Functionalized 2-Hydrazinobenzothiazole with Bithiophene as a Colorimetric Sensor for Lethal Cyanide Ions and Its Application in Food Samples
R. Tamizhselvi, Rangaswamy Chinnabba Bhaskar, Somanahalli Kalleshappa Ashok Kumar, Sonaimuthu Mohandoss, Yong Rok Lee, Ayyakannu Arumugam Napoleon
Abstract
High Resolution Image Download MS PowerPoint Slide A newly synthesized Schiff’s base 2-(2-([2,2′-bithiophen]-5-ylmethylene)hydrazinyl)benzothiazole ( BT ) was obtained from the condensation reaction between 2-hydrazinobenzothiazole and 2,2-bithiophene-5-carboxaldehyde. The prepared probe BT was subjected to a confirmation of the structural arrangement through NMR, FTIR, ESI-HRMS, and single-crystal XRD spectral analysis. The BT colorimetric sensor showed selectivity and sensitivity toward the cyanide (CN – ) ion over other common anions such as ClO 4 –, Cl –, Br –, F –, I –, NO 2 –, OH –, HSO 4 –, and H 2 PO 4 – in a partial aqueous system CH 3 CN/H 2 O (8:2, v/v). The probe BT detects CN – with the lowest detection range as low as 1.33 × 10 –8 M (3.59 ppm); in comparison to that given by WHO guidelines, it is significantly lower. The stoichiometric interaction between the probe BT 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 –3 M –1 . Additionally, these results were further supported by the FTIR and DFT calculations, as well as the 1 H NMR titration analysis, which complemented the binding data. The sensor probe BT 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 BT 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.