• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.198-202
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• 2004

Hydrogen bond is an important factor in the structures of carbohydrates. Because of great strength, short range, and strong angular dependence, hydrogen bonding is an important factor stabilizing the structure of carbohydrate. In this study, conformational properties and the hydrogen bonds in GlcNAc( ${\beta}$1,3)Gal(${\beta}$)OMe in DMSO are investigated through NMR spectroscopy and molecular dynamics simulation. Lowest energy structure in the adiabatic energy map was utilized as an initial structure for the molecular dynamics simulations in DMSO. NOEs, temperature coefficients, SIMPLE NMR data, and molecular dynamics simulations proved that there is a strong intramolecular hydrogen bond between O7' and HO3' in GlcNAc( ${\beta}$1,3)Gal(${\beta}$)OMe in DMSO. In aqueous solution, water molecule makes intermolecular hydrogen bonds with the disaccharides and there was no intramolecular hydrogen bonds in water. Since DMSO molecule is too big to be inserted deep into GlcNAc(${\beta}$1,3)Gal(${\beta}$)OMe, DMSO can not make strong intermolecular hydrogen bonding with carbohydrate and increases the ability of O7' in GlcNAc(${\beta}$1,3)Gal(${\beta}$)OMe to participate in intramolecular hydrogen bonding. Molecular dynamics simulation in conjunction with NMR experiments proves to be efficient way to investigate the intramolecular hydrogen bonding existed in carbohydrate.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2238-2246
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• 2012

Molecular dynamics simulations have been performed to investigate hydrogen bonding characteristics of hydroxyl groups in glucose aqueous solutions with different concentrations. The hydrogen bonding abilities and strength of different O and H atom types have been calculated and compared. The acceptor/donor efficiencies have been predicted and it has been found that: (1) O2-HO2 and O3-HO3 are more efficient intramolecular hydrogen bonding acceptors than donors; (2) O1-HO1, O4-HO4 and O6-HO6 are more efficient intramolecular hydrogen bonding donors than acceptors; (5) O1-HO1 and O6-HO6 are more efficient intermolecular hydrogen bonding acceptors than donors while hydroxyl groups O2-HO2 and O4-HO4 are more efficient intermolecular hydrogen bonding donors than acceptors. The hydrogen bonding abilities of hydroxyl groups revealed that: (1) the hydrogen bonding ability of OH2-$H_w$ is larger than that of hydroxyl groups in glucose; (2) among the hydroxyl groups in glucose, the hydrogen bonding ability of O6-HO6 is the largest and the hydrogen bonding ability of O4-HO4 is the smallest; (3) the intermolecular hydrogen bonding ability of O6-HO6 is the largest; (4) the order for intramolecular hydrogen bonding abilities (from large to small) is O2-HO2, O1-HO1, O3-HO3, O6-HO6 and O4-HO4.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.140-146
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• 2016

Using density functional Theory, we studied local structure of liquid ethylene glycol and 1,3-propanediol. For both liquid, making intramolecular hydrogen bonding is not preferred, because relative energy between with and without intramolecular hydrogen bond is only -1.95kcal/mol, which is far less than intermolecular hydrogen bonding energy, about -7.5kcal/mol. Also, hydrogen bond induce polarization of hydroxyl group and make $2^{nd}$ hydrogen bond more stronger. This effect was small in intramolecular hydrogen bond of ethylene glycol. When considering energy per hydrogen bond, making only one intermolecular hydrogen bond for ethylene glycol pair is energetically favored, while two intermolecular hydrogen bond can be formed in 1,3-propanediol pair.

• Bulletin of the Korean Chemical Society
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• 제22권7호
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• pp.693-698
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• 2001

Ab initio density functional calculations on the structural isomers, the hydration energies, and the hydrogen bond many-body interactions for gauche-, trans-protonated ethylenediamine-(water)3 complexes (g-enH+(H2O)3, t-enH+(H2O)3) have been performed. The structures and relative stabilities of three representative isomers (cyclic, tripod, open) between g-enH+(H2O)3 and t-enH+(H2O)3 are predicted to be quite different due to the strong interference between intramolecular hydrogen bonding and water hydrogen bond networks in g-enH+(H2O)3. Many-body analyses revealed that the combined repulsive relaxation energy and repulsive nonadditive interactions for the mono-cyclic tripod isomer, not the hydrogen bond cooperativity, are mainly responsible for the greater stability of the bi-cyclic isomer.

• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.3090-3093
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• 2011

Curcumin is a natural product with antioxidant, anti-inflammatory, antiviral and antifungal functions. As it is known that the excited state intramolecular hydrogen transfer of curcumin are related to its medicinal antioxidant mechanism, we investigated its excited state dynamics by using femtosecond transient absorption spectroscopy in an effort to understand the molecule's therapeutic effect in terms of its photophysics and photochemistry. We found that stronger intermolecular hydrogen bonding with solvents weakens the intramolecular hydrogen bonding and decelerates the dynamical process of the enolic hydrogen. Exceptions are found in methanol and ethylene glycol due to their nature as simultaneous hydrogen bonding donor-acceptor and high viscosity solvent, respectively.

• 대한화학회지
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• 제59권6호
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• pp.541-544
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• 2015

• 한국염색가공학회지
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• 제20권4호
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• pp.21-30
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• 2008

To understand the complex hydrogen bonding structure, several phenolic derivatives and benzoxazine model compounds are synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR). The estimation of molar extinction coefficients for various types of hydrogen bonding species is systematically carried out by the curve-resolving of FT-IR spectra. The distribution of hydrogen bonding species in benzoxazine model dimers is quantitatively analyzed. It is revealed that benzoxazine dimers and BA-a polybenzoxazine are mainly composed of intramolecular interaction rather than intermolecular interaction.

• 대한화학회지
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• 제54권3호
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• pp.275-282
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• 2010

분자 내 수소결합 가능성을 가지고 있는 2-fluorocyclopropanemethanol과 2-chlorocyclopropanemethanol에 대하여 MP2/6-311++G(d,p) 방법과 B3LYP/6-311++G(d,p) 방법으로 최적화 계산을 수행하였다. 두 분자 모두 가장 안정한 conformer에서 O-H의 수소가 F나 Cl을 향하고 있어 수소결합 가능성을 보이기는 하나 $H{\cdots}F$, $H{\cdots}Cl$ 거리가 van der Waals radii보다 커서 강한 수소결합이라 보기 힘들고 두 번째 안정한 conformer의 경우가 가까운 $H{\cdots}F$, $H{\cdots}Cl$ 거리를 보이며 더 강한 수소결합 가능성을 보였다. 그러나 에너지가 5 ~ 7 kJ 더 높게 나타났다. Methanol group과 F나 Cl이 서로 반대 방향을 향할 때 일반적으로 안정하나 앞의 가장 안정한 conformer보다는 에너지가 높다.

• 한국자기공명학회논문지
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• 제8권2호
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• pp.127-138
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• 2004

We obtained the chemical shifts of amide protons (NHs) in helical peptides at various temperatures and trifluoroethanol (TFE) concentrations using 2-dimensional NMR spectroscopy. These NH chemical shifts and their temperature dependence exhibited characteristic periodicity of 3-4 residues per cycle along the helix, where downfield shifted NHs showed larger temperature dependence. In an attempt to understand these observations, we focused on hydrogen bonding changes in the peptides and examined the validity of two possible explanations: (1) changes in intermolecular hydrogen bonding caused by differential solvation of backbone carbonyl groups by TFE, and (2) changes in intramolecular hydrogen bonding due to disproportionate variations in the hydrogen bonding within the peptide helix. Interestingly, the slowly exchanging NHs, which were on the hydrophobic side of the helix, showed consistently larger temperature dependences. This could not be explained by the differential solvation assumption, because the slowly exchanging NHs would become more labile if the preceding carbonyl groups were preferentially solvated by TFE. We suggest that the disproportionate changes in intramolecular hydrogen bonding better explain both the temperature dependence and the exchange behavior observed in this study.

• Journal of Information Display
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• 제2권3호
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• pp.18-31
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• 2001

We utilize Fourier transform infrared (IR) spectroscopy to probe intramolecular hydrogen bonding in $smectic-C^{\ast}$ liquid crystal phases. Infrared spectra of aligned smectic liquid crystal materials vs. temperature and of isotropic liquid crystal mixtures vs. concentration were measured in homologs, both with and without hydrogen bonding. Hydrogen bonding significantly changes the direction and magnitude of the vibrational dipole transition moments, causing marked changes in the IR dichroic absorbance profiles of hydrogen bonded molecular subfragments. A GAUSSIAN94 computation of the directions, magnitudes, and frequencies of the vibrational dipole moments of molecular subfragments shows good agreement with the experimental data. The results show that IR dichroism can be an effective probe of hydrogen bonding in liquid crystal phases.