Evolution from Lyotropic Liquid Crystal to Helical Fibrous Organogel of an Achiral Fluorescent Twin-Tapered Bi-1,3,4-oxadiazole Derivative

We report an unprecedented hierarchical self-assembly of an achiral twin-tapered bi-1,3,4-oxadiazole derivative (2,2-bis(3,4,5-trioctanoxyphenyl)-bi-1,3,4-oxadiazole, BOXD-T8). This molecule can form a layer-structured lyotropic liquid crystal and further forms a helical fibrous organogel in DMF at concentrations above 0.6 wt%. The self-assembly process of BOXD-T8 in DMF is accompanied by a change in its fluorescence. The pitches of the helical fibers are non-uniform, and both left-and right-handed helical fibers are observed in equal quantities. Intermolecular pi-pi interactions between aromatic segments have been demonstrated to be the driving force for aggregate formation. This helical structure of BOXD-T8 is dependent on the solvent, concentration, and the layer-structured intermediate liquid-crystalline state.