Journal article
Why are ionic liquid ions mainly associated in water? A Car-Parrinello study of 1-ethyl-3-methyl-imidazolium chloride water mixture
The Journal of chemical physics, Vol.129(10), pp.104505-104505-13
09/09/2008
Handle:
https://hdl.handle.net/2376/107964
PMID: 19044922
Abstract
In this study we present the results of a first principles molecular dynamics simulation of a single 1-ethyl-3-methyl-imidazolium chloride
[
C
2
C
1
im
]
[
Cl
]
ion pair dissolved in 60 water molecules. We observe a preference of the in plane chloride coordination with respect to the cation ring plane as compared to the energetic slightly more demanding on top coordination. Evaluation of the different radial distribution functions demonstrates that the structure of the hydration shell around the ion pair differs significantly from bulk water and that no true ion pair dissociation in terms of completely autonomous solvation shells takes place on the timescale of the simulation. In addition, dipole moment distributions of the solvent in distinct solvation shells around different functional parts of the
[
C
2
C
1
im
]
[
Cl
]
ion pair are calculated from maximally localized Wannier functions. The analysis of these distributions gives evidence for a depolarization of water molecules close to the hydrophobic parts of the cation as well as close to the anion. Examination of the angular distribution of different
O
H
(
H
2
O
)
-
X
angles in turn shows a linear coordination of chloride accompanied by a tangential orientation of water molecules around the hydrophobic groups, being a typical feature of hydrophobic hydration. Based on these orientational aspects, a structural model for the obvious preference of ion pair association is developed, which justifies the associating behavior of solvated
[
C
2
C
1
im
]
[
Cl
]
ions in terms of an energetically favorable interface between the solvation shells of the anion and the hydrophobic parts of the cation.
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Details
- Title
- Why are ionic liquid ions mainly associated in water? A Car-Parrinello study of 1-ethyl-3-methyl-imidazolium chloride water mixture
- Creators
- C Spickermann - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyJ Thar - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyS Lehmann - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyS Zahn - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyJ Hunger - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyR Buchner - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyP Hunt - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyT Welton - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, GermanyB Kirchner - Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, Linnéstrasse 2,D-04103 Leipzig, Germany
- Publication Details
- The Journal of chemical physics, Vol.129(10), pp.104505-104505-13
- Academic Unit
- Molecular Biosciences, School of
- Publisher
- American Institute of Physics
- Grant note
- DFG
- Identifiers
- 99900547368701842
- Resource Type
- Journal article