Results 261 to 270 of about 10,014,931 (288)

The crucial role of water in shaping low-barrier hydrogen bonds

Physical Chemistry Chemical Physics, 2016
Low-barrier hydrogen bonds (LBHBs) are key components in a range of chemical processes, often appearing in metal-mediated catalytic applications.
Michael T, Ruggiero, Timothy M, Korter
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Energetics of a Low Barrier Hydrogen Bond in Nonpolar Solvents

Journal of the American Chemical Society, 1996
A measure of the strength of a low barrier hydrogen bond (LBHB) in apolar organic media was obtained using synthetic molecules derived from Kemp's triacid. The structures feature unusually rigid conformations that enforce intramolecular hydrogen bonds in a dicarboxylic acid, its corresponding acid-amide and their respective conjugate bases. Analysis of
Yoko Kato, Leticia M. Toledo, Julius Rebek   +2 more
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Are Short, Low-Barrier Hydrogen Bonds Unusually Strong?

Accounts of Chemical Research, 2010
In a symmetric hydrogen bond (H-bond), the hydrogen atom is perfectly centered between the two donor atoms. The energy diagram for hydrogen motion is thus a single-well potential, rather than the double-well potential of a more typical H-bond, in which the hydrogen is covalently bonded to one atom and H-bonded to the other.
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Low-barrier hydrogen bonds:Abinitio and DFT investigation

Journal of Computational Chemistry, 1998
High-level ab initio and DFT molecular orbital calculations have been used to investigate the physical properties of a model low-barrier hydrogen bond (LBHB) system: formic acid–formate anion. In the gas phase, it is found that the hydrogen bond formed is extraordinarily short and strong [ca.
Ganesh A. Kumar, Yongping Pan, C. Jay Smallwood, Michael A. McAllister   +3 more
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Evidence of a Low-Barrier Hydrogen Bond in the Tryptophan Synthase Catalytic Mechanism

Biochemistry, 1996
In the absence of other substrates, L-Ser reacts rapidly with the tryptophan synthase alpha 2 beta 2 bienzyme from Salmonella typhimurium at pH 7.8 and 25 degrees C to give an equilibrating mixture of species dominated by comparable amounts of the L-Ser external aldimine Schiff base, E(Aex1), and the alpha-aminoacrylate Schiff base, E(A-A).
O, Hur, C, Leja, M F, Dunn
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Low-Barrier Hydrogen Bond between Phosphate and the Amide Group in Phosphopeptide

Journal of the American Chemical Society, 2005
As the conversion between the monoionic (1) and diionic (2) form of the phosphate occurs, the phosphorylated peptides or proteins can not only cause the formation of a hydrogen bond between the phosphate group and the amide group but also change the strength of the hydrogen bond to form low-barrier hydrogen bonds (LBHBs). This reversible protonation of
Jin-Tang, Du, Yan-Mei, Li, Wei, Wei, Guo-Shi, Wu, Yu-Fen, Zhao, Kenji, Kanazawa, Tadashi, Nemoto, Hiroshi, Nakanishi   +7 more
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ChemInform Abstract: Low‐Barrier Hydrogen Bonds and Enzymic Catalysis.

ChemInform, 1994
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
W. W. CLELAND, M. M. KREEVOY
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Low barrier hydrogen bonds in sterically modified Schiff bases

Journal of the Chemical Society, Perkin Transactions 2, 2002
Five derivatives of an ortho-hydroxy Schiff base (2-(N-alkyl-α-iminoethyl)phenols) with very short intramolecular hydrogen bonds (dO(H)⋯N ≤ 2.500 A) were synthesised. The crystal structures were determined. The steric repulsion of the substituted methyl group results in an unusual strengthening of the hydrogen bonds, decreasing the barrier for the ...
Aleksander Filarowski, Aleksander Koll, Tadeusz Glowiak   +2 more
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Low barrier hydrogen bonds within salicylate mono-anions

Tetrahedron, 2001
Abstract Progressive incorporation of electron-withdrawing substituents into the aromatic ring of salicylic acid selectively acidifies the ArOH group, until the intrinsic pKa values of the ArOH and ArCO2H groups become matched, as in the case of 3-chloro-5-nitrosalicylic acid.
William L. Mock, Layne A. Morsch
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The low-barrier hydrogen bond in enzymic catalysis

2010
Publisher Summary This chapter describes the various aspects of the low-barrier hydrogen bond in enzymic catalysis. Hydrogen bonds come in a continuum of bond lengths and strengths. The first examples of enzymatic reactions where low-barrier hydrogen bonds played a role involved enolization of the substrate to change the p K of a key group in the ...
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