A thio-urea based chromogenic and fluorogenic chemosensor for expeditious detection of Cu2+, Hg2+ and Ag+ ions in aqueous medium

A novel simple reversible fluorescent and colorimetric multiple metal ions chemosensor L based on the thiourea has been designed, synthesized, and characterized by H-1 NMR, IR spectroscopy, ESI-MS spectrometry and elemental analyses. The chemosensor L successfully detect Cu2+, He2+ and Ag+ based on binding site-signalling approach, where the thiourea group acts as binding site and the pyridine linked benzene ring acts as signalling unit. Distinct changes on UV-vis, fluorescence spectra and electrochemical behavior have been detected with the addition of Cu2+, Hg2+ and Ag+ ions along with the visual colour change in 1:1 methanol -water solution in the presence of other cations and anions (Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Mn2+, Cr3+, F-, Br-, Cl-, AcO-, HSO4-, H2PO4- and CN-). The detection limits reach up to 10.67, 11.14 and 8.54 mu M for Cu2+, He2+ and Ag+ ions respectively. L has been successfully applied for the determination of Cu2+, Hg2+ and Ag+ ions in real water samples. The minimum energy structure of L has been optimised by DFT calculations. (C) 2018 Elsevier B.V. All rights reserved.