Synthesis and spectroscopic characterization of sensor for naked-eye detection of cyanide ion in solution media using a new Schiff-base based on thiophene

Development of anion sensors is of great interest in supramolecular chemistry due to their chemical and biological importance [1]. Schiff base ligands are considered because they are easily prepared by the condensation between aldehydes and imines [2,3]. Among the various anions, cyanide is one of the most concerned anion, because it is known as one of the most rapidly acting and powerful poisons [4]. In this research, a new reactive ligand such as ethyl 2-{[1-(2-hydroxyphenyl) methylidene] amino}-4, 5, 6, 7-tetrahydro-1-benzothiophene-3-carboxylate was synthesized by a condensation reaction. In the first step, amine was synthesized from salicyl aldehyde substituted thiophene compounds. The synthesized receptor was detected by UV-Vis, FT-IR spectroscopy, 1H-NMR and melting point. Sensitivity and reactivity behavior of receptor with different anions was determined in the presence of different solvents. Also, the sensor sensitivity to various anions was investigated by UV-Vis (Fig.1) and 1H-NMR spectroscopy. The receptor exhibited significant color and spectral changes in the CN- anion in the DMF solvent. However, a significant change in the color of other anions, such as F-, Cl-, Br-, AcO-, H2PO4-, HSO4-, HCO3-, ClO4-, N3-, NO3-, NO2-, SO42-, SCN-, OH- in DMF was not observed.