A new benzothiazole azo dye colorimetric chemosensor for detecting Pb2+ ion

Moein Ghorbanian; Sakineh Asghari; Mahmood Tajbakhsh

doi:10.1016/j.saa.2023.122652

A new benzothiazole azo dye colorimetric chemosensor for detecting Pb²⁺ ion

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Aug 5:296:122652. doi: 10.1016/j.saa.2023.122652. Epub 2023 Mar 21.

Authors

Moein Ghorbanian¹, Sakineh Asghari², Mahmood Tajbakhsh³

Affiliations

¹ Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar 47416-95447, Iran. Electronic address: moein.qorbanian@gmail.com.
² Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar 47416-95447, Iran. Electronic address: s.asghari@umz.ac.ir.
³ Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar 47416-95447, Iran. Electronic address: tajbaksh@umz.ac.ir.

PMID: 36989695
DOI: 10.1016/j.saa.2023.122652

Abstract

In this work, a new benzothiazole azo dye sensor (BTS) was synthesized, and its cation binding affinity was studied using the colorimetric method, UV-vis, and ¹H NMR spectral data. The results revealed that the sensor BTS exhibits a remarkable tendency for Pb²⁺ ion to perform spontaneous visual color change from blue (BTS) to pink (BTS + Pb²⁺), without any color change in the aqueous solutions of other cations such as Hg²⁺, Cu²⁺, Al³⁺, Ni²⁺, Cd²⁺, Ag⁺_, Ba²⁺, K⁺, Co²⁺, Mg²⁺, Na⁺, Ca²⁺, Fe²⁺, and Fe³⁺ ions. The observed selectivity could be due to the formation of the complex (BTS + Pb²⁺⁾, which led to a blue shift from 586 nm (BTS) to 514 nm (BTS + Pb²⁺) in the UV spectrum. The job's plot provided the stoichiometry ratio of the complex (BTS + Pb²⁺) to be 1:1. The limit of detection (LOD) of BTS for Pb²⁺ ion sensing was obtained at 0.67 µM. Additionally, the binding constant for BTS toward Pb ²⁺ ion was studied using the Benesi-Hildebrand equation. As a result of the BTS test paper strips investigations, it was found that the synthesized sensor BTS could be used as a rapid colorimetric chemosensor for the detection of the Pb²⁺ ions in the distilled, tap, and sea waters.

Keywords: 1,5-dihydroxynaphthalene; Azo dyes; Benzothiazoles; Colorimetric chemosensors; Metal cations.