A new salt bridge based on the hydrophobic room-temperature molten salt

Abstract

A conceptually new salt bridge based on a hydrophobic room-temperature molten salt (ionic liquid) has been demonstrated to be a promising alternative to traditional salt bridges based on a concentrated aqueous KCl phase. 1-Methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide (C 8mimC 1C 1N), which is immiscible with water and forms a liquid-liquid two-phase system, exhibits a stable phase-boundary potential when sandwiched by two aqueous electrolyte solutions. The phase-boundary potential between the interface is determined by the partition of C 8mim + and C 1C 1N - ions in the aqueous phase (W) and is little affected by the type of electrolytes and their concentrations in W, provided that ions dissolved in W are hydrophilic enough. The gelation of the molten salt phase does not affect the phase-boundary potential. The new salt bridge is free from most of the problems inherent to KCl-based salt bridges. © 2006 The Chemical Society of Japan.