A new method for synthesizing benzofuran-2-carboxamide derivatives with a symmetrical chemosensor for naked-eye detection of CN– ions based azo-thiazolidine-2,4‑dione (S-AT) and evaluation of antibacterial activity and molecular docking studies

A new symmetric chemosensor including a thiazolidine-2,4-dions (TZD) and an azo chromophore was synthesized and employed as a colorimetric sensor. Visual investigations of detecting anions showed that the sensor acts as a highly sensitive and selective chromogenic detector of cyanide ions (CN⁻). The observable color change from Yellow to Orange for CN⁻ allows the detection of this ion without the use of advanced equipment, even with the naked eye. The sensor limit of detection (LOD) was determined to be 0.145 μM for CN⁻ ions. The Job plot indicates that the sensor (S-AT) binds to CN⁻ with a stoichiometric ratio of 1:2. This sensor can be used in the real world, including environmental monitoring and chemical analysis, because of its ability to quickly and accurately detect dangerous CN⁻s. Also, S-AT against Gram-positive bacteria (S. aureus) shows a significant result. An attempt has been made to clarify the results of the treatment of S-AT with CN⁻ to understand the mechanism in which the sequence of events leads to a change in the color of the reactant. It has been demonstrated computationally that in this case the basicity of CN⁻ is dominant over its nucleophilicity and causes proceeding a new route in which a five atoms 6π electrocyclic ring closure occurs that is followed by extrusion of carbonyl sulfide molecules and finally affords benzofuran-2-carboxamide moiety whose presence is compatible with the experimental FT-IR, UV–Vis spectra, and ¹H NMR. The effectiveness of some related proposed structures for treating Cancer and Alzheimer’s disease were explored through docking studies, and significant results were obtained.