A highly sensitive triazole-based perfectly water soluble novel bis-Schiff base reversible fluorescent-colorimetric chemosensor for fast detection of Pb²⁺ ions

A reversible fluorescent-colorimetric azino bis-Schiff base receptor for the detection of Pb2+ in aqueous medium has been developed for the first time. Receptor L exhibits an excellent selective and rapid fluorescent-colorimetric response towards Pb2+. The sensitivity of the fluorescent-based assay (0.53 nM) and colorimetric assay (1.0 nM) for Pb2+ is sufficiently good in comparison to previously reported literature. From H-1 NMR data, Job plot measurement and the ESI-MS spectrum, a 1 : 2 stoichiometric complexation between L and Pb2+ has been established. Receptor L shows a remarkable detection ability in a wide pH range of 4-8 and it has been successfully utilised in the determination of Pb2+ in aqueous solution of bovine serum albumin protein and in real samples. The geometry of L has been optimized by both DFT studies and NMR, FTIR and mass spectra. Moreover, we have studied molecular docking of the probe L.