Spectroscopy and Electrochemistry of Cobalt(III) Schiff Base Complexes

Böttcher, Arnd; Takeuchi, Toshihiko; Hardcastle, Kenneth I.; Meade, Thomas J.; Gray, Harry B.; Cwikel, Dory; Kapon, Moshe; Dori, Zvi

doi:10.1021/ic961146v

Cited by 276 publications

(209 citation statements)

References 13 publications

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“…The Co-O distances are similar to those found in related complexes e.g. [17,24]. The geometry of the ligand is in principle similar to that of 1, the dihedral angle between almost planar (within 0.043(2) Å ) N=C-C=C-O fragment and the phenyl ring plane is 33.63(12)°.…”

Section: Molecular Structuressupporting

confidence: 78%

“…Table 3 shows the results of antibacterial activity studies of ligand and its complex evaluated by Fig. 2 Perspective view of the ligand, H 2 hpac (1) together with labeling scheme [17]; the displacement ellipsoids are drawn at 50 % probability level, hydrogen atoms are shown as spheres of arbitrary radii. Intramolecular hydrogen bond is drawn as dashed line CgA denotes the midpoint of the phenyl ring Symmetry codes:…”

Section: Biological Propertiesmentioning

confidence: 99%

“…A number of model complexes with cobalt(II) and cobalt(III) have been prepared with particular emphasis on the reactivity of the metal ions in the transmethylation reaction and on the reversible absorption of molecular oxygen [12][13][14][15][16][17][18]. As a continuation of our studies on Schiff bases [19] we have performed the preparation and characterization of [Co III (hpac)py 3 ]PF 6 (hereafter referred to as 2).…”

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confidence: 99%

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

et al. 2012

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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

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Section: Molecular Structuressupporting

confidence: 78%

Section: Biological Propertiesmentioning

confidence: 99%

mentioning

confidence: 99%

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

et al. 2012

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“…The affinity of the coordinated zinc for the histidine and cysteine residues has been used to generate transition metal inhibitors of enzymatic activity and DNA-protein interaction (21)(22)(23)(24). Displacement of the zinc ion by a Co(III) Schiff base complex [Co(III)-sb] has been shown to inhibit DNA binding of at least 1 other zinc finger transcription factor (25) and enzymatic function of non-DNA binding proteins (25)(26)(27)(28).…”

mentioning

confidence: 99%

Targeted inhibition of Snail family zinc finger transcription factors by oligonucleotide-Co(III) Schiff base conjugate

Harney

Lee²,

Manus³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…Since complexes with relatively labile axial ligands exhibit higher activities, Gray and co-workers [2] assumed that axial binding of cobalt to biological targets was somehow involved in the mechanism (or mechanisms) of action. Herein we report the preparation and single and crystal structure of a cobalt(II) complex with two very labile axial H2O ligands.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of tetraaqua(o-phenanthroline)cobalt(II) sulfate dihydrate, [C12H8N2 )Co(H2O)4]S04 · 2H2O

Zhu¹,

Pan²,

Wang³

et al. 2002

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of material C0SO4 · 6H2O (1 g) was dissolved in water (5 ml) and was added to íerí-C4H900H (5 ml). With stirring to the solution was added a solution of phenanthroline (5 mmol in 5 ml of acetonitrile). Dichloromethene (5 ml) was carefully injected to the bottom of the above solution. The resulting solution with a clear layer was stood still in air. Five hours later a great amount of light pink crystals suitable for X-ray were deposited at the bottom of the flask. The product was washed with water and methanol, and dried in vacuum under CaCk. Analysis: found: C 32.5%, H 4.5%, Ν 6.18%, C12H20N2O10SC0 requires C 32.5%, Η 4.6%, Ν 6.32%.* Correspondence author (e-mail: hlzhu@wist.edu.cn) DiscussionThe discovery that certain cobalt complexes are potent antiviral agents [ 1 ] prompted us to initiate an investigation of cobalt interactions with proteins and nucleic acids. Since complexes with relatively labile axial ligands exhibit higher activities, Gray and co-workers [2] assumed that axial binding of cobalt to biological targets was somehow involved in the mechanism (or mechanisms) of action. Herein we report the preparation and single and crystal structure of a cobalt(II) complex with two very labile axial H2O ligands. The title complex comprises a discrete phenanthrolinatocobalt(ü) tetrahydrated di-cation, a sulfate anion and two uncoordinated water molecules. In the cation, each cobalt(II) atom is six-coordinated, with two nitrogen atoms from a phenanthroline ligand and four oxygen atoms from four molecules in a slightly distorted octahedral geometry. ) between plane I and the phenanthroline inside the molecule is mostly parallel. Two kinds of one-dimentional chains coming from appreciable phen-phen interactions between the molecules are found. Inside each chain, the phen rings are parallel to each other, and the interplanar distance is 3.45 Â, slightly shorter than that (3.48 Â) in the complex of literature [3]. Between the neighboring chains the phen rings are nearly perpendicular one another with the dihedral angle 77.4(8)°. All oxygen atoms, including those from the sulfate anion, coordinated and uncoordinated water molecules in the title complex, contribute to the formation of hydrogen bonds, and a large number of interlinked inter-and intramolecular hydrogen bonds join the molecules to form a network structure. Criterion for /obs, N(hkl)gi.

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Spectroscopy and Electrochemistry of Cobalt(III) Schiff Base Complexes

Cited by 276 publications

References 13 publications

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

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

Targeted inhibition of Snail family zinc finger transcription factors by oligonucleotide-Co(III) Schiff base conjugate

Crystal structure of tetraaqua(o-phenanthroline)cobalt(II) sulfate dihydrate, [C12H8N2 )Co(H2O)4]S04 · 2H2O

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