Herein, the synthesis and characterizations of (Z)-4-((4-nitrophenyl)amino)pent-3-en-2-one (HL) ligand and its Zn(II) complex are reported. The compounds were characterized using elemental and thermogravimetric (TGA) analysis, electrochemical studies, FTIR, UV-Vis, 1H and 13C{H}NMR, HRMS, and PXRD techniques. Antimicrobial activity was screened on some Gram-positive and Gram-negative bacteria. DFT predictions were achieved using B3LYP, ωB97XD and M06-2X functional with 6-31+G(d,p) and LANL2DZ basis sets for nonmetallic and metallic atoms, respectively. The therapeutic potentials of the compounds were evaluated based on protein binding affinity, ADME/T and drug-likeness properties. The experimental results revealed the formation of a complex in which two ligands coordinated to the zinc ion in a tetrahedral arrangement through their carbonyl and amino groups. The antimicrobial study showed that the complex possesses higher antimicrobial activity than free ligand and the control (Streptomycin). B3LYP emerged as the best performing functional having yielded the best IR spectra and geometrical parameters relative to the experimental data. The density functional theory (DFT) predictions revealed that the complex is more active than the ligand, and its formation is thermodynamically feasible and exothermic. The docking results revealed that the binding affinities of the compounds are in agreement with the in-vitro data, and they possess drug-like properties. KEY WORDS: Schiff base, Zinc complex, Antimicrobial, DFT, Docking study Bull. Chem. Soc. Ethiop. 2023, 37(3), 633-651. DOI: https://dx.doi.org/10.4314/bcse.v37i3.8

The escalating global challenge of antibiotic resistance amid rising oxidative stress emphasizes the critical necessity for innovative antimicrobial strategies. This study, reported synthesis of Schiff base ligand, ( Z )‐2‐[(4‐nitrobenzylidene)amino]phenol (HL), derived from c ondensation between 2‐aminophenol and 4‐nitrobenzaldehyde, and it Co(II), Ni(II), Cu(II), and Zn(II) complexes. The compounds were characterized using NMR, FTIR, UV−Vis, MS, TGA, SEM‐EDX, and elemental (CHN) analysis. In addition, solid‐state structure of HL was obtained using single‐crystal x‐ray diffraction. The characterizations show that the ligand coordinated to the metal ions through the oxygen and nitrogen atoms of phenolic and imine moieties, resulting in a homoleptic mononuclear complexes of the form ML ₂ , in which, M represents cobalt, nickel, copper, or zinc, and L stands for the ligand. Stability studies using time‐dependent UV−Vis spectroscopy in a 5% DMSO solution showcases the stability of the complexes with constant stability ( K ) as 3.76 × 10 ³ , 3.51 × 10 ³ , 3.30 × 10 ³ , and 2.88 × 10 ³ for NiL ₂ , CuL ₂ , CoL ₂ , and ZnL ₂ , respectively. Antibacterial and antioxidant activities were evaluated against selected bacteria and DPPH radical, with the complexes outperforming the ligand. Notably, Ni(II) complex showed superior activity, with MIC value as low as 3.9 µg/mL against Bacillus subtilis and IC ₅₀ values of 2.3 µM on DPPH radical. DFT calculations at the B3LYP/Def2TZVP level supported the experimental results and provided additional insight into the geometry of the complexes. Molecular docking further validated the biological study results, providing insights into the mechanisms of action and binding affinities against the receptor.

Numerous personal care products contain Bisphenol-A (BPA), a hormone disruptor that ultimately finds its way into waterways. A combination of experimental investigations and Monte-Carlo simulations (MCS) were used to explore zerovalent iron nanoparticles (nZVI) for their removal. The nZVI exhibited an absorption peak (λmax) at 373 nm with a mesoporous structure (pore size 2.138 nm), 159.419 m2 g−1 surface area, and crystalline peaks. The adsorption processes were positively influenced by batch parameters. BPA adsorption on nZVI varied with temperature as predicted by Freundlich and Langmuir isotherms, achieving a maximum adsorption capacity (qmax) of 982.13 mgg−1 at 308 K and pH 2. The adsorption process at 303 and 308 K was physisorption, whereas, at 313 K, it was chemisorption suitably described by pseudo-second-order kinetics. The exothermic and spontaneous nature of the adsorption processes were demonstrated by the negative values of enthalpy (−ΔH°) and free energy (−ΔG°) that decreased with increasing temperatures (308–328 K). The density function theory and MCS studies showed that BPA's phenyl ring, isopropyl, and hydroxyl groups interacted electrostatically with nZVI, specifically crystal plane 121 with the most negative adsorption energy (ΔEads), enhancing BPA removal. Through optimized adsorption mechanisms, nZVI can effectively remove BPA from wastewater.