Hydrogen-Bonding and the Dissolution Mechanism of Uracil in an Acetate Ionic Liquid: New Insights from NMR Spectroscopy and Quantum Chemical Calculations

2013 ◽  
Vol 117 (15) ◽  
pp. 4109-4120 ◽  
Author(s):  
João M. M. Araújo ◽  
Ana B. Pereiro ◽  
José N. Canongia Lopes ◽  
Luís P. N. Rebelo ◽  
Isabel M. Marrucho
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Dissolution Mechanism

Problems with a conformation assignment of aryl-substituted resorc[4]arenes

2011 ◽  
Vol 76 (10) ◽  
pp. 1199-1222 ◽  
Author(s):  
Jakub Kaminský ◽  
Hana Dvořáková ◽  
Jan Štursa ◽  
Jitka Moravcová
Keyword(s):  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Quantum Chemical Calculations ◽  
Dynamic Process ◽  
Quantum Chemical ◽  
Energy Barrier ◽  
Π Interactions ◽  
Temperature Range ◽  
Acid Catalyzed

Acid-catalyzed condensation of resorcinol with 3,5-diisopropoxybenzaldehyde and 3,5-dihydroxybenzaldehyde afforded aryl substituted resorc[4]arenes 1a and 1b, respectively. All 16 hydroxyls in 1b were acetylated providing resorc[4]arene 1c. The conformational behaviour of 1a, 1b and 1c was studied by NMR spectroscopy and quantum chemical calculations. It was found that the stabilization of their conformations is an effect of competing π-π and OH-π interactions, hydrogen bonding and steric features, respectively. As a result, C2 symmetrical boat conformations 1a, 1b and 1c with aryls in axial positions were identified in all cases. In case of 1c also the formation of C2 symmetrical conformation with aryls in equatorial positions (boat-eq) was identified. Moreover, compounds 1a and 1b being able to create hydrogen bonds, adopt also symmetrical C4 crown conformations. For 1c(boat-ax), the boat-boat conversion with energy barrier of 80 kJ/mol was observed, while the 1c(boat-eq) was found to be rigid in the whole accessible temperature range. Both conformers of 1c exhibit also second dynamic process – rotation of bridge aryl rings (ΔG‡ = 66 kJ/mol).

Molecular structure, reorientational dynamics, and intermolecular interactions in the neat ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

2004 ◽  
Vol 76 (1) ◽  
pp. 255-261 ◽  
Author(s):  
J. H. Antony ◽  
D. Mertens ◽  
Tobias Breitenstein ◽  
Andreas Dölle ◽  
P. Wasserscheid ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Ion Pairs ◽  
Md Simulations ◽  
Liquid Structure ◽  
Distribution Functions ◽  
Reorientational Dynamics ◽  
Pair Distribution Functions

Results on the molecular and liquid structure and the reorientational dynamics are reported for the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). In quantum-chemical calculations for [BMIM][PF6] in the gas phase, hydrogen bonding between the proton at carbon 2 in the aromatic ring and the fluorine atoms of the hexafluorophosphate anion was found. From the analysis of 13C relaxation data, the reorientational motions were evaluated, and the Vogel-Fulcher-Tammann and Arrhenius activation energies for the overall and internal reorientational motions, respectively, of the different 13C-1H vectors are given as well as correlation times at 300 K. By performing molecular dynamics (MD) simulations, pair distribution functions between moieties in the cation and the phosphorous atom in the anion were determined. The pair distribution function for the proton at carbon 2 exhibits a particular sharp and strong maximum indicating a strong interaction with the anion. The quantum-chemical calculations, the motional parameters, and the results from the MD simulations support the existence of hydrogen bonding and the formation of ion pairs in the ionic liquid.

Weak intramolecular and intermolecular hydrogen bonding of benzyl alcohol, 2-phenylethanol and 2-phenylethylamine in the adsorption on graphitized thermal carbon black

2015 ◽  
Vol 17 (37) ◽  
pp. 24282-24293 ◽  
Author(s):  
V. V. Varfolomeeva ◽  
A. V. Terentev
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Carbon Black ◽  
Benzyl Alcohol ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Intermolecular Hydrogen Bonding ◽  
Weak Hydrogen Bond ◽  
Graphitized Thermal Carbon Black ◽  
Flexible Molecules

The present paper discusses the contemporary state of the studies of the weak hydrogen bond contribution to the adsorption of flexible molecules. We formulated the problems which can be solved today only using the NCI method and quantum chemical calculations.

scholarly journals Understanding the ionic liquid [NC4111][NTf2] from individual building blocks: an IR-spectroscopic study

2015 ◽  
Vol 17 (13) ◽  
pp. 8518-8529 ◽  
Author(s):  
Kenny Hanke ◽  
Matin Kaufmann ◽  
Gerhard Schwaab ◽  
Martina Havenith ◽  
Conrad T. Wolke ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Spectroscopic Study ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Molecular Level ◽  
Building Blocks ◽  
Spectroscopic Methods ◽  
Ir Spectroscopic

This study uses complementary spectroscopic methods in combination with quantum chemical calculations to explore at a molecular level the ionic liquid [NC4111][NTf2] from single ions to the bulk.

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