Density functional theory (DFT) and natural bond orbital (NBO) study of vibrational spectra and intramolecular hydrogen bond interaction of l-ornithine–l-aspartate

2015 ◽  
Vol 136 ◽  
pp. 338-346 ◽  
Author(s):  
Linwei Li ◽  
Chengjun Wu ◽  
Zhiqiang Wang ◽  
Lixia Zhao ◽  
Zhen Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Hydrogen Bond Interaction ◽  
Functional Theory ◽  
Bond Interaction ◽  
Intramolecular Hydrogen

An X-ray crystallographic and density functional theory study of (3Z)-4-(5-ethylsulfonyl-2-hydroxyanilino)pent-3-en-2-one and (3Z)-4-(5-tert-butyl-2-hydroxyanilino)pent-3-en-2-one

2013 ◽  
Vol 69 (3) ◽  
pp. 258-262
Author(s):  
Kate J. Akerman ◽  
Orde Q. Munro
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Density Functional ◽  
Intermolecular Hydrogen Bond ◽  
Functional Theory ◽  
One Dimensional ◽  
X Ray ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The Schiff base enaminones (3Z)-4-(5-ethylsulfonyl-2-hydroxyanilino)pent-3-en-2-one, C13H17NO4S, (I), and (3Z)-4-(5-tert-butyl-2-hydroxyanilino)pent-3-en-2-one, C15H21NO2, (II), were studied by X-ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C—C=C—N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino–phenol group canted relative to the rest of the molecule; the twist about the N(enamine)—C(aryl) bond leads to dihedral angles of 40.5 (2) and −116.7 (1)° for (I) and (II), respectively. Compound (I) has a bifurcated intramolecular hydrogen bond between the N—H group and the flanking carbonyl and hydroxy O atoms, as well as an intermolecular hydrogen bond, leading to an infinite one-dimensional hydrogen-bonded chain. Compound (II) has one intramolecular hydrogen bond and one intermolecular C=O...H—O hydrogen bond, and consequently also forms a one-dimensional hydrogen-bonded chain. The DFT-calculated structures [in vacuo, B3LYP/6-311G(d,p) level] for the keto tautomers compare favourably with the X-ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86 kJ mol−1lower in energy than the enol tautomers for (I) and (II), respectively.

scholarly journals Study on the interaction between catechin and cholesterol by the density functional theory

2020 ◽  
Vol 18 (1) ◽  
pp. 357-368
Author(s):  
Kaiwen Zheng ◽  
Kai Guo ◽  
Jing Xu ◽  
Wei Liu ◽  
Junlang Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Charge Transfer ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Micelle Formation ◽  
Aromatic Rings ◽  
Hydrogen Bond Interaction ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractCatechin – a natural polyphenol substance – has excellent antioxidant properties for the treatment of diseases, especially for cholesterol lowering. Catechin can reduce cholesterol content in micelles by forming insoluble precipitation with cholesterol, thereby reducing the absorption of cholesterol in the intestine. In this study, to better understand the molecular mechanism of catechin and cholesterol, we studied the interaction between typical catechins and cholesterol by the density functional theory. Results show that the adsorption energies between the four catechins and cholesterol are obviously stronger than that of cholesterol themselves, indicating that catechin has an advantage in reducing cholesterol micelle formation. Moreover, it is found that the molecular interactions of the complexes are mainly due to charge transfer of the aromatic rings of the catechins as well as the hydrogen bond interactions. Unlike the intuitive understanding of a complex formed by hydrogen bond interaction, which is positively correlated with the number of hydrogen bonds, the most stable complexes (epicatechin–cholesterol or epigallocatechin–cholesterol) have only one but stronger hydrogen bond, due to charge transfer of the aromatic rings of catechins.

P-Chiral, N-phosphoryl sulfonamide Brønsted acids with an intramolecular hydrogen bond interaction that modulates organocatalysis

2019 ◽  
Vol 17 (38) ◽  
pp. 8690-8694 ◽  
Author(s):  
Minglei Yuan ◽  
Ifenna I. Mbaezue ◽  
Zhi Zhou ◽  
Filip Topic ◽  
Youla S. Tsantrizos
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Transfer Hydrogenation ◽  
Bronsted Acids ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Hydrogen Bond Interaction ◽  
Bond Interaction ◽  
Brönsted Acid ◽  
Intramolecular Hydrogen

An intramolecular H-bond in the Brønsted acid OttoPhosa I accelerates the reaction and increases enantioselectivity for the transfer hydrogenation of quinolines.

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