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

[Image: see text] 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.