Unveiling the ion sensing capabailities of ‘click’ derived chalcone-tailored 1,2,3-triazolic isomers for Pb(ii) and Cu(ii) ions: DFT analysis

Abstract

In this study, two novel chalcone-derived 1,2,3-triazole-appended positional isomers (probe 6 and probe 9) were synthesized via the ‘CuAAC’ (Cu(I) – catalysed alkyne azide cycloaddition) methodology for the purpose of metal ion detection. The synthesized probes underwent characterization utilizing standard spectroscopic methodologies including FTIR, NMR (¹H and ¹³C), and mass spectrometry. Subsequently, the sensing capabilities of these probes were explored using UV-Vis and fluorescence spectroscopy, wherein their selective recognition potential was established for Pb(II) and Cu(II), both of which can pose serious health hazards when prevalent in the environment above permissible limits. Both the probes exhibited fairly low limits of detection (LoD), determined as 5.69 μM and 6.55 μM in the case of probe 6 for Pb(II) and Cu(II) respectively; whereas the probe 9 exhibited an LoD of 5.06 μM and 7.52 μM for Pb(II) and Cu(II), respectively. The job's plot for the probe demonstrates the formation of a 1 : 1 complex between the metal and ligand. Furthermore, the interaction of the free probes with the metal ions in the metal–ligand complex was elucidated through ¹H NMR analysis and validated theoretically using Density Functional Theory (DFT) simulations with the B3LYP/6-311G++(d,p) and B3LYP/LANL2DZ basis sets for geometry optimization of the probes and their corresponding metal complexes. These findings offer a reliable approach to Cu(II) and Pb(II) ion detection and can be further used for the potential applications in environmental monitoring and analytical chemistry.