A 'turn-on' fluorescent probe for the detection of Cu2+ in living cells based on a signaling mechanism of NN isomerization

A novel fluorescent probe A based on coumarin associated with a NN double bond was conveniently designed and synthesized for Cu2+, and both rapid colorimetric and fluorescence turn-on detection can be achieved, showing a visible color change from pink to yellow and a significant fluorescence enhancement, respectively. The probe exhibits high selectivity toward Cu2+ over other metal ions and excellent sensitivity with a detection limit of 20 nM, and it can be monitored in a wide range of pH (3–10) in aqueous systems. Besides, the probe has been applied in living cells.