A novel pyrazole biscoumarin based chemosensors for the selective detection of Cu2+ and Zn2+ ions

• A novel chemosensor based on pyrazole biscoumarin molecule (PBC) was described.
• PBC chemosenses selectively Cu2+ and Zn2+ visible by naked eye.
• No spectral changes even in the presence of other common metal ions.
• The binding ratio PBC to Cu2+ and Zn2+ as 1:1 and 2:1 respectively.

A novel chemosensor based on pyrazole biscoumarin molecule “4-hydroxy-3-((4-hydroxy-2-oxo-2H-chromen-3-yl)(1,3-diphenyl-1H-pyrazol-4-yl)methyl)-2H-chromen-2-one” (PBC) was synthesized by a simple method. The chemosensing properties of PBC towards transition metal ions like Cu2+ and Zn2+ by naked eye, UV–Visible and fluorescence spectroscopic methods were described. The PBC solution with Cu2+ and Zn2+ ion showed brown and blue colour respectively. The UV–Visible spectra of PBC with Cu2+ and Zn2+ ions exposed their corresponding absorption maxima. Further, the Job’s plot method confirmed the 1:1 and 2:1 stoichiometry of the complex formation between the PBC with Cu2+ and Zn2+ ions respectively. The fluorescence enhancement of PBC on binding with Cu2+ and Zn2+ is due to the inhibition of photo induced electron transfer mechanism.

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