RESUMO
A new rhodamine 6G based fluorescent and colorimetric chemosensor, containing N-methyl imidazole nucleus, for the selective detection of Hg2+ ion was designed and synthesized. The results of UV-Vis and fluorescence spectral study indicated that the receptor is selective and sensitive towards Hg2+ with no noticeable interference with other competitive metal ions. The addition of Hg2+ to the receptor induced a rapid color change to pink from colorless and the turn-on fluorescence response toward Hg2+ among different cations was studied. The stoichiometric ratio of 1:1 between the receptor and Hg2+ was supported by Job's plot. The color change and turn-on fluorescence response upon addition of Hg2+ ion was ascribed by the spirolactam ring-opening mechanism. The probable mode of binding between the receptor and Hg2+ was confirmed by 1H NMR and Mass spectral study. For the practical application, its electrospun nanofiber test strips successfully applied to recognize Hg2+ ion in aqueous media. Graphical Abstract Schematic representation of Hg2+ detection by rhodamine based sensor.
RESUMO
A combination of Pd(OAc)2 (5 mol %), PPh3 (10 mol %), and Et3B (200 mol %) promotes the formation of allyl phenyl sulfones from the allylic alcohols directly with excellent yields under mild conditions. The activation of an alcohol group is not necessary which is achieved in situ. The conjugated dienols also were equally effective for the said transformation.