• Title/Summary/Keyword: 수소결합

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Continuous Coprecipitantion Preconcentration-Hydride Generation for Arsenic in Inductively Coupled Plasma-Atomic Emission Spectrometry (연속적 공침 선농축-수소화물 발생법을 이용한 ICP-AES에서의 비소의 감도 개선)

  • Kim, Chang-Gyu;Pak, Yong-Nam
    • Journal of the Korean Chemical Society
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    • v.48 no.6
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    • pp.583-589
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    • 2004
  • In a stream of aqueous sample, trace arsenic ions were quantitatively coprecipitated and detected in ICP-AES through hydride generation. In was used as a coprecipitating reagent. The precipitate was collected on a filter and dissolved by HCl. The eluted As was sent into the reaction coil to generate hydrides and analyzed by ICP. With optimal conditions, and with a sample of 0.3 mL, an enrichment of 70 was obtained with the sampling speed of 10/hr. When compared with coprecipitation and hydride generation technique, the sensitivity was increased by 7 and 10 times, respectively. The limit of detection limit$(3{\sigma})$ was 0.020 ${\mu}g\;L^{-1}$ and the precision was 7-10%. Separation of $As^{3+}\;and\;As^{5+}$ were possible using citric acid in hydride generation.

A Study on the Hydrated and Dehydrated $Mn^{2+}$-Exchanged Zeolite A ($Mn^{2+}$-치환 제올라이트 A 의 수화 및 탈수 구조에 관한 연구)

  • Jong Yul Park;Yang Kim;Un Sik Kim;Sang Gu Choi
    • Journal of the Korean Chemical Society
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    • v.33 no.6
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    • pp.623-632
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    • 1989
  • The positions and interaction energies of framework atoms and water molecules of $Mn^{2+}$-exchanged zeolite A were calculated using some potential energy functions and an optimization program. The sum of interaction energies of framework atoms in dehydrated $Mn_{4,5}Na_3-A$ was approximately the same as those of thermally stable $Ca^{2+}$-or $Mg^{2+}$-exchanged zeolite A. Since $Mn^{2+}$ ions can form good coordination bonds with framework oxygens even in dehydrated state, $Mn^{2+}$-exchanged zeolite A is considered to be thermally stable. The optimized positions of framework atoms and ions in this work are agreed well with the crystallographic data. Three groups of water molecules are found in hydrated $Mn^{2+}$-exchanged zeolite A; W(I) group of water molecules having only hydrogen bonds, W(II) group coordinated to $Na^+$ ion, and W(III) group coordinated to $Mn^{2+}$ ion. The average binding energy of each group of water molecules decrease in the order of W(III) > W(II) > W(I). The activation energies in the dehydration reaction of each group of water molecules increased in accordance with their binding energy.

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Comparative Molecular Similar Indice Analysis on Fungicidal Activity of N-phenyl-O-phenylthionocarbamate Derivatives against Rice Sheath Blight and Phytophthora Blight (벼잎집무늬마름병균 및 고추역병균에 대한 N-Phenyl-O-phenyl-thionocarbamate 유도체들의 살균활성에 관한 비교분자 유사성 분석)

  • Soung, Min-Gyu;Yoo, Jae-Won;Jang, Seok-Chan;Sung, Nack-Do
    • Applied Biological Chemistry
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    • v.50 no.3
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    • pp.187-191
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    • 2007
  • Comparative molecular similarity indice analysis (CoMSIA) models on the fungicidal activities of N-phenyl substituents (X) in N-phenyl-O-phenylthionocarbamate derivatives against rice sheath blight (Rhizoctonia solani: RS) and phytophthora blight (Phytophthora capsici: PC) were derived. Also, the characterizations of H-bonds between substrates and ${\beta}-tubulin$ were discussed quantitatively. It was revealed that, from the contour maps of CoMSIA models, the H-bond acceptor field contributed the most highly to fungicidal activity for two fungi in common. It is predicted that the selectivity in the fungicidal activity between two fungi is caused by results from the roles of H-bond donor disfavor functional groups in RS and H-bond acceptor disfavor functional groups in PC when these two groups induced at meta- and para-position on the N-phenyl ring. And also, if the substituents (X) are steric disfavor group, negative charge favor groups are introduced at the metaposition in RS and H-bond acceptor group is introduced at the para-position in PC, the antifungal activity against two fungi will be likely able to be increased.

Quantum Mechanical Investigations for the Interactions between Fullerene and Encapsulated Waters (풀러렌-물 클러스터의 상호작용에 대한 양자 역학적 이론 연구)

  • Kim, Sung-Hyun;Shin, Chang-Ho;Kim, Ji-Sun;Kang, So-Yung;Kim, Seung-Joon
    • Journal of the Korean Chemical Society
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    • v.59 no.1
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    • pp.9-17
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    • 2015
  • The density functional theory (DFT) calculations on $(H_2O)_n@C_{60}$, (n=1-10) complexes have been performed to elucidate hydrogen interaction between fullerene and water clusters. The optimized geometries, harmonic vibrational frequencies, and binding energies are predicted at various levels of theory. The harmonic vibrational frequencies for the molecules considered in this study show all real numbers implying true minima. We also compare the H-bond interaction between $(H_2O)_n$ and $(H_2O)_n@C_{60}$, (n=1-10) clusters.

Ab Initio Studies on Hydrogen-Bonded Dimers of Fluoromethanes with Ammonia and Water (플루오르화메탄들과 암모니아 및 물과의 수소결합 이량체들에 관한 Ab Initio 연구)

  • Soon-Ki Lee;Seung-Hoon Kim
    • Journal of the Korean Chemical Society
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    • v.37 no.4
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    • pp.408-415
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    • 1993
  • Systematic ab initio SCF calculations have been performed on the hydrogen-bonded dimers of fluoromethanes involving $CH_4,\;CH_3F,\;CH_2F_2\;and\;CHF_3$ with ammonia and water applying basis sets of 9s5p/5s and 9s5p1d/5p1d. Various ground state properties of these stable dimeric complexes have been evaluated. We compared these with corresponding properties of isolated monomers. We report equilibrium geometries, stabilization energies, dipole moments and force constants of intermolecular bonds. The effects arising as a consequence of the non-additive behavior of hydrogen bonding in chain-like oligomers are discussed. Systematic, methodical errors due to the use of the SCF approximation and the basis set dependence of the computed results are pointed out.

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The molecular dynamics study of TBAB hydrogen hydrate structure (TBAB를 첨가한 수소 하이드레이트의 분자 동역학 연구)

  • Choi, Seungho;Park, Chansu;Kim, Soomin;Woo, Sungmin;Shin, Jaeho;Kim, Yangdo
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.153.1-153.1
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    • 2010
  • 가스 하이드레이트는 낮은 온도와 높은 압력에서 물과 천연가스 분자가 물리적으로 안정한 결합을 하고 있는 결정질의 화합물이다. 현재 130개 이상의 가스분자들이 물분자와 결합하여서 Clathrate 하이드레이트를 형성하는 것으로 보고 되어 있다. 수소의 경우 하이드레이트를 형성하기 위해서 약 200MPa 이상의 높은 압력이 필요하다. TBAB는 semi-clathrate 하이드레이트를 형성하는 첨가제로 알려져 있으며 수소 하이드레이트의 형성 압력을 완화시키기 위한 촉진제로서 많은 연구가 수행되고 있다. Wataru Shimada는 XRD 패턴을 사용하여 semi-clathrate 하이드레이트의 특수한 결정 모델을 분석하였다. 이 모델의 경우, 대기압 하에서 TBAB와 물분자의 화학 양론적 비를 1:38로 제시하였다. 이는 처음으로 TBAB 하이드레이트 결정구조를 밝혀냈지만, 분자 동역학적 부문에서는 그 데이터가 정확히 정의 되지 않았다. 본 연구는 Wataru Shimada 모델을 수소 TBAB 하이드레이이트의 분자 동역학 연구에 적용시켰으며, 실험에서 나온 데이터를 바탕으로 RDF(Radial Distribution Function)와 MSD(Mean Square Displacement)를 측정했다.

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High Pressure Effect of Vibration in a Hydrogen Bonding Crystal :$NH_4I$ (수소결합을 가진 결정내의 진동의 고압효과 : $NH_4I$)

  • Jeon Seung-Joon
    • Journal of the Korean Chemical Society
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    • v.36 no.5
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    • pp.627-631
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    • 1992
  • A simple one dimensional model was proposed to describe a hydrogen bonding in crystals, which was based on the Lippincott's empirical potential. The model was used to calculate internal stretching vibrational frequencies of $NH_4I$ crystal at high pressures. The calculated results were in agreement with Raman experimental results qualitatively. At relatively lower high pressures, as pressure increases internal stretching vibrational frequencies shift lower due to increase of the hydrogen bonding effect. At higher pressures, the frequencies shift higher due to the repulsive contribution of interatomic potential induced by the reduction of interatomic distance as pressure increases.

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Ab Initio Studies on Hydrogen-Bonded Trimers Formed between Hydrogen Cyanide and Hydrogen Fluorides (시안화수소와 플루오르화수소와의 수소결합 삼합체들에 관한 Ab Initio 연구)

  • Rhee, Soon Ki;Lee, Hyun Jin
    • Journal of the Korean Chemical Society
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    • v.40 no.3
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    • pp.187-195
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    • 1996
  • Ab initio SCF calculations have been carried out for the five conceivable trimers formed between one hydrogen cyanide and two hydrogen fluorides using a basis set of TZ+P quality. Several ground state properties of these trimeric complexes have been evaluated, and compared with those of isolated monomers and appropriate dimers. Computed equilibrium geometries, stabilization energies, and dipole moments are given in order to suppliment the available experimental data. At this level of approximation, intramolecular bond distances are consistently shorter than experimental ones. However, intermolecular distances upon complex formation, and dipole moments are overestimated compared with experimental ones. HCN$(HF)_2$ trimer appears to be the most favourable among the five kinds of trimer complex, and also more stable than $(HCN)_2HF$. The typical features of the non-additivity of intermolecular interaction are relatively strong in the HCN$(HF)_2$ trimer.

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