skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure

Abstract

X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1114}][NTf{sub 2}], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1444}][NTf{sub 2}]. The peak in the diffraction data characteristic of charge ordering in [N{sub 1444}][NTf{sub 2}] is shifted to longer distances in comparison to [N{sub 1114}][NTf{sub 2}], but the peak characteristic of short-range correlations is shifted in [N{sub 1444}][NTf{sub 2}] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N{sub 1114}]{sup +} and [N{sub 1444}]{sup +} proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N{sub 1444}]{sup +} as to [N{sub 1114}]{sup +} because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N{sub 1114}]{sup +} cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N{sub 1114}][NTf{sub 2}], whereas polar and non-polar structure factors aremore » essentially the same in [N{sub 1444}][NTf{sub 2}]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids.« less

Authors:
; ; ;  [1];  [2]
  1. Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970 São Paulo, SP (Brazil)
  2. Departamento de Física da Matéria Condensada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, 13083-859 Campinas, SP (Brazil)
Publication Date:
OSTI Identifier:
22660732
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 144; Journal Issue: 22; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AMMONIUM COMPOUNDS; FLUORINE COMPOUNDS; MOLECULAR DYNAMICS METHOD; MOLECULAR STRUCTURE; MOLTEN SALTS; PEAKS; SIMULATION; STRUCTURE FACTORS; TEMPERATURE RANGE 0273-0400 K; X-RAY DIFFRACTION

Citation Formats

Lima, Thamires A., Paschoal, Vitor H., Faria, Luiz F. O., Ribeiro, Mauro C. C.,, and Giles, Carlos. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure. United States: N. p., 2016. Web. doi:10.1063/1.4953414.
Lima, Thamires A., Paschoal, Vitor H., Faria, Luiz F. O., Ribeiro, Mauro C. C.,, & Giles, Carlos. Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure. United States. https://doi.org/10.1063/1.4953414
Lima, Thamires A., Paschoal, Vitor H., Faria, Luiz F. O., Ribeiro, Mauro C. C.,, and Giles, Carlos. 2016. "Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure". United States. https://doi.org/10.1063/1.4953414.
@article{osti_22660732,
title = {Comparing two tetraalkylammonium ionic liquids. I. Liquid phase structure},
author = {Lima, Thamires A. and Paschoal, Vitor H. and Faria, Luiz F. O. and Ribeiro, Mauro C. C., and Giles, Carlos},
abstractNote = {X-ray scattering experiments at room temperature were performed for the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1114}][NTf{sub 2}], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1444}][NTf{sub 2}]. The peak in the diffraction data characteristic of charge ordering in [N{sub 1444}][NTf{sub 2}] is shifted to longer distances in comparison to [N{sub 1114}][NTf{sub 2}], but the peak characteristic of short-range correlations is shifted in [N{sub 1444}][NTf{sub 2}] to shorter distances. Molecular dynamics (MD) simulations were performed for these ionic liquids using force fields available from the literature, although with new sets of partial charges for [N{sub 1114}]{sup +} and [N{sub 1444}]{sup +} proposed in this work. The shifting of charge and adjacency peaks to opposite directions in these ionic liquids was found in the static structure factor, S(k), calculated by MD simulations. Despite differences in cation sizes, the MD simulations unravel that anions are allowed as close to [N{sub 1444}]{sup +} as to [N{sub 1114}]{sup +} because anions are located in between the angle formed by the butyl chains. The more asymmetric molecular structure of the [N{sub 1114}]{sup +} cation implies differences in partial structure factors calculated for atoms belonging to polar or non-polar parts of [N{sub 1114}][NTf{sub 2}], whereas polar and non-polar structure factors are essentially the same in [N{sub 1444}][NTf{sub 2}]. Results of this work shed light on controversies in the literature on the liquid structure of tetraalkylammonium based ionic liquids.},
doi = {10.1063/1.4953414},
url = {https://www.osti.gov/biblio/22660732}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 22,
volume = 144,
place = {United States},
year = {Tue Jun 14 00:00:00 EDT 2016},
month = {Tue Jun 14 00:00:00 EDT 2016}
}