A homochiral metal–organic framework with interconnected double-helical channels constructed by figure-eight ligands

Abstract The development of new molecular building blocks for the construction of elaborate molecular assemblies extends the chemical space for materials exploration. Representative organic components for the design of homochiral metal-organic frameworks (MOFs) usually exhibit C1- or C2-symmetry. Herein, we synthesized a chiral D2-symmetric ligand via functionalization of a figure-eight macrocycle, cyclobisbiphenylenecarbonyl (CBBC). This ligand adopts a distinctive concave-type tetradentate coordination geometry, and the resulting MOF, CBBCMOF, features a quasi-honeycomb framework enveloped by double-helical ligand assembly. The pore size of the chiral nanochannel exceeds 10 Å, which enables CBBCMOF to encapsulate various guest molecules, including aromatic hydrocarbons, alcohols, and dyes. Furthermore, CBBCMOF achieves the enantioselective encapsulation of racemic 1,1′-bi-2-naphthol with a high enantiomeric excess (up to 68% ee). Thus, CBBCMOF functions as a stationary phase to separate the enantiomers of medium-sized chiral molecules. These results demonstrate that highly symmetric chiral molecules such as CBBC function as an effective building block for the design of advanced porous materials.