X-Ray Studies and Antibacterial Activity in Copper and Cobalt Complexes With Imidazole Derivative Ligands

Abstract

The complexes Diaqua-bis(5-nitroimidazole)-copper(II)-dinitrate (1); Tetrakis(4-phenylimidazole)-copper(II)-dinitrate, ethanol solvate (2); Bis(4-phenylimidazole)-bis(acetate)-copper(II) (3); Hexakis(4-phenylimidazole)-cobalt(II)-acetate (4) and Bis(2-phenylimidazole)-bis(acetate)-cobalt(II) (5), have been synthesized. Their structures were determined by X-ray analysis.The antimicrobial activities of these complexes have been screened in vitro against the microorganisms Escherichia coli, Klebsiella pneumoniae, Shigella flexneri, Salmonella typhi, Salmonella enteritidis, Salmonella enterica, Staphylococcus aureus, Listeria monocytogenes. Complexes (1) and (3) showed antimicrobial activity over Gram positive and negative bacteria by a bacteriostatic effect. On the other hand, complexes (4) and (5) showed antibacterial activity with a bacteriolytic effect over Gram positive and negative bacteria.The cytotoxicity of complexes (3) and (4) was tested in vitro. These complexes presented cytotoxic effect to values near the MIC.

Influence of ligand positional isomerism on the molecular and supramolecular structures of cobalt(II)-phenylimidazole complexes

“…The tetrahedral complex 8 (with 5-phenylimidazole) was also concurrently isolated with complex 7, most likely due to the small difference in the CFSE between the octahedral and tetrahedral geometry in Co II complexes. Our conclusions are in agreement with the two previously structurally characterized complexes [Co(O 2 CMe) 2 (LH) 2 ] and [Co(L 0 H) 6 ]-(O 2 CMe) 2 (Atria et al, 2011). The more sterically demanding ligand LH allows only two molecules to participate in coordination, whereas the less sterically demanding L 0 H ligand can lead even to 1:6 complexes (not identified in our work).…”

“…) was based on (i) their tendency to coordinate terminally as mono-or bidentate ligands, thereby often excluding the possibility of forming coordination polymers, (ii) their ability to act as counterions, and (iii) their size, shape and charge, in order to study their effect on the metal coordination geometry, as well as their spatial role in the motif formation and packing organization. A search in the Cambridge Structural Database (CSD; Groom et al, 2016) showed only two Co II complexes with the LH and L 0 H ligands, both comprising acetate ions (coordinated or as counterions) (Atria et al, 2011).…”

Antibacterial Activities of Azole Complexes Combined with Silver Nanoparticles

“…Co has a larger atomic radius than Cu, and it has been reported that the bond length between Co and its ligand could favor antibacterial activity [ 35 ]. In addition, copper is an essential trace element for many biological processes [ 36 ]. As the data analysis further indicates, complexes 5 , 8 and 9 showed more moderate activities than 3 and 4 .…”

Synthesis, Characterization and Antibacterial Activity of Cobalt(iii) Complex With Phenanthroline and Maltose

“…We used a plate assay to distinguish bactericidal from bacteriostatic action modes of the antimicrobial complexes [16,17]. This method was based on the use of β-galactosidase as an appropriate marker of cellular lysis.…”