A highly sensitive on-off fluorescent chemosensor for Cu²⁺ based on coumarin

Chemosensor C1, namely, 3-acetoacetyl-7-hydroxycoumarin, was synthesized and exhibited highly selective and sensitive fluorescence sensing ability for Cu²⁺ over other metal ions under physiological conditions. The fluorescence quenching response of C1 for Cu²⁺ indicated that C1 can be used as an on-off fluorescent chemosensor to selectively detect Cu²⁺. The binding process was confirmed by UV–vis absorption, fluorescence measurement, mass spectroscopy, IR spectra and DFT calculation. To test the practical use of the probe, the determination of Cu²⁺ in real water samples was evaluated. The application of the fluorescent probe in monitoring intracellular Cu²⁺ in HeLa cells has also been demonstrated.