Chiral Bis- and Multi-Macrocycles Based on Pillararenes: Design Strategies, Chiral Inversion Mechanisms, and Emerging Properties
Pillar[n]arenes, macrocyclic hosts with unique pillar-shaped architectures, exhibit dynamic planar chirality arising from restricted rotation of their hydroquinone units. This review summarizes recent advances in constructing chiral bis- and multi-macrocycles by fusing additional rings onto pillararene backbones. These systems serve as privileged platforms for chiral inversion molecular machines, particularly molecular universal joints (MUJs), and for integrating pillararenes with other macrocycles to create chiral platforms with circularly polarized luminescence (CPL). The design strategies, chiral inversion mechanisms, and attractive properties of these materials are discussed, highlighting their potential in chiral recognition, asymmetric catalysis, and chiral luminescent materials.