A quinazolin-based Schiff-base chemosensor for colorimetric detection of Ni(2+) and Zn(2+) ions and ‘turn-on’ fluorometric detection of Zn(2+) ion

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 (1)H-NMR, IR spectroscopy, ESI-MS spectrometry and theoretical studies. The receptor showed appreciable colorimetric λ(max) shift for both Ni(2+) and Zn(2+) ions and fluorometric “turn on” response in presence of only Zn(2+) ion. The Jobs plot analysis revealed that receptor forms 2 : 1 complex with both the ions Ni(2+) and Zn(2+), further confirmed by ESI-MS analysis. The single crystal structure of L–Ni(2+) complex (1) has also been determined. The colorimetric detection limits were calculated to 7.9 nM and 7.5 nM respectively for Ni(2+) and Zn(2+) 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.