Interplay of Ion-Conduction and Nanoscale Self-Assembly in Amphiphilic Janus-Type Hexa-peri-hexabenzocoronenes

• Published in: ACS applied nano materials Vol. 7; no. 14; pp. 16256 - 16263
• Main Authors: Weigold, Svenja, Spyridakou, Marianna, Tzourtzouklis, Ioannis, Freudenberg, Jan, Bunz, Uwe H. F., Müllen, Klaus, Floudas, George
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26.07.2024
• Subjects: amphiphilic HBCs; nanoscale self-assembly; ion conduction; discotic liquid crystals
• ISSN: 2574-0970; 2574-0970
• DOI: 10.1021/acsanm.4c02204

Ionic discotic liquid crystals combine ion conduction with fluid, yet ordered, liquid crystal phases at ambient temperature, making them suitable nanomaterials for ion transport and energy storage. A series of Janus-type hexa-peri-hexabenzocoronenes (HBCs) with ionic (sulfonate) groups covalently bonded to the HBC core, and tetraalkylammonium counterions (sizes from 0.15 to 0.95 nm) are synthesized and investigated with respect to the self-assembly and ion dynamics. We find that the counterion size affects the nanoscale self-assembly and ionic conductivity in opposite ways. Smaller counterions act as structure formers, whereas larger ones act as structure breakers. The latter exhibits the highest ion dc-conductivity. We quantify the effect of Coulomb interactions on the self-assembly, the glass temperature T g (which was found to vary by 30 K), and the dc-conductivity (varying by 4 orders of magnitude). The precise synthesis of tailor-made ionic discotic liquid crystals with the HBC core and the characterization of their physical properties revealed that ion-conduction and nanoscale self-assembly in HBCs can be modulated by tuning electrostatic interactions, e.g., by adjusting the size of counterions.