Synthesis and spectroscopic studies and Naked-eye detection of hydrogen carbonate ions in aqueous media based on an azo-azomethine chemosensor

Azo compounds are an interesting class of organic compounds which have found wide application in the field of chemicals sciences. Dyes are also found in food, pharmaceutical, paints, polymers, and standard materials used in adsorption chromatography [1]. They are increasingly used in textile, leather and plastic industries [2]. Anions play an essential role in the field of biology, industry and environmental science. [3]. Colorimetric chemosensors are attractive due to enhanced selectivity, sensitivity, low cost, convenient operation and fast detection character [4]. bicarbonate is, as the dominant buffering system in the human body. And has been celebrated for years as a multi-use household item and additive in food and dental products [5].In this work, we have synthesized a new optical and colorimetric properties of chemosensor 4-((E)-(2,5-dichlorophenyl)diazenyl)-2-((E)-((4 hydroxyphenyl)imino) methyl)phenol (L) for hydrogen carbonate ions by the naked–eye detection and UV–vis spectroscopy. This ligand reveals visual changes toward HCO3- anions in aqueous media. No considerable color changes were observed against the addition of any other anions. The sensitivity and selectivity of receptor to bicarbonate anion were specified with UV-vis spectroscopy and 1H NMR titration methods. The detection limit of the receptor towards HCO3- have 2.17×10-7 mol L-1. Therefore this chemosensor is sensitive to detect bicarbonate anion in aqueous solutions. Stability constants of these complexes were determined by Benesi–Hildebrand plot technique. Stoichiometry of the complexes was determined as (Ligand/anion) 1:1 with Job’s plot technique. The designed chemosensor may be applied for the quick detection of hydrogen carbonate anions in the basic pH range.