Functionalized 2-Hydrazinobenzothiazole with Bithiophene as a Colorimetric Sensor for Lethal Cyanide Ions and Its Application in Food Samples.

A newly synthesized Schiff's base 2-(2-([2,2'-bithiophen]-5-ylmethylene)hydrazinyl)benzothiazole () was obtained from the condensation reaction between 2-hydrazinobenzothiazole and 2,2-bithiophene-5-carboxaldehyde. The prepared probe was subjected to a confirmation of the structural arrangement through NMR, FTIR, ESI-HRMS, and single-crystal XRD spectral analysis. The colorimetric sensor showed selectivity and sensitivity toward the cyanide (CN) ion over other common anions such as ClO, Cl, Br, F, I, NO, OH, HSO, and HPO in a partial aqueous system CHCN/HO (8:2, v/v). The probe detects CN with the lowest detection range as low as 1.33 × 10 M (3.59 ppm); in comparison to that given by WHO guidelines, it is significantly lower. The stoichiometric interaction between the probe and analyte CN was found to be 1:1 (BT/CN) binding mode using Jobs plot, and further association binding affinity was calculated to be 6.64 × 10 M. Additionally, these results were further supported by the FTIR and DFT calculations, as well as the H NMR titration analysis, which complemented the binding data. The sensor probe was successfully employed in a cotton swab test kit approach and also in smartphone-assisted applications for the determination of CN ions. Finally, the outstanding sensing properties of probe aided the quantitative detection of CN ions, and it could be further applied to a variety of food samples, including apple seeds, sprouting potatoes, and cassava.