Synthesis of Quinoline-based New Organic Chemosensors and its Application in Fluorophoric Detection of Metal-ions in Environmental Samples and Confirmation of Results using Molecular Modelling: A Complete Study

Abstract

Quinoline-based two new ligands have been synthesized (QL1 and QL2) by reacting 8-quinoline carboxylic acid with derivatives of L-valine under a condensation reaction. The synthesized ligands were characterized by spectroscopic techniques such as 1H NMR, UV, IR, HRMS and CHNS. The 3D structures of both ligands were optimized for the lowest energy and the HOMO-LUMO orbitals were developed. The photoluminescence analysis of both ligands showed the fluorescence emission wavelengths on 492 and 508 nm, respectively for QL1 and QL2. The substituents on the quinoline ring influence the change in fluorescence emission wavelengths. Synthesized ligands acted as selective fluorescence turn-off chemosensors for Cu2+ ions and demonstrated the sensitive detection of Cu2+ ions in different water samples at the nanomolar scale. The interaction between metal ion and ligands were also studied by developing DFT structures.