LAUSR

Abstract A colorimetric and fluorometric turn-on probe L, (E)-1-((pyridin-4-yl)methylene) thiosemicarbazide has been synthesized and characterized by X-ray single crystal analysis, 1H- NMR, ESI-MS, UV–vis spectra and elemental analysis. The probe L, functioned as dual ions sensor to detect important metal ions Cu2+ and Ag+ in 1:1 methanol–water (v/v) solution in the presence of other cations (Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Hg2+, Pb2+, Cr3+, Al3+ and Fe2+ ions) based on binding site-signalling approach, where both the thiourea moiety and pyridine N atom acts as binding sites for Ag+ ions and only pyridine N atom acts as binding site in case for Cu2+. The binding stoichiometries of probe L, with the metal ions Cu2+ and Ag+ have been confirmed by Job's plot, ESI-mass spectral analysis and DFT studies. The colorometric detection limits reached upto 1.7 and 2.2 μM for Cu2+ and Ag+ and fluorometric detection limit upto 1.6 μM for Ag+ ions. The probe L has been successfully applied for the determination of Cu2+ and Ag+ ions in real water samples.