Dioxygen affinities and catalytic oxidation activities of cobalt complexes with Schiff bases containing crown ether

Sun, Bin; Chen, Jun‐Ru; Hu, Jian‐Yong; Li, Xianjun

doi:10.1016/j.jinorgbio.2006.03.004

Cited by 17 publications

(5 citation statements)

References 22 publications

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“…Many four- to-five coordinate cobalt compounds were synthesized over 40 years ago, partly in an effort to make reversible oxygen carriers. ,,, While these compounds mainly failed in their ability to reversibly bind oxygen, they have been shown to be effective catalysts for the oxidation of a variety of small molecules including oxygen. ,,, Potentially, most similar complexes of cobalt with tetradentate ligands containing strong donors like nitrogen should also have the capacity to additionally bind two molecules of cyanide and thus function as cyanide scavengers, as we have recently observed in the case of a water-soluble cobalt porphyrin (CoTMPyP). ,, Consequently, it is not altogether surprisingly that we now find the Schiff-base macrocyclic complex CoN 4 [11.3.1] binds two cyanide anions (Figures and ) and is an efficacious cyanide antidote when given to mice both before and after the administration of an LD 40 dose of NaCN (5.0 mg/kg ip) (Figures and ). We have also shown that following recovery from acute effects there are no obvious short-term neuromuscular sequelae resulting from either the toxicant or the toxicant plus antidote (Figure ), an encouraging result.…”

Section: Discussionmentioning

confidence: 99%

Cyanide Scavenging by a Cobalt Schiff-Base Macrocycle: A Cost-Effective Alternative to Corrinoids

Lopez-Manzano

Cronican

Frawley

et al. 2016

Chem. Res. Toxicol.

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The complex of cobalt(II) with the ligand 2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]heptadeca-1(17)-2,11,13,15-pentaene (CoN4[11.3.1]) has been shown to bind two molecules of cyanide in a cooperative fashion with an association constant of 2.7 (±0.2) × 105. In vivo, irrespective of whether it is initially administered as the Co(II) or Co(III) cation, EPR spectroscopic measurements on blood samples show that at physiological levels of reductant (principally ascorbate) CoN4[11.3.1] becomes quantitatively reduced to the Co(II) form. However, following addition of sodium cyanide, a dicyano Co(III) species is formed, both in blood and in buffered aqueous solution at neutral pH. In keeping with other cobalt-containing cyanide-scavenging macrocycles like cobinamide and cobalt(III) meso-tetra(4-N-methylpyridyl)-porphine, we found that CoN4[11.3.1] exhibits rapid oxygen turnover in the presence of the physiological reductant ascorbate. This behavior could potentially render CoN4[11.3.1] cytotoxic and/or interfere with evaluations of the antidotal capability of the complex toward cyanide through respirometric measurements, particularly since cyanide rapidly inhibits this process, adding further complexity. A sublethal mouse model was used to assess the effectiveness of CoN4[11.3.1] as a potential cyanide antidote. The administration of CoN4[11.3.1] prophylactically to sodium cyanide-intoxicated mice resulted in the time required for the surviving animals to recover from “knockdown” (unconsciousness) being significantly decreased (3 ± 2 min) compared to that of the controls (22 ± 5 min). All observations are consistent with the demonstrated antidotal activity of CoN4[11.3.1] operating through a cyanide-scavenging mechanism, which is associated with a Co(II) → Co(III) oxidation of the cation. To test for postintoxication neuromuscular sequelae, the ability of mice to remain in position on a rotating cylinder (RotaRod test) was assessed during and after recovery. While intoxicated animals given CoN4[11.3.1] did recover ~30 min more quickly than controls given only toxicant, there were no indications of longer-term problems in either group, as determined by continuing the RotaRod testing up to 24 h after the intoxications and routine behavioral observations for a further week.

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Section: Discussionmentioning

confidence: 99%

Cyanide Scavenging by a Cobalt Schiff-Base Macrocycle: A Cost-Effective Alternative to Corrinoids

Lopez-Manzano

Cronican

Frawley

et al. 2016

Chem. Res. Toxicol.

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“…Traditionally,m ost composite catalysts are based on metals such as cobalt, copper, iron, manganese,a nd iridium for the allylic oxidation of cyclohexene. [124][125][126][127] However,t hese oxidation reactions usually proceeded in the liquid phase and it was extremely difficult to recycle these catalystsf rom homogeneous systems. Yang et al preparedaseries of bimetallic FeCo/g-C 3 N 4 catalysts for the selectiveo xidation of cyclohexenet o2 -cyclohexene-1-one in aqueouss olution.…”

Section: Organicreaction Catalystsmentioning

confidence: 99%

Metal/Graphitic Carbon Nitride Composites: Synthesis, Structures, and Applications

Wang

et al. 2016

Chemistry An Asian Journal

113

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Graphitic carbon nitride (g-C N ) has been widely used in fields related to energy and materials science. However, nanostructured g-C N photocatalysts synthesized by traditional thermal polycondensation methods have the disadvantage of small specific surface areas and wide band gaps; these limit the catalytic activity and application range of g-C N . Based on the unique nanostructure of g-C N , it is a feasible method to modify g-C N with metals to design novel metal-semiconductor composites. Metals alter the photochemical properties of g-C N , in particular, narrow the band gap and expand photoabsorption into the visible range, which improves the photocatalytic performance. This review covers recent progress in metal/g-C N nanocomposites for photocatalysts, organic systems, biosensors, and so on. The aim is to summarize the synthetic methods, nanostructures, and applications of metal/g-C N nanocomposite materials, as well as discuss future research directions in these areas.

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“…applicability in different oxidation reactions, [10][11][12][13] in particular for the oxidation of phenols, alcohols, flavonoides, nitroalkanes, hydrazines or olefins. [14][15][16] In addition, cobalt complexes have gained importance because of their application as potential hypoxia-activated prodrugs. 17 Phosphoesterase enzyme in biological systems plays a vital role in the functioning DNA fragmentation, RNA replication, bone metabolism, chemotherapy and bio-remediation of organophosphate pesticides.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and phosphatase activity of a Cobalt(II) phenanthroline complex

Garai¹,

Dey²,

Yadav

et al. 2017

J Chem Sci

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A mononuclear cobalt(II) complex, [Co(phen) 2 Cl 2 ], (phen = 1,10-phenanthroline) has been synthesized and structurally characterized by different spectroscopic methods including single crystal X-ray structural study. X-ray crystal structural analysis revealed that the cobalt(II) complex crystallizes in a monoclinic system with C2/c space group and exists in cis-configuration in its crystalline state. Room temperature magnetic measurement accounts for 3e paramagnetism and indicates high spin cobalt(II) in the solid state. The cobalt(II) complex has been evaluated as a functional model for phosphatase enzyme by using 4-nitrophenylphosphate (PNPP) as a standard substrate in aqueous DMF medium. This mononuclear cobalt(II) complex exhibits good hydrolytic phosphoester cleavage efficiency with k cat value of 3.78 × 10 2 h −1 .

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Dioxygen affinities and catalytic oxidation activities of cobalt complexes with Schiff bases containing crown ether

Cited by 17 publications

References 22 publications

Cyanide Scavenging by a Cobalt Schiff-Base Macrocycle: A Cost-Effective Alternative to Corrinoids

Cyanide Scavenging by a Cobalt Schiff-Base Macrocycle: A Cost-Effective Alternative to Corrinoids

Metal/Graphitic Carbon Nitride Composites: Synthesis, Structures, and Applications

Synthesis and phosphatase activity of a Cobalt(II) phenanthroline complex

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