Insights into the isomeric effect on the self-assembly of donor-acceptor type aggregation-induced emission luminogens: Colour-tuning and shape-controlling

Abstract In this study, we reported the synthesis and aggregation-induced emission (AIE) properties of a new molecular system, comprised of six positional isomers. The presence of electron donor (D) and acceptor (A) units endows them with intramolecular charge transfer (ICT) effects. We studied how changing the positions of the D/A units affects the AIE properties, ICT strength as well as the energy levels of the molecular orbitals. In addition, the self-assembly behaviors of them show distinct isomeric effect: With the D/A units repositioning, various self-assembly architectures with sizes ranging from microscale to nanoscale appear sequentially, including filaments, sheets, rods, irregular particles, needles, fibrous interlocking textures. It was verified that the D/A units on para-position that pose linear dipole-dipole interaction would favor the formation of well-defined structures, otherwise the resulting assembly would be underdeveloped or ill-shaped due to low degree of order in the molecular packing. This study probed the relationships between molecular structure and self-assembly behaviour, and further makes the self-assembly customizable.