NOVEL SERIES OF SCHIFF BASE QUINOLINE LIGANDS ANDCATALYTIC OXIDATIVE DETECTION OF THE Cu2+ AND Fe3 + IONS, A TURN-OFF FLUOROPHORIC STUDY
A novel series of Schiff base-quinoline ligands was synthesised (1a-3c) by introducing different electron- withdrawing and donating aromatic moieties in the basic structure of the quinoline derivatives, in a Schiff basereaction. Synthesised ligands were characterised using spectroscopic methods such as 1H-NMR, UV, IR, HRMSandCHNS. The photoluminescence studies were performed to detect Cu 2+ and Fe 3+ in a sample matrix containing other competing cations. The prepared ligand showed fluorescence emission wavelengths in the 475-495 nmrange. Theinfluence of the substituents' electronic effect changes the ligands' fluorescence emission wavelengths. Inthepresence of the oxidising reagents, the synthesised ligands get oxidised and act as turn-off fluorescencechemosensors, specifically, for Cu 2+ and Fe 3+ ions at the nanomolar scale, in the presence of other interferingions. The ligand's energy-minimised structure, possible geometry, interaction between metal ions and ligands and energygap between HOMO-LUMO orbitals were studied by developing DFT structures.
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