Imidazole-derived new colorimetric/fluorometric chemosensor for the sensitive recognition of CN− ions: Real-time application in food samples and fluorescence bio-imaging

Abstract

On account of the supreme toxicity of CN− ions in the physiological systems, it is essential to develop a sensitive chemosensor to detect cyanide ions. Herein, we designed a new 5-(3-(4,5-diphenyl-1H-imidazol-2-yl)-2-hydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (BMA) sensor, which exhibits tremendous colorimetric as well as fluorometric behaviour towards CN− ions. This could be due to the nucleophilic attack of CN− ions on the dione-vinyl site, which induces intramolecular charge transfer (ICT) capabilities. The cyanide recognition mechanism of BMA was verified by optical experiments such as UV–visible and fluorescence spectroscopy, NMR, and mass analysis. Moreover, the structural characterization was done by 1H NMR titration and HRMS analysis, and the molecular orbital interactions were studied by TDDFT calculations. The sensor BMA exhibited a rapid response towards CN− ions (10 sec) with low detection limit (7.87 nM), great pH stability in the physiologically applicable pH range (6–12) and had good sensitivity and selectivity towards CN− ions. Encouraged by these detection properties, we successfully used sensor BMA to determine CN− ions in real water and food samples. To validate the colorimetric behavior of the sensor BMA, test paper strip experiments were carried out in the laboratory. We also extensively studied the effect of the sensor in Escherichia coli (E.coli) bacterial cells.