A hydrazone dual-functional fluorescent probe based on carbazole and coumarin groups for the detection of Cu2+ and ClO−: Application in live cell imaging and actual water samples

A new hydrazone derivative LL3 based on carbazole and coumarin was prepared by the condensation of 7-diethylaminocoumarin-3-carbohydrazide with 3-aldehyde-N-butyl carbazole and its structure was characterized using FT-IR, 1H NMR, 13C NMR, MS and elemental analysis techniques. LL3 could be used as a dual-functional fluorescent probe to identify Cu2+ and ClO−. Probe LL3 could recognize Cu2+ and formed a 2:1 complex. Under a 365 nm UV lamp, the color changed from yellowish to blue-green which could be readily distinguished by the naked eye. Meanwhile, under the catalysis of ClO−, the imine bond of probe LL3 was hydrolyzed to obtain carbazolealdehyde, resulting in specific UV-Vis and fluorescence phenomena, so as to realize the detection of ClO−. The recognition mechanism was proved by spectrometric titrations, Job's plots, FT-IR, 1H NMR, mass spectroscopy (MS) and density functional theory (DFT) calculation analysis. The results of live cell imaging showed that LL3 could be used as a fluorescent probe to detect Cu2+ and ClO− in Hela cells. In addition, the probe LL3 could also be made into a test strip for the detection of Cu2+ in actual water samples.