• 폴리머
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• 제35권5호
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• pp.444-450
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• 2011

천연 알지네이트를 저분자화시키기 위해 과산화수소/초음파를 사용하였다. 이때 반응 온도 시간, 과산화수소 농도 그리고 초음파 조사 조건 등이 저분자화 생성물에 미치는 영향을 검토하였다. 생성된 저분자 알지네이트의 화학적 구조를 규명한 결과 주로 1,4-glycosidic bond가 끓어져서 저분자화가 진행되고 특정조건에서 생성물에 formate 그룹이 형성됨을 확인할 수 있었다. 생성물의 분자량은 MALS가 부착된 GPC를 사용하여 측정하였다. 2 wt%의 고분자 알지네이트 용액을 50 $^{\circ}C$의 초음파 분위기에서 0.5시간 동안 반응시켰을 때 분자량이 450 kDa에서 15.9 kDa로 저하되었다. 또한 분자량분포도는 상당히 좁고 반응 조건에 따라 큰 변화 없이 일정함(~2)을 확인할 수 있었다.

• 대한화학회지
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• 제18권2호
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• pp.126-131
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• 1974

비수용성 긴고리 지방족 아민인$(n-C_8H_{17})_3N$과 $(n-C_8H_{17})_3NCH_3Cl$을 사용하여 산도가 틀린 텅그스텐산수용액(pH=2, 4, 6)으로 부터 용매추출법에 의하여 유기용매에 녹는 다중텅그스텐산아민염을 제조하는데 성공하였다. 제조된 텅그스텐산 아민염의 분자량을 벤젠용매에서 더미스트를 이용한 감도 1/$4000^{\circ}C$의 훼트스톤 브리지를 사용하여 측정할 수 있었다. 분자량 측정결과와 화학분석 및 적외선 스펙트럼으로 부터 pH=2, 4에서 생긴 아민염은 메타텅그스텐산염, pH=6에서 생긴 아민염은 파라텅그스텐산염이 아니고 미지의 새로운 다중텅고스텐산염임을 알 수 있었다.

• 한국재료학회지
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• 제16권6호
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• pp.367-372
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• 2006

Polytetrafluoroethylene (PTFE) surface was modified for improving hydrophilicity by ion irradiation in environmental gas of $N_2$ and $NH_3$, respectively. The water contact angle onto the PTFE surface increased from $104{\circ}$ to over $140{\circ}$ by Ar ion irradiation in $N_2$ gas. In the case of $NH_3$ as environmental gas, there were a slight increase of contact angle from ion dose of $1{\times}10^{15}\;to\;5{\times}10^{15}\;ions/cm^2$, and its dramatic decrease to the value of 35o at the conditions of ion dose higher than $1{\times}10^{16}\;ions/cm^2$. It was found from SEM results that the surface morphology of PTFE was changed into one with filament structure after Ar ion irradiation in $N_2$ gas environments. On the contrary, Ar ion irradiation in $NH_3$ gas condition induced the PTFE surface with network structure. Hydrogen ion irradiation resulted in a little change of PTFE surface morphology, comparing with the case of Ar ion irradiation. The water contact angle of hydrogen ion irradiated PTFE surface in reactive gas decreased with increment of ion dose. Hydrogen ion irradiation could improve hydrophilicity with little change of surface morphology. It might be considered from FT-IR results that the improvement in wettability of PTFE surface by ion irradiation in $N_2$ and $NH_3$ gases could be due to the hydrophilic groups of NHx bonds.

• 대한화학회지
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• 제9권3호
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• pp.128-133
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• 1965

Hydrazonium diphosphate 結晶은 單斜晶係에 屬하여 單位格子는 $a=4.52{\pm}0.02, b=8.06{\pm}0.03, c=10.74{\pm}0.03 {\AA}$ 및 ${\beta}=100{\pm}0.5^{\circ}$이다. 單位格子속에는 2個의 化學單位가 들어있으며 空間群은 $P2_1/C$이다. 이 物質의 結晶構造를 Flourier 合成法과 Patterson 合成法에 依하여 決定하였다. $PO_4^{+++}$ 이온은 大略 regular 한 正四面體를 이루고 있으며 P-O 距離의 平均値는 $1.55{\AA}$이다. $N_2H_6^{++}$ 이온에서 N-N 距離는 $1.40{\AA}$이며 이값은 $N_2H_6SO_4$結晶에서의 값과 一致한다. 한 分子內에는 對稱의 中心이 있으며 各 N 原子는 2.62, 2.79 및 $2.89{\AA}$의 距離를 갖인 N…O型 水素結合을 이루고 있다. 또 다른 $PO_4^{+++}$이온 間에는 $2.63{\AA}$의 距離를 가진 한個의 O…O 水素結合을 이루고 있다. 이 物質의 構造는 上記한 N…O 및 O…O水素結合으로 三次元的 network를 이루고 있다.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1859-1864
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• 2011

Two lanthanide complexes, $[Ln(NO_3)_2(H_2O)_3(L)_2](NO_3)(H_2O)$ {Ln = Eu (1), Tb (2); L = 2-(4-pyridylium)-ethanesulfonate, $(4-pyH)^+-CH_2CH_2-SO_3^-)$}, were prepared from lanthanide nitrate and 4-pyridineethanesulfonic acid in $H_2O$ under microwave-heating conditions. Complexes 1 and 2 are isostructural, and the lanthanide metal in both complexes is coordinated to nine oxygen atoms. The pyridyl nitrogen in the ligand is protonated to give a zwitter ion that possesses an $NH^+$ (pyridyl) positive end and an $SO_3^-$ negative end. All O-H and N-H hydrogen atoms participate in hydrogen bonds to generate a two-dimensional (complex 1) or a three-dimensional network (complex 2). Complex 1 exhibits an intense red emission, whereas complex 2 exhibits an intense green emission in the solid state at room temperature.

• 한국결정학회지
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• 제16권1호
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• pp.6-10
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• 2005

4-Nitrobenzaldehyde와 3-nitroaniline의 Schiff-base 축합 반응으로 잠재적 연결 리간드 (4-Nitro-benzylidene)-(3-nitro-phenyl)-amine (1)이 합성되었다. 리간드 1과 $PdCl_2(NCPh)_2$ 반응에서 가수 분해로 인한 예상 밖의 생성물 $trans-PdCl_2(NO_2-C_6H_4-NH_2)_2$ (2)가 분리되었다 X-ray 회절법으로 화합물 1과 2가 구조적으로 규명되었다. 화합물 2에서 3-nitroaniline의 $NH_2$ 수소 원자들은 Cl 원자와 분자간 NH${\cdot}\;{\cdot}\;{\cdot}\;$Cl 수소 결합에 참여하고 있다.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3255-3260
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• 2011

Two novel binuclear metal-organic coordination complexes $[Cd_2(L)_2(bpy)_2(H_2O)_2]{\cdot}6H_2O$ (1), $[Cd_2(L)_2(phen)_2-(H_2O)_2]{\cdot}2H_2O$ (2) (where L = 2-methylquinoline-3,4-dicarboxylate dianion, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by single crystal Xray diffraction, spectral method (IR), elemental analysis and thermal gravimetric analysis (TGA). Both 1 and 2 consist of two Cd(II) atoms bridged by two monoatomic bridging carboxylate groups from two L ligands, and the second carboxylate group of each L is monodentately coordinated to Cd(II), creating a sevenmembered chelating ring. The coordination at each metal nucleus is completed by a water molecule and a chelating bidentate molecule. The 3D structures of the complexes are stabilized by ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds.

• BMB Reports
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• 제33권3호
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• pp.268-275
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• 2000

In contrast to the pyrimidine (6-4)pyrimidone photoproduct [(6-4) adduct], its Dewar valence isomer (Dewar product) is low mutagenic and produces a broad range of mutations with a 42 % replicating error frequency. In order to determine the origin of the mutagenic property of the Dewar product, we used experimental NMR restraints and molecular dynamics to determine the solution structure of a Dewar·lesion DNA decamer duplex, which contains a mismatched base pair between the 3'-T residue and an opposed G residue. The 3'-T of the Dewar lesion forms stable hydrogen bonds with the opposite G residue. The helical bending and unwinding angles of the DW/GA duplex, however, are much higher than those of the DW/AA duplex. The stable hydrogen bonding of the G 15 residue does not increase the thermal stability of the overall helix. It also does not restore the distorted backbone conformation of the DNA helix that is caused by the forming of a Dewar lesion. These structural features implicate that no thermal stability, or conformational benefits of G over A opposite the 3'-T of the Dewar lesion, facilitate the preferential incorporation of an A. This is in accordance with the A rule during translesion replication and leads to the low frequent $3'-T{\rightarrow}C$ mutation at this site.

• Archives of Pharmacal Research
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• 제15권1호
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• pp.52-57
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• 1992

The molecular structure of a natural compound was determined by single crystal X-ray diffraction analysis. The compound was isolated by methanol extraction and repeated chromatography from the stem of Paulownia tomentosa. Yellow prismatic crystals of the compound, which were recrystallized from tetrahydrofuran, are triclinic, with a = 7.310 (6), b = 10.753(6), c = 11.586(5) ${\AA}.\;\alpha= 93.30(6),\;\beta=105.62(10),\;\gamma=109.49(7)^\circ,\;D_x=1.514,\;D_m=1.51 g/cm^3$, space group P1 and Z = 2. The structure was solved by direct method, and refined by least-squares procedure to the final R-value of 0.032 for 1271 independent reflections $(F\le3\sigma{(F))}$. The compound is one of new furanquinone analogue. The molecule has a nearly planar conformation with an intramolecular hydrogen bond. In the crystal, the planar molecules are arranged as a prallel sheet-like pattern, and these stackings are stabilized by the O-H...O type intermolecular hydrogen bonds. The other intermolecular contacts appear to be the normal van der Waals interactions.

• Archives of Pharmacal Research
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• 제3권1호
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• pp.37-49
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• 1980

Chlorpropamide, $C_{10}H_{13}N_{2}O_{3}SCI$, forms orthofombic crystals of space group $P_{2}_{ 1}2_{1}2_{1}$ with a 9.066 $\pm$ 0.004, b = 5.218 $\pm$ 0.003, c = 26, 604 $\pm$, 0.008 $\AA$, and four molecules per cell. Three dimensional photographic data were collected with Mo-K$\alpha$ radiation. The structure was determined using Patterson, Fourier and Difference syntheses methods and refined by the block-diagonal least-squares methods with anisotropic thermal parameters for all nonhydrogen atoms and isotropic thermal parameters for all hydrogen atomes. The final R value was 0.10 for the 1823 observed independent reflections. The dihedral angle between the planes through the benzene ring and the urea goup is 99$^{\circ}$. The conformational angle formed by the projection of the S-C(1) with that of N(1)-C(7) when the projection is taken along the S-N(1) bond is 76$^{\circ}$. The molecule appears to form with neighbouring molecules two hydrogen bonds, N(1)..H...O(3) and N(2)-H...0(2) of lengths 2.774 and 2.954$\AA$ respectively related by screw diads parallel to the a axis. Adjacent molecules parallel to b and c axis are bound together by van der Wasls forces.