A quinazolin-based Schiff-base chemosensor for colorimetric detection of Ni2+ and Zn2+ ions and ‘turn-on’ fluorometric detection of Zn2+ ion

Abstract

Herein, we have reported a novel quinazolin-based Schiff base chemosensor (E)-2-benzamido-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (L). L has been designed, synthesised and characterised by ¹H-NMR, IR spectroscopy, ESI-MS spectrometry and theoretical studies. The receptor showed appreciable colorimetric λ_max shift for both Ni²⁺ and Zn²⁺ ions and fluorometric “turn on” response in presence of only Zn²⁺ ion. The Jobs plot analysis revealed that receptor forms 2 : 1 complex with both the ions Ni²⁺ and Zn²⁺, further confirmed by ESI-MS analysis. The single crystal structure of L–Ni²⁺ complex (1) has also been determined. The colorimetric detection limits were calculated to 7.9 nM and 7.5 nM respectively for Ni²⁺ and Zn²⁺ in methanol–Tris–HCl buffer medium (10 mM, pH 7.2, 1 : 1 v/v). The chemosensor L can be applied for the recovery of contaminated water samples.