An efficient fluoroionophore for selective recognition of Hg2+ and Cu2+ ions

An azo-phenol based receptor 2 viz., 1-(6-nitrobenzothiazole-2-ylazo)naphthalene-2-ol has been designed, synthesized and characterized. The sensing behavior of receptor for different metal ions viz. Na+, K+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Hg2+, Ag+ and Cd2+ has been studied in aqueous acetonitrile solution and was found specific for both the Hg2+ and Cu2+ transition metal ions. The chemosensor upon interaction with Hg2+ and Cu2+ ions shows well defined naked-eye visible color change from a yellow-green to pink and blue respectively, with a significant red-shift in absorption spectra. The estimated association constant and, enhancement and quenching in fluorescence emission spectra respectively, reveals the affinity of chemosensor for Hg2+ and Cu2+ ions. The FT-IR spectral analysis have suggested the probability of complexation, in the reaction medium, between metal ions and 2, through naphthol OH, azo N and thiazole N as a potential coordination sites.

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