Ionic liquids, i.e. molten salts with a melting point at or below room temperature have received increasing interest during the last decade as novel designer solvents and materials.[1] Due to their low volatility and adjustable physical properties such as polarity, miscibility and conductivity, which can be controlled by proper choice of anion and cation respectively, they are particularly attractive for both laboratory as well as industrial applications. Knight and Shaw discovered in 1938 the first ionic liquids with thermotropic mesophases.[2] Later Seddon and Bruce investigated the liquid crystalline phases of these amphiphilic N-alkyl-pyridinium salts in more detail.[3] The results have stimulated research endeavours into ionic liquid crystals by many groups, because the presence of charged species in a liquid crystalline phase gives access to unprecedented properties such as ionic conductivity. Ionic liquid crystals are useful electrolytes for dye-sensitized solar cells and anisotropic media for electrochemistry, being solvent, electrolyte and template at the same time.[4] Furthermore, the anionic and cationic moieties provide additional design parameters beyond mesogenic core structure and side chain. This special issue of Materials is devoted to recent research progress in the field of ionic liquid crystals.

References:

[1] Reviews on ionic liquids: a) Ranke, J.; Stolte, S.; Stoermann, R.; Arning, J. Chem. Rev. 2007, 107, 2183-2206. b) Van Rautwijk, F.; Sheldon, R. A. Chem. Rev. 2007, 107, 2757-2785. c) Binnemans, K. Chem. Rev. 2007, 107, 2592-2614. d) Parvulescu, K. Chem. Rev. 2007, 107, 2615-2665. e) Imperato, G.; Koenig, B.; Chiappe, C. Eur. J. Org. Chem. 2007, 1049-1058. f) Riisager, A.; Fehrmann, R.; Haumann, M.; Wasserscheid, P. Top. Catal. 2006, 40, 91-102. g) Abbott, A. P.; McKenzie, K. J. Phys. Chem. Chem. Phys. 2006, 8, 4265-4279. h) Li, S.-G. Chem. Commun. 2006, 1049-1063. i) Baudequin, C.; Bregeon, D.; Levillain, J.; Guillen, F.; Plaquevent, J.-C.; Gaumont, A.-C. Tetrahedron Asym. 2005, 16, 3921-3945. j) Binnemans, K. Chem. Rev. 2005, 105, 4148-4204. k) Jain, N.; Kumar, A.; Chauhan, S.; Chauhan, S. M. S. Tetrahedron 2005, 61, 1015-1060. l) Welton, T. Coord. Chem. Rev. 2004, 248, 2459-2477. m) Wasserscheid, P.; Welton, T. (eds.); Ionic Liquids in Synthesis, Wiley-VCH, Berlin 2003.
[2] Knight, G. A.; Shaw, B. D. J. Chem. Soc. 1938, 682-683.
[3] a) Holbrey, J. D.; Seddon, K. R. J. Chem. Soc. Dalton Trans. 1999, 2133-2140. b) Gordon, C. M.; Holbrey, J. D.; Kennedy, A. R.; Seddon, K. R. J. Mater. Chem. 1998, 8, 2627-2636. c) Bowlas, C. J.; Bruce, D. W.; Seddon, K. R. Chem. Commun. 1996, 1625-1626.
[4] Yamanaka, N.; Kawano, R.; Kubo, W.; Kitamura, T.; Wada, T.; Watanabe, M.; Yanagida, S. Chem. Commun. 2005, 740-742.

• task-specific ionic liquids
• hybrid materials
• supramolecular aggregates
• metallomesogens
• hydrogen-bonded liquid crystals
• unconventional mesogens
• molecular magnets
• luminescent liquid crystals
• ion transport materials
• ionic self-assembly