scholarly journals Computational evidence for intramolecular hydrogen bonding and nonbonding X···O interactions in 2'-haloflavonols

2012 ◽  
Vol 8 ◽  
pp. 112-117 ◽  
Author(s):  
Tânia A O Fonseca ◽  
Matheus P Freitas ◽  
Rodrigo A Cormanich ◽  
Teodorico C Ramalho ◽  
Cláudio F Tormena ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Quantum Theory ◽  
Intramolecular Hydrogen Bond ◽  
Natural Bond Orbital ◽  
Intramolecular Hydrogen Bonding ◽  
Nbo Analysis ◽  
Conformational Isomerism ◽  
Intramolecular Hydrogen ◽  
Stereoelectronic Interactions

The conformational isomerism and stereoelectronic interactions present in 2'-haloflavonols were computationally analyzed. On the basis of the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis, the conformer stabilities of 2'-haloflavonols were found to be dictated mainly by a C=O···H–O intramolecular hydrogen bond, but an unusual C–F···H–O hydrogen-bond and intramolecular C–X···O nonbonding interactions are also present in such compounds.

scholarly journals Does the Intramolecular Hydrogen Bond Affect the Spectroscopic Properties of Bicyclic Diazole Heterocycles?

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Paweł Misiak ◽  
Alina T. Dubis ◽  
Andrzej Łapiński
Keyword(s):  
Hydrogen Bond ◽  
Quantum Theory ◽  
Intramolecular Hydrogen Bond ◽  
Natural Bond Orbital ◽  
Spectroscopic Properties ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Nbo Method ◽  
Acceptor Group ◽  
Intramolecular Hydrogen

The formation of an intramolecular hydrogen bond in pyrrolo[1,2-a]pyrazin-1(2H)-one bicyclic diazoles was analyzed, and the influence of N-substitution on HB formation is discussed in this study. B3LYP/aug-cc-pVDZ calculations were performed for the diazole, and the quantum theory of atoms in molecules (QTAIM) approach as well as the natural bond orbital (NBO) method was applied to analyze the strength of this interaction. It was found that the intramolecular hydrogen bond that closes an extra ring between the C=O proton acceptor group and the CH proton donor, that is, C=O⋯H–C, influences the spectroscopic properties of pyrrolopyrazine bicyclic diazoles, particularly the carbonyl frequencies. The influence of N-substitution on the aromaticity of heterocyclic rings is also discussed in this report.

scholarly journals Separation of planar rotamers through intramolecular hydrogen bonding in polysubstituted 5-nitrosopyrimidines

2014 ◽  
Vol 50 (94) ◽  
pp. 14892-14895 ◽  
Author(s):  
L. Čechová ◽  
E. Procházková ◽  
I. Císařová ◽  
M. Dračínský ◽  
Z. Janeba
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bond ◽  
Chemical Species ◽  
Intramolecular Hydrogen Bonding ◽  
Nitroso Group ◽  
Group Orientation ◽  
Intramolecular Hydrogen

Unique isolation of pairs of planar rotamers, planamers, as chemical species differing only in nitroso group orientation, separable through the presence of a single intramolecular hydrogen bond, is reported.

scholarly journals THE STUDY OF HYDROGEN BONDING AND RELATED PHENOMENA BY ULTRAVIOLET LIGHT ABSORPTION: PART VI. THE EFFECT OF STERIC INTERACTIONS ON THE INTRAMOLECULAR HYDROGEN BOND IN o-NITROPHENOL

1960 ◽  
Vol 38 (10) ◽  
pp. 1852-1864 ◽  
Author(s):  
J. C. Dearden ◽  
W. F. Forbes
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bond ◽  
Alkyl Substituent ◽  
Intramolecular Hydrogen Bonding ◽  
Vibration Band ◽  
Absorption Bands ◽  
Steric Interactions ◽  
Stretching Vibration ◽  
Intramolecular Hydrogen

Intramolecular hydrogen bonding occurring in o-nitrophenol is discussed with special reference to the effects of the steric interactions on the absorption bands and on the bonding. An alkyl substituent vicinal to the OH group, or a methyl group vicinal to the NO2 group appears to strengthen the intramolecular hydrogen bond in o-nitrophenol. The O—H vibrational stretching frequency in o-nitrophenol appears to be more susceptible to steric than to mesomeric interactions, and a methyl substituent vicinal to the nitro group in o-nitrophenols is found to give rise to a characteristic O—H stretching vibration band. For 6-t-butyl-2-nitrophenol, a special, "protected" hydrogen bond is postulated. In some of the o-nitrophenols, intermolecular hydrogen bonding gives rise to appreciable ultraviolet intensity decreases presumably because of increased steric interactions.

THE STUDY OF HYDROGEN BONDING AND RELATED PHENOMENA BY ULTRAVIOLET LIGHT ABSORPTION: PART V. INTRAMOLECULAR HYDROGEN BONDING IN ANILINES AND PHENOLS

1960 ◽  
Vol 38 (10) ◽  
pp. 1837-1851 ◽  
Author(s):  
J. C. Dearden ◽  
W. F. Forbes
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bond ◽  
Light Absorption ◽  
Intramolecular Hydrogen Bonding ◽  
Electrostatic Model ◽  
Spectral Change ◽  
Substituted Phenols ◽  
Spectral Changes ◽  
Intramolecular Hydrogen

Information concerning intramolecular hydrogen bonding in phenols and anilines can be obtained from ultraviolet spectra by a variety of methods. One method is to note the spectral changes observed between the corresponding o-substituted phenols and anisoles. A second method is to compare the spectral changes between o-substituted phenols or anilines and the corresponding meta isomers. A third method is to note the absence of an appreciable spectral change, on altering the solvent conditions, which may also indicate the formation of an intramolecular hydrogen bond. The conclusions deduced from the three methods confirm previously stated generalizations concerning the nature of the hydrogen bond. One notable exception is that the spectral changes ascribed to the intramolecular hydrogen bond in o-nitrophenol can be explained in terms of an electrostatic model of the hydrogen bond.

scholarly journals Conformational analysis and intramolecular interactions in monosubstituted phenylboranes and phenylboronic acids

2013 ◽  
Vol 9 ◽  
pp. 1127-1134 ◽  
Author(s):  
Josué M Silla ◽  
Rodrigo A Cormanich ◽  
Roberto Rittner ◽  
Matheus P Freitas
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Conformational Analysis ◽  
Conformational Equilibrium ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Interactions ◽  
Coupling Constant ◽  
Intramolecular Hydrogen ◽  
Phenylboronic Acids ◽  
Electron Donation

A 1 TS J F,H(O) coupling pathway, dictated by a hydrogen bond, in some 2-fluorobenzoic acids has been observed, while such an interaction does not occur in 2-fluorophenol. Thus, this work reports the conformational analysis of 2-fluorophenylboronic acid (1), in order to evaluate a possible intramolecular OH∙∙∙F hydrogen bond in comparison to an nF→pB interaction, which mimics the quantum nF→σ*OH hydrogen bond that would be expected in 2-fluorophenol. 2-Fluorophenylborane (3), which does not experience hydrogen bonding, was used to verify whether nF→pB interaction governs the conformational equilibrium in 1 due to a predominant OH∙∙∙F hydrogen bond or to other effects. A series of 2-X-phenylboranes (X = Cl, Br, NH2, PH2, OH and SH) were further computationally analyzed to search for electron donors to boron, capable of influencing the conformational equilibrium. Overall, the intramolecular OH∙∙∙F hydrogen bond in 1 is quite stabilizing and dictates the 1 h J F,H(O) coupling constant. Moreover, electron donation to the empty p orbital of boron (for noncoplanar BH2 moiety relative to the phenyl ring) is also significantly stabilizing for the NH2 and PH2 derivatives, but not enough to make the corresponding conformers appreciably populated, because of steric effects and the loss of πCC→pB resonance. Thus, the results found earlier for 2-fluorophenol about the lack of intramolecular hydrogen bonding are now corroborated.

THE STUDY OF HYDROGEN BONDING AND RELATED PHENOMENA BY SPECTROSCOPIC METHODS: PART VIII. THE ULTRAVIOLET AND INFRARED SPECTRA OF SOME 2,4-DINITRODIPHENYLAMINES

1964 ◽  
Vol 42 (12) ◽  
pp. 2674-2683 ◽  
Author(s):  
A. Balasubramanian ◽  
J. B. Capindale ◽  
W. F. Forbes
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Spectral Data ◽  
Intramolecular Hydrogen Bond ◽  
Infrared Spectra ◽  
Positive Charge ◽  
Spectroscopic Methods ◽  
Amino Group ◽  
Strong Type ◽  
Intramolecular Hydrogen

The ultraviolet spectra of a number of 2,4-dinitrodiphenylamines suggest that these compounds are generally non-planar in a number of different solvents. The infrared and ultraviolet spectral data in different solvents also suggest that an intramolecular hydrogen bond is present in these molecules, at least in inert solvents. There is evidence that a p-nitro substituent is necessary to increase the positive charge on the amino group sufficiently to permit it to form this fairly strong type of hydrogen bond.

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