• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1113-1117
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• 2009

The one-dimensional coordination polymers, $[Cu^{II}(L)(NO_3)_2]_n$ (1) and {$[Cu^{II}(L)(NO_3)]{\cdot}2H_2O}_{2n} (2), were synthesized from $Cu(NO_3)_2{\cdot}3H_2O$ and 2-[(pyridin-3-ylmethyl)amino]ethanol (L, PMAE) in methanol by controlling the molar ratio of copper(II) salt. Copper(II) ion in 1 has one pyridine group of PMAE whose an aminoethanol group coordinates adjacent copper(II) ion. As the pyridine group is bonded to neighboring copper(II) ion, 1 becomes a one-dimensional chain. Contrary to 1, the structure of 2 shows that the oxygen atom of ethoxide group is bridged between two copper(II) ions, which forms a dinuclear complex. Additionally, the pyridine group of PMAE included one dinuclear unit is coordinated to the other dimeric one each other, which leads to a one-dimensional polymer. Due to the structural differences, 1 exhibits weak antiferromagnetic interaction, while 2 shows strong antiferromagnetic interaction. Due to direct spin exchange via oxygen of PMAE 2 has a much strong spin coupling than 1.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1967-1971
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• 2012

A hexavalent chromium (Cr (VI)) is one of the hazardous substances regulated by the RoHS. The determination of Cr (VI) in various polymers and printed circuit board (PCB) has been very important. In this study, the three different analytical methods were investigated for the determination of a hexavalent chromium in Acrylonitrile Butadiene Styrene copolymer (ABS) and PCB. The results by three analytical methods were obtained and compared. An analytical method by UV-Visible spectrometer has been generally used for the determination of Cr (VI) in a sample, but a hexavalent chromium should complex with diphenylcarbazide for the detection in the method. The complexation did make an adverse effect on the quantitative analysis of Cr (VI) in ABS. The analytical method using diphenylcarbazide was also not applicable to printed circuit board (PCB) because PCB contained lots of irons. The irons interfered with the analysis of hexavalent chromium because those also could complex with diphenylcarbazide. In this study, hexavalent chromiums in PCB have been separated by ion chromatography (IC), then directly and selectively detected by inductively coupled plasma atomic emission spectrometry (ICP-AES). The quantity of Cr (VI) in PCB was 0.1 mg/kg.

• 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.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1752-1756
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• 2006

This study explores and interprets in a new way the complex solvent and the temperature dependence of the NMR shifts for the N-$CH_2$ protons in tris(N,N-diethyldithiocarbamato) iron(III) in acetone, benzene, carbon disulfide, chloroform, dimethylformamide and pyridine. The NMR shifts are interpreted in terms of the Fermi contact interaction and the dipolar term from the multipole expansion of the interaction of the electron orbital angular momentum and the electron spin dipolar-nuclear spin angular momentum. This analysis yields a direct measure of the effect of the solvent system on the environment of the transition metal ion. The results are analysed in terms of the crystal field environment of the transition metal ion with contributions from (a) the dithiocarbamate ligand (b) the solvent molecules and (c) the interaction of the effective dipole moment of the polar solvent molecule with the transition metal ion complex.

• Food Science and Biotechnology
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• 제17권4호
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• pp.842-845
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• 2008

This study was carried out to investigate the bactericidal efficacy of concentration (0.1, 0.2, and 0.4 ppm) and exposure time (10 and 30 min) of ozone on bacterial reduction rate of Salmonella typhimurium KCTC 2541 and Staphylococcus aureus ATCC 13515 in the distilled water (DW), and DW supplemented with 0.2% soluble starch (SS), and metal ion (MC) using argentums (Ag) and copper (Cu). The significant bactericidal differences of S. aureus were showed in the treatments of DW and SS, respectively, at the concentration of ozone above 0.1 ppm for 10 min, comparing the respective initial bacterial counts. The bacterial reduction of S. aureus was more sensitive than that of S. typhimurum at the same concentration of ozone. The bacterial reduction rate of SS treatment was slightly lower than that of DW treatment at the same concentration of ozone (p<0.05), however, the bacterial reduction rate of strains improved in the MC treatment compared to the DW treatment at the same concentration of ozone.

• 대한화학회지
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• 제68권3호
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• 한국토양비료학회지
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• 제28권2호
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• pp.114-122
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• 1995

토양유기물(土壤有機物)에 의한 중금속(重金屬)의 흡착(吸着)현상을 구명(究明)하기 위하여 이탄토(泥炭土)에서 humic acid를 분리정제(分離精製)하여, humid acid-metal complex 생성반응(生成反應)에 대한 mechanism을 조사(調査)하였다. 1. Humic acid-metal complex의 흡광도(吸光度)는 장파장영역(長波長領域)에서 단파장영역(短波長領域)으로 갈수록 Zn-HA > Cd-HA > Cu-HA의 순(順)으로 증가(增加)하였다. 2. Humic acid의 carboxyl group과 phenolic OH group들이 중금속(重金屬) ion들과 반응(反應)하여 complex를 생성(生成)하였으며 그 생성량(生成量)은 Cu > Zn ≧ Cd의 순(順)이었다. 3. Humic acid-medal complex의 안정도(安定度) 상수(常數)는 pH가 증가(增加)함에 따라 增加하였으며 1차(次) 안정도(安定度) 상수(常數)는 Zn>Cd>Cu 순(順)이었고, 2차(次) 안정도(安定度) 상수(常數)는 Cu>Zn>Cd의 순(順)이었으며, 總安定도 常數는 Cu>Zn>Cd의 순(順)이었다. 4. Humlc acid와 중금속(重金屬)ion들 상호(相互) 간(間)의 평균결합수(平均結合數)는 pH가 증가(增加)함에 따라 Cu>Zn>Cd의 順으고 增加하였다. 5. Humic acid에 의한 중금속(重金屬) ion들의 complex생성과정(生成課程)에서 barboxyl group만이 관여(關與)하는 것과 car-boxyl gruup 및 phenolic OH group이 동시(同時)에 관여(關與)하는 두가지 흡착(吸着)mechanlsm을 제안할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.471-475
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• 2004

The solubility of N,N'-Bis(salicylidene) ethylenediamine (n-salen) and N,N'-bis(3,5-di-tert-butylsalicylidene) ethylenediamine (t-butyl-salen) was studied with in-situ UV-VIS spectrometer. n-Salen is 3-5 times more soluble than t-butyl-salen in liquid or supercritical $CO_2$. This behavior may be attributed to Lewis acid-base interaction between salen and $CO_2$. The chelation of salen with $Co^{++}$ ion in supercritical condition was confirmed to be fast enough above room temperature. However, the metal ion extraction capability of t-butyl salen is relatively poor because of its low solubility and ionic nature of complex.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2711-2718
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• 2012

The alkylation of the ambident enolates of a methyl glycinate Schiff base with ethyl chloride was studied at B3LYP and MP2 levels with $6-31+G^*$ basis set. The free (E)-enolates and (Z)-enolate are similar in energy and geometry. The transition states for the alkylation of the free (E)/(Z)-enolate with ethyl chloride have similar energy barriers of ~13 kcal/mol. However, with a lithium ion, the (E)-enolate behaves as an ambident enolate and makes a cyclic lithium-complex in bidentate pattern which is more stable by 11-23 kcal/mol than the (Z)-enolate-lithium complexes. And the TS for the alkylation of (E)-enolate-lithium complex coordinated with one methyl ether is lower in energy than those from (Z)-enolate-lithium complexes by 4.3-7.3 kcal/mol. Further solvation model (SCRF-CPCM) and reaction coordinate (IRC) were studied. This theoretical study suggests that the alkylation of ambident enolates proceeds with stable cyclic bidentate complexes in the presence of metal ion and solvent.

• Mass Spectrometry Letters
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• 제3권2호
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• pp.29-38
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• 2012

A new approach of volatile compounds analysis is proposed using a linear ion trap Orbitrap mass spectrometer coupled with gas chromatography through an atmospheric pressure photoionization interface. In the proposed GC-HRMS/MS approach, direct chemical composition analysis is made for the precursor ions in high resolution MS spectra and the structural identifications were made through the database search of high quality MS/MS spectra. Successful analysis of a complex perfume sample was demonstrated and compared with GC-EI-Q and GC-EI-TOF. The current approach is complementary to conventional GC-EI-MS analysis and can identify low abundance co-eluting compounds. Toluene co-sprayed as a dopant through API probe significantly enhanced ionization of certain compounds and reduced oxidation during the ionization.