Aggregation-Induced Emission and Organogels with Chiral and Racemic Pyrene-Substituted Cyanostyrenes

The synthesis, photophysical investigations, and organogel formation of pyrene-phenyl acrylonitriles (1-6) bearing mono-, di-, and trichiral and racemic substitutions were studied. The molecules self-assemble in water and show remarkable emission wavelength and intensity changes associated with distinct color changes. Cryo-scanning electron microscopy (Cryo-SEM) images show the formation of uniform nanoaggregates for the monosubstituted derivatives and network-like structures for di- and trisubstituted derivatives. The favorable pi-pi stacking ability of the coplanar pyrene ring, steric restrictions due to the cyano group, and beneficial noncovalent interactions from the citronellol moiety allow the molecules to form excellent organogels with fibrous and twisted ribbon morphology for the racemic and chiral derivatives. The organogels based on small molecules could be of high relevance for potential investigations involving soft biological matter.