Synthesis and Self-assembly of Benzoperylene Benzimidazoles: Tunable Morphology with Aggregation-Induced Enhanced Emission

Benzoperylene benzimidazoles (BPBIs) based pi-systems were synthesized and their self-assembly in both non-polar and polar solvents investigated. Due to the presence of donor and acceptor functional groups, BPBIs absorb light up to 600 nm and display red fluorescence (575-800 nm). Depending on the solvent and side chain, BPBIs self-assemble into various nanostructures such as nanoribbons, nanorods, nanofibers and nanoparticles. Notably, these ordered nanostructures are formed by BPBIs in both polar and non-polar solvents without the aid of hydrogen bonding and amphiphilic interactions due to the presence of a large rigid pi-system. Interestingly, BPBIs follow a weakly cooperative mechanism during the self-assembly. Moreover, BPBIs show aggregation-induced enhanced emission (AIEE) in all the self-assembled nanostructures which is not common for rigid pi-systems.