A Pyrimidine-Based Schiff Base Fluorescent Chemosensor for Selective Detection of Mg²⁺: Synthesis, Real Water Analysis, Antibacterial, DFT and Molecular Docking Study.

内容摘要

A new Schiff-base fluorescent probe namely methyl 2-(((2-hydroxypyridin-3-yl) methylene) amino) pyrimidine-5-carboxylate (HL) has been designed and synthesized. Structural characterization of the purely synthesized compound was acquired by IR spectroscopy, 1H NMR, 13C NMR and Mass spectra. The Schiff base compound was explored as chemosensor for various transition as well as alkali metal ions viz. (Na+, K+, Ca2+, Ba2+, Sr2+, Cd2+, Ni2+, Co2+, Cu2+, Mn2+, Mg2+, Zn2+ and Fe3+). The study clearly reveals that the probe HL can rapidly and selectively recognize Mg2+, with the detection limit (LOD) of 7.2 × 10- 7 M. The results of fluorescence spectroscopic studies clearly reveals that a remarkable enhancement of the fluorescence intensity of the probe HL was observed in presence of Mg2+ ions, which was barely impacted by other metal cations. The stoichiometric ratio of HL to Mg²⁺ was determined to be 1:1 from Job's plot, B-H plot, 1H NMR titration, Mass spectra and the binding constant was calculated as 3.7 × 10⁴ M⁻¹ using the Benesi-Hildebrand method. Reversibility nature of the complex has been studied in presence of EDTA, which in turn regenerated free ligand for further Mg2+ sensing. HL further exhibits INHIBIT logic gate behaviour with Mg²⁺ and EDTA as inputs, as observed from the emission response at 414 nm. Over a broad pH range (9-12), this chemosensor shows excellent fluorescence sensing abilities to Mg2+. The probe HL has also been utilized for the detection of Mg2+ in real water samples. In addition, HL showed moderate antibacterial activity against Escherichia coli and Staphylococcus aureus, highlighting its bioactive potential.