Butterfly Mesogens Based on Carbazole, Fluorene or Fluorenone: Mesomorphous, Gelling, Photophysical, and Photoconductive Properties

Abstract We report a straightforward and generic synthesis of several new series of annulated π‐extended poly‐(hetero)aromatic hydrocarbons (PAH), with carbazole, fluorene and fluorenone central building blocks by the Suzuki‐Miyaura/Scholl tandem reactions. The corresponding series of ditriphenylene discogens with a carbazole or a fluorenone central core, respectively, possess hexagonal columnar mesophases with broad mesophase ranges and high clearing points, as well as demonstrate a strong aggregation tendency in organic solvents as supergelators. The laterally‐substituted ditriphenylene mesogens based on dimethyl‐fluorene core exhibit a rich polymorphism with rectangular and hexagonal columnar mesophases from low temperatures onward, whereas their dioctyl‐fluorene homologues melt directly into the isotropic liquid without showing mesophases. These latter family of compounds are luminescent with very high fluorescent quantum yields, of around 70 % in solution, and show outstanding photocurrent behavior with charge carrier mobility in the 10 −2 cm 2 V −1 s −1 range, as measured by photocurrent transient time‐of‐flight (TOF) technique. This straightforward molecular design and simple synthetic strategy proved to be both potent and resilient, and could be generally applied to the fabrication of a great variety of other heteroarene molecular systems as organic semiconductors and electroluminescent materials for potentially low‐cost applications.