Pyranone based probe for the selective and specific recognition of zinc ions

Abstract

Schiff base 4-Hydroxy-6-methyl-3-[1-(pyridine-4-ylmethylimino)-ethyl]-pyran-2-one (DP) was synthesized for the sensing of Zn2+ ions by stirring mixture of dehydroacetic acid and 4-picolylamine moieties in 1:1 M ratio and characterized thoroughly by different spectral techniques. The probe provided extremely selective and specific detection of Zn2+ ions in both UV–Vis and fluorescence emission investigations. The selectivity of DP probe towards Zn2+ ions were demonstrated by a significant band shift and quenching in the DP’s absorbance band and emission band, respectively for Zn2+ ions whereas no changes were seen for the other metals. Binding stoichiometry among DP and Zn2+ ions was found to be 2:1 using Job's plot analysis of both absorption and emission studies and were then validated by 1H NMR titrations and HRMS titrations. The binding constant (Ka) and detection limit (LOD) for Zn2+ ions were measured using both studies with the help of B-H equation and were found to be 8.7 × 104 M−1 and 1.7 × 10−7 mol/L respectively via emission studies. DFT studies thoroughly authenticated the experimental results. The sensing capability of probe showed strong selective behavior with no change in its detection of Zn2+ ions with the addition of competitive metals. Its application at practically over a range of 2–12 pH and stability over a long length of time further demonstrated DP’s superiority for Zn2+ ions detection. FESEM images too showed clear change onto the Zn2+ ions addition in DP led us an obvious confirmation of complexation. The Probe was too employed for quantitative detection of Zn2+ ions in the collected real water samples.