In situ Raman spectroscopic measurements of water in the region of OH vibration were conducted up to 0.4 GPa at 23 and 52 degrees C. The frequencies of the decomposed OH stretching bands initially decreased with increasing pressure, reached a minimum at 0.15 GPa and increased up to 0.3 GPa and then decreased, which corresponds to the variations of the strength of hydrogen bonding. This variatio...

The interfacial structure of water in contact with TiO2 is the key to understand the mechanism of photocatalytic water dissociation as well as photoinduced superhydrophilicity. We investigate the interfacial molecular structure of water at the surface of anatase TiO2, using phase-sensitive sum frequency generation spectroscopy together with spectra simulation using ab initio molecular dynamic t...

Trp-Trp pairs have emerged as a successful strategy for β-hairpin stabilization. Using loop 3 of Vammin as a template, we experimentally demonstrate that the contribution of Trp-Trp pairs to β-hairpin stability depends on β-sheet periodicity, that is, they are stabilising at non-hydrogen-bonded sites, but not at hydrogen-bonded positions.

Four complementary hydrogen bonds between sulfamides and ureas link adjacent hydrogen-bonded ribbons to form sheets in the solid-state; this interaction is investigated in solution using model urea and sulfamide compounds.

Four series of hydrogen bonded complexes of formamide and substituted benzoic acids and benzoates were studied in the light of substituent effect on intermolecular interactions. The analysis based on energy of interaction, geometry, QTAIM-derived properties of hydrogen bond critical point and energy of hydrogen bonds were made and discussed. The opposite effect of the substituent on hydrogen bo...

The structures of two compounds of L-tartaric acid with quinoline, viz. the proton-transfer compound quinolinium hydrogen (2R,3R)-tartrate monohydrate, C9H8N+.C4H5O6-.H2O, (I), and the anhydrous non-proton-transfer adduct with quinaldic acid, bis(quinolinium-2-carboxylate) (2R,3R)-tartaric acid, 2C10H7NO2.C4H6O6, (II), have been determined at 130 K. Compound (I) has a three-dimensional honeycom...

Acting as hydrogen bond acceptors, heterocyclic compounds could interact with a hydrogen bond donor, where either the heteroatom or the p system is the bonding site. The hydrogen bonded complexes of heterocyclic compounds with methanol (MeOH) were studied using matrix isolation FTIR spectroscopy and theoretical calculations based on density functional theory. Four heterocyclic compounds, furan ...

Photoisomerization of a protein bound chromophore is the basis of light sensing of many photoreceptors. We tracked Z-to-E photoisomerization of Cph1 phytochrome chromophore PCB in the Pr form in real-time. Two different phycocyanobilin (PCB) ground state geometries with different ring D orientations have been identified. The pre-twisted and hydrogen bonded PCB(a) geometry exhibits a time consta...

2-Methoxyalkanols exhibit interesting variations with regard to equilibrium species of non hydrogen bonded, intramolecular hydrogen bonded and intermolecular hydrogen bonded forms [1-9]. 2-Methoxyethanol in particular has been found to behave as an anion as well as a bidentate ligand in its metal complexes [10-14], Trimethylsiloxyalkanols, Me3SiO(CH2)nOH synthesized through a simple way, are a ...

BACKGROUND Trimethoprim [2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine] is an antifolate drug. It selectively inhibits the bacterial dihydrofolate reductase (DHFR) enzyme. RESULTS In the crystal structures of trimethoprim (TMP)-hydrogen phthalate (1) and trimethoprim-hydrogen adipate (2), one of the N atoms of the pyrimidine ring is protonated and it interacts with the deprotonated carb...