Self-Assembly and Fluorescence of Tetracationic Liquid Crystalline Tetraphenylethene

Jakob Knelles (1) , Stuart Beardsworth (1) , Korinna Bader (1) , Johanna R. Bruckner (1) , Andrea Buehlmeyer (1) , Robert Forschner (1) , Kevin Schweizer (1) , Wolfgang Frey (1) , Frank Giesselmann (1) , Yann Molard (2, 3) , Sabine Laschat (1)

1 Universität Stuttgart [Stuttgart]
2 ISCR - Institut des Sciences Chimiques de Rennes
3 ScanMAT - Synthèse Caractérisation Analyse de la Matière

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: tetraphenylethene; ionic self-assembly; liquid crystals; fluorescence; aggregation-induced emission

Domains: Chemical Sciences

Jakob Knelles, Stuart Beardsworth, Korinna Bader, Johanna R. Bruckner, Andrea Buehlmeyer, et al.. Self-Assembly and Fluorescence of Tetracationic Liquid Crystalline Tetraphenylethene. ChemPhysChem, 2019, 20 (17), pp.2210-2216. ⟨10.1002/cphc.201900569⟩. ⟨hal-02278421⟩