Molecular Pivot-Hinge Installation to Evolve Topology in Rare-Earth Metal-Organic Frameworks

Linker desymmetrization has been witnessed as a powerful design strategy for the discovery of highly connected metal-organic frameworks (MOFs) with unprecedented topologies. Herein, we introduce molecular pivot-hinge installation as a linker desymmetrization strategy to evolve the topology of highly connected rare-earth (RE) MOFs, where a pivot group is placed in the center of a linker similar to a hinge. By tuning the composition of pivot groups and steric hindrances of the substituents on various linker rotamers, MOFs with various topologies can be obtained. The combination of L-SO₂ with C_2v symmetry and 12-connected RE₉ clusters leads to the formation of a fascinating (4,12)-c dfs new topology. Interestingly, when replacing L-SO₂ with a tetrahedra linker L-O, the stacking behaviors of RE-organic layers switch from an eclipsed mode to a staggered stacking mode, leading to the discovery of an intriguing hjz topology. Additionally, the combination of the RE cluster and a linker [(L-(CH₃ )₆ )] with more bulky groups gives rise to a flu topology with a new 8-c inorganic cluster. The diversity of these RE-MOFs was further enhanced through post-synthetic installation of linkers with various functional groups. Functionalization of each linker with acidic and basic units in the mesoporous RE-based PCN-905-SO₂ allows for efficient cascade catalytic transformation within the functionalized channels.