Chiral aggregation-induced emission molecules: Design, circularly polarized luminescence, and helical self-assembly

Aggregation-induced emission (AIE) molecules have been developed into many branches since their discovery in 2001. A new branch of them is chiral AIE molecules with circularly polarized luminescence properties, which have important potentials in 3D display and optoelectronic devices. There are in general two strategies to design chiral AIE molecules. One is to chemically modify AIE molecules with chiral peripheries in which chirality is transferred from the peripheries to AIE luminogens to endow them with chirality. The other strategy is to physically mix AIE molecules with chiral additives in which chirality is transferred to the AIE molecules by noncovalent interactions. The successful hybridization of chirality and AIE luminogens gives rise to chiral AIE molecules, which have chiroptical properties and the ability to self-assemble into helical architectures upon aggregation. In contrast to conventional molecular chirality, these novel chiral AIE aggregates have enhanced performance in emission efficiency, dissymmetry factor, and the advantage of not suffering from the aggregation-caused quenching (ACQ) effect. By deliberately selecting proper chiral motifs and AIE luminogens, well-defined helical architectures with amplified chiroptical properties can be fabricated. In this chapter, we summarize the progress in the molecular design, chiroptical properties, and helical self-assembly of chiral AIE molecules.