Influence of OH⋯N and NH⋯O inter- and intramolecular hydrogen bonds in the conformational equilibrium of some 1,3-disubstituted cyclohexanes through NMR spectroscopy and theoretical calculations

2011 ◽  
Vol 78 (5) ◽  
pp. 1599-1605 ◽  
Author(s):  
Paulo R. de Oliveira ◽  
Renan V. Viesser ◽  
Palimécio G. Guerrero ◽  
Roberto Rittner
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Conformational Equilibrium ◽  
Theoretical Calculations ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Synthesis of 4-Aryl-3(5)-(2-hydroxyphenyl)pyrazoles by Reaction of Isoflavones and their 4-Thio Analogues with Hydrazine Derivatives

2007 ◽  
Vol 60 (12) ◽  
pp. 905 ◽  
Author(s):  
Albert Lévai ◽  
Artur M. S. Silva ◽  
José A. S. Cavaleiro ◽  
José Elguero ◽  
Ibon Alkorta ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Hydrazine Hydrate ◽  
1H Nmr ◽  
Theoretical Calculations ◽  
Intramolecular Hydrogen Bonds ◽  
Nmr Study ◽  
Intramolecular Hydrogen ◽  
New Compounds

4-Aryl-3(5)-2-(hydroxyphenyl)pyrazoles have been prepared by the reaction of isoflavones and their 4-thio analogues with hydrazine hydrate and phenylhydrazine in hot pyridine. The reaction mechanism for the formation of these pyrazoles is discussed. All the new compounds have been fully characterized by NMR spectroscopy. In [D6]DMSO, a 1H NMR study allows observation of the presence of both pyrazole annular tautomers, due to the presence of intramolecular hydrogen bonds in each tautomer (OH···N and NH···O). Theoretical calculations have been carried out on tautomers and conformers of compounds 20 (3(5)-(2-hydroxy-4-methoxyphenyl)-5(3)-methyl-4-phenylpyrazole) and 21 (3(5)-(2-hydroxy-4-methoxyphenyl)-4-(2-methoxyphenyl)-5(3)-methylpyrazole), including the absolute shieldings (GIAO/B3 LYP/6–311++G**) of 21.

scholarly journals Molecular dynamics of (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone in solution studied by NMR spectroscopy

2012 ◽  
Vol 10 (1) ◽  
pp. 241-247 ◽  
Author(s):  
Ibrahim Mamedov ◽  
Uwe Eichhoff ◽  
Abel Maharramov ◽  
Musa Bayramov ◽  
Yegana Mamedova
Keyword(s):  
Molecular Dynamics ◽  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Rotational Barrier ◽  
Intramolecular Hydrogen Bonds ◽  
Barrier Energy ◽  
Intramolecular Hydrogen

AbstractThe formation of hydrogen bonds and the molecular dynamics for molecules (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone, (E)-4-bromoacetophenone thiosemicarbazone have been investigated in solution using NMR. The results confirm the formation of different O-H…O type intramolecular hydrogen bonds in the oxime molecule. The rotational barrier energy and energy of intramolecular hydrogen bonds have been determined.

Determination of intramolecular hydrogen bonds in amikacin in water solution by NMR spectroscopy

1995 ◽  
Vol 51 (11) ◽  
pp. 1959-1963 ◽  
Author(s):  
Elena Gaggelli ◽  
Nicola Gaggelli ◽  
Antonella Maccotta ◽  
Gianni Valensin ◽  
Domenico Marini ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Water Solution ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Intramolecular hydrogen bonds involving organic fluorine in the derivatives of hydrazides: an NMR investigation substantiated by DFT based theoretical calculations

2015 ◽  
Vol 17 (23) ◽  
pp. 15226-15235 ◽  
Author(s):  
Sandeep Kumar Mishra ◽  
N. Suryaprakash
Keyword(s):  
Hydrogen Bonds ◽  
Theoretical Calculations ◽  
Two Dimensional ◽  
Dimensional Solution ◽  
Intramolecular Hydrogen Bonds ◽  
Solution State ◽  
Nmr Techniques ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Organic Fluorine

The rare examples of intramolecular hydrogen bonds (HB) of the type the N–H⋯F–C, detected in a low polarity solvent in the derivatives of hydrazides, by utilizing one and two-dimensional solution state multinuclear NMR techniques, are reported.

scholarly journals Conformational equilibrium in supramolecular chemistry: Dibutyltriuret case

2015 ◽  
Vol 11 ◽  
pp. 2105-2116 ◽  
Author(s):  
Karina Mroczyńska ◽  
Małgorzata Kaczorowska ◽  
Erkki Kolehmainen ◽  
Ireneusz Grubecki ◽  
Marek Pietrzak ◽  
...  
Keyword(s):  
Experimental Data ◽  
Hydrogen Bonds ◽  
Systematic Approach ◽  
Conformational Equilibrium ◽  
Variable Temperature ◽  
Single Bond ◽  
Intramolecular Hydrogen Bonds ◽  
Title Molecule ◽  
Study Association ◽  
Intramolecular Hydrogen

The association of substituted benzoates and naphthyridine dianions was used to study the complexation of dibutyltriuret. The title molecule is the simplest molecule able to form two intramolecular hydrogen bonds. The naphthyridine salt was used to break two intramolecular hydrogen bonds at a time while with the use of substituted benzoates the systematic approach to study association was achieved. Both, titrations and variable temperature measurements shed the light on the importance of conformational equilibrium and its influence on association in solution. Moreover, the associates were observed by mass spectrometry. The DFT-based computations for complexes and single bond rotational barriers supports experimental data and helps understanding the properties of multiply hydrogen bonded complexes.

Photoswitchable Intramolecular Hydrogen Bonds in 5-Phenylazopyrimidines Revealed By In Situ Irradiation NMR Spectroscopy

2017 ◽  
Vol 24 (2) ◽  
pp. 492-498 ◽  
Author(s):  
Eliška Procházková ◽  
Lucie Čechová ◽  
Jonas Kind ◽  
Zlatko Janeba ◽  
Christina M. Thiele ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Organic fluorine involved intramolecular hydrogen bonds in the derivatives of imides: NMR evidence corroborated by DFT based theoretical calculations

RSC Advances ◽  
2015 ◽  
Vol 5 (105) ◽  
pp. 86013-86022 ◽  
Author(s):  
Sandeep Kumar Mishra ◽  
N. Suryaprakash
Keyword(s):  
Hydrogen Bonds ◽  
Theoretical Calculations ◽  
Rare Occurrence ◽  
Intramolecular Hydrogen Bonds ◽  
Multinuclear Nmr ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Organic Fluorine

The rare occurrence of intramolecular hydrogen bonds (HBs) of the type N–H⋯F–C is detected in the derivatives of imides in a low polarity solvent by using multi-dimensional and multinuclear NMR experiments.

scholarly journals Resonance-assisted stabilisation of hydrogen bonds probed by NMR spectroscopy and path integral molecular dynamics

2015 ◽  
Vol 51 (73) ◽  
pp. 13986-13989 ◽  
Author(s):  
M. Dračínský ◽  
L. Čechová ◽  
P. Hodgkinson ◽  
E. Procházková ◽  
Z. Janeba
Keyword(s):  
Molecular Dynamics ◽  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Path Integral ◽  
Quantum Effects ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen ◽  
Nuclear Quantum Effects

Nuclear quantum effects are shown to be important for resonance stabilisation of intramolecular hydrogen bonds.

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