A novel benzothiazole based azocalix[4]arene as a highly selective chromogenic chemosensor for Hg2+ ion: A rapid test application in aqueous environment

A novel calix[4]arene derivative containing benzothiazole azo groups at the upper rim was synthesized as chromogenic chemosensor, and its binding and sensing properties with heavy metal ions (Pb2+, Hg2+, Ni2+, Cd2+, Cu2+, Zn2+, Co2+, Fe2+, Mn2+, Cr3+, Ag+) were investigated by UV–vis spectroscopy and voltammetric techniques. The results of spectroscopic and voltammetric experiments showed that the chromogenic chemosensor has high selectivity towards Hg2+ ion over the other heavy metal ions. Moreover, it was shown that the interaction between Hg2+ and the chromogenic chemosensor occurs by means of the benzothiazole azo groups at the upper rim by using differential pulse voltammetry. The stoichiometric ratio and the association constant were determined as 1:1 and (6.1 ± 0.3) × 105 L mol−1 for the complex between Hg2+ and the ionophore. Furthermore, we prepared a rapid test kit for early detection of Hg2+ in aqueous environment in the concentration range of 1 × 10−4 to 1 × 10−2 M.