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Title: Investigation of Dynamics in BMIM TFSA Ionic Liquid through Variable Temperature and Pressure NMR Relaxometry and Diffusometry

Abstract

A comprehensive variable temperature, pressure and frequency multinuclear ( 1H, 2H, and 19F) magnetic resonance study was undertaken on selectively deuterated 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMIM TFSA) ionic liquid isotopologues. This study builds on our earlier investigation of the effects of increasing alkyl chain length on diffusion and dynamics in imidazolium-based TFSA ionic liquids. Fast field cycling 1H T 1 data revealed multiple modes of motion. Through calculation of diffusion coefficient (D) values and activation energies, the low- and high-field regimes were assigned to the translational and reorientation dynamics respectively. Variable-pressure 2H T 1 measurements reveal site-dependent interactions in the cation with strengths in the order MD 3 > CD 3 > CD 2, indicating dissimilarities in the electric field gradients along the alkyl chain, with the CD 2 sites having the largest gradient. Additionally, the α saturation effect in T 1 vs. P was observed for all three sites, suggesting significant reduction of the short-range rapid reorientational dynamics. This reduction was also deduced from the variable pressure 1H T 1 data, which showed an approach to saturation for both the methyl and butyl group terminal methyl sites. Pressure-dependent D measurements show independent motions for both cations and anions, with the cationsmore » having greater D values over the entire pressure range.« less

Authors:
 [1];  [2];  [3];  [4];  [1];  [5];  [6];  [7];  [1]
  1. Hunter College, New York, NY (United States). Dept. of Physics; CUNY Graduate School, New York, NY (United States)
  2. Hunter College, New York, NY (United States). Dept. of Physics; CUNY Graduate School, New York, NY (United States); Univ. of Puerto Rico, Mayaguez, PR (United States). Dept. of Physics
  3. CUNY Graduate School, New York, NY (United States); Brooklyn College, Brooklyn, NY (United States). Physics Dept.
  4. Hunter College, New York, NY (United States). Dept. of Physics
  5. Univ. of Kelaniya (Sri Lanka). Dept. of Physics
  6. CUNY Graduate School, New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Division
  7. Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Division
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States); Brooklyn College, Brooklyn, NY (United States); Hunter College, New York, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Professional Staff Congress City Univ. of New York (PSC CUNY) (United States); Office of Naval Research (ONR) (United States)
Contributing Org.:
CUNY Graduate School, New York, NY (United States); Univ. of Puerto Rico, Mayaguez, PR (United States); Univ. of Kelaniya (Sri Lanka)
OSTI Identifier:
1358032
Report Number(s):
BNL-113880-2017-JA
Journal ID: ISSN 0013-4651; R&D Project: CO-004; KC0301010
Grant/Contract Number:
AC02-98CH10886; SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 8; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; BMIM TFSA; FFC NMR; PGSE; NMR; variable pressure; ionic liquid

Citation Formats

Pilar, Kartik, Rua, Armando, Suarez, Sophia N., Mallia, Christopher, Lai, Shen, Jayakody, J. R. P., Hatcher, Jasmine L., Wishart, James F., and Greenbaum, Steve. Investigation of Dynamics in BMIM TFSA Ionic Liquid through Variable Temperature and Pressure NMR Relaxometry and Diffusometry. United States: N. p., 2017. Web. doi:10.1149/2.0301708jes.
Pilar, Kartik, Rua, Armando, Suarez, Sophia N., Mallia, Christopher, Lai, Shen, Jayakody, J. R. P., Hatcher, Jasmine L., Wishart, James F., & Greenbaum, Steve. Investigation of Dynamics in BMIM TFSA Ionic Liquid through Variable Temperature and Pressure NMR Relaxometry and Diffusometry. United States. doi:10.1149/2.0301708jes.
Pilar, Kartik, Rua, Armando, Suarez, Sophia N., Mallia, Christopher, Lai, Shen, Jayakody, J. R. P., Hatcher, Jasmine L., Wishart, James F., and Greenbaum, Steve. Thu . "Investigation of Dynamics in BMIM TFSA Ionic Liquid through Variable Temperature and Pressure NMR Relaxometry and Diffusometry". United States. doi:10.1149/2.0301708jes. https://www.osti.gov/servlets/purl/1358032.
@article{osti_1358032,
title = {Investigation of Dynamics in BMIM TFSA Ionic Liquid through Variable Temperature and Pressure NMR Relaxometry and Diffusometry},
author = {Pilar, Kartik and Rua, Armando and Suarez, Sophia N. and Mallia, Christopher and Lai, Shen and Jayakody, J. R. P. and Hatcher, Jasmine L. and Wishart, James F. and Greenbaum, Steve},
abstractNote = {A comprehensive variable temperature, pressure and frequency multinuclear (1H, 2H, and 19F) magnetic resonance study was undertaken on selectively deuterated 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMIM TFSA) ionic liquid isotopologues. This study builds on our earlier investigation of the effects of increasing alkyl chain length on diffusion and dynamics in imidazolium-based TFSA ionic liquids. Fast field cycling 1H T1 data revealed multiple modes of motion. Through calculation of diffusion coefficient (D) values and activation energies, the low- and high-field regimes were assigned to the translational and reorientation dynamics respectively. Variable-pressure 2H T1 measurements reveal site-dependent interactions in the cation with strengths in the order MD3 > CD3 > CD2, indicating dissimilarities in the electric field gradients along the alkyl chain, with the CD2 sites having the largest gradient. Additionally, the α saturation effect in T1 vs. P was observed for all three sites, suggesting significant reduction of the short-range rapid reorientational dynamics. This reduction was also deduced from the variable pressure 1H T1 data, which showed an approach to saturation for both the methyl and butyl group terminal methyl sites. Pressure-dependent D measurements show independent motions for both cations and anions, with the cations having greater D values over the entire pressure range.},
doi = {10.1149/2.0301708jes},
journal = {Journal of the Electrochemical Society},
number = 8,
volume = 164,
place = {United States},
year = {Thu May 11 00:00:00 EDT 2017},
month = {Thu May 11 00:00:00 EDT 2017}
}

Journal Article:
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  • Composition dependent structural and dynamical properties of aqueous hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF{sub 6}]) ionic liquid (IL) have been investigated by using all-atom molecular dynamics simulation. We observe that addition of water does not increase significant number of dissociated ions in the solution over the pure state. As a consequence, self-diffusion coefficient of the cation and anion is comparable to each other at all water concentration similar to that is observed for the pure state. Voronoi polyhedra analysis exhibits strong dependence on the local environment of IL concentration. Void and neck distributions in Voronoi tessellation are approximately Gaussian for pure ILmore » but upon subsequent addition of water, we observe deviation from the Gaussian behaviour with an asymmetric broadening with long tail of exponential decay at large void radius, particularly at higher water concentrations. The increase in void space and neck size at higher water concentration facilitates ionic motion, thus, decreasing dynamical heterogeneity and IL reorientation time and increases self-diffusion coefficient significantly.« less
  • Dynamic crossover above T g has been recognized as a characteristic feature of molecular dynamics of liquids approaching glass transition. Experimentally, it is manifested as a change in Vogel–Fulcher–Tammann dependence or a breakdown of the Stokes–Einstein and related relations. In this study, we report the exception from this rather general pattern of behavior. By means of dielectric, ultrasonic, rheological, and calorimetric methods, dynamics of two good ionic conductors (BMIm) 2[Co(NCS) 4] and (EMIm) 2[Co(NCS) 4] of less common stoichiometry (2:1) was studied in a very broad temperature range. However, none of the mentioned dynamic changes was observed in the entiremore » studied temperature range. On the contrary, the single VFT and the same fractional Walden coefficient were found for conductivity and viscosity changes over 12 decades. Finally and moreover, ultrasonic studies revealed that the data at temperatures which cover the normal liquid region cannot be fitted by a single exponential decay, and the Cole–Cole function should be used instead.« less
  • Dynamic crossover above T g has been recognized as a characteristic feature of molecular dynamics of liquids approaching glass transition. Experimentally, it is manifested as a change in Vogel Fulcher Tammann dependence or a breakdown of the Stokes Einstein and related relations. In this paper, we report the exception from this rather general pattern of behavior. By means of dielectric, ultrasonic, rheological, and calorimetric methods, dynamics of two good ionic conductors (BMIm) 2[Co(NCS) 4] and (EMIm) 2[Co(NCS) 4] of less common stoichiometry (2:1) was studied in a very broad temperature range. However, none of the mentioned dynamic changes was observedmore » in the entire studied temperature range. On the contrary, the single VFT and the same fractional Walden coefficient were found for conductivity and viscosity changes over 12 decades. Furthermore, ultrasonic studies revealed that the data at temperatures which cover the normal liquid region cannot be fitted by a single exponential decay, and the Cole Cole function should be used instead.« less
  • A fast ionic composite is prepared by dispersion of Ionic liquid [Bmim][PF{sub 6}] in Li{sub 2}SO{sub 4}−Li{sub 2}O−P{sub 2}O{sub 5} glass matrix by mixing and through grinding. Amorphous/glassy nature of the samples is confirmed by X-Ray diffraction (XRD). Surprisingly, the electrical conductivity of the samples is found to be increasing by ∼ 2 orders of magnitude and exhibits typical Arrhenius behavior with low activation energy. DC polarization and impedance spectroscopy measurements suggest that samples are essentially ionic in nature. The conductivity isotherms were also obtained at different temperatures (T < 100 °C) and found to be appreciably stable at leastmore » for ∼ 10 days.« less