Stepwise construction of coordinative linkages and dynamic covalent linkages for a porous metal-organic framework.

A cyclic trinuclear complex is synthesized from AgI and 1H-pyrazole-4-carbaldehyde. Reticulation of the complex with 1,3,5-tris(4-aminophenyl)benzene through Schiff-base reaction affords a porous FDM-72 framework. Amine choice is systematically investigated as it may initiate metal reduction. This study proposes a new route and its amine selection criterion to synthesize Ag-based frameworks.

Water-Harvesting Metal-Organic Frameworks with Gigantic Al24 Units and their Deconstruction into Molecular Clusters.

In contrast to the vast Al-oxo molecular cluster chemistry, Al-based building units for metal-organic framework (MOF) construction are limited in structural diversity and complexity. Synthesis of single crystalline MOFs based on this "hard" metal is further complicated by the poor reversibility of the Al-organic coordination linkages. Here, a strategy to employ two kinds of linkages with distinct strength-strong Al-carboxylate linkage and weak Cu-pyrazol N linkage-gives FDM-91 (FDM=Fudan Materials) with gigantic Al24 -based units. After replacing the weak moieties with organic linkers post-synthetically, two new stable MOFs with exceptional water harvesting capacity (up to 0.53 g g-1 ) and outstanding cycling performance are developed. Linkage-selective dissociation of FDM-91 further leads to the isolation of the Al24 molecular clusters. The versatile chemistry performed here to reinforce or deconstruct MOFs provides a new way to make important extended and discrete structures.

Snapshots of Postsynthetic Modification in a Layered Metal-Organic Framework: Isometric Linker Exchange and Adaptive Linker Installation.

Terminal ligand exchange and framework linker exchange have been frequently practiced as powerful tools to functionalize reticular structures such as metal-organic frameworks (MOFs). Herein, we report the postsynthetic modification (PSM) of a 6-connected layered MOF (hxl topology) to achieve a 12-connected fcu framework. In the PSM process, isometric linker exchange in the layers and linker installation between adjacent layers by the substitution of modulating ligands happen simultaneously. Snapshots of PSM at different time points reveal that the hxl domain is adaptively reorganized to create sites for new linker installation, and gradually the fcu domain dominates the crystal. Detailed kinetic analysis suggests that, although adaptive linker installation requires interlayer expansion of stackings in situ, it is kinetically faster than isometric linker exchange in the layers.

Emerging porous materials in confined spaces: from chromatographic applications to flow chemistry.

Searching for porous materials that can be employed as solid stationary phases for chromatographic separations, porous membrane matrixes and solid supports for catalysis has become an active research area. Strategies for embedding emerging porous materials in columnar systems and their subsequent applications (separation and catalysis) have been developed, which benefit from the remarkable progress in the discovery and development of porous materials based on metal-organic coordination or dynamic covalent bonding such as metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), porous organic cages, and porous organic polymers. In this review, porous materials that have been confined within capillary columns as packed, monolithic and open tubular columns are discussed. Progress in chromatographic separation and continuous flow catalytic synthesis is reviewed according to three major strategies. Applications of porous materials in membrane-separation fibre membrane systems and microfluidic devices with various functions are also highlighted.