Synthesis, characterization, theoretical calculations of novel benzoic acid based azo molecules and their use in effective extraction of Hg(II) ions from aqueous medium

Abstract

In this study, two series of benzoic acid derivative azo compounds were synthesized using coupling reaction and characterized by various spectroscopic techniques. By using o-, m-, p-chloroaniline and o-, m-, p-nitroaniline as starting materials, the effects of the directing groups on the color intensity of azo dyes were investigated. It was concluded that the nitro group increased both the reaction efficiency and the color intensity. Optimized molecular structures, vibrational and electronic transition spectra, NMR chemical shift values, frontier molecular orbitals and MEP diagrams of each molecule were calculated using the 6-311G(d,p) basis set. All calculations were performed and compared with both Density Functional Theory (DFT) and Hartree-Fock (HF) methods. Experimental and theoretical results were found to be quite compatible with each other. The extraction capabilities of all synthesized azo derivatives were investigated using various transition metal picrates such as Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ cations. Solvent extraction studies of azo derivatives revealed that all compounds showed strong binding ability against Cu2+ and especially Hg2+ ions and were able to remove the Hg2+ cation from aqueous medium at a high rate (97.3%).