• 분석과학
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• 제19권4호
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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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• 제25권8호
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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.

• 대한화학회지
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• 제30권4호
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• pp.377-382
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• 1986

광학활성인 ${\Delta}-[Co(en)_3]^{3+}$ion을 이용하여 라세미체인 $[Co(ox)_3]^{3-}$ 이온을 광학분할한 후 얻어진 ${\bigwedge}-[Co(ox)_3]^{3-}$ 이온의 라세미화를 여러가지 혼합용매 즉, 물-유기용매(유기용매=에탄올, 이소푸로필알코올, 아세톤 및 디옥산)내에서 조사하였다. 라세미화속도는 물<에탄올<이소프로필 알코올<디옥산의 순서로 증가하였고 그 순서는 첨가한 유기용매의 polarizability의 증가순서와 일치하였다. 이상의 결과와 ${\Delta}H^{\neq}$와 ${\Delta}S^{\neq}$를 고려하면 ${\bigwedge}-[Co(ox)_3]^{3-}$의 라세미화메카니즘은 가능한 라세미화메카니즘중 twist메카니즘으로 진행됨을 알 수 있었다.

• 대한화학회지
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• 제28권2호
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• pp.114-120
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• 1984

$-24^{\circ}C$ 그리고 $-78^{\circ}C$에서 코발트 화합물인 PVP-CoTPP 즉 poly(4-vinyl pyridine)-mesotetraphenylporphinatocobalt(II)의 가역적인 산소화반응에 대해서 살펴보았다. PVP-CoTPP를 $-78^{\circ}C$에서 산소와 접촉시키면 산소분압에 따라 흡착량이 증가하여 산소분압이 700mmHg에 이르면 흡착되는 산소의 양이 Co(II)와 $O_2$가 같은 몰비로 붙는 양과 거의 비슷해졌다. 반면에 -24, $0^{\circ}C$로 온도가 높아짐에 따라 산소의 흡착량은 점점 더 감소하였다. 한편 ERR분광기에 의해 $PVP-CoTPP-O_2$화합물을 살펴본 결가 Co(II)의 전자가 $O_2$쪽으로 이동하여 수퍼옥사이드 형태의 $Co(III)-O_2^-$를 이루고 있는 것 같다

• 분석과학
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• 제15권2호
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• pp.97-101
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• 2002

Co(II)착물들을 세자리 Schiff base-NOIPH, 네자리 Schiff base-$NOTDH_2$ 및 $TNBPH_4$ 로부터 합성하였으며, 이 착물들의 산화-환원 과정 mecanism을 지지 전해질로서 0.1 M TBAP를 포함한 DMF용액에서 작업전극으로 유리질 탄소전극을 사용하여 순환 전압-전류법과 펄스 차이 전압-전류법에 의해서 알아 보았다. [Co(II)$(NOIP)_2$]와 [Co(II)(NOTD)$(H_2O)_2$] 착물의 환원은 Co(III)/Co(II)의 반응이 비가역적으로 진행되고 Co(II)/Co(I)의 반응이 준가역적으로 진행되는 일전자의 2단계반응이 확산 지배적으로 일어났다. 반면에 [$Co(II)_2$(TNBP)] 착물의 환원반응은 $Co(II)_2$가 Co(II)/Co(I)로 진행되는 준가역적이며 일전자 일단계의 반응이 확산지배적으로 일어났다.

• 자원리싸이클링
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• 제11권6호
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• pp.12-17
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• 2002

$CuCl_2$-$NiCl_2$-$CoCl_2$용액으로부터 구리를 분리하기 위해 추출제로 Alamine336과 LIX84를 사용하여 추출실험을 하였다. 염산용액에서 Alamine336과 LIX84에 의한 구리, 코발트, 니켈의 분배계수와 구리의 분리계수는 금속이온과 염소이온간에 형성되는 착물의 농도에 큰 영향을 받았다. 염소이온농도가 0.5에서 4.0M사이인 용액에서 코발트로부터 구리의 분리성은 LIX84가 Alamine336보다 우수하였다. 염소이온농도가 1.0M인 용액에서 LIX84와 Alamine336의 부피백분율을 5에서 40%까지 변화시켜 추출한 결과 LIX84로 추출하는 경우 Alamine336에 비해 더 높은 구리의 분리계수를 얻었다.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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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.

• 대한화학회지
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• 제7권1호
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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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• 제30권8호
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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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• 제1권3호
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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.