Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (9): 1605-1610.doi: 10.3866/PKU.WHXB201407012


Hydrogen-Bonding Interactions between Ionic Liquid 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate and Water

SONG Da-Yong1,2, CHEN Jing1   

  1. 1. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu Province, P. R. China;
    2. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2014-05-21 Revised:2014-06-30 Published:2014-08-29
  • Contact: CHEN Jing
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (973) (2011CB201404) and National Natural Science Foundation of China (21133011).


Attenuated total reflectance infrared (ATR-IR) spectroscopy, two- dimensional correlation spectroscopy, and quantum chemical calculations were used to elucidate the hydrogen-bonding interactions between an ionic liquid (IL), namely 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][OTf]), and water over a wide concentration range. It was found that water molecules are isolated from each other and embedded in the IL environment at low water concentrations (0.1<x(D2O)< 0.3). The water molecules occupy the IL interstices, and one water molecule forms two hydrogen bonds, with two [OTf]- anions."[OTf]-…HOH… [OTf]-"hydrogen-bonded complexes exist in the [emim][OTf]- water system. In this concentration range, the hydrogen-bonding interaction sites between the cation and water is the alkyl C―H rather than the aromatic C―H. At higher water concentrations, the water molecules form hydrogen bonds with themselves, producing water clusters in the mixture. The hydrogen-bonding interaction site between the cation and water is the aromatic C―H rather than the alkyl C―H.

Key words: Ionic liquid, Hydrogen bonding interaction, Attenuated total reflectance infrared spectroscopy, Two-dimensional correlation spectroscopy