Synthesis, characterization and antibacterial activity of cobalt(III) complexes with pyridine–amide ligands

Braicu

Not Bot Hort Agrobot Cluj

et al. 2011

The antibacterial properties of differently copper and cobalt amino acids complexes on agar plates was investigated in the present study. The antibacterial activity of amino acid complexes was evaluated against on three bacteria strains (Escherichia coli, Bacillus cereus, Micrococcus luteus). Generally, the amino acids complexes were mainly active against gram-positive organisms, species like Micrococcus luteus being the most susceptible strain tested. It was registered a moderate antibacterial activity against Bacillus cereus. The microorganisms Escherichia coli, which are already known to be multi-resistant to drugs, were also resistant to the amino acids complexes but also to the free salts tested. Escherichia coli were susceptible only to the CoCl 2 and copper complex with phenylalanine. The complexes with leucine and histidine seem to be more active than the parent free ligand against one or more bacterial species. Moderate activity was registered in the case of complexes with methionine and phenylalanine. From the complexes tested less efficient antibacterial activity was noted in the case of complexes with lysine and valine. These results show that cobalt and copper complexes have an antibacterial activity and suggest their potential application as antibacterial agents.

Section: Discussionmentioning

confidence: 93%

Antibacterial Activity of Copper and Cobalt Amino Acids Complexes

Braicu

Not Bot Hort Agrobot Cluj

et al. 2011

“…This synthetic strategy leads to the generation of heterodimetallic complexes [8][9][10] and networks [11] of a highly ordered nature. Utilizing this strategy, we have recently demonstrated the Co 3+ coordination complex 1 [7] as the building block for the preparation of {Zn 2+ -Co 3+ -Zn 2+ }, [8] {Cd 2+ -Co 3+ -Cd 2+ }, [9] and {Hg 2+ -Co 3+ -Hg 2+ } [9] heterodimetallic complexes (Scheme 1). The selection of the peripheral metal ion was based on the possible application of the exposed Lewisacidic metal ion in organic transformations.…”

Section: Introductionmentioning

confidence: 98%

“…[7][8][9][10][11] A coordination complex as the building block offer many benefits such as spectroscopic and magnetic properties as well as structural rigidity. Such an induced rigidity has the ability to place the auxiliary functional groups in a preorganized conformation with an option to control the geometrical placement of such groups.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structures, and Heterogeneous Catalytic Applications of {Co³⁺–Eu³⁺} and {Co³⁺–Tb³⁺} Heterodimetallic Coordination Polymers

2010

Self Cite

“…Potent antibacterial activity of cobalt(II) and cobalt(III) Schiff base complexes have been reported in different studies [25,26]. Table 3 shows the results of antibacterial activity studies of ligand and its complex evaluated by Fig.…”

Section: Biological Propertiesmentioning

confidence: 94%

Synthesis, Antibacterial Studies and Crystal Structures of Tridentate Schiff Base Ligand and It’s Cobalt(III) Complex

et al. 2012

The crystal structures of 4-[(2-hydroxyphenyl) imino]-2-pentanone (H 2 hpac, 1) and its cobalt(III) complex [Co III (hpac)py 3 ] ? ÁPF 6 -(2) have been determined by X-ray diffraction. The ligand 1 crystallizes in orthorhombic chiral P2 1 2 1 2 1 space group, with a = 8.8405(4) Å , b = 10.5349(8) Å , c = 11.2292)7( Å ), and the complex 2-in the centrosymmetric monoclinic P2/n space group, with a = 16.496(5) Å , b = 10.171(2) Å , c = 16.646(5) Å , and b = 95.53(3)°. In the ligand molecule quite strong intramolecular hydrogen bond closes six-membered ring. The bond length pattern within this ring suggests the significant conjugation and the structure might be therefore regarded as the intermediate between keto-enamine and zwitterionic forms, and the intramolecular hydrogen bond falls into category of resonance-assisted hydrogen bonds. In turn, intermolecular O-HÁÁÁO hydrogen bonds connect the molecules of the ligand into infinite chains along [100] direction. In the complex, the Co(III) ion is hexa-coordinated, by two oxygen and one nitrogen atoms of the doubly-deprotonated ligand 1 and by three nitrogen atoms from three pyridine ligands. The coordination polyhedron is close to a slightly distorted octahedron. The in vitro antimicrobial activity of the Schiff base ligand and its corresponding complex have been tested against human pathogenic bacterias such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli.Keywords Schiff base Á Tridentate ligands Á Co complex Á Hydrogen bonds Á Biological activity Results and DiscussionAcetylacetone (acac) or pentane-2,4-dione is often used as a good precursor in organic synthesis and as a building block of metal-organic complexes [1,2]. Its anion acts as the bidentate ligand and is known to form complexes with many transition metal ions [3][4][5]. A general method of preparation of such complexes consists in a reaction of a metal ion with acetylacetone in presence of a base which easily separates the proton. Replacement of the ketone functional group by the imine one results in corresponding bidentate Schiff bases, which also proved to be useful ligands. If 2-hydroxy aniline is used as the amine, one can prepare the tridentate ligand. Such a ligand-4-[(2-hydroxyphenyl)imino]-2-pentanone (hereafter referred to as 1), known as H 2 hpac, where H 2 represents the dissociable enolic -OH and hydroxyphenyl protons-has been already prepared and used for making the square-planar mixed-ligand nickel(II) complex with deprotonated H 2 hpac (i.e. hpac), which coordinates through the enolate oxygen, the imine nitrogen and the deprotonated hydroxyphenyl oxygen atoms. Additionally, the neutral N-donor, imidazole, has been used as an ancillary ligand [6]. Such