Cross-linking Zr-based metal-organic polyhedra via postsynthetic polymerization

Abstract

Metal-organic polyhedra (MOPs) are discrete cage molecules and have potential as supramolecular building blocks for constructing extended frameworks. However, utilizing MOPs for postsynthetic polymerization has poorly explored possibly due to fragile nature of typical Cu-based MOPs. Although MOP-polymer hybrid materials were recently reported to target enhanced processability, there is still lack of evidence for intrinsic porosity originated from the MOP cages. In this presentation, we show a novel synthetic strategy involving cross-linking of MOPs via covalent bond by exploiting condensation between the MOP and flexible organic molecules. An amine-functionalized Zr-based MOP is cross-linked with acyl chloride linkers in the crystalline state to form cross-linked MOPs. The condensation results in a cross-linked system without significant changes in the structure of Zr-based MOP. Such cross-linked MOPs provide a microporous tetrahedral cage based on gas sorption analysis. This cross-linking strategy highlights the potential of MOPs as building blocks and bridges two classes of materials, namely metal-organic polyhedra and polymers.