• Macromolecular Research
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• 제8권3호
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• pp.125-130
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• 2000

Resorcinol formaldehyde resins are synthesized by polycondensation of resorcinol with formal-dehyde and have various structures by the condensation type. The influence of polycondensation type on the stability and structure of the resorcinol formaldehyde resin was studied by molecular mechanics and molecular dynamics. The resins formed by 2,6-polycondensation and 4,6-polycondensationwith head-to-tail orientations have structures of intramolecular hydrogen bonds between 1-hydroxyl groups and between outer hydroxyl groups of the adjacent resorcinols, respectively. The resin formed by 2,6-polycon-densation with head-to-head orientation has a structure that inner hydroxyl groups cluster in the center of the molecule. Energetical stability of the resin is affected by both the intramolecular hydrogen bonds and the steric' hindrance by phenyl group.

• Archives of Pharmacal Research
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• 제8권1호
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• pp.1-6
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• 1985

The crystal structure or $\gamma$-hydroxy-$\betha$-aminobutyric acid was determined by MULTAN system with X-ray intensity data on a diffractometer and refined by the least-squares method to an R-value 0.034 for 711 reflections. The crystals were orthorhombic, space group $P2_{1}2_{1}2_{1}$, Z = 4, with a = 10.220, b = 8.257 and c = 6.556$\AA$. The molecule takes the zwitterionic form and skeletal conformation is trans-transform. The molecules are held together by intra-and intermolecular NH-O and OH--O hydrogen bonds.

• Journal of Microbiology and Biotechnology
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• 제8권2호
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• pp.158-164
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• 1998

Crystal structural analyses of the API-TLCK complex revealed that the ${\epsilon}$-amino group (NZ) of the lysyl part of TLCK forms hydrogen bonds with OD1 of $Asp^225$ which is a substrate specificity determinant of API, OG of $Ser^214$, O of $Ser^214$, OG1 of $Thr^189$, and O of $Thr^189$ l89/. The ${\beta}$-carboxyl oxygen of $Asp^225$ forms hydrogen bonds with the NE1 of $Trp^182$. From these observations, it is thought that besides $Asp^225$, $Thr^189$, $Ser^214$, and $Trp^182$ may also contribute to the steric specificity for lysine and high proteolytic activity of API. The side-chain hydroxyl groups of $Thr^189$ and $Ser^214$ were removed to elucidate the role of these hydrogen bonds in the $S_1$-pocket. The $k_{cat}$/$K_m$ of T189V, S214A, and T189V.S214A were decreased to 1/4, 1/3, and 1/46, respectively, of the value for native API. The decreased activities were mainly due to the increase of $K_m$. The CD and fluoroscence spectra of the three mutants were similar to those of wild-type API. With regards to the kinetic parameters ($K_i\;and\;k_2$) of mutants for the reaction involving TLCK and DFP, $k_2$decreased by increase of $K_1$ only. These results suggest that the decreased catalytic activity of these mutants is caused by the partial loss of the hydrogen bond network in the $S_1$-pocket. On the other hand, the similarity of enzymatic properties between W182F and the native enzyme suggests that the hydrogen bond between OD2 of $Asp^225$ and NE1 of $Trp^182$ is not directly related to the reaction of $Asp^225$ with the substrate.

• 폴리머
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• 제37권3호
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• pp.288-293
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• 2013

A group of molecularly imprinted polymers (MIPs) with specific recognition for chiral (S)-ibuprofen were successfully prepared based on hydrogen bonds, utilizing ${\alpha}$-methacrylic acid as a functional monomer. The IR analysis of MIPs showed that the blue- and red-shifted hydrogen bonds were formed between templates and functional monomers in the process of self-assembly imprinting and re-recognition, respectively. According to UV-Vis analysis, we found that the ratio of host-guest complexes between template molecule and functional monomer was 1:1. The effect of cross-linker's quantity on the polymerization was studied by transmission electron microscope (TEM). The adsorption selectivity experiments indicated that MIPs exhibited higher selectivity to (S)-ibuprofen than those to ketoprofen and (R)-ibuprofen, (S)-ibuprofen's structural analogs.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.2017-2022
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• 2012

Three isostructural lanthanide coordination polymers, $[Ln(L)_3(H_2O)_2](H_2O)_3$ {Ln = Eu (1), Tb (2), Gd (3); L = $trans$-3-(3-pyridyl)acrylate, (3-py)-CH=CH-COO}, were prepared from HL, lanthanide nitrate, and NaOH in $H_2O$ by microwave heating. In all coordination polymers, the metal is bonded to eight oxygen atoms, and all pyridyl nitrogen atoms do not coordinate to the metals. All polymers have a 1-D loop-connected chain structure. The hydrogen atoms in the aqua ligands and lattice water molecules all participate in the hydrogen bonds of the O-$H{\cdots}O$ or O-$H{\cdots}N$ type. The hydrogen bonds connect the 1-D chains to create a 2-D network. Polymer 1 exhibited red luminescence in the solid state at room temperature.

• Bulletin of the Korean Chemical Society
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• 제31권4호
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• pp.881-886
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• 2010

A novel Schiff base N-(2,4-dinitro-phenyl)-N'-(1-phenyl-ethylidene)-hydrazine has been synthesized and structurally characterized by X-ray single crystal diffraction, elemental analysis, IR spectra and UV-vis spectrum. The crystal belongs to monoclinic with space group P21/n. The molecules are connected via intermolecular O-$H{\cdots}O$ hydrogen bonds into 1D infinite chains. The crystal structure is consolidated by the intramolecular N-$H{\cdots}O$ hydrogen bonds. weak intermolecular C-$H{\cdots}O$ hydrogen bonds link the molecules into intriguing 3D framework. Furthermore, Density functional theory (DFT) calculations of the structure, stabilities, orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the title compound were performed by means of Gaussian 03W package and taking B3LYP/6-31G(d) basis set. The time-dependent DFT calculations have been employed to calculate the electronic spectrum of the title compound, and the UV-vis spectra has been discussed on this basis. The results show that DFT method at B3LYP/6-31G(d) level can well reproduce the structure of the title compound.

• 한국식품저장유통학회지
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• 제21권6호
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• pp.838-843
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• 2014

본 연구에서는 근적외 분광법을 이용하여 양념용 채소로 많이 사용되는 파, 마늘, 양파의 건조 불균일성을 관찰하였다. 대류식 온풍건조기에서 건조 위치에 따른 양념채소류의 건조 상태 차이를 조사한 결과, 건조 트레이의 높이나 위치에 따라 바람의 온도와 습도에 차이가 발생하여 건조가 균일하게 되지 않았다. 건조 정도가 다른 양념채소류의 2차 미분 근적외 스펙트럼을 비교한 결과 1,390 nm에서 1,400 nm 부근의 수소결합이 약한 물이 먼저 증발되었고 1,420 nm 부근의 수소결합이 강한 물은 건조 후에도 잔존함을 관찰할 수 있었다. 초분광 NIR 이미징 기법으로 측정한 스펙트럼을 주성분분석함으로써 건조채소의 건조도를 가시적으로 판별할 수 있었다.

• 대한화학회지
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• 제17권2호
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• pp.105-114
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• 1973

몰포리노치오세미카바자이드의 결정 구조가 X-선 해석에 의하여 결정되었다. 세포 상수는 a=4.19(2), b=6.56(2), c=26.67(4)$A^{\circ}$ 이고, 단위 세포는 4분자를 포함하며, 공간 군은 $P2_12_12_1$이다. 원자좌표치는 최소자승법으로 정밀화하였으며 R값은 651개의 관측 반사를 써서 계산한 결과 0.07이다. 아미노 질소 원자는 a-축에 평행한 2회의 나선 축에 의하여 옮겨지는 다른 분자의 황원자와 3.48 및 3.49$A^{\circ}$의 수소결합을 하고 있으며 아미노 질소 원자는 a-축에 평행한 2회의 나선 축에 의하여 옮겨지는 다른 분자의 아미노 질소 원자와 3.04${\AA}$의 수소결합을 하고 있다. 이들 3개의 수소결합은 분자들을 2회의 나선축 부근에 배열하게 한다. 수소결합 이외로 분자들을 연결하는 힘은 van der waals의 힘이다.

• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.153-158
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• 2012

The hydrogenation of $AlB_2$-type BaGaGe exhibits a metal to insulator (MI) transition, inducing a puckering distortion of the original hexagonal [GaGe] layers. We investigate the electronic structure changes associated with the hydrogen-induced MI transition, using extended H$\ddot{u}$ckel tight-binding band calculations. The results indicate that hydrogen incorporation in the precursor BaGaGe is characterized by an antibonding interaction of $\pi$ on GaGe with hydrogen 1s and the second-order mixing of the singly occupied antibonding $\pi^*$ orbital into it, through Ga-H bond formation. As a result, the fully occupied bonding $\pi$ band in BaGaGe changes to a weakly dispersive band with Ge pz (lone pair) character in the hydride, which becomes located just below the Fermi level. The Ga-Ge bonds within a layered polyanion are slightly weakened by hydrogen incorporation. A rationale for this is given.

• 대한화학회지
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• 제16권2호
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• pp.59-63
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• 1972

In connection with two electron binding energy of each bond of saturated hydrocarbons, C-C bond fission and hydrogen abstraction from C-H bond are discussed by means of two center Huckel method. A beautiful correlation could be noticed between the observed bond dissociation energy and the calculated bond energy except for n-butane. Bond dissociation energies between C-C bond were also related to C-C bond fission. We could also find a very close relation between the relative easiness of hydrogen abstraction and the calculated binding energy of C-H bond. In other words, C-H bonds of tertiary hydrogen have been noticed as most weakely bonded and hence the tertiary hydrogen would most easily from the paraffins. In addition, the C-H binding energy is discussed applying ionic character of C-H bond which is derived from its dipole moment (0.4D)