A highly sensitive and selective colorimetric and off–on fluorescent chemosensor for Cu2+ based on rhodamine 6G hydrazide bearing thiosemicarbazide moiety

A rhodamine derivative (R1) has been synthesized by an additive reaction of rhodamine 6G hydrazide with methyl 2-isothiocyanatobenzoate, which exhibits high selectivity and sensitivity as a fluorescent sensor toward Cu2+ under physiological conditions. The detection limit of Cu2+ ion is 47.2 nM. Moreover, R1 could sense Cu2+ by “naked eye” with a color change from colorless to pink. This selective signaling behavior is not affected by other canions that might be present in the environmental samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in HeLa cells was also demonstrated.