Preserving Hierarchical Integrity During Primary Structure Modification of Spherulitic MOFs

A new zinc-based metal-organic framework (MOF), JUK-74, forms reproducible hyper-branched spherulitic superstructures through a linker design that preserves the MOF-74-type topology while subtly reorganizing the local coordination environment. This architecture enables a rare combination of high-order morphological control and access to a chemically addressable tetrazine core, allowing post-synthetic modification (PSM) at the primary-structure level without loss of the tertiary superstructure. The inverse electron-demand Diels-Alder (iEDDA) reaction provides a fast, mild, chemoselective, and efficient route to introduce pendant primary amines, a functionality that is notoriously difficult to incorporate into MOFs by either pre-synthetic or post-synthetic approaches. Structural, spectroscopic, and microscopic analyses confirm that functionalization proceeds throughout the material volume while the spherulitic morphology remains intact. Gas sorption and isosteric heat measurements further show that the modified framework retains an accessible porous architecture, while the introduced amine groups exert only a constrained influence on low-loading carbon dioxide adsorption. Collectively, these results establish a general strategy for combining hierarchical superstructure formation with precise covalent functionalization in MOFs, opening a route to robust and chemically sophisticated porous materials.