Synthesis and Computational Study of an Optical Fluorescent Sensor for Selective Detection of Ni2+ Ions.

Abstract

The presence of an abnormal amount of Ni2+ 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 Ni2+ ions in aqueous solution. The structure of P was confirmed by 1H NMR and Fourier transform infrared (FTIR) spectroscopy. The Ni2+ 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 Ni2+ 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 Ni2+ ions in neutral medium with a high association constant (K) value of 3.6 × 105 M-2 for the complex formation between the P and Ni2+ ions. Job's plot and DFT calculations proved that the binding stoichiometry of P for Ni2+ 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.