• Molecules and Cells
• /
• 제25권3호
• /
• pp.352-357
• /
• 2008

Osteoprotegerin (OPG) is a soluble decoy receptor that inhibits osteoclastogenesis and is closely associated with bone resorption processes. We have designed and determined the solution structures of potent OPG analogue peptides, derived from sequences of the cysteine-rich domain of OPG. The inhibitory effects of the peptides on osteoclastogenesis are dose-dependent ($10^{-6}M-10^{-4}M$), and the activity of the linear peptide at $10^{-4}M$ is ten-fold higher than that of the cyclic OPG peptide. Both linear and cyclic peptides have a ${\beta}$-turn-like conformation and the cyclic peptide has a rigid conformation, suggesting that structural flexibility is an important factor for receptor binding. Based on structural and biochemical information about RANKL and the OPG peptides, we suggest that complex formation between the peptide and RANKL is mediated by both hydrophobic and hydrogen bonding interactions. These results provide structural insights that should aid in the design of peptidyl-mimetic inhibitors for treating metabolic bone diseases caused by abnormal osteoclast recruitment.

• 대한화학회지
• /
• 제16권6호
• /
• pp.361-368
• /
• 1972

5%트리옥틸아민과 5%옥틸알콜이 든 헥산유기용매 1l는 62g의 $WO_3$를 추출할 수 있었는데 반하여 아민만을 사용했을 경우는 37g의 $WO_3$밖에 추출할 수 없었다. 유기용매 추출과정에서 이러한 알콜의 아민-텅스텐 화합물의 용해도의 상승작용 및 아민과 텅스텐산간의 상호작용을 핵자기 공명분광학을 이용하여 연구하였다. 텅스텐은 고분자형의 텅스텐산 이온상태로 유기층으로 추출되어 다중텅스텐산 트리옥틸 암모니움염을 형성함을 알 수 있었으며 이 염은 텅스텐산이온과 알콜간에 수소결합을 형성함으로써 탄화수소 용매에서 더욱 안정화됨을 알 수 있었다.

• 대한화학회지
• /
• 제21권6호
• /
• pp.434-439
• /
• 1977

4-피리돈과 루티돈의 전자구조를 SCF MO-CI PPP 방법과 configuration analysis 법을 사용하여 연구하였다. 계산결과와 스펙트럼 분석치와는 잘 일치하였으며 첫번째 $({\pi},{\pi}^*)$ 단일상태는 두 화합물 모두 장축 방향으로 편극되어 있다. Configuration analysis 결과 가장 낮은 $({\pi},{\pi}^*)$ 단일 상태에서는 C=O 작용기의 ${\pi}$ 결합궤도로 부터 디비닐아민 부분의 ${\pi}^*$ 반결합 궤도로 전하가 이동되어 있으나 가장 낮은 $({\pi},{\pi}^*)$ 삼중상태에서는 반대로 디비닐아민 부분으로 부터 C=O 작용기 쪽으로 전하가 이동되어 있음을 알 수 있다.

• Bulletin of the Korean Chemical Society
• /
• 제27권12호
• /
• pp.2040-2044
• /
• 2006

Dielectric studies of methyl acrylate with 1-propanol, 1-butanol, 1-heptanol and 1-octanol binary mixtures have been carried out over the frequency range from 10 MHz to 10 GHz at temperatures of 283, 293, 303 and 313 K using Time Domain Reflectometry (TDR) for various concentrations. The Kirkwood correlation factor and excess inverse relaxation time were determined and discussed to yield information on the molecular structure and dynamics of the mixture. The values of the static dielectric constant, relaxation time and the Kirkwood correlation factor decrease with increased concentration of methyl acrylate in alcohol. The Bruggman plot shows a non-linearity of the curves for all the systems studied indicates the heterointeraction which may be due to hydrogen bonding of the OH group of alcohol with C=O of the methyl acrylate. The excess inverse relaxation time values are negative for all the systems at all the temperatures indicates that the solute-solvent interaction hinders the rotation of the dipoles of the system.

• Bulletin of the Korean Chemical Society
• /
• 제32권3호
• /
• pp.768-778
• /
• 2011

Calixpyrroles and related macrocycles are non-planer synthetic anion receptors that have attracted considerable attentions in recent years. Although the synthesis of calix[4]pyrrole (known as meso-octamethylporphyrinogen) was reported more than 100 years ago, the anion binding properties were first discovered in 1996. The simple calix[4]pyrroles can be synthesized in single step in high yield by condensation of pyrrole with acetone. The compounds showed preferential binding for halide anions including fluoride, phosphate, carboxylate, and chloride in organic media. Efforts to improve the anion affinity of calix[4]pyrrole and to enhance its selectivity have led to the synthesis of a variety of new calixpyrrole derivatives. Among the various modifications, introduction of straps on one side of the calix[4]pyrroles are the most effective. Incorporation of aromatic rings other than pyrroles also exhibited interesting binding behaviour. Introduction of signalling units as part of the strapping element enable to detect the anions on chromogenic or fluorogenic fashion. Finding of the anion transport properties across the membrane and cytotoxic effects of the calix[4]pyrroles open new window for calixpyrrole-related research. The polymer-incorporated systems have also been employed as anion complexants in solvent-solvent extraction. These old, yet easy-to-make macrocycles have well advanced more recently with the discovery of the ion-pair complexation properties. In this review, the synthetic developments and anion binding properties of calixpyrroles for the last decades will be discussed and will cover the advances in calixpyrrole chemistry.

• 한국세라믹학회지
• /
• 제54권5호
• /
• pp.406-412
• /
• 2017

$70V_2O_5-10Fe_2O_3-13P_2O_5-7B_2O_3$ glasses were prepared to study the electrical conductivity and catalytic properties of the structural change with crystallization. The structural changes were analyzed by determining the molecular volume from the sample density; using X-Ray Diffraction (XRD) analysis, which indicated that $V_2O_5$, $VO_2$ and $B_2O_3$ crystals in heat-treated more than 1h samples. Especially a new crystalline phase of non-stoichiometric $Fe_{0.12}V_2O_5$ was formed after 6 h heat treatment. The V-O bonding change after crystallization was analyzed by Fourier Transform Infrared Spectroscopy (FTIR); V ion change from $V^{5+}$ to $V^{4+}$ was shown by XPS. Conductivity and catalytic properties were examined based on the polaronic hopping of V and Fe ions, which exhibited different valence states with crystallization.

• Bulletin of the Korean Chemical Society
• /
• 제24권7호
• /
• pp.961-966
• /
• 2003

A quantum-chemical study of conformations and electronic structures of polyheterocyclic derivatives with vinylenediheteroatom substituents at the 3- and 4-positions was performed to search for novel blue-lightemitting conjugated polymers. Conformational potential energy curves of the polymers were constructed as a function of the helical angle (a) through semiempirical Hartree-Fock band calculations at the Austin model 1 level. It is found that poly(3,4-vinylenedioxythiophene) possesses a quite flat curve in the range of α = 51.4°- 120°. Replacing S atoms for O atoms greatly increases repulsion between the neighboring units, and thereby the units become perpendicular to one another. Because of the hydrogen bonding between O and NH, poly(3,4- vinylenedioxypyrrole) is predicted to be anti-coplanar and poly(3,4-vinylenediaminofuran) to be nearly anticoplanar. According to the modified extended Huckel band calculations, the HOMO-LUMO gaps (HLGs) of the polymers, unless the polymer chains are twisted, are close to or slightly smaller than those of their respective mother polymers. Among the polymers, poly(3,4-vinylenedioxythiophene) is presumed to be the most probable candidate for a blue-light emitter because its HLG is within the range of the electronic requirement for blue-light emitters.

• Bulletin of the Korean Chemical Society
• /
• 제28권2호
• /
• pp.193-199
• /
• 2007

Raman and fluorescence spectroscopies were employed to study the coil effects on the intermolecular structure of a rod-coil liquid crystalline (LC) oligomer, the esterification products of ethyl 4-[4'-oxy-4-biphenylcarbonyloxy]- 4'-biphenylcarboxylate with poly(propylene)oxides (PPO) (DP=12) and poly(ethylene oxide)s (PEO) (DP=12). Three different vibrational modes (carbonyl, aromatic C-H, and aromatic C=C) obtained from the Raman experiment at variable temperature indicate that PPO and PEO coils induce the hydrogen bonding in a different manner. Further information about the micro-environment around the mesogenic unit obtained by fluorescence excitation spectra of P12-4 (LC with PPO coil) and 12-4 (LC with PEO coil) suggests that the mesogenic unit of P12-4 is quite different from that of 12-4 in intermolecular structure. This study supports the results obtained only from Raman spectroscopy, providing more accurate information about the intermolecular structural changes of liquid crystalline polymers at a molecular level during the phase transitions.

• Bulletin of the Korean Chemical Society
• /
• 제34권8호
• /
• pp.2381-2386
• /
• 2013

A new series of Mn(II) and Mo(VI) complexes containing the Schiff bases hydrazinecarbothioamide and hydrazinecarboxamide of 5,6-dimethyl-1H-indol-2,3-dione have been synthesized. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, molecular weight determinations and spectral studies viz. electronic IR, ESR, $^1H$ NMR and $^{13}C$ NMR and X-ray diffraction spectral studies. The magnetic moment values of the manganese(II) complexes are in the range of 5.80-6.15 B.M. suggesting a high spin state of manganese in these complexes. The spectral data are consistent with a tetrahedral geometry around Mn(II) and an octahedral geometry for Mo(VI), in which the ligands act as bidentate chelating agents, coordinated through the nitrogen and sulfur/oxygen atoms. The ligands and their metal complexes have been tested against a number of pathogenic fungi and bacteria at different concentrations and were found to possess sufficient fungicidal and bactericidal properties. Further, the complexes were also tested for their antifertility activity in male albino rats and the results were indeed positive.

• 한국산학기술학회논문지
• /
• 제11권7호
• /
• pp.2565-2569
• /
• 2010

실리콘 태양전지 셀을 제작하고 효율을 측정하는데 있어 texturing 효과에 대하여 상관성을 조사하였다. Texturing은 $HNO_3$, KOH, NaOH를 각각 사용한 IPA혼합 에칭용액을 만들어서 샘플을 제작하였다. 셀의 분석은 FTIR 과 XRD를 이용하였으며, 실리콘 태양전지 셀의 효율과 화학적인 특성 사이의 상관성을 조사하였다. FTIR 데이터의 950~1350 $cm^{-1}$ 영역에서 픽의 생김새와 셀 표면의 반사도 사이에는 상관성이 있으며, 픽의 쪼개짐이 많으면 표면에서 결합의 상호작용이 활발하지 않다는 것을 의미하며 이러한 표면에서 반사가 잘 일어나지 않으면서 효율이 증가하는 것을 확인하였다.