• Analytical Science and Technology
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• v.19 no.4
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• pp.309-315
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• 2006

Two piperazine-templated metal sulfate complexes, $(C_4N_2H_{12})[Ni(H_2O)_6](SO_4)_2$, I and ($C_4N_2H_{12}$) $[Co(H_2O)_6](SO_4)_2$, II, have been synthesized by hydro/solvothermal reactions and their crystal structures analyzed by single crystal X-ray diffraction methods. Complex I crystallizes in the monoclinic system, $P2_1/n$ space group, a=12.920(3), b=10.616(2), $c=13.303(2){\AA}$, ${\beta}=114.09(1)^{\circ}$, Z=4, $R_1=0.030$ for 3683 reflections; II: monoclinic $P2_1/n$, a=12.906(3), b=10.711(2), $c=13.303(2){\AA}$, ${\beta}=114.10(2)^{\circ}$, Z=4, $R_1=0.032$ for 4010 reflections. The crystal structures of the piperazine-templated metal(II) sulfates demonstrate zero-dimensional compound constituted by diprotonated piperazine cations, metal(II) cations and sulfate anions. The structures of complex I and II are substantially isostructural to that of the previously reported our piperazine-templated copper(II) sulfate complex $(C_4N_2H_{12})[Cu(H_2O)_6](SO_4)_2$. The central metal(II) atoms are coordinated by six water molecules in the octahedral geometry. The crystal structures are stabilized by three-dimensional networks of the $O_{water}-H{\cdots}O_{sulfate}$ and $N_{pip}-H{\cdots}O_{sulfate}$ hydrogen bonds between the water molecules and sulfate anions and protonated piperazine cations. Based on the results of thermal analysis, the thermal decomposition reactions of the complex I was analyzed to have three distinctive stages whereas the complex II proceed through several stages.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1137-1142
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• 2004

A spectrophotometric and first derivative spectrophotometric method was developed in aquatic Tween 80 micellar solutions for selective determination of nickel without using any pre-separation step. 1-(2-Pyridylazo)-2-naphthol (PAN), as a sensitive chromogenic complexing agent formed a red-colored Ni(II)-PAN complex in Tween 80 media with satisfactory solubility and stability. Conditions such as pH, PAN concentration, type and concentration of micellizing agent were optimized. Molar absorptivity of Ni-PAN complex was found $4.62\;{\times}\;10^4L\;cm^{?1}\;mol^{?1}$ at 569 nm, under the optimum condition. Calibration graphs were derived by zero, first and second derivative spectrophotometry at maximum wavelengths of 569, 578 and 571 nm with linear ranges of 30-1800, 20-2500 and 30-2000 ng $mL^{?1}$ , respectively. Precision as standard deviation as well as accuracy as recovery percent were in the range of 1-20 ng $mL^{?1}$, and 93.3-103.3%, respectively, for the entire of the linear ranges. Spectrophotometric detection limit was 3 ng $mL^{?1}$ and effects of diverse ions on the first derivative determination of nickel were studied to investigate selectivity of the method. Interferences of cobalt and copper on the nickel determination were prevented using o-phenanthroline as masking agent. The recommended procedures were applied to the various synthetic and stainless steel alloys, tea leaves and human hair, with satisfactory results.

• Journal of the Korean Chemical Society
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• v.30 no.4
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• pp.377-382
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• 1986

Racemic tris-oxalatocobaltate (III) complex ions were optically resolved by an optical active complex, ${\Delta}$-tris-ethylenediamine cobalt (III), and then racemization of ${\bigwedge}-[Co(ox)_3]^{3-}$ obtained was investigated in various mixed solvent such as water-organic solvent (organic solvents=ethanol, iso-propyl alcohol, acetone, and dioxane). The rate of racemization was increased with following order; water < ethanol < acetone < isopropyl alcohol < dioxane; which is the same order for polarizability of organic solvent added. Considering ${\Delta}H^{\neq},\;{\Delta}S^{\neq}$ and above facts for the racemization of ${\bigwedge}-[Co(ox)_3]^{3-}$, it seems to be twist mechanism of plausible mechanisms.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.114-120
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• 1984

The reversible oxygenation of a solid stae polymeric cobalt(II) porphyrin complex, PVP-CoTPP was studied at 0, -24 and $-78^{\circ}C$. When PVP-CoTPP was contacted with $O_2 $at$-78^{\circ}C$ the oxygen uptake increased with oxygen partial pressure. At about 700mmHg $O_2$, the amount of oxygen taken up corresponded approximately one oxygen molecule to one Co(II) complex. The amount of $O_2$ taken up by PVP-CoTPP decreased with increasing temperature. When $16O_2$ was admitted to the Co(II) complex a EPR signal corresponding to $O_2^-$ increased with a decrease in Co(II) signal. The results suggest that an electron is transfered from Co(II) in PVP-CoTPP to oxygen forming a $Co(III)-O_2^-$ complex where $O_2^- $is superoxide type.

• Analytical Science and Technology
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• v.15 no.2
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• pp.97-101
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• 2002

Co(II) complexes with tridentate Schiff base-NOIPH and tetradentate Schiff base-$NOTDH_2$ and $TNBPH_4$ were synthesized. The redox process of the complexes in DMF solution containing 0.1M TBAP was investigated at glassy carbon electrode by cyclic voltammetry and differential pulse voltammetry techniques. Reduction step of [Co(II)$(NOIP)_2$] and [Co(II)$(H_2O)_2$] complexes were observed in two step as one electron process of irreversible or quasi-reversible and diffusion-controlled reaction. [$Co(II)_2$(TNBP)] complex was observed in one step as one electron process of quasi-reversible and diffusion-controlled reaction.

• Resources Recycling
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• v.11 no.6
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• pp.12-17
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• 2002

Solvent extraction experiments have been performed to separate copper from $CuCl_2$-$NiCl_2$-$CoCl_2$$ solutions using Alamine336 and LIX84. The complex formation tendency between metal ions and chloride ion had a great effect on the distribution coefficients of Cu, Co and Ni ions and separation factor of Cu to Co and Ni. In the experimental ranges of chloride ion concentration from 0.5 to 4.0 M, LIX84 was superior to Alamine336 in separating copper from cobalt. When the volume percentage of LIX84 and Alamine336 was varied from 5 to 40%, LIX84 was more effective than Alamine336 in separating Cu from Co and Ni in solutions in which the chloride ion concentration was 1.0 M.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1727-1731
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• 2014

Dichloromethane liquid droplets containing a cobalt dipyrromethene trimer deposited on a graphite surface were found to form coffee ring, toroid ring, or volcano dot structures due to the redistribution of the solute during solvent evaporation. The shapes and size distributions of the ring structures depended on the drying temperature. The shape differences were attributed to the fact that the solvent evaporation rate controlled the self-assembly process that yielded the coffee stain and pinhole structures.

• Journal of the Korean Chemical Society
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• v.7 no.1
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• pp.34-37
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• 1963

Cobalt(Ⅲ) ion gives two step waves with $E_{1/2}$－0.1V(?)(vs.S.C.E.) and $E_{1/2}$－1.37V(vs. S.C.E.) from a base electrolyte consisting of 0.1 M TEA＋sodium borate＋0.0002% gelatin. The first wave results from the reduction Co(Ⅲ) to Co(Ⅱ). The second wave corresponding to the reduction Co(Ⅱ) to Co(0) and this wave is diffusion controlled. The diffusion current constant of the second wave is 2.7. Under these-conditions, diffusion current of the second wave is proportional to the concentration of Co (Ⅱ) in the range of $10^{-3}{\sim}10^{-4}$ M.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1771-1777
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• 2009

The homogeneous B$F_3$ containing chiral Co(III) salen complexes were anchored non-covalently on the surfaces of mesoporous SBA-16 silica containing aluminum species. The Brönsted and Lewis acidic sites are attributed to the immobilization of fluorine functionalized chiral salen complexes on the supports. The FT-IR, UV, ESCA, and NMR analyses were performed to determine the structure of synthesized chiral salen catalysts. These heterogeneous catalysts could be applied in asymmetric ring opening of terminal epoxides by water and phenol derivatives. They showed very high enantioselectivity and yield more than 98% in the catalytic synthesis of optically active products.

• Bulletin of the Korean Chemical Society
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• v.1 no.3
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• pp.105-109
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• 1980

A general spectroscopic method is described for studies on the complex formation between metal ions and ligands, and is applied to $Cu^{2+}$ and $Ca^{2+}$binding to glycosaminoglycans. The order of binding constants for both ions is heparin >dermatan sulfate >chondroitin sulfate. The electrostatic forces are shown to be the predominant factor in the interaction. The 2- to 3-fold higher affinity for $Cu^{2+}$ than for $Ca^{2+}$ is obtained for heparin and dermatan sulfate, but little difference for chondroitin sulfate. These results are explained as chelation of both carboxyl and sulfate groups to $Cu^{2+}$ in former cases. The difference of binding constants among glycosaminoglycans is related to proposed various biological functions of the biopolymers.