NMR evidence of hydrogen bond in 1-ethyl-3-methylimidazolium-tetrafluoroborate room temperature ionic liquid

Jing Fang Huang, Po Yu Chen, I. Wen Sun, S. P. Wang

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The 1-ethyl-3-methylimidazolium-tetrafluoroborate (EMI-BF4) room-temperature molten salt was investigated with NMR techniques. Diffusion coefficients measured at temperatures ranging from 300 to 360 K indicate phase-change occurred in the vicinity of 333 K, which is supported by 11B quadrupolar relaxation rates. Combined with the sizes of diffusion particles obtained form the Stokes-Einstein equation, this phase change is ascribed to that the diffusion particle is transformed from "discrete ion-pair" to "individual ion" at temperatures above 335 K due to decomposition of the EMI-BF4 ion pair. Analysis of the 13C dipole-dipole relaxation rates identifies the formation of hydrogen bond(C2H…F) between the counter ions, EMI+ and BF4-. That the values of viscosity in EMI-BF4 are higher than those in EMI-AlCl4 at corresponding temperatures is therefore understood according to the viscosity approach employed to investigate the H-bonding in molten salts.

Original languageEnglish
Pages (from-to)591-603
Number of pages13
JournalSpectroscopy Letters
Volume34
Issue number5
DOIs
Publication statusPublished - 2001 Jan 1

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Spectroscopy

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