Benzo[d]imidazo [2,1-b]thiazole-based fluorescent sensor for Zn2+ ion detection

In this study, we have synthesized and evaluated three benzo[d]imidazo[2,1-b]thiazole-based sensors (BIT-1, BIT-2 and BIT-3). Among them, BIT-3 namely 2-(benzo[d]imidazo[2,1-b]thiazol-2-yl)-5-methoxyphenol was introduced as a selective fluorescence chemosensor for Zn2+ ion detection. The presence of zinc ions enhanced fluorescence property of BIT-3 at 404 nm due to formation of a 1:1 complex between the chemosensor and the Zn2+ ion. Control experiments showed that the analogous ions do not have fluorescence enhancement effect and some of them even quench the fluorescence dramatically. The data obtained from UV-vis absorption analysis, fluorescence measurements and H-1 NMR spectroscopy approved the interaction between BIT-3 and Zn2+ ion. The sensor probe BIT-3 exhibits a selective fluorescence enhancing property via a chelation-enhanced fluorescence (CHEF) upon addition of Zn2+. Thus, a selective fluorescent chemosensor BIT-3 establishes an important sensing platform for real-time monitoring of Zn2+ ion in aqueous environment.