A simple and efficient pyrazole based colorimetric chemosensor for sensing Hg2+, Zn2+, Cu2+ions and a selective sensing of Hg2+ions in the presence of Zn2+and Cu2+ions and its application in real samples

A simple colorimetric chemosensor (E)-4((4-diethylamino)-2-hydroxybenzylidene)amino)-1,5-dimethyl-2phenyl-1,2, dihydro-3H-pyrazole-3-one (M2) M2 ) was synthesized and characterized by NMR, Mass spectra, IR and UV spectra, along with solvatochromism. The synthesized compound showed colorimetric sensing towards Hg2+ 2 + ion with high selectivity and sensitivity. The UV-Vis absorption spectra studies demonstrated that the proposed sensor could detect Hg2+ 2 + directly in acetonitrile solution over other metal ions. In the presence of Hg2+ 2 + ion, the probe exhibits instantaneous color change from colorless to yellow as a naked-eye detection. The binding ratio of the probe with metal has been identified to be of 1:1 using Job's Plot and the obtained limit of detection is 8.83 x 10_8 _ 8 M. The binding interaction of probe with the Hg2+ 2 + is confirmed using 1 H NMR titration, ESI mass, and DFT calculation.