Synthesis and Computational Study of an Optical Fluorescent Sensor for Selective Detection of Ni 2+ Ions.

The presence of an abnormal amount of Ni 2+ in the human body causes various health issues. Therefore, this work aimed to synthesize the curcumin-based fluorescence-on sensor P [2,6-bis(( E )-4-chlorobenzylidene)-cyclohexan-1-one] that was capable of selectively responding to Ni 2+ ions in aqueous solution. The structure of P was confirmed by 1 H NMR and Fourier transform infrared (FTIR) spectroscopy. The Ni 2+ ion sensing was based on the fluorescence enhancement of the fluorophore ( P ) in neutral aqueous medium. The response of the P -based sensor was highly selective toward Ni 2+ ions, whereas the possible interferences from other metal cations were negligible. P had a fast response; it was selective and had a sensitive detection limit (LOD = 2 × 10 -10 M) toward Ni 2+ ions in neutral medium with a high association constant ( K ) value of 3.6 × 10 5 M -2 for the complex formation between the P and Ni 2+ ions. Job's plot and DFT calculations proved that the binding stoichiometry of P for Ni 2+ was 2:1. P was recovered using EDTA as a chelating agent after being employed as a fluorescent sensor. These characteristics ensured the potential use of P as a new class of chemosensor for environmental applications.