In Situ Tröger's Base Scaffold Reconstruction Enables Programmable Growth of Missing‐Linker Defective Zirconium Metal‐Organic Framework Single‐Crystals

ABSTRACT Defect engineering of metal‐organic frameworks (MOFs) offers vast opportunities for the manipulation of their local structures and has led to extensive discoveries from fundamental knowledge to property evolution. In this context, Zr‐MOFs, known for their exceptional structural robustness and chemical stability, are at the forefront of this rapidly evolving field. However, the development of defect chemistry in Zr‐MOFs has so far been limited to only a few examples and is generally tailored at the micro or nanocrystalline scale. In this work, we report that the in situ Tröger's base (TB) scaffold reconstruction, which occurs under the modular conditions typical for Zr‐MOF crystallization, can yield linker defective Zr‐MOF single‐crystals with sizes exceeding 300 μm. We designed three carboxylate‐functionalized V‐shaped TB ligands carrying distinct substituent (H, Me, and F). Upon crystallization with Zr 4+ ions, the methanodiazocine nucleus undergoes strap elimination reactions to produce planar diamine moieties. This skeleton reconstruction, accompanied by pronounced geometry reformation, engenders substantial lattice strain during the crystal growth, which in turn drives linker elimination and generates missing‐linker defects. The missing‐linker defects within the single‐crystals were thoroughly validated through a combination of complementary techniques. We also demonstrate that the large single‐crystals exhibit higher missing‐linker defect density than the microcrystalline powders, presumably due to the greater internal stress accumulated in the former. Moreover, the large single‐crystals with higher density of Lewis acidic Zr sites exhibit enhanced reactivity than the microcrystalline powders in the heterogeneous degradation of glyphosate (GPh), producing benign N ‐formyl glycine as the major product.