New Molecular Azo-Azomethine Receptor for Colorimetric Detection of Inorganic Anions

A new azommerhine receptor, HL, was synthesized by reaction of 2-(3,4-dimethoxy phenyl)ethan-1-amine and 2-hydroxy-5-((4-nitro phenyl)diazenyl)benzaldehyde in pure EtOH. The sensing ability of HL was investigated qualitatively towards various anions, such as F-, Cl-, Br-, I-, NO3-, AcO-, CN-, HSO4- and H2PO4- (as their sodium salts), by visual examination of color changes in dry DMSO. Furthermore, the anion recognition behavior of, HL, was explored using UV-Vis spectroscopy in dry DMSO and also in semi-aqueous solution (DMSO: H2O, 7:3, v/v). The prepared receptor could instantly detect inorganic CN-, AcO- over other anions in semi-aqueous media, at low limit of CN- about 7×10-7 M. which is lower than the World Health Organization (WHO) permissible level.Moreover, the stoichiometry between HL with CN-, AcO- were determined from UV-Vis spectral changes with the help of Benesi–Hildebrand method. The results indicated that the mentioned anions interact with HL in a 1:1 stoichiometry with binding constants of CN-: 3.1×104 M, AcO- : 3.6×104 M .