• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.38-38
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• 2011

Covalently bonded halogen ligands possess unusual charge distributions, attracting both electrophilic and nucleophilic molecular ligands to form halogen bonds. In many biochemical systems, halogen bonds and hydrogen bonds coexist. The interplay between halogen and hydrogen bonds has been actively studied in various three-dimensional bulk molecular co-crystals. It was found that halogen bonds could be complementary to hydrogen bonds due to their similar bond strength and dissimilar directionality. In those ensemble-averaging approaches, however, it was not possible to extract local information such as individual bond configurations and nano-level domain structures, which is a crucial part of supramolecular studies. In this study, we directly visualize the individual molecular configuration of a brominated molecule and the role of halogen bonds on Au(111) using scanning tunneling microscopy. The precise arrangement of observed molecular structures was reproduced by first-principle studies and explained in the context of halogen and hydrogen bonds. We discuss the distances and the strengths of the observed halogen bonds and hydrogen bonds, which are consistent with previous bulk data.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.129-129
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• 2012

Covalently bonded halogen ligands possess unusual charge distributions, attracting both electrophilic and nucleophilic molecular ligands to form halogen bonds. In many biochemical systems, halogen bonds coexist with hydrogen bonds, being complementary to them due to their similar bond strength and dissimilardirectionality. In this study, we directly visualize the individual molecular configuration of chlorinated 1,5-dichloroanthraquinone and brominated 1,5-dibromoanthraquinone molecules on Au(111) using scanning tunneling microscopy. The precise arrangements of observed molecular structures were explained in the context of halogen and hydrogen bonds. We discuss the distances and the strengths of the observed halogen and hydrogen bonds, which are consistent with previous bulk data.

• 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.23 no.12
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• pp.1811-1815
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• 2002

We have calculated energies and structures for the hydrogen bonded clusters between trimethyl phosphate and nitric acids. The hydrogen bond lengths between phosphoryl oxygen and the proton of nitric acid are short compared to normal hydrogen bonds, and the H-bond strengths are fairly strong. The hydrogen bond length becomes longer, and the strength becomes weaker, as more nitric acids are bound to the TMP. The average H-bond strengths for the $TMP-(HNO_3)_n$ complexes with n = 1, 2, and 3, are 9.6, 7.9 and 6.4kcal/mol at 300K respectively. Weak hydrogen bonds between nitrate oxygen and methyl proton might contribute to the stability of the clusters. Not only the BSSE but also the fragment relaxation energies should be considered to calculate hydrogen bond strengths for the complexes accurately.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.1037-1040
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• 2011

The dinuclear complex 1 with cooperative hydrogen bonds can be prepared by the metal-directed reaction of Eq. (2). This work shows that the coordinated hydroxyl group trans to the secondary amino group is deprotonated more readily than that trans to the tertiary amino group and acts as the hydrogen-bond accepter. The lattice water molecules in 1 act as bridges between the two mononuclear units through hydrogen bonds. The complex is quite stable as the dimeric form even in various polar solvents. The complex exhibits a weak antiferromagnetic interaction between the metal ions in spite of relatively long Cu$\cdots$Cu distance. This strongly supports the suggestion that the antiferromagnetic behavior is closely related to the cooperative hydrogen bonds.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2025-2028
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• 2014

Anion receptor 1 based on acylhydrazone has been designed and synthesized. UV-vis and $^1H$ NMR titration showed that receptor 1 is selective receptor for dihydrogen phosphate ($H_2PO_4{^-}$). Dihydrogen phosphate was complexed by the receptor 1 via at least 4 hydrogen bonding interactions, contributing from two amide N-Hs and two imine C-Hs. In addition, nitrogen in the aromatic ring could make 2 additional hydrogen bondings with OH groups in the dihydrogen phosphate. However, the receptor 1 could make only 4 hydrogen bonds with halides. Therefore, receptor 1 could bind anions through hydrogen bonds with a selectivity in the order of $H_2PO_4{^-}$ > $Br^-$ > $Cl^-$ in highly polar solvent such as DMSO.

• Food Science and Preservation
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• v.5 no.1
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• pp.65-71
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• 1998

The changes in gel characteristics of soy protein as a result of various reagents that alter specific interactions which affect the formation and textural properties of gels, were studied. The reagents were added to 15% soy protein solutions prior to heat treatment. The gels were not formed with urea, indicating that hydrogen bonds significantly contributed to the formation and hardness of soy protein gel. Hydrophobic interactions and disulfide bonds compensated for hydrogen bonds and the contributions of electrostatic interactions to gel hardness are relatively insignificant. The farce primarily responsible for gel cohesiveness appeared to be disulfide bonds, because a significant decrease in cohesiveness was found only with the presence of N-ethylmaleimide. Adhesiveness decreased only with the addition of urea, and thus the contribution of hydrogen bonding to adhesiveness of gel could be concluded to be resent. However, adhesiveness was suggested to be interpreted not only wile molecular forces involved in gel formation but also with hydration properties of protein.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.316-319
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• 2017

A new approach to improving the electrical characteristics and optical response of a polysilicon-based metal-semiconductor-metal (MSM) photodetector is proposed. To understand the cause of current restriction in the MSM photodetector, modified trap mechanisms are suggested, which include interfacial electron traps at the metal/polysilicon interface and silicon dangling bonds between silicon crystallite grains. Those traps were passivated using hydrogen ion implantation with subsequent post-annealing. Photodetectors that were ion-implanted under optima conditions exhibited improved photoconductivity and reduced dark current instability, implying that the hydrogen bonds in the polysilicon influence the simultaneous decreases in the density of dangling bonds at grain boundaries and the trapped positive charges at the contact interface.

• Archives of Pharmacal Research
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• v.13 no.3
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• pp.246-251
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• 1990

Intermolecular interaction between barbiturates and membrane components such as phospholipid and cholesterol were investigated on $^1$H-NMR spectra and infrared spectra. According to previous reports, barbiturates interacted with phospholipid through intermolecular hydrogen bonds. We also investigated thi observation using dipalmitoyl-phosphatidylcholine (DPPC) as phospholipid in deuterochloroform, and characterized quantitatively. Also, the observed drug could interact with cholesterol which is one of the major components of biomembranes through hydrogen bonds. It was the carbonyl groups of barbiturate and the hydroxyl group of cholesterol that formed hydrogen bond complex. In addition to spectroscopic studies, we investigated the direct effect of phenobarbital on lipid multibilayer vesicles, whose compositions were varied, by calorimetric method. Phenobarbital caused a reduction in the temperature of phase transition of vesicles. These studies may provided a basis for interpreting the mode of action of barbiturates.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.95-99
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• 2012

Two novel copper(II) complexes, [Cu(dmamhp)$(H_2O)_2(SO_4)]_n$ (1) and [Cu(dmamhp)$(NO_3)_2(H_2O)]{\cdot}H_2O$ (2) [dmamhp = 2-dimethylaminomethyl-3-hydroxypyridine] have been synthesized and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 displays a double one-dimensional chains structure, in which each chain is constituted with the distorted octahedral copper(II) complex bridged through bidentate sulfate ligands resulting in a coordination polymer. The bifurcated hydrogen bonds and $\pi-\pi$ interactions play important roles in the formation of the double chains structure. On the other hand, compound 2 adopts a distorted square pyramidal geometry around copper(II) ion and exists as a discrete monomer. There are intermolecular bifurcated hydrogen bonds and $\pi-\pi$ stacking interactions between the monomeric units. The magnetic properties revealed that the paramagnetic behaviors are dominantly manifested and there are no intermolecular magnetic interactions in both compound 1 and 2.