HYDROGEN BONDING IN DIASTEREOISOMERIC α-β AMINOALCOHOLS: A REINVESTIGATION OF THE EPHEDRINES BY N.M.R

1960 ◽  
Vol 38 (1) ◽  
pp. 125-130 ◽  
Author(s):  
James B. Hyne
Keyword(s):  
Hydrogen Bonding ◽  
Polar Solvents ◽  
Relative Stabilities ◽  
Hydrogen Bonded

The results of an n.m.r. study of the diastereoisomeric ephedrine and ψ-ephedrine molecules in non-polar solvents are interpreted and discussed in terms of the relative stabilities of the intramolecularly hydrogen-bonded conformers.

Theoretical study of hydrogen bonding interactions in substituted nitroxide radicals

2021 ◽  
Author(s):  
Thufail M. Ismail ◽  
Neetha Mohan ◽  
P. K. Sajith
Keyword(s):  
Hydrogen Bonding ◽  
Interaction Energy ◽  
Electrostatic Potential ◽  
Molecular Electrostatic Potential ◽  
Theoretical Study ◽  
Nitroxide Radicals ◽  
Hydrogen Bonding Interactions ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Interaction energy (Eint) of hydrogen bonded complexes of nitroxide radicals can be assessed in terms of the deepest minimum of molecular electrostatic potential (Vmin).

Understanding water structure from Raman spectra of isotopic substitution H2O/D2O up to 573 K

2017 ◽  
Vol 19 (32) ◽  
pp. 21540-21547 ◽  
Author(s):  
Qingcheng Hu ◽  
Haiwen Zhao ◽  
Shunli Ouyang
Keyword(s):  
Hydrogen Bonding ◽  
Raman Spectra ◽  
Water Structure ◽  
Free Water ◽  
Isotopic Substitution ◽  
Structure Model ◽  
Single Donor ◽  
Hydrogen Bonded

The OH/OD stretch band features on Raman spectra of isotopic substitution H2O/D2O at temperatures up to 573 K are correlated with a multi-structure model that water has five dominant hydrogen bonding configurations: tetrahedral, deformed tetrahedral, single donor, single hydrogen bonded water and free water.

Concomitant polymorphs of 1,3-bis(3-fluorophenyl)urea

2016 ◽  
Vol 72 (9) ◽  
pp. 692-696 ◽  
Author(s):  
Christina A. Capacci-Daniel ◽  
Jeffery A. Bertke ◽  
Shoaleh Dehghan ◽  
Rupa Hiremath-Darji ◽  
Jennifer A. Swift
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Engineering ◽  
Structural Motif ◽  
Parallel Orientation ◽  
One Dimensional ◽  
Monoclinic Form ◽  
Engineering Studies ◽  
Hydrogen Bonded

Hydrogen bonding between urea functionalities is a common structural motif employed in crystal-engineering studies. Crystallization of 1,3-bis(3-fluorophenyl)urea, C13H10F2N2O, from many solvents yielded concomitant mixtures of at least two polymorphs. In the monoclinic form, one-dimensional chains of hydrogen-bonded urea molecules align in an antiparallel orientation, as is typical of many diphenylureas. In the orthorhombic form, one-dimensional chains of hydrogen-bonded urea molecules have a parallel orientation rarely observed in symmetrically substituted diphenylureas.

CAN SEMIEMPIRICAL QUANTUM MODELS CALCULATE THE BINDING ENERGY OF HYDROGEN BONDING FOR BIOLOGICAL SYSTEMS?

2009 ◽  
Vol 08 (04) ◽  
pp. 691-711 ◽  
Author(s):  
FENG FENG ◽  
HUAN WANG ◽  
WEI-HAI FANG ◽  
JIAN-GUO YU
Keyword(s):  
Hydrogen Bonding ◽  
Amino Acid ◽  
Amino Acid Residue ◽  
Density Functional ◽  
Biological Systems ◽  
Binding Energies ◽  
Semiempirical Model ◽  
Hydrogen Bonded Systems ◽  
High Level ◽  
Hydrogen Bonded

A modified semiempirical model named RM1BH, which is based on RM1 parameterizations, is proposed to simulate varied biological hydrogen-bonded systems. The RM1BH is formulated by adding Gaussian functions to the core–core repulsion items in original RM1 formula to reproduce the binding energies of hydrogen bonding of experimental and high-level computational results. In the parameterizations of our new model, 35 base-pair dimers, 18 amino acid residue dimers, 14 dimers between a base and an amino acid residue, and 20 other multimers were included. The results performed with RM1BH were compared with experimental values and the benchmark density-functional (B3LYP/6-31G**/BSSE) and Möller–Plesset perturbation (MP2/6-31G**/BSSE) calculations on various biological hydrogen-bonded systems. It was demonstrated that RM1BH model outperforms the PM3 and RM1 models in the calculations of the binding energies of biological hydrogen-bonded systems by very close agreement with the values of both high-level calculations and experiments. These results provide insight into the ideas, methods, and views of semiempirical modifications to investigate the weak interactions of biological systems.

Hydrogen bonding and conformation in cis- and trans-2-alkoxy-3-hydroxytetrahydrofurans

1968 ◽  
Vol 46 (1) ◽  
pp. 21-24 ◽  
Author(s):  
W. W. Zajac Jr. ◽  
F. Sweet ◽  
R. K. Brown
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectra ◽  
Hydroxyl Absorption ◽  
Cis And Trans ◽  
In Cis ◽  
Infrared Data ◽  
Hydrogen Bonded

Infrared spectra show both free and hydrogen bonded hydroxyl absorption in several trans-2-alkoxy-3-hydroxytetrahydrofurans. The extent of non-bonded hydroxyl is greater than that of bonded hydroxyl. Suggestions are made of possible conformations which might account for the infrared data.

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