Aqueous solutions of hydroxyl-functionalized ionic liquids: Molecular dynamics studies
Amol Chandrakar1, B L Bhargava1
1School of Chemical Sciences, National Institute of Science Education & Research - Bhubaneswar, P.O: Jatni, Khurda, Odisha, 752050, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai, 400094, India.
Journal of Molecular Graphics & Modelling
|September 4, 2020
Summary
The length of hydroxyalkyl chains in imidazolium bromide solutions dictates aggregate structure. Longer chains form thin films stabilized by dispersion and hydrogen bonds, influencing ion and molecule dynamics.
Area of Science:
- Physical Chemistry
- Materials Science
- Computational Chemistry
Background:
- Ionic liquids, particularly imidazolium-based ones, are versatile materials with tunable properties.
- Understanding the self-assembly and structural behavior of ionic liquids in aqueous solutions is crucial for their application.
- The influence of alkyl chain length on the aggregation behavior of functionalized ionic liquids requires further investigation.
Purpose of the Study:
- To investigate the structural and dynamic properties of aqueous solutions of 1-(n-hydroxyalkyl)-3-(n-hydroxyalkyl) imidazolium bromide ([HOCnCmOHIm][Br]).
- To elucidate the effect of varying hydroxyalkyl chain lengths (n, m = 2, 6, 10, 14) on the aggregate structures and dynamics.
- To understand the intermolecular interactions governing the self-assembly in these ionic liquid solutions.
Main Methods:
- Atomistic molecular dynamics (MD) simulations were employed to model the aqueous solutions.
- Radial distribution functions, angular distributions, and aggregation numbers were computed to characterize structures.
- Ion and molecule diffusion coefficients were calculated to investigate system dynamics.
Main Results:
- Aggregate structures are strongly dependent on the length of the hydroxyalkyl chains.
- Long-distance spatial correlations emerge in solutions with long cation substituents due to intercalated structures.
- A thin film-like structure forms with longer chains, stabilized by alkyl chain dispersion interactions and inter-cation hydrogen bonding; anions are located near the film surface.
Conclusions:
- The hydroxyalkyl chain length is a critical factor controlling the self-assembly and morphology of [HOCnCmOHIm][Br] in water.
- The observed film-like structures and associated interactions provide insights into the behavior of functionalized ionic liquids.
- These findings contribute to the design and application of ionic liquids in various fields, such as nanotechnology and materials science.
Keywords:
Hydoxyl functionalized ionic liquidsInterdigitated structureMolecular dynamicsSelf-assemblyMore Related Videos
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