Dual liquid Crystalline/Gel behavior with AIE effect promoted by Self-assembly of pyrazole dendrons

Abstract

This work describes the rich self-assembly behavior obtained by grafting a pyrazole-derived platform at the focal point of poly(benzyl ether) dendrons. Liquid crystals and supergels made out of fibers are obtained by supramolecular organization of non-discoid entities, and they notably increment the photoluminescence in these aggregated states (Aggregation-Induced Emission, AIE). The novel focal point, which is derived from 3,5-dimethyl-4-phenyl-1H-pyrazole, shows great tendency to arrange both wedge-shaped or cone-shaped dendrons in columnar arrangements by the formation of supramolecular polymers by hydrogen-bonding following the cylinder model. Two different linkers, amide or ether groups, connecting with the pyrazole-based apex are investigated, obtaining similar mesomorphic behavior, but different luminescent properties. A combined study of NMR, IR and X-ray diffraction allows establishing analogies between the fiber mesoscopic organization and the columnar organization in the liquid crystalline phase.