Synthesis and Characterization of Novel Organocobaloximes as Potential Catecholase and Antimicrobial Activity Agents

Abstract

An asymmetric, potentially bidentate dioxime ligand (H₂L) was formed by condensation of 4-biphenylchloroglyoxime and napthyl-1-amine. Two equivalents of H₂L were reacted with CoCl₂ · 6H₂O under appropriate conditions with deprotonation of the dioxime ligand. A series of new organocobaloxime derivatives of the type [CoR(HL)₂Py], [CoRL₂PyB₂F₄], and [CoRL₂Py(Cu(phen))₂] (H₂L = 4-(napthyl-1-amino)biphenylglyoxime; phen = 1,10-phenathroline; R = izopropyl and benzyl; Py = pyridine) were synthesized. The products were characterized by elemental analysis, molar conductance, FT-IR, ¹H NMR, and magnetic susceptibility measurements. Catecholase-like activity properties of all complexes were also studied. All complexes are catalysts for the oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butyl-1,2-benzoquinone in methanol. Antimicrobial activity studies of H₂L and the six complexes were carried out on standard strains (human pathogenic) of bacteria (Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Bacillus cereus, Enterococcus faecalis, Streptococcus pneumoniae, Listeria monocytogenes, Bacillus subtilis, Escherichia coli, Pseudominas aeruginosa, Salmonella typhi) and the yeast Candida albicans. The compounds showed a significant inhibition of the growth of the Gram-positive bacteria tested. Among the tested microorganisms, S. aureus was the most sensitive strain, especially to H₂L and its complexes.

Recent Advances and Prospects in the Chemistry of o‐Benzoquinones

“…Tomes and co‐workers developed a novel porphyrin based copper complex (CuP1S) which was found to be effective in ortho ‐benzoquinone synthesis by catechol oxidation in the presence of air . Some recently synthesized organocobaloximes also act as good catalysts in the synthesis of 3,5‐di‐tert‐butyl‐1,2‐benzoquinone by the oxidation of 3,5‐di‐tert‐butylcatechol in methanol …”

“…One of the most important applications lies in the field of total synthesis of natural products. A novel protocol for the total synthesis of Mycoleptodiscin A, was reported recently . Diels‐Alder reaction of diterpenoid based ortho ‐benzoquinones with alkynes found utility in the synthesis of racemic isolophanthinA, isolophanthin B and abietatrien‐3 β ‐ol …”