Ferrocene and triazole-appended rhodamine based multisignaling sensors for Hg²⁺ and their application in live cell imaging

Abstract

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.