Dual-applicable imidazole-schiff base fluorescent sensor for precise determination of Cu2+ in aqueous media and living cells

An acyl hydrazide probe ( E )- N′ -(1-(7-(diethylamino)-2-oxo-2 H -chromen-3-yl)ethylidene)-4- (4,5-diphenyl-1 H -imidazol-2-yl)benzohydrazide (DDB), based on imidazole and coumarin structures was synthesized and structurally characterized by FT-IR, 1 H, 13 C NMR, and HR-MS. The sensing behavior of the probe was investigated using fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy. The probe DDB exhibits sensitive and selective recognition of Cu 2+ in EtOH-H 2 O (1:1, v /v) through the weakened fluorescence effect upon chelation. The detection limit of DDB for Cu 2+ is 7.25 nm. As can be seen from the Job's plot, the binding constant of DDB to Cu 2+ is 2.24 × 10 5  M −1 , and the stoichiometric ratio of DDB to Cu 2+ is 1:1. The reusability of the probe was evaluated by alternately adding Cu 2+ and EDTA to the DDB solution. The probe DDB was used to quantitatively detect Cu 2+ in actual water samples from different water sources. The recovery rate is within the acceptable range, indicating that the probe DDB can be used for the quantitative detection of Cu 2+ in actual water samples. The potential application of this probe in fingerprint detection was studied, providing inspiration for the development of fingerprint detection and anti-counterfeiting technologies. In addition, this probe has been successfully applied to the monitoring of Cu 2+ in living cells.