Synthesis, experimental and theoretical characterization, and antimicrobial studies of some Fe(II), Co(II), and Ni(II) complexes of 2-(4,6-dihydroxypyrimidin-2-ylamino)naphthalene-1,4-dione

摘要

The work reported the synthesis and characterisation ofFe(2+), Co2+, and Ni2+ complexes of 2-(4,6-dihydroxypyrimidin-2-ylamino)naphthalene-1,4-dione (HL). Thespectroscopic and elemental analysis results obtainedwere consistent with the adoption of theformulas, [ML2] (M=Fe and Co) and [ML2(H2O)] (M=Ni) for the metal complexes. Electronic spectra and magnetic moments of the metal complexes corroborated octahedral geometry for Ni(II) complex and tetrahedral geometry for Fe(II) and Co(II) complexes. However, quantum-chemical calculations using density functional theory predicted trigonal bipyramidal geometry for Ni(II) complex and provided corroborative explanations for the structures of the other complexes. Conductance measurements in dimethylsulfoxide indicate that the complexes are non-electrolytes. The antimicrobial potential of the compounds was evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Proteus mirabilis, Klebsiella oxytoca, Aspergillus niger, A.flavus, and Rhizopus stolonifer. The compounds gavemoderate to good antimicrobial activity. However, the bacterial and fungal organisms were more susceptible to the cobalt complex and ligand respectively than the other compounds at concentration of 10mg/mL. The compounds were also assessed for their antioxidant potential using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay.The compounds displayed good DPPH radical scavenging activities. The nickel complex exhibited the best DPPH radical scavenging activity compared tothe other compounds.