Liquids intermediate between 'molecular' and 'ionic' liquids: Liquid Ion Pairs?

摘要

Ionic liquids comprised of tetradecyltrihexyl-and tetrabutyl-phosphonium cations paired with chloride or sulfonyl amide anions exhibit properties that reflect strong ion association, including comparatively low viscosity as well as a degree of volatility, and hence exemplify an interesting intermediate state between true ionic and true molecular liquids. Room temperature ionic liquids are currently attracting considerable attention as potentially benign solvents for many areas of chemistry, as well as electrochemical devices such as rechargeable lithium batteries, fuel cells, electrochemical capacitors, and photoelectrochemical solar cells. This interest in ionic liquids can be attributed to the properties variously exhibited by some, though not all, members of the family, such as low volatility, nonflammability, electrochemical and thermal stability, and high ionic conductivity—all of which can be tailored through careful choice of cation and anion.