Ionic liquids: Polarity (adjustable) Very low vapor pressure Liquid ranges (> 300 °C) Solubility of gases & a wide range of compounds Immiscibility with solvents Hydrophilicity/lipophilicity (adjustable) Acidity (adjustable)
Charge distribution for [C4mim][PF6]. (4-1-PF6) Red corresponds to regions of high relative negative charge, and blue to high relative positive charge. New ionic liquid made up of a cobalt-carbonyl anion and imidazolium cation. The liquid is catalytically active in its own right.
Ionic liquids can form structures in their own right such as a stable smectic liquid crystal eg. [C14mim][PF6]. Ionic liquids made of dialkylimidazolium cations and appropriate anions are useful alternative media of special properties to be employed.
The phase preference of the three forms of thymol blue in [bmim][PF6].
Utilizing recyclable gases to activate the proton switch: (a) Thymol blue in the upper aqueous phase at pH = 13; (b) Bubbling CO 2 through the RTIL/aqueous system, note the change in dye color; (c) The yellow form of thymol blue in the RTIL phase; (d) Bubbling NH 3 through the RTIL/aqueous system, note the darker color of the dye; (e) The blue form of thymol blue settling into the top aqueous phase.
Solid/liquid separations utilizing the low melting [dmim][PF6]: (a) An acidic thymol blue solution residing over solid [dmim][PF6] prior to melting; (b) After melting the salt, thymol blue partitioned to the [dmim][PF6]; (c) Recrystallization of [dmim][PF6] leaves behind a red residue; (d) An alkaline wash is added to remove the dye from the solid surfaces; (e) The colorless crystalline [dmim][PF6] solid after washing. a b c d e
Figure 1 | A class apart. Ionic liquids show a range of properties. Here, hydrophobic EMIm NTf 2 (bottom phase) is separated from hydrophobic C 9 H 20 by blue-dyed H 2 O. Involatility was assumed to be a characteristic common to all members of the class, until Earle showed otherwise.