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

The presence of an abnormal amount of Ni2+ in the humanbody causes various health issues. Therefore, this work aimed to synthesizethe curcumin-based fluorescence-on sensor P [2,6-bis((E)-4-chlorobenzylidene)-cyclohexan-1-one]that was capable of selectively responding to Ni2+ ionsin aqueous solution. The structure of P was confirmed by H-1 NMR and Fourier transform infrared(FTIR) spectroscopy. The Ni2+ ion sensing was based onthe fluorescence enhancement of the fluorophore ( P ) in neutral aqueous medium. The response of the P -based sensor was highly selective towardNi(2+) ions, whereas the possible interferences from othermetal cations were negligible. P hada fast response; it was selective and had a sensitive detection limit(LOD = 2 x 10(-10) M) toward Ni2+ ionsin neutral medium with a high association constant (K) value of 3.6 x 10(5) M-2 for thecomplex formation between the P andNi(2+) ions. Job's plot and DFT calculations provedthat the binding stoichiometry of P forNi(2+) was 2:1. P was recoveredusing EDTA as a chelating agent after being employed as a fluorescentsensor. These characteristics ensured the potential use of P as a new class of chemosensor for environmentalapplications.

Automated summary

This work synthesized a curcumin-based fluorescence-on sensor (P) capable of selectively responding to Ni2+ ions in aqueous solution. P exhibited high selectivity towards Ni(2+) ions with negligible interferences from other metal cations. It had a fast response, sensitive detection limit (LOD = 2 x 10(-10) M), and a high association constant (K = 3.6 x 10(5) M-2) for complex formation with Ni(2+) ions. P could be recovered using EDTA as a chelating agent and showed great potential as a chemosensor for environmental applications.