Phenothiazine attached Ru(bpy)₃²⁺derivative as highly selective “turn-ON” luminescence chemodosimeter for Cu²⁺

Abstract

The design of a highly selective "turn-ON" luminescence chemodosimeter for Cu(2+) is reported. The design strategy made use of the ability of Cu(2+) ions to oxidize aromatic amines in acetonitrile solution. The aromatic amine employed here is a phenothiazine moiety which is covalently linked to one of the bipyridine units of Ru(bpy)(3)(2+). Excitation of the Ru(bpy)(3)(2+) leads to electron transfer from the phenothiazine moiety to the MLCT excited state of Ru(bpy)(3)(2+) which resulted in efficient quenching of the luminescence. In the presence of excess Cu(2+), phenothiazine moiety is oxidized to a stable entity which is incapable of electron donation to the MLCT excited state of Ru(bpy)(3)(2+). The emission of the Ru(bpy)(3)(2+) moiety is thus restored and we show that this strategy can be used as the basis for sensing micromolar amounts of Cu(2+). Only Cu(2+) is capable of this reaction, making this an interesting, hitherto unexplored strategy for the selective detection of micromolar amounts of Cu(2+).