Real-time probing of mercury using an efficient “turn-on” strategy with potential as in-field mapping kit and in live cell imaging

Based on a rhodamine scaffold as a fluorophore and 2-aminothiazole as a receptor, we present a highly selective and sensitive sensor ( TS ). An enhanced photophysical response (fluorescence as well as absorption) accompanied by high sensitivity and selectivity was observed upon interaction of TS with Hg 2+ among various competitive cations (Ag + , Al 3+ , Ba 2+ , Ca 2+ , Co 3+ , Co 2+ , Cd 2+ , Fe 3+ , Fe 2+ , K + , Li + , Mg 2+ , Mn 2+ , Cu 2+ , Pb 2+ , Ni 2+ , Na + and Zn 2+ ) in CH 3 CN : H 2 O (7 : 3 v/v, HEPES buffer 10 mM pH 7.0). The synthesized sensor can detect Hg 2+ as low as 0.326 μM with a complexation constant of 2.37 × 10 6 M −1 . This complexation between TS and Hg 2+ is reversible in the presence of ethylenediaminetetraacetate (EDTA). Furthermore, single crystal X-ray diffraction (XRD) and Job's plot results show a 1 : 1 binding stoichiometry. The most interesting feature of the sensor is the real-time determination of Hg 2+ in real contaminated water. Furthermore, the fabricated sensor can be employed as an intracellular monitoring agent for live cell imaging of the HeLa cell line.