Hierarchical Amplification of Chirality in Anion-Coordinated Tetrahedral Cages

Abstract

Chirality is vital in asymmetric catalysis, biological systems, and materials science. However, the control of chiral transfer and amplification remains challenging but fascinating. Herein, we report the chirality transferred from the chiral carbon centers to the ‘aniono’ tetrahedral cages, which were constructed through the self-assembly of chiral C3-symmetric tris-bis(urea) ligands and oxoanions (PO43− or CO32−). The host-guest interaction can further alter the chirality, resulting in enhanced CD intensity accompanied by a redshift. Furthermore, anions have a great influence on the chiral behavior of the mixed-ligand (chiral and achiral ligand mixed in different proportions) cages due to the existence of structural transformation. Upon the self-assembly and subsequent host-guest chemistry, we establish a hierarchical chiral system at the supramolecular level, featuring controllable chiral transfer and amplification.