A new mechanism for selective recognition of cyanide in organic and aqueous solution

Abstract

A simple colorimetric and fluorimetric chemosensor 3,5‐dinitro‐(N‐phenyl)benzamide (DNBA), was synthesized for selective determination of cyanide anion in organic and aqueous solutions via novel chemodosimeter approach. The chemosensor DNBA showed a chromogenic and fluorogenic selective response to CN– against competing anions such as F–, AcO–, and H2PO4– in organic (DMSO and ACN) and in aqueous solutions (in DMSO/H2O: 8:2, v/v). The intensive colorimetric and fluorimetric color changes were observed in ambient light and UV‐light (λex. 365 nm) after cyanide interacted with DNBA. A method that can be used in the synthesis of new biologically active benzisoxazole compound was described by the reaction of DNBA with TBACN and KCN in DMSO or DMSO/H2O, respectively. All interaction mechanisms between DNBA and cyanide and fluoride anions were demonstrated by experimental studies using various spectroscopic methods such as UV/Vis, fluorescence, 1H/13C NMR, and mass spectrometry as well as X‐ray diffraction method. In addition, the experimental results were also explained with theoretical data. The spectroscopic results showed that cyanide interacts with three different mechanisms; deprotonation, nucleophilic aromatic substitution, and formation of benzisoxazole ring.