Ferrocene and Triazole-Appended Rhodamine Based Multisignaling Sensors for Hg2+ and Their Application in Live Cell Imaging

Two triazole-appended ferrocene–rhodamine conjugates, C47H45N7O3Fe (2) and C49H49N7O3Fe (3), have been synthesized, and their electrochemical, optical, and metal cation sensing properties have been explored in aqueous medium. The newly synthesized receptors are simple, easily synthesizable, and display very high “turn on” fluorescence response for Hg2+ as well as I– in an aqueous environment. Quantification of the absorption titration analysis shows that the receptors 2 and 3 can detect the presence of Hg2+ even at very low concentrations (∼3 ppb). The mode of metal coordination has been studied by DFT calculations. Furthermore, the receptors 2 and 3 are less toxic toward MCF-7 cells and could detect intracellular Hg2+ by fluorescent imaging studies.