Chiroptical property of TPE triangular macrocycle crown ethers from propeller-like chirality induced by chiral acids

Herein, novel tetraphenylethylene (TPE) triangular macrocycles bearing three crown ether rings were synthesized by connecting three TPE crown ether units at the cis-position with three ethynylene bridging linkers. The macrocycles showed typical aggregation-induced emission (AIE) effect and a high fluorescence quantum yield up to 92%. They could exhibit both circular dichroism (CD) and circularly polarized luminescence (CPL) signals in the presence of enantiomers of chiral acids. Moreover, the chiroptical signals in a film became stronger with the increasing rigidity of the macrocycles. Exceptionally, the chiroptical signals of the macrocycles in solid were ascribed to the induced prevailing single-handed propeller-like conformations of TPE units rather than to the supramolecular helical micro-/nanofiber self-assembled structure.