Carboxamide-Based Probe for Highly Selective Detection of Copper Ions: Synthesis, Spectroscopic Analysis, Theoretical Investigations and Catalytic Activity

A carboxamide based fluorescent probe N2,N6-bis(5-(p-tolyl)thiazol-2-yl)pyridine-2,6-dicarboxamide was synthesized by the condensation reaction between pyridine-2,6-dicarboxylic and amino derivative of thiazole and characterized by FT-IR spectroscopy, 1H NMR, 13C NMR, UV-vis spectroscopy and LC-MS spectral studies. Absorption and fluorescence titrations were used to study the fluorescent. The probe exhibits high selectivity and sensitivity towards Cu2+ ions over a spectrum of metal ions (Cu2+, Co2+, Ni2+, Hg2+, Cr3+, Al3+, Fe2+, Sn2+ and Pb2+). Using Job’s plot measurements, the binding stoichiometry mode of the probe with the Cu2+ ion was estimated to be 2:1. The Benesi-Hildebrand equation yielded a stability constant value of 8.252 × 107 M–2 for the fluorescent probe. It was found that the fluorescent probe’s limit of detection (LOD) for the Cu2+ ion was 0.0242 µM. DFT analyses have also been performed to support the sensing technique. The Cu(II) complex's catalytic activity was assessed using the one-pot azide–alkyne cycloaddition click reaction in water without the use of any supplementary agents.