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Theoretical study o...
Theoretical study of the conformational equilibrium of 1,4-dioxane in gas phase, neat liquid, and dilute aqueous solutions
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Barata-Morgado, Rute (author)
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Luz Sanchez, M. (author)
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- Fernández Galván, Ignacio (author)
- Uppsala universitet,Teoretisk kemi
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Corchado, Jose C. (author)
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Elena Martin, M. (author)
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Munoz-Losa, Aurora (author)
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Aguilar, Manuel A. (author)
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(creator_code:org_t)
- 2013-09-05
- 2013
- English.
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In: Theoretical Chemistry accounts. - : Springer Science and Business Media LLC. - 1432-881X .- 1432-2234. ; 132:10, s. 1390-
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- The conformational equilibrium of 1,4-dioxane in the gas phase, in the pure liquid, and in aqueous solution has been studied by means of the Average Solvent Electrostatic Potential from Molecular Dynamics (ASEP/MD) method and the Integral Equation Formalism for the Polarizable Continuum Model (IEF-PCM). The dioxane molecule was described at the DFT(B3LYP)/aug-cc-pVTZ level. In the three phases, the equilibrium is almost completely shifted toward the chair conformer, with populations of the twist-boat conformers lower than 0.01 %. The equilibrium is dominated by the internal energy of the molecule, as the solute-solvent interaction free energies are very similar in the three conformers considered (chair, 1,4 twist-boat, and 2,5 twist-boat). In the pure liquid, where the dioxane-dioxane interaction is dominated by the Lennard-Jones term, the structure is characteristic of a van der Waals liquid. However, the decrease in the C-H distance from gas phase to solution, the increase in the C-H vibrational frequencies, and the presence of a shoulder in the O-Haxial pair radial distribution function point to the presence of a weak C-H-O hydrogen bond. The analysis of the occupancy maps of water oxygen and hydrogen atoms around the 1,4-dioxane molecule confirms this conclusion. Contrary to what is found in small water-dioxane clusters, in the liquid, there is a preference for oxygen atoms to interact with axial hydrogen atoms to form C-H-O hydrogen bonds. Comparison of ASEP/MD and IEF-PCM results indicates that including specific interactions is very important for an adequate description of the solute-solvent interaction; however, the influence of these interactions does not translate in changes in the relative stability of the conformers because it cancels out when energy differences are calculated.
Keyword
- 1
- 4-Dioxane
- ASEP/MD
- QM/MM
- Conformational equilibrium
- Solvent effect
Publication and Content Type
- ref (subject category)
- art (subject category)
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