The Structure of a Room-Temperature Ionic Liquid with and without Trace Amounts of Water: The Role of C-H…F Interactions in 1-n-Butyl-3-Methylimidazolium Tetrafluoroborate

摘要

Room temperature ionic liquids (RTILs) have been considered as a "green", recyclable alternative to the traditional volatile organic solvents because of their chemical and physical properties, such as being liquid at room temperature, air and moisture stability, high solubility power, and virtually no vapor pressure. Being hygroscopic, RTILs can absorb a significant amount of water. Their properties (e.g., solubility, polarity, viscosity, and conductivity) are not only changed by, but also are dependent on the amount of absorbed water. Rates of chemical reactions and efficiencies of various processes in RTILs are, therefore, dependent on absorbed water. As a consequence, information on the structures of RTILs and their interactions with water are important not only fundamentally but also for various industrial applications. Various studies have been made using either experimental techniques, such as FT-IR, Near-IR, fluorescence, viscosimetry, conductivity, and pulsed-gradient spin-echo NMR diffusion coefficient measurements, or theoretical calculations.