• • Pillar[5]arene exhibits eight conformers (four enantiomeric pairs) due to free rotation of paraphenylene-methylene units; introducing bulky substituents restricts rotation, yielding stable planar chirality (pS/pR) as demonstrated by Ogoshi et al. (Org Lett, 2011, 13: 1264–1266). This enables isolation of enantiomers, critical for chiral materials and catalysis.
• • Planar chirality in pillararenes is exclusively derived from macrocyclic skeletal architecture, offering a novel approach for constructing chiral bis- and multi-macrocyclic systems (refs 14,15). This structural feature underpins the design of molecular universal joints (MUJs) with controllable chiral inversion.
• • Integration of pillararenes with other macrocycles or construction of pillararene-fused giant macrocycles yields chiral platforms with excellent properties, particularly circularly polarized luminescence (CPL). For instance, AIE-active chiral [3]rotaxanes with switchable CPL were reported (Angew Chem Int Ed, 2021, 60: 9507–9515), demonstrating tunable chiroptical responses.
• • Catalytic enantioselective synthesis of planar chiral pillar[5]arenes via asymmetric Sonogashira coupling has been achieved (Angew Chem Int Ed, 2025, 64: e202415190), providing a direct route to enantiopure planar chiral macrocycles, which is essential for applications in asymmetric catalysis and chiral recognition.