Spontaneous Resolution of Chiral Janus-Type Double-Layered Metallocyclic Strips Incorporating Möbius Ring and Circular Helicate
Li Zhang, Boyang Li, Ran Li, Yue Wang, Sheng Ye, Peng Zhang, Biao Wu
Abstract
Homochiral metal–organic macrocyclic complexes are of great significance owing to their chirality and well-defined internal cavities that potentially have the ability to mimic complicated biological processes. Here we report a novel metal/anion-coordination co-driven strategy for the formation of nanoscale supramolecular metallocycles with unique topology, large size, and desired chirality. The enantiomeric Janus-type metallocyclic strips are assembled based on the synergistic coordination of sulfate anions and Co II ions to a bifunctional achiral ligand combining the o -phenylene-(bis)urea anion-chelating and 8-hydroxyquinoline metal-coordinating sites. The inherent chirality arises from two types of helical chiralities (triply twisted Möbius ring and circular helicate), which is observed for the first time for metal–organic complex systems. Notably, spontaneous chiral resolution by conglomerate crystallization into a pair of enantiomers ( P- or M - Co 9 ) is realized, which is attributed to the multiple weak intermolecular interactions facilitating the hierarchically helical superstructure.