Adaptive chirality of an achiral cage: Chirality transfer, induction, and circularly polarized luminescence through aqueous host–guest complexation

Abstract

Chirality transfer, induction, and circularly polarized luminescence (CPL) using supramolecular hosts, such as macrocycles and cages, have been explored for wide-ranging applications in chiral recognition, sensing, catalysis, and chiroptical functional materials. Herein, we report the adaptive chirality of an achiral tetraphenylethene (TPE)-based octacationic cage (1) induced by binding with enantiopure deoxynucleotides (A, T, C, and G) through host–guest (H–G) complexation in water. The hydrophobic cavity of the cage efficiently stabilizes the hydrogen-bonded dimerization of deoxynucleotides (A2, T2, C2, and G2) to form H–G complexes in 1∶2 ratios. Given the photophysical properties and dynamic rotational conformation of the TPE units of the cage, cage⊃ deoxynucleotide complexes exhibited excellent chiroptical properties based on chirality transfer and induction from the chiral guest to the achiral host. For this supramolecular system, the cage showed a unique adaptive chirality of the double clockwise-typed (PP) rotational conformation of the two TPE units, which was induced by chiral guests (e.g., A2, T2, C2, and G2) through H–G complexation in water. Furthermore, the adaptive chirality of the cage⊃deoxynucleotide complexes successfully induced CPL signals in homogeneous aqueous solutions. This study provides insights for the construction of adaptive chirality from an achiral TPE-based octacationic cage with dynamic conformational nature, and might facilitate further design of chiral functional materials for several applications, such as chiral recognition, sensing, displays, catalysis, and other chiral fluorescent supramolecular systems based on aqueous H–G complexation.