Anna Getsis and Anja-Verena Mudring, Ruhr-University Bochum, Germany, have shown that the ionic liquids [C₁₂mim]₃Br and [C₁₂mpyr]Br, both doped with TbBr₃, as well as the neat compounds [C₁₂mim]₃[TbBr₆] and [C₁₂mpyr]₃[TbBr₆], are interesting new materials.

These ionic liquids form liquid crystalline mesophases over a wide temperature range and the imidazolium compounds showed a strong green luminescence. The color of the emission could be switched between green and blue-white depending on the excitation energy used.

These materials are of interest for liquid crystal displays due to their color-switching abilities. Additionally, the inclusion of the Tb³⁺ ion introduces magnetic anisotropy which could make alignment of the mesophase in an external magnetic field possible leading to electrically and magnetically switchable devices.

• Switchable Green and White Luminescence in Terbium-Based Ionic Liquid Crystals
  A. Getsis, A.-V. Mudring,
  Eur. J. Inorg. Chem. 2011.
  DOI: 10.1002/ejic.201100168