Structural and spectroscopic characterization, electronic properties, and biological activity of the 4-(3-methoxyphenyl)piperazin-1-ium 4-(3-methoxyphenyl)piperazine-1-carboxylate monohydrate

In this study, 4-(3-methoxyphenyl)piperazin-1-ium 4-(3-methoxyphenyl)piperazine-1-carboxylate monohydrate was synthesized and characterized by using spectroscopic (XRD, FT-IR, FT-Ra, and NMR) techniques. Theoretical calculations were performed in the DFT method using the B3LYP functional and the 6–311 +  + G(d,p) basis set and compared with the experimental results. It was determined that the geometric parameters and spectroscopic data obtained from the DFT calculations were in high agreement with the experimental results. The HOMO–LUMO energy gap was calculated at 5.19 eV, while this value was experimentally found at 4.26 eV from the UV–Vis absorption spectrum. Although the experimental and theoretical values are different from each other, according to both results, this synthesized structure has low reactivity and a tendency to be stable. Also, the electronic (MEP, Fukuki functions, and charge analyses), nonlinear optical, and thermodynamic properties (heat capacity, entropy, enthalpy change, and Gibbs free energy) of the title complex were investigated. Electrophilic and nucleophilic regions were found to be the same in all of the electronic investigation analyses. The first hyperpolarizability value was calculated to be 25 times (9.27 × 10–30 esu) greater than that of the urea used for comparison. Therefore, it has very good nonlinear optical properties. The change in the values of calculated thermodynamic properties depending on the temperature change shows that the thermodynamic system of the structure changed. Finally, antimicrobial activity studies were carried out to evaluate the biological activity of this synthesized complex, the experimental results were supported by molecular docking studies, and the toxicological and physicochemical properties of the complex were investigated.