduced and thermal elementary steps. In a structurally related molecular pentad with two peripheral triarylamine (TAA) electron donors attached covalently to a central [Ru(bpy)]-NDI-[Ru(bpy)] core but no sacrificial reagents present, photoexcitation only leads to NDI (and TAA), whereas NDI is unattainable due to rapid electron transfer events counteracting charge accumulation.