Exploring pyrrole, furan, and thiophene-based Schiff bases for selective cerium (III) ion recognition: Experimental and computational investigation

In this study, we report the design and synthesis of a novel heterocycle-based hydrazone accomplished via condensation reaction between chloroquinoline hydrazine and heterocyclic carbaldehyde derivatives and the resulting heterocycle-chloroquinoline hydrazone hybrid Schiff base ligands were successfully characterized using spectral techniques. The hybrid probes exhibited remarkable optical responses, showing high sensitivity, selectivity, and rapid detection ability toward Ce 3+ ions as studied through UV–visible and fluorescence titration experiments. The probes 3a–3c exhibited low limits of detection (LOD) for Ce(III) established as 6.14 nM, 7.57 nM, 8.57 nM and good binding constant found to be 5.91 × 10 4 M −1 , 1.40 × 10 4 M −1 , and 2.39 × 10 4 M −1 , respectively. The stoichiometric ratio was estimated as (1:1) ratio for metal-ligand complex by Job plot analysis. The DFT calculations were performed using B3LYP/6-311G++(d,p) for free probes and B3LYP/SDD for corresponding metal complexes to provide insights into binding interactions. The integrated experimental and theoretical findings formulate a reliable and precise detection framework for the detection of Ce(III) ions, having potential applications in ecological monitoring and analytical chemistry. In this study, we report the design and synthesis of a novel heterocycle-based hydrazone accomplished via condensation reaction between chloroquinoline hydrazine and 6-heterocyclic carbaldehyde. The hybrid probes exhibited remarkable optical responses, showing high sensitivity, selectivity, and rapid detection ability toward Ce 3+ ions in a CH₃CN:H₂O (4:1) solvent system. The probes 3a–3c exhibited low limits of detection LoD for Ce(III) established as 6.14 nM, 7.57 nM, 8.57 nM and good binding constant found to be 5.91 × 10 4 M −1 , 1.40 × 10 4 M −1 , and 2.39 × 10 4 M −1 , respectively. The DFT calculations were performed using B3LYP/6-311G++(d,p) for free probes and B3LYP/SDD for corresponding metal complexes to provide insights into binding interactions.