Selective Synthesis of Fluorine Liquid Crystals with a Triphenyleno[2,3- b ]benzofuran Core: Heterocyclic Annulation, Columnar Mesophase, and Fluorescence

Fluorinated discotic liquid crystals are highly promising organic semiconductor materials for electronic device research. Their exceptional self-assembly properties and thermal stability enable the formation of long-range, ordered columnar structures, which are critical for efficient charge transport, ultimately enhancing the performance and reliability of organic electronic devices. Novel fluorinated triphenyleno[2,3-b]benzofuran-based derivatives were synthesized via both inter/intramolecular nucleophilic aromatic substitution (SNAr) and selective annulation with n-BuLi/t-BuLi, respectively. All of the compounds possess excellent thermal stability and self-assemble into a hexagonal columnar mesophase, with clearing temperatures decreasing with increasing alkyl chain length, while the extent of conjugation and the number of fluorine atoms broaden the mesomorphic range, likely due to enhanced intermolecular interactions. These compounds exhibit blue-violet fluorescence in solution, with absolute fluorescence quantum yields reaching up to 29%, and behave as n-type semiconductors with electron mobilities in the 10⁻³ cm²/(V s) range, which falls within the typical range for molecular material-based devices.