Generation by Electron Transfer of an Emitting State Not Observed by Photoexcitation in a Linked Ru(bpy)32+−Methyl Viologen

The molecule in which a methyl viologen (MV2+) moiety is coupled through a three-carbon chain to one bipyridine in Ru(bpy)32+ (bpy = 2,2‘bipyrine), [Ru(bpy)2(4-(2-(1‘-methyl-4−4‘-bipyridinediium-1-yl)propyl)-4‘-methyl-2,2‘-bipyridine), abbreviated RuII(bpy)2(MV2+-bpy)4+], does not emit upon photoexcitation because of rapid quenching of the MLCT state by the MV2+. The integrated steady-state photoemission intensity is