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Self-Assembly and Fluorescence of Tetracationic Liquid Crystalline Tetraphenylethene |
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| Authors: | Jakob Knelles Dr. Stuart Beardsworth Korinna Bader Dr. Johanna R. Bruckner Andrea Bühlmeyer Robert Forschner Kevin Schweizer Dr. Wolfgang Frey Prof. Dr. Frank Giesselmann Prof. Dr. Yann Molard Prof. Dr. Sabine Laschat |
| Affiliation: | 1. Institut für Organische Chemie, Universität Stuttgart, Germany These coauthors contributed equally to this work.;2. Institut für Organische Chemie, Universität Stuttgart, Germany;3. Institut für Physikalische Chemie, Universität Stuttgart, Germany;4. University of Rennes, CNRS, ISCR, UMR 6226, ScanMAT – UMS, 2001 Rennes, France |
| Abstract: | A series of tetraguanidinium tetraphenylethene (TPE) arylsulfonates with different chain lengths was prepared via ionic self-assembly of tetraguanidinium TPE chloride and the respective methyl arylsulfonates. Liquid crystalline properties were studied by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. Tetraguanidinium TPE arylsulfonates with chain lengths of C8–C12 displayed hexagonal columnar mesophases over a broad temperature range, while derivatives with longer chains showed oblique columnar phases. In solution all compounds displayed aggregation-induced emission behaviour. Temperature-dependent luminescence spectra of the bulk phase of the tetraguanidinium TPE arylsulfonate with C14 side chains revealed a strong luminescence both in the solid state and the oblique columnar mesophase. The emission behaviour was rationalized by a unique combination of restriction of intramolecular rotation of the TPE core, Coulomb interaction between the guanidinium cations and π–π interactions of the anionic arylsulfonate moieties. |
| Keywords: | aggregation-induced emission fluorescence liquid crystals ionic self-assembly tetraphenylethene |