Open Access

ARTICLE

A Novel Design Strategy for Chitosan containing azobased Schiff bases for Colorimetric Sensing of Anions

NIDHI NIGAM, SANTOSH KUMAR^#, P.K.DUTTA^*, TAMAL GHOSH^*

Department of Chemistry, Motilal Nehru National Institute of Technology, Allahabad-211004, India.
# Konkuk University, Seoul, South Korea

* Corresponding Authors: e-mail: (PKD), (TG)

Journal of Polymer Materials 2018, 35(1), 137-148.

Abstract

The present investigation deals with the anion sensing studies of prepared chitosan/methyl red dye: chitosan/hydroxy nitro azobenzaldehyde (CHNAB) and chitosan/hydroxy methyl azobenzaldehyde (CHMAB) derivatives under mild conditions. These derivatives were synthesized by 79% and ≥ 90% deacetylated chitosan, in isopropyl alcohol/water mixture and dimethyl sulfoxide. The polymers were well characterized by thermal analysis (differential scanning calorimetry, DSC and thermogravimetric analysis,TGA), FTIR, ¹H-NMR, ESI-Mass spectra, birefringence and antibacterial activity and reported elsewhere. The optical property of the derivatives is an advantageous property prompted us to evaluate its anion sensing properties by UV-titrimetric method. UV–visible titration was carried out in DMSO to evaluate the binding affinities toward a set of anions (F^-, Cl^-, Br^-, I^-, CN^-, AcO^-, HSO₄ ^- and H₂ PO₄ ^- ). In the present study, it is observed that cyanide is mainly operating as a nucleophile. These cyanide anion sensing phenomena were analyzed by UV–vis titration in dimethyl sulfoxide. The plausible sensing mechanism of the chitosan derivative for CN-recognition was established. The study on the novel design strategy may be used for sensing anions.

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