Ionic liquid crystals formed by self-assembly around an anionic anthracene core.
We have designed and synthesised a series of modular, mesogenic complexes based on anthracene-2,6-disulfonate and trialkoxybenzyl-functionalised imidazolium cations. Each complex contains a central, rigid, dianionic anthracene core and two flexible monocations bearing paraffin chains anchored on imidazolium rings. Anthracene-2,6-disulfonate can be crystallised with various simple alkylammonium ions and, in the case of +N(CH3)2(C16H33)2, a crystal structure determination has shown that the long paraffinic chains are intercalated between the anthracene moieties. The dianion forms columnar mesophases with trialkoxybenzylimidazolium cations, as identified by polarising optical microscopy and X-ray scattering measurements. Differential scanning calorimetry studies confirmed mesomorphic behaviour from room temperature to about 200 degrees C for alkyl chains containing 8, 12 and 16 carbon atoms. The strong luminescence of anthracene is maintained in the mesophase and fluorescence measurements confirmed the presence of J aggregates in all cases. The new functional materials described herein provide an easy access to stable and luminescent mesomorphic materials engineered by an ionic self-assembly process.
Olivier
Jean-Hubert
JH
Laboratoire de Chimie Organique et Spectroscopies Avancées (LCOSA), Ecole Européenne de Chimie, Polymères et Matériaux, CNRS, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France.
Camerel
Franck
F
Barberá
Joaquín
J
Retailleau
Pascal
P
Ziessel
Raymond
R