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

The design of a highly selective turn-ON luminescence chemodosimeter for Cu2+ is reported. The design strategy made use of the ability of Cu2+ 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 Cu2+, 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 Cu2+. Only Cu2+ is capable of this reaction, making this an interesting, hitherto unexplored strategy for the selective detection of micromolar amounts of Cu2+.