A rhodamine-based fluorescent sensor for selective detection of Cu2+ in aqueous media: Synthesis and spectroscopic properties

Two new chemosensors, rhodamine B derivative bearing 3-formyl-6-nitrochromone (L-1) and 3-formyl-6-methylchromone (L-2) units were designed and synthesized using microwave irradiation for the selective detection of Cu2+ in aqueous media. Copper triggers the formation of highly fluorescent ring-open spirolactam. The fluorescence intensity was remarkably increased upon the addition of Cu2+ within a minute, while the other metal ions caused no significant effect. More importantly, the resulting complexes can be used as a reversible fluorescence sensor for CN-. The recognition ability of the sensors was investigated by fluorescence titration, Job's plot, H-1 NMR spectroscopy and density functional theory (DFT) calculations. (C) 2019 Published by Elsevier B.V.