Selective Detection of Mercury Ion Using a Carboxamide Based Probe: Synthesis, Spectroscopic and Theoretical Investigation

A carboxamide based fluorescent probe N 2 , N 6 -bis(5-(4-chlorophenyl)thiazol-2-yl)pyridine-2,6-dicarboxamide (L) was synthesized by the condensation reaction between pyridine-2,6-dicarboxylic and amino derivative of thiazole. Structural characterization of (L) was executed by FT-IR, UV–visible, 1 H-NMR, 13 C-NMR and mass spectral studies. By employing absorption and fluorescence titrations to investigate the sensing phenomenon with various metal ions (Cu 2+ , Co 2+ , Ni 2+ , Hg 2+ , Cr 3+ , Al 3+ , Fe 2+ , Sn 2+ and Pb 2+ ), it was identified that probe (L) show selective fluorescent sensing behavior towards the Hg 2+ ion among other targeted metal ions. Using Job’s plot measurements, the binding stoichiometry mode of (L) with the Hg 2+ ion was estimated to be 1:1. The Benesi-Hildebrand equation yielded a stability constant value of 6.162 × 10 7 M ‒2 for the fluorescent probe. Limit of Hg 2+ ion was ascertained 0.0352 μM for the designed fluorescent probe (L). DFT analyses have also been performed to support the suitability of applied sensing technique and experimental outputs.