Ionic Liquids and Green Reaction/Separation Engine
Ionic liquids are composed of organic cations and anions whose unfavorable packing allows them to form liquids at conditions near ambient without the need for added solvents. Mezger et al. (p. 424) explored the structure of a series of room-temperature ionic liquids at a charged sapphire surface, using high-energy x-ray reflectivity, as a function of temperature. All of the liquids had a fluorinated anion, tris(pentafluoroethyl)trifluorophosphate, and all showed strong surface layering, with the cation adsorbing on the negatively charged sapphire surface. This layering, which decayed exponentially with distance into the bulk, is likely to represent a common feature of ionic liquids at charged interfaces.
Science 17 October 2008:
Vol. 322 no. 5900 p. 341