We investigated structural changes, phase diagram, and vibrational properties of hydrogen hydrate in filled-ice phase C(2) by using first principles molecular dynamics simulation. It was found that the experimentally reported "cubic" structure is unstable at low temperature and/or high pressure: The "cubic" structure reflects the symmetry at high (room) temperature where the hydrogen bond netwo...

Four binol based pyrrole carboxamide chiral receptors has been synthesized and effectively used as a Chirality Conversion Reagent (CCR) for underivatized amino acids. Three points of interactions take place for the conversion process. They are the reversible imine formation, the internal resonance assisted Hydrogen Bonding (RAHB) and the additional hydrogen bonds between the amino acids and the...

The hydrogen-disordered structure of ice, Ic, makes it difficult to analyze the vibrational normal modes in far-infrared region (i.e., molecular translation band). To clarify origin energy-splitting hydrogen bond vibrations this area, a 64-molecule supercell was constructed and calculated using first-principles density functional theory. results were good agreement with inelastic neutron scatte...

This work describes in-depth NMR characterization of a unique low-barrier hydrogen bond (LBHB) between an active site residue from the enzyme and a bound inhibitor: the complex between secreted phospholipase A(2) (sPLA(2), from bee venom and bovine pancreas) and a transition-state analog inhibitor HK32. A downfield proton NMR resonance, at 17-18 ppm, was observed in the complex but not in the f...

The aim of this work is to investigate polymer[middle dot][middle dot][middle dot]substrate interactions for a polymer nanocomposite material: poly(ethylene oxide) (PEO) confined in graphite oxide (GO). Six discrete and simplified models (one for PEO and five for GO) have been chosen in order to reproduce the most likely PEO···GO interactions. Twelve potential interaction energy curves have bee...

The dicyclo-hexyl-amine salt of RG108 (N-phthalyl-l-tryptophan) co-crystallizes with a water mol-ecule and a disordered mol-ecule of dimethyl-formamide (DMF), viz. dicyclo-hexyl-aminium (S)-2-(1,3-dioxoisoindolin-2-yl)-3-(1H-indol-3-yl)propanoate dimethyl-formamide solvate monohydrate, C(12)H(24)N(+)·C(19)H(13)N(2)O(4) (-)·C(3)H(7)NO·H(2)O. The conformation of the deprotonated compound is const...

In the solid state, the title compound, C12H16BrNO5 [systematic name: 4-bromo-2-((1E)-{[1,3-dihy-droxy-2-(hy-droxy-meth-yl)propan-2-yl]iminium-yl}meth-yl)-6-meth-oxy-benzen-1-olate], C12H16BrNO5, is found in the keto-amine tautomeric form, with an intra-molecular iminium-N-H⋯O(phenolate) hydrogen bond and an E conformation about the C=N bond. Both gauche (two) and anti relationships are found f...

We show that the cooperative reinforcement between hydrogen bonds in guanine quartets is not caused by resonance-assisted hydrogen bonding (RAHB). This follows from extensive computational analyses of guanine quartets (G(4)) and xanthine quartets (X(4)) based on dispersion-corrected density functional theory (DFT-D). Our investigations cover the situation of quartets in the gas phase, in aqueou...

in this work, a molecular dynamics simulation of the transport of water - methanol mixture through the single wall carbon nanotube (swcnt) is reported. methanol and water are selected as fluid molecules since water represents a strongly polar molecule while methanol is as an intermediate between polar and strongly polar molecules. some physical properties of the methanol-water mixture such as r...