No abstract

In contrast to the vast Al-oxo molecular cluster chemistry, Al-based building units for metalorganic 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 Alcarboxylate linkage and weak Cu-pyrazol N linkagegives FDM-91 (FDM = Fudan Materials) with gigantic Al 24 -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 À 1 ) and outstanding cycling performance are developed. Linkage-selective dissociation of FDM-91 further leads to the isolation of the Al 24 molecular clusters. The versatile chemistry performed here to reinforce or deconstruct MOFs provides a new way to make important extended and discrete structures.

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.