Density functional theory studies of transannular1H?1HJ-coupling in half-cage alcohols and rigid 1,3- and 1,4-diols: conformational dependencies and implications for intramolecular hydrogen bond detection in carbohydrates

2001 ◽  
Vol 39 (S1) ◽  
pp. S115-S125 ◽  
Author(s):  
Michael Barfield ◽  
Jon M. Bergset ◽  
Daniel J. O'Leary
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Density Functional ◽  
Functional Theory ◽  
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.

Theoretical study of the ground and excited states of 1-methylamideanthraquinone and its complex with fluoride anion

2016 ◽  
Vol 15 (04) ◽  
pp. 1650033
Author(s):  
Bing-Qiang Wang ◽  
Xiao-Fen Yin ◽  
Yan-Yun Dong ◽  
Cai-Yun Zhang
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Proton Transfer ◽  
Density Functional ◽  
Intermolecular Hydrogen Bond ◽  
Emission Spectra ◽  
Intramolecular Proton Transfer ◽  
Fluoride Anion ◽  
Functional Theory ◽  
Intramolecular Hydrogen

We have performed a series of calculations using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) for 1-methylamideanthraquinone (MAAQ). In the S0 state of MAAQ, amide group is coplanar with anthraquinone, and an intramolecular hydrogen bond [Formula: see text] is formed. The [Formula: see text] transition has an intramolecular charge transfer character. Two stable structures (planar nMAAQ and twisted tMAAQ) have been obtained in the S1 state of MAAQ. Thereinto, nMAAQ is lower by 0.105[Formula: see text]eV than tMAAQ in energy, so nMAAQ is the dominant conformation in the S1 state of MAAQ and the emission spectra of tMAAQ cannot be observed in the solution of MAAQ. Excited state intramolecular proton transfer (ESIPT) between C[Formula: see text]O and N–H was not observed in the S1 state of MAAQ. Upon addition of fluoride anion, only twisted conformations were obtained in both S0 and S1 states of MAAQ-F[Formula: see text]. An intermolecular hydrogen bond [Formula: see text] is formed in the S0 state, and intermolecular proton transfer happens in the S1 state for MAAQ-F[Formula: see text].

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.

Elucidation of the active surface and origin of the weak metal–hydrogen bond on Ni/Pt(111) bimetallic surfaces: a surface science and density functional theory study

2003 ◽  
Vol 544 (2-3) ◽  
pp. 295-308 ◽  
Author(s):  
John R Kitchin ◽  
Neetha A Khan ◽  
Mark A Barteau ◽  
Jingguang G Chen ◽  
Boris Yakshinskiy ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Surface Science ◽  
Density Functional ◽  
Active Surface ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Bimetallic Surfaces
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