A highly sensitive reversible fluorescent-colorimetric azino bis-Schiff base sensor for rapid detection of Pb2+ in aqueous media

Abstract

A reversible fluorescent-colorimetric azino bis-Schiff based receptor for the detection of Pb²⁺ in aqueous medium has been developed for the first time. Receptor L exhibits an excellent selective fluorescent-colorimetric rapid response towards Pb²⁺. The sensitivity of the fluorescence based assay (8 nM) for Pb²⁺ is sufficiently low in comparison to that previously reported in the literature. From ¹H NMR data, the Job plot measurement and the ESI-MS spectrum, 2 : 1 stoichiometric complexation between L and Pb²⁺ has been established. Microstructural features of L and L + Pb²⁺ have been investigated by using SEM images for better understanding the interaction between the chemosensor and Pb²⁺. Receptor L shows remarkable detection ability in a wide pH range of 4–10 and it has been successfully utilised in the determination of Pb²⁺ in aqueous solution of bovine serum albumin protein. The geometry of L has been optimized both by DFT calculations and single crystal X-ray studies and that of the Pb²⁺ complex has been optimized by DFT calculations.