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

Two new chemosensors, rhodamine B derivative bearing 3-formyl-6-nitrochromone (L ) and 3-formyl-6-methylchromone (L ) 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, ¹H NMR spectroscopy and density functional theory (DFT) calculations.