A highly selective chemosensor derived from benzamide hydrazones for the detection of cyanide ion in organic and organic-aqueous media: design, synthesis, sensing and computational studies

Abstract

ABSTRACT A new, highly sensitive and selective chemosensing method has been developed for the detection of cyanide ion using benzamide hydrazone receptors (R1-R4). The sensing ability of these compounds towards CN− in the presence of Br −, HSO4 −, Cl−, OH−, I−, F−, AcO−, NO2 − and NO3 − in DMF and DMF-Aqueous mixture (DMF:H2O, 9:1 v/v) was investigated. The binding characteristics of the probe with cyanide ions carried out by 1 H NMR titrations indicated the deprotonation of N-H group through H-bond interactions between benzamide hydrazones and cyanide ions; it has been theoretically supported by DFT. The binding constant (Ka) and stoichiometry of the host–guest complex formed was calculated by the Benesi–Hildebrand (B–H) plot, and strong interaction of the probe with CN- ions forming a 1:2 binding stoichiometry has been noted in this study. In a DMF and aqueous medium for CN− ion, the lower limit of detection (LOD in ppm) is compared to the limit of quantification (LOQ in ppm), which is quite better in terms of sensitivity.