Effect of π‒conjugation on aggregation–induced emission of α–cyanostilbene incorporated polycyclic aromatic hydrocarbons

Abstract

The development of facile approaches to inhibit aggregation‒caused quenching of polycyclic aromatic hydrocarbons (PAHs) due to strong π‒π interactions is a necessity to be employed in organic electronic applications. In this work, this challenging task was addressed by using α–cyanostilbene moiety in the PAH structures to achieve an opposite phenomenon, aggregation‒induced emission (AIE). The design, synthesis, and AIE properties of α–cyanostilbene consisting of PAHs (e.g., pyrene, anthracene, and naphthalene) were broadly explored. The results indicate that the steric hindrance due to cyano units and rotator vinylenes facilitate the PAH molecules to attain a twisted conformation which induced distinctive AIE attributes without requiring bulky groups on the PAHs. As a result of the extended π‒conjugation and intramolecular charge transfer in the D–π–A–π–D design, these molecules rendered variable emission colors ranging from green–to–yellowish/green–to–orange and also a white emission in THF‒water solvent system.