Abstract:The complex [Ru(bpy)2L] 2+ , where bpy = 2,2'-bipyridine, L = 4-(phenylethynyl)-2,2'-bipyridine, was prepared in its racemic and resolved forms (and . The phenylethynyl unit on the bipyridine for the complex acts as a binding site for -cyclodextrin in water (1:1 complex, K = 3390 M -1 ) or -cyclodextrin (2:1 complex, K1 = 887 M -1 , K2 = 8070 M -1 ). The presence of the cyclodextrin provides partial protection to the complex under light-activated water oxidation conditions.