Journal article
The importance of timescale for hydrogen bonding in imidazolium chloride ionic liquids
Physical chemistry chemical physics : PCCP, Vol.16(8), pp.3675-3685
02/28/2014
Handle:
https://hdl.handle.net/2376/106815
PMID: 24419252
Abstract
Hydrogen bond (H-bond) dynamics have been investigated for "hot" 1-ethyl-3-methylimidazolium chloride and "cold" 1-butyl-3-methylimidazolium chloride ionic liquids (IL). While the average number of H-bonds remains constant for a ≈100 °C temperature change we show that the underlying dynamics of the H-bonding changes dramatically. H-bond dynamics are investigated based on distance and angle criteria, and on the H-bond state (zero, single or bifurcated H-bonds). Temperature effects on the cation ring reorientational dynamics are also examined. Angle deformations are found to be more important than bond stretching in determining the lifetime of individual H-bonds, and decay occurs on two time scales related to the magnitude of the deviation from linearity. Rapid angular oscillation of the anion breaks the H-bond (for the first time) and minimal temperature effects indicate that H-bonds are readily reformed even near the melting point. Intermittent H-bonds repeatedly break and reform over a longer timescale, and exhibit very strong temperature effects. In the hot IL H-bonding with ring and alkyl chain H-atoms occurs, ring reorientational dynamics is anisotropic and the corresponding lifetimes are similar to the intermittent H-bond lifetimes. In the cold IL ring H-atoms dominate the H-bonding and intermittent H-bonds last for ≈5 ns, ring reorientation occurs on a much slower timescale. The hot IL favours single H-bonds, but the individual ions often change, while the cold IL favours bifurcated H-bonds with the same co-located ions.
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Details
- Title
- The importance of timescale for hydrogen bonding in imidazolium chloride ionic liquids
- Creators
- Ioannis Skarmoutsos - Department of Chemistry, Imperial College London, London, SW7 2AZ, UK. p.hunt@imperial.ac.ukTom WeltonPatricia A Hunt
- Publication Details
- Physical chemistry chemical physics : PCCP, Vol.16(8), pp.3675-3685
- Academic Unit
- Molecular Biosciences, School of
- Publisher
- England
- Identifiers
- 99900546968701842
- Language
- English
- Resource Type
- Journal article