Colorimetric and turn-on Fluorescence Chemosensor for Hg Ion Detection in Aqueous Media.

A new rhodamine 6G based fluorescent and colorimetric chemosensor, containing N-methyl imidazole nucleus, for the selective detection of Hg ion was designed and synthesized. The results of UV-Vis and fluorescence spectral study indicated that the receptor is selective and sensitive towards Hg with no noticeable interference with other competitive metal ions. The addition of Hg to the receptor induced a rapid color change to pink from colorless and the turn-on fluorescence response toward Hg among different cations was studied. The stoichiometric ratio of 1:1 between the receptor and Hg was supported by Job's plot. The color change and turn-on fluorescence response upon addition of Hg ion was ascribed by the spirolactam ring-opening mechanism. The probable mode of binding between the receptor and Hg was confirmed by H NMR and Mass spectral study. For the practical application, its electrospun nanofiber test strips successfully applied to recognize Hg ion in aqueous media. Graphical Abstract Schematic representation of Hg detection by rhodamine based sensor.