• 대한화학회지
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• 제36권6호
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• pp.894-905
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• 1992

산소가 포화된 메탈올 용액에서 Superoxo형인 [Co(Ⅲ)(SED)(Py)$O_2$]와 [Co(III)(SOPD)(Py)$O_2$]들의 균일 산화 활성 촉매에 의한 hydrazobenzene(H2AB)의 산화 주생성물은 trans-azobenzene (t-AB)이고 반응 속도상수 k = 7.692 ${\times}$ $10^{-2}$ M/sec 및 5.076 ${\times}$ $10^{-2}$ M/sec이나 ${\mu}$-peroxo형인 [Co(III)(SED)(Py)]$_2O_2$에 의한 주생성물은 cis-azobenzene (c-AB)이 선택적으로 생성되고 반은 속도상수 k = 1.266 ${\times}$ $10^{-2}$ M/sec로 주어짐을 UV-visible 흡광도법으로 알아보았다. 이들 산화반응은 다음과 같이 균일 산소 첨가 착물촉매에 의하여 산화주생성물이 선택적으로 다르게 생성된다. $H_2$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 및 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 + $H_2O_2$.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1299-1304
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• 2007

New sulfur functionalized cyclopentadiene ligands, 1-[2-(thioanisole)]-2,5-dimethylcyclopentadiene (3), 1-[2- (thioanisole)]-2,3,5-trimethylcyclopentadiene (4), and 1-[2-(thioanisole)]-2,3,4,5-tetramethylcyclopentadiene (5), were prepared. In these ligands, the S-donor atom is connected to a cyclopentadiene ring by a rigid phenylene spacer. CpCo(III)-diiodo half-sandwich complexes (6-8) were obtained from reaction the ligands (3- 5) with Co2(CO)8, followed by treatment of I2. Substitution reaction of CpCo(III)-diiodo complexes with MeLi yielded the corresponding CpCo(III)-dimethyl complexes (9-11). Further transformation to the corresponding cationic cobalt complexes (12-14) were achieved by reaction of the CpCo(III)-dimethyl complexes with HB(ArF)4·2Et2O and trapping with CD3CN. The new sulfur functionalized cyclopentadiene ligands having a rigid phenylene spacer and the corresponding cobalt complexes were characterized by 1H, 13C and 19F NMR spectroscopy. The diiodo Complex 6 was also characterized by a single crystal X-ray diffraction method.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1293-1296
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• 2006

In this study, a solid phase extraction method has been developed for the preconcentration and separation of the elements Cr(III), Fe(III), Co(II) and Pb(II) at trace levels by using a column packed with Amberlite XAD-1180 resin loaded with 4-(2-pyridylazo)-resorcinol (PAR) reagent. After preconcentrating, the metals retained on the column were eluted with 20 mL of 3 mol/L $HNO_3$ and then determined by flame atomic absorption spectrometry (FAAS). The factors affecting the recovery of the elements, such as pH, type and concentration of eluent, volume of sample and elution solution, and matrix components, were also ascertained. The recoveries of Cr(III), Fe(III), Co(II) and Pb(II) were found to be $99\;{\pm}\;4,\;97\;{\pm}\;3,\;95\;{\pm}\;3$ and $98\;{\pm}\;4$%, respectively, under the optimum conditions at 95% confidence level and the relative standard deviations found by analyzing of nine replicates were $\leq4.4$%. The preconcentration factors for Cr(III), Fe(III), Co(II) and Pb(II) were found as 75, 125, 50 and 75 respectively. The detection limits (DL, 3s/b) were 3.0 $\mu g/L$ for Cr(III), 1.25 $\mu g/L$ for Fe(III), 3.3 $\mu g/L$ for Co(II), and 7.2 $\mu g/L$ for Pb(II). The recoveries achieved by adding of metals at known concentrations to samples and the analysis results of Buffalo river sediment (RM 8704) show that the described method has a good accuracy. The proposed method was applied to tap water, stream water, salt and street dust samples.

• 방사성폐기물학회지
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• 제20권4호
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• pp.371-382
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• 2022

Carbonates are inorganic ligands that are abundant in natural groundwater. They strongly influence radionuclide mobility by forming strong complexes, thereby increasing solubility and reducing soil absorption rates. We characterized the spectroscopic properties of Am(III)-carbonate species using UV-Vis absorption and time-resolved laser-induced fluorescence spectroscopy. The deconvoluted absorption spectra of aqueous Am(CO₃)₂^- and Am(CO₃)₃^3- species were identified at red-shifted positions with lower molar absorption coefficients compared to the absorption spectrum of aqua Am³⁺. The luminescence spectrum of Am(CO₃)₃^3- was red-shifted from 688 nm for Am³⁺ to 695 nm with enhanced intensity and an extended lifetime. Colloidal Am(III)-carbonate compounds exhibited absorption at approximately 506 nm but had non-luminescent properties. Slow formation of colloidal particles was monitored based on the absorption spectral changes over the sample aging time. The experimental results showed that the solubility of Am(III) in carbonate solutions was higher than the predicted values from the thermodynamic constants in OECD-NEA reviews. These results emphasize the importance of kinetic parameters as well as thermodynamic constants to predict radionuclide migration. The identified spectroscopic properties of Am(III)-carbonate species enable monitoring time-dependent species evolution in addition to determining the thermodynamics of Am(III) in carbonate systems.

• 공업화학
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• 제16권1호
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• pp.74-80
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• 2005

탁질입자 및 인의 효과적인 제거 특성을 고찰하기 위해서 물리화학적 인자들(pH, 알칼리도, 응집제의 종류)의 체계적인 고찰을 수행하였다. AI(III)과 Fe(III)계 응집제들은 제타전위 값이 거의 영에 수렴하는 pH 7~9 영역에서 높은 탁도 제거율 및 인 제거율을 나타내었다. 응집제의 주입량이 증가함에 따라 탁도는 급격하게 감소하는 경향을 보였으며, 인의 경우에는 금속이온과의 당량적 결합에 기인하여 비례적으로 감소하였다. 고속카메라(Motion Scope 2000, Redlake Co.)를 이용하여 플럭의 생성과정을 가시화하였고 광학현미경을 통해서 플럭의 성상과 형태를 고찰하였다. Fe(III)계 응집제에 의해 생성된 플럭들은 Al(III)계 응집제에 의해 생성된 플럭들에 비해 치밀하였으며 침강성도 뛰어났다.

• 대한화학회지
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• 제34권6호
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• pp.569-581
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• 1990

DMF 용매에서 산소 첨가된 네자리 Schiff base cobalt(III)의 균일 촉매에 의하여 2,6-di-tert-butylphenol의 산화 주생성물인 2,6-ditert-butylbenzoquinone (BQ)일 때에는 O$_2$/Co몰 결합비가 1:1인 superoxo cobalt(III) 착물 곧 [Co(III)(Schiff base)(L)]$O_2$ (Schiff base; SED, SOPD and o-BSDT, L; DMF and Py)들의 활성촉매에 의하여 생긴다. 또, 산화생성물인 3,3',5,5'-tetra-tert-butyldiphenoquinone (DPQ)은 $O_2$/Co의 몰비가 1:2인 $\mu$-peroxo cobalt(III) 착물인 [Co(III)(SND)(L)]$_2$O$_2$ (L; DMF 및 Py)의 활성촉매에 의하여 생성된다. 이들 균일 활성촉매인 superoxo 및 $\mu$-peroxo cobalt(III) 착물들의 확인은 DMF나 DMSO 용매에서는 어렵다. 그러나 pyridine 용매에서는 산소흡착에 의한 PVT 법과 0.1 M TEAP의 지지전해질과 유리질 탄소전극을 사용한 순환 전압전류법으로 1:1 oxygen adduct인 superoxo 착물들은 $O_2$-의 prewave가 없는 3단계 환원과정으로만 일어나는 것으로 확인할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제31권4호
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• pp.891-894
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• 2010

Thermal properties of a series of Co $\beta$-diketonates have been systematically investigated and it is found that tris(3,5-heptanedionato) cobalt(III) ($Co(hd)_3$) with the lowest melting point among them can be a better precursor than tris(2,2,6,6-tetramethyl-3,5-heptanedionato cobalt(III) ($Co(tmhd)_3$), one of the most popular precursors to date, under suitable conditions. Isothermal TGA study shows that $Co(hd)_3$ would work better at higher temperature, while $Co(dmhd)_3$ would be a better precursor at lower temperature.

• 대한화학회지
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• 제33권5호
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• pp.504-509
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• 1989

N,N'-dimethylethylenediamine-N,N'-di-${\alpha}$-butyric acid(dmedba)와 세자리 아미노산과의 코발트(III) 착물인 [Co(dmedba)(L-aa)] (L-aa = S-methyl-L-cysteine, L-methionine, L-glutamic acid, L-aspartic acid)는$ s-cis-[Co(dmedba)Cl_2]-^ 착물과 아미노산과의 반응으로부터 얻었다. 아미노산들은 [Co(dmedda)(L-dd)] 착물과 같이 아민과 카르복실그룹을 통하여 배위되었다. 이 착물들의 구조는 ^1H-NMR, IR, UV$ 스펙트럼 데이타와 원소분석으로 확인하였다.

• 방사성폐기물학회지
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• 제19권2호
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• pp.161-176
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• 2021

In this study, the electrochemical behavior of Sm on the binary liquid Al-Ga cathode in the LiCl-KCl molten salt system is investigated. First, the co-reduction process of Sm(III)-Al(III), Sm(III)-Ga(III), and Sm(III)-Ga(III)-Al(III) on the W electrode (inert) were studied using cyclic voltammetry (CV), square-wave voltammetry (SWV) and open circuit potential (OCP) methods, respectively. It was identified that Sm(III) can be co-reduced with Al(III) or Ga(III) to form Al_zSm_y or Ga_xSm_y intermetallic compounds. Subsequently, the under-potential deposition of Sm(III) at the Al, Ga, and Al-Ga active cathode was performed to confirm the formation of Sm-based intermetallic compounds. The X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analyses indicated that Ga₃Sm and Ga₆Sm intermetallic compounds were formed on the Mo grid electrode (inert) during the potentiostatic electrolysis in LiCl-KCl-SmCl₃-AlCl₃-GaCl₃ melt, while only Ga₆Sm intermetallic compound was generated on the Al-Ga alloy electrode during the galvanostatic electrolysis in LiCl-KCl-SmCl₃ melt. The electrolysis results revealed that the interaction between Sm and Ga was predominant in the Al-Ga alloy electrode, with Al only acting as an additive to lower the melting point.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1729-1732
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• 2011