Studies on the translational and rotational motions of ionic liquids composed of N -methyl- N -propyl-pyrrolidinium (P13) cation and bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts

Kikuko Hayamizu, Seiji Tsuzuki, Shiro Seki, Kenta Fujii, Masahiko Suenaga, Yasuhiro Umebayashi

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Abstract

Room-temperature ionic liquids (RTIL, IL) are stable liquids composed of anions and cations. N -methyl- N -propyl-pyrrolidinium (P13, Py13, PYR13, or mppy) is an important cation and produces stable ILs with various anions. In this study two amide-type anions, bis(trifluoromethanesulfonyl)amide [N (SO 2 CF3)2, TFSA, TFSI, NTf2, or Tf2 N] and bis(fluorosulfonyl)amide [N (SO2 F) 2, FSA, or FSI], were investigated. In addition to P13 -TFSA and P13 -FSA, lithium salt doped samples were prepared (P13 -TFSA-Li and P13 -FSA-Li). The individual ion diffusion coefficients (D) and spin-lattice relaxation times (T1) were measured by H1, F 19, and L7 i NMR. At the same time, the ionic conductivity (σ), viscosity (), and density (ρ ) were measured over a wide temperature range. The van der Waals volumes of P13, TFSA, FSA, Li (TFSA)2, and Li (FSA)3 were estimated by molecular orbital calculations. The experimental values obtained in this study were analyzed by the classical Stokes-Einstein, Nernst-Einstein (NE), and Stokes-Einstein-Debye equations and Walden plots were also made for the neat and binary ILs to clarify physical and mobile properties of individual ions. From the temperature-dependent velocity correlation coefficients for neat P13 -TFSA and P13 -FSA, the NE parameter 1- was evaluated. The ionicity (electrochemical molar conductivity divided by the NE conductivity from NMR) and the 1- had exactly the same values. The rotational and translational motions of P13 and jump of a lithium ion are also discussed.

Original languageEnglish
Article number194505
JournalJournal of Chemical Physics
Volume133
Issue number19
DOIs
Publication statusPublished - Nov 21 2010

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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