• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2544-2548
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• 2011

Two pyridinecarboxamide cobalt dicyanide building blocks and Mn(III) compounds have been employed to assemble cyanide-bridged heterometallic complexes, resulting in three trinuclear cyanide-bridged $Co^{III}-Mn^{II}$ complexes: $\{[Mn(MeOH)_4][Co(bpb)(CN)_2]_2\}{\cdot}2MeOH{\cdot}2H_2O$ (1), $\{[Mn(MeOH)_4][Co(bpmb)(CN)_2]_2\}{\cdot}2MeOH{\cdot}2H_2O$ (2) and $\{[Mn(DMF)_2(en)_2][Co(bpb)(CN)_2]_2\}{\cdot}2DMF{\cdot}H_2O$ (3) ($bpb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)benzenate, $bpmb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, en = ethylenediamine). Single crystal X-ray diffraction analysis shows their similar sandwich-like structures, in which the two cyanide-containing building blocks act as monodentate ligands through one of their two cyanide groups to coordinate the Mn(II) center. For complex 3, it was further linked into one-dimensional structure by ethylenediamine acting as bridges. Investigation of the magnetic properties of complex 3 reveals weak antiferromagnetic coupling between the neighboring Mn(II) centers through the bridging ethylenediamine molecule. A best-fit to the magnetic susceptibilities of complex 3 gave the magnetic coupling constant J = -0.073(2) $cm^{-1}$.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.2
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• pp.133-146
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• 2012

Three different derivatives were obtained in the synthesis of cobalt-binding BLM-A2 and characterized by NMR and Mass spectrometry. It was found that Component 1 is Co(II)($2H_2O$)(BLM-A2), component 2 is Co(III)($OOH^-$)(BLM-A2) and component 3 is Co(III)($H_2O$)($OH^-$)(BLM-A2), respectively. Component 2 and 3 were interestingly dominated when CoBLM-A2 complex was synthesized under basic condition. In this experiment, it was revealed newly that the brown form (component 1) was 6-coordinated structure composed with not 5 ligands but 4 ligands from BLM-A2 and with $2H_2O$ as the axial ligands. The component 3 exhibiting a novel ligand configuration is found, and the structure of component 3 was observed to be very similar to that of component 1 in the kind of their ligands but one of the axial ligand is $OH^-$ instead of $H_2O$. These ligand configurations are different from the green form (component 2) exhibiting 6-coordinate structure composed of 5 ligands from BLM-A2 and one ligand of $OOH^-$, being consistent with former studies.

• Resources Recycling
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• v.7 no.3
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• pp.3-10
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was treated by adsorbing colloidal flotation using Fe(III) or Al(IlI) as flocclant and a sodium lamyl sulfate as a collector. Parameters such as pH, surfactant concentration, Fe(III) or Al(III) concentration, gas flow rate, etc., W앙e considered. The flotation with Fe(III) showed 99.8% removal efficiency of cohalt on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, and flotation time 30 min. When the waste solution, was treated with 35% $H_2O_2$ prior to adsorbing colloidal flotation, the optimal pH for removing cobalt shifted m to weak alkaline range and flotation could be applied in wider range of pH as compared to non-use of $H_2O_2$. Additional use of 20 ppm Al(III) after precipitation of 50 ppm Co(II) with 50 ppm Fe(III) made the optimal pH range for preferable flotation w wider. Foreign ions such as, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $Ca^{2+}$ were adopted and their effects were observed. Of which sulfate ion was f found to be detrimental to removal of cob퍼t ion by flotation. Coprecipitation of Co ion with Fe(III) and Al(III) resulted in b better removal efficiency of cobalt IOn 피 the presence of sulfate ion.

• The Journal of the Korean dental association
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• v.18 no.8 s.137
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• pp.657-667
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• 1980

This study was undertaken to observe the salivary gland of the white rat when exposed to single and fractionated doses of Cobalt-60 irradiation. One hundred fifty white rats of the experiment were devided into control and 3 experimental groups. In experimental groups, group I receivcd 1200 rads everyweek untill 4800 rads reached, group II received 1500 rads and group III received 2000 rads with single dose. irradiation was carried out using a RAC-120 Cobalt-60 Teletherapy Unit with a dose rate 84.3 r/min, field size 4×5 cm measured at 80 from source. Rats were serially sacrificed at the following postirradiation time intervals: 1, 3, 5, 7, 10, 14, 21, 28, 35, and 42days. At sacrifice, the parotid and submandibular glands were dissected out in toto, and stained with: 1) hematoxylin and eosin; 2) periodic acid Shiff; 3) toludine blue.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1381-1385
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• 2006

Cobalt (cyclam) complex has been successfully immobilized onto SBA-15, and proven to be an active catalyst for the epoxidation of styrene with tert-butyl hydroperoxide as a terminal oxidant. The selectivity for styrene oxide was observed to be up to 66% with 40% styrene conversion after 12h reaction time. The reversible redox cycle between Co(III) and Co(II) couple which was supposed to play key role during the epoxidation reaction was supported by a cyclic voltametry analysis. The textural properties of the catalyst was characterized by XRD, N2 adsorption-desorption, and TEM analysis.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.193-194
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• 2006

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.280-280
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• 2013

In green plants, energy generation is accomplished through light-harvesting photosystem, which utilize abundant visible light and multi-stepwise redox reaction to oxidize water and reduce NADP+, transferring electrons efficiently with active cofactors1. Inspired by natural photosynthesis, artificial solar water-splitting devices are being designed variously. However, the several approaches involving immobilization2, conjugation3, and surface modification4 still have limitations. We have made artificial photosynthesis templates by self-assembling tyrosine-based peptide to mimick photosystem II. Porphyrin sensitizer absorbing blue light strongly was conjugated with the templates and they were hybridized with cobalt oxide through the reduction of cobalt ions in an aqueous solution. The formation of hybrid templates was characterized using TEM, and their water oxidation performance was measured by fluorescence oxygen probe. Our results suggest that the bio-templated assembly of functional compounds has a great potential for artificial photosynthesis.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.261-272
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• 1992

Tetradentate Schiff base Cobalt(II)(3MeOSED)$(H_2O)_2$ complexe was synthesized and allowed to react with dry oxygen to form oxygen adducts of Cobalt(III) complexes such as ${\mu}$-peroxo type [Co(III)(3MeOSED)(DMF)]$_2O_2$ and [Co(III)(3MeOSED)(DMSO)]$_2O_2$in DMF and DMSO or superoxo type [Co(III)(3MeOSED)(Py)]$O_2$ in pyridine. The oxygen adducted complex was investigated by cyclic voltammetry and DPP method with glassy carbon electrode in 0.1M TEAP-DMF (-DMSO,-Py) as supporting electrolyte solution. As a result the reduction reaction process occurred to four steps including prewave Of $O_2^-$in 1 : 1 oxygen adducted superoxo type [Co(III)(3MeOSED)(Py)]$O_2$complex and three steps not including prewave of $O_2^-$ in 1 : 2 oxygen adducted ${\mu}$-peroxo type [Co(III)-(3MeOSED)(DMF)]$_2O_2$ and [Co(III)(3MeOSED)(DMSO)]$_2O_2$. A superoxo type [Co(III)(3MeOSED)(L)]$O_2\;(L: CH_3OH)$ was generated with oxygen in methanol. Selectively oxidized hydrazobenzene $(H_2AB)$ to trans-azobenzene(t-AB) and the rate constant k for oxidation reaction of the following equation is $(2.96 {\pm} 0.2)$${\times}$ $10^{-1}$M/sec. $H_2AB$ + Co (II)(3MeOSED)$(L_2)+O_2\;{\rightleftarrow^K}$ [Co(III)(3MeOSED)(L)]$O_2{\cdot}H_2AB{\longrightarrow^K}$ Co(II(3MeOSED)$(L)_2$+t-AB+$H_2O_2 $.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.894-905
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• 1992

Dioxygen binding and homogeneous catalytic oxidation of hydrazobenzene were investigated by employing tetradentate Schiff base Cobalt(II) complexes such as Co(II)(SED)$(Py)_2$, Co(II)(SOPD)$(Py)_2$ and Co(II)(SND)$(Py)_2$ in saturated oxygen methanol solvent. The major product of hydrazobenzene ($H_2$AB) oxidation by catalysts of superoxo type [Co(III)(SED)(Py)$O_2$] and [Co(III)(SOPD)(Py)$O_2$] complexes are trans-azobenzene (t-AB) and rate constants k for oxidation reaction was 7.692 ${\times}$ $10^{-2}$ M/sec for [Co(III)(SED)(Py)$O_2$] and 5.076 ${\times}$ $10^{-2}$ M/sec for [Co(III)(SOPD)(Py)$O_2$]. But cis-azobenzene (c-AB) are obtained as a major product with ${\mu}$-peroxo type [Co(III)(SED)(Py)]$_2O_2$ catalyst, and rate constant k is 1.266 ${\times}$ $10^{-2}$ M/sec. The rate constants of oxidation reaction has been studied spectrophotometrically and the rate law established. A mechanism involving a intermediate activated complexes of catalyst, hydrazobenzene and oxygen has been proposed. $H_2$AB + Co(II)(Schiff base)$(Py)_2$ + $O_2$ ${\rightleftharpoons}_{MeOH}^K$ Co(III)(Schiff base)(Py)$O_2$${\cdot}$$H_2$AB + Py $\longrightarrow^k$ Co(II)(Schiff base)$(Py)_2$ + t-AB + $H_2O_2$(Scchiff base : SED and SOPD). $H_2$AB + 2Co(II)(SND)$(Py)_2$ + $O_2$ ${\rightleftharpoons}_{MeOH}^K$ [Co(III)(SND)(Py)]$_2O_2$${\cdot}$H_2$AB + 2Py ${\longrightarrow}^k$ (Co(II)(SND)$(Py)_2$ + c-AB + $H_2O_2$.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.334-338
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• 2003

The crystal structure of $[Co(phen)_2(Cl)(H_2O)] Clㆍ2H_2O$(phen=1,10-phenanthroline) has been determined by X-ray crystallography. It crystallizes in the triclinic system, space group P1, with lattice parameters a=9.662(2), b=11.445(1), c=13.037(2)${\AA}$ ${\alpha}$=64.02(1), ${\beta}$=86.364(9), ${\gamma}=78.58(2)^°$, and Z=2. The coordinated cations contain a six-coordinated cobalt atom chelated by two phen ligands and one chloride anion and one water ligand in cis arrangement. In addition to the chloride coordinated to the cobalt, there are one chloride ion and four water molecules which complete the crystal structure. In the solid state, the title compound forms three dimensional network structure through hydrogen bonds, within which exists the strongest hydrogen bond (O(3)-O(4)=2.33${\AA}$). The intermolecular hydrogen bonds connect the $[Co(phen)_2(Cl)(H_2O)]1+,\;H_2O$ moieties and chloride ion.