• Bulletin of the Korean Chemical Society
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• v.33 no.7
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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.

• Journal of Information Display
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• v.2 no.3
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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.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.2045-2050
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• 2006

The interstitial hydrogen bonding in NiTi solid and its effect on the metal-to-metal bond is investigated by means of the EH tight-binding method. Electronic structures of octahedral clusters $Ti_4Ni_2$ with and without hydrogen in their centers are also calculated using the cluster model. The metal d states that interact with H 1s are mainly metal-metal bonding. The metal-metal bond strength is diminished as the new metal-hydrogen bond is formed. The causes of this bond weakening are analyzed in detail.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1161-1164
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• 2004

Calculations are presented for phenol ?acetonitrile - $(water)_n$ (n = 1-3) clusters. We examine the nature of interactions in the mixed clusters by calculating and comparing the structures, relative energies and harmonic frequencies of isomers with different type of hydrogen bonding. The conformers exhibit quite different patterns in the shifts of the CN and OH stretching frequencies, depending on the type of hydrogen bonding. Cyclic hydrogen bonding among the water molecule(s), acetonitrile and phenolic OH proves very important in determining the relative stability. It is also shown that acetonitrile tends to bind to the OH group of phenol in low energy conformers.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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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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• v.16 no.7
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• pp.574-577
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• 1995

Solvatochromic effect and hydrogen bonding interaction of NPNOH, NPNO- and NPNOR were investigated. Electronic transition energies of the dyes were plotted against empirical solvent polarity parameters, Taft's π* and Reichardt's ET(30). Good correlations were observed when the excitation energies were plotted against the energy calculated by multiple linear regression method which was developed by Taft. There is an intrinsic difference between betaine for ET(30) polarity scale and the azoderivative, which is derived from the specific hydrogen bond incurred with probe molecules and solvents. The hydrogen bonding plays a very important role for stabilization of an excited state molecule by solvents especially when a solute possesses a negative charge as with NPNO-.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.249-259
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• 1988

The solvent effects of MeOH-solvent dimers were studied via AM1 Hamiltonian and supermolecule methods. Methanol, ethanol, acetone, dimethylsulfoxide, N,N-dimethylformamide, tetrahydrofuran, dioxane, and acetonitrile were considered as solvent molecules. Optimized geometries, electron densities, molecular energies, and hydrogen-bonding energies of monomers and dimers were calculated. We found that the stabilization energies contributed to the hydrogen-bonding were decreased in the order of dimethylsulfoxide > ethanol > N,N-dimethylformamide > acetone > methanol > tatrahydrofuran > dioxane > acetonitrile, and this order was explained by using the change of electron density and energy partition functions.

• Textile Coloration and Finishing
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• v.20 no.4
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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.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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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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• v.32 no.spc8
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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.