Benzotiazole‐Based Colorimetric Chemosensor for the Effective Detection of Hazardous Cyanide Ions

Abstract

AbstractA new hydrazone based on 5‐nitrofurfural and 2‐hydrazinobenzothiazole (L) was introduced as a colorimetric chemosensor for rapid, selective, and sensitive detection of CN− ions in aqueous media. The chemosensor L was characterized using spectral methods such as FT‐IR, 1H, 13C NMR, UV‐Vis, and mass spectrometry. The interaction of L with the CN− ion provides a marked color change from yellow to blue‐green or blue, depending on the concentration of cyanide ions. The change in colour as well as in absorption maxima make it possible to detect CN− ions with the naked eye. The detection limit of the chemosensor L is 0.26 μM, which is below the WHO limit for cyanide ions in drinking water. Other competing anions (F−, Cl−, Br−, I−, SCN−, ClO3−, ClO4−, SO32−, H2PO4−, HSO4−, and NO3−) showed little effect on the detection of cyanide ions. Quantum chemical calculations confirm the recognition mechanism, which is based on the formation of a molecular complex of the −NH‐hydrazine fragment of the chemosensor L with cyanide ion. The chemosensor L applied on the paper and polymeric test strips can be used in experiments to detect cyanide ions in samples of drinking and river water.