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Hydrogen bond
About: Hydrogen bond is a research topic. Over the lifetime, 57701 publications have been published within this topic receiving 1306326 citations.
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TL;DR: The crystal structure of the collagen triple-helical peptide (Pro-Hyp-Gly)4- Pro-Hyp Hyp-Ala-(pro-Hyp Gly)5 shows evidence for the existence of interchain contacts between α-carbon hydrogens from Gly and Hyp residues, and carbonyl groups from gly and Pro residues on neighboring chains as discussed by the authors, and the geometrical disposition of these contacts makes it reasonable to describe them as Cα-H···O=C hydrogen bonds.
204 citations
TL;DR: The hydrogen-bonded and free OH stretch modes of Cl-(H2O)n (n = 1−5) have been observed by vibrational predissociation spectroscopy in the 2.6−3.2 μm region as mentioned in this paper.
Abstract: The hydrogen-bonded and free OH stretch modes of Cl-(H2O)n (n = 1−5) have been observed by vibrational predissociation spectroscopy in the 2.6−3.2 μm region. Besides demonstrating that all clusters form strong ionic hydrogen bonds, the spectra provide clear evidence of water−water hydrogen-bonding networks in n = 4 and n = 5, with the broad spectrum of n = 5 resembling that of large neutral water clusters. No water−water hydrogen bonding is seen in n = 2 and n = 3, but these clusters appear to be solvated asymmetrically. While the data suggest that Cl- ion is solvated on the surface of water clusters, there are discrepancies between the observed spectra and ab initio predictions. This disagreement may stem from either zero-point motion or high cluster temperature, which tend to disrupt hydrogen bonding among the waters.
204 citations
TL;DR: The K state, an early intermediate of the bacteriorhodopsin photocycle, is produced in crystals in a photostationary state at 100K, with 40% yield, and its X-ray diffraction structure is determined to 1.43 A resolution.
204 citations
TL;DR: The β-dicarbonyls exhibit both of these features, and in ways which have singled them out for detailed study for many years as mentioned in this paper, they provide the best known examples of keto ⇆ enol tautomerism, with the advantage of slow proton transfer and high concentrations of the enol Tautomers in most cases.
Abstract: Proton transfer and hydrogen bonding are two aspects of the chemistry of hydrogen that respectively govern the behaviour and structure of many molecules, both simple and complex, from water to DNA. The β-dicarbonyls exhibit both of these features, and in ways which have singled them out for detailed study for many years. They provide the best known examples of keto ⇆ enol tautomerism, with the advantage of slow proton transfer and high concentrations of the enol tautomers in most cases. These enols are stabilized by intramolecular OHO hydrogen bonds which at various times have been thought of as being centred, linear hydrogen bonds that are somehow incorporated into the delocalised π system to give “aromatic” systems. Research involving structural, spectroscopic and computational techniques has deepened our understanding of these compounds and changed our picture of them. The hydrogen bonding is surprisingly strong, surprising since it is neither centred, nor linear, nor involved in the ring’s delocalized bonding, although it is certainly coupled to it. This review deals with controversies that have surrounded the β-dicarbonyls and discusses the current view that the enol tautomers are a double-minimum potential well with a low energy barrier. The review ends with a brief look at the β-thioxoketones, which provide an analogous system based on a heteronuclear SHO hydrogen bond in the enol or enethiol tautomer.
204 citations
TL;DR: The behaviour of water at mosaic hydrophilic/hydrophobic surfaces of different silicas and in biosystems was studied in different dispersion media over wide temperature range using 1H NMR spectroscopy with layer-by-layer freezing-out of bulk water and interfacial water, thermally stimulated depolarization current (TSDC) and quantum chemical methods.
204 citations