Synthesis, characterization, and antimicrobial activity of copper(II) and iron(III) complexes with sodium barbitone in selected pathogens

Objectives: The rapid emergence of antimicrobial resistance has increased the search for potent therapeutic agents, such as metal-based transition compounds with biological activities. Therefore, this study aims to examine therapeutic compounds of barbitone complexes with copper(II) and iron(III) ions against Salmonella Typhi, Pseudomonas glycinea, Ralstonia solanacearum, Erwinia carotovora, Streptococcus faecalis (bacterial pathogens) and Serpula lacrymans, Trichophyton verrucosum, Epidermophyton floccosum (fungal strains). Materials and Methods: The metal complexes were synthesized by reacting copper(II) sulphate pentahydrate and iron(III) chloride hexahydrate with sodium barbitone using stoichiometric metal-ligand ratios (1:1 and 1:2) in a water-methanol medium. The complexes were characterized by melting points, solubility, color, and gravimetric analysis. Ultraviolet-visible (UV-Vis) and Infrared spectroscopic methods were used to establish the mode of coordination at the metal center. Results: The synthesized compounds were tested against the five bacterial pathogens ( S . Typhi , P. glycinea, R. solanacearum, E. carotovora , and S. faecalis ) and three fungal strains ( S. lacrymans, T. verrucosum , and E. floccosum ), and they were obtained as stable, colored solids. The complexes were formulated as [CuL(H2O) SO4].4H2O, [CuL2(H2O)SO4].4H2O, [FeL(H2O)Cl3].5H2O, and [FeL2(H2O)Cl3].5H2O where L represents (NaC8H11N2O3). The melting points of the formed complexes ranged from 120°C to 192°C, and the percentage yields from 62% to 71%. Coordination occurred through deprotonated nitrogen and oxygen atoms, while the UVVis bands indicate an octahedral geometry. Conclusion: All metal complexes demonstrated antimicrobial activity against tested pathogens, with copper(II) complexes showing superior antibacterial activity to iron complexes. The findings, based on the zone of inhibition screening, provide a basis for future assessment involving minimum inhibitory concentration determination and toxicity investigation before therapeutic potential can be fully evaluated.