A series of nine Ce(iv)-based metal organic frameworks with the UiO-66 structure containing linker molecules of different sizes and functionalities were obtained under mild synthesis conditions and short reaction times. Thermal and chemical stabilities were determined and a Ce-UiO-66-BDC/TEMPO system was successfully employed for the aerobic oxidation of benzyl alcohol.

Over the past decade, the zirconium-terephthalate UiO-66 has evolved into one of the most intensely studied metal–organic frameworks (MOFs) to date. Among the most fascinating and pervasive features of this material are defects, and their influence on a multitude of its properties. However, the simultaneous occurrence of two defect types, missing linkers and missing nodes, limits the extent to which certain material properties can be accurately matched to the framework’s defect structure. In this contribution, we present a strategy to unequivocally create missing linker defects in UiO-66, by first synthesizing terephthalate frameworks doped with a thermolabile linker, trans-1,4-cyclohexane-dicarboxylate (cdc), followed by postsynthetic thermal decomposition of the latter. Characterization of the mixed-linker materials before and after cdc removal by powder X-ray diffraction, thermogravimetric analysis, N2 physisorption, and NMR spectroscopy confirmed a homogeneous distribution of cdc, and thus also of the formed defects, throughout the materials. The UiO-66 structure is shown to tolerate up to 4.3 missing linker defects per [Zr6O4(OH)4]12+ node, with higher defect densities compromising the framework’s structural integrity and porosity. Importantly, no increase in specific surface area was seen after additional missing linker defects were formed, providing compelling evidence that high porosity often observed in modulated UiO-66 samples should rather be attributed to missing cluster defects.

Peptide bond hydrolysis catalyzed by NU-1000 MOF revealed key structural features that influence the catalytic performance of Zr₆ based MOFs.

Heterogeneous palladium single-site MOF catalysts for the oxidative coupling of arenes via C–H/C–H: superior TONs due to active site isolation.

While titanium-based metal-organic frameworks (MOFs) have been widely studied for their (photo)catalytic potential, only a few Ti IV MOFs have been reported due to the high reactivity of the employed titanium precursors. Here, we present the synthesis of COK-47, the first Ti carboxylate MOF based on sheets of Ti IV O6 octahedra, which can be synthesized with a range of different linkers. COK-47 can be synthesized as an inherently defective nanoparticulate material, rendering it a highly efficient catalyst for the oxidation of thiophenes. Its structure was determined by continuous rotation electron diffraction and studied in depth by X-ray total scattering, EXAFS and solid-state NMR. In addition, its photoactivity was investigated via electron paramagnetic resonance and demonstrated by catalytic photodegradation of rhodamine 6G. Metal-organic frameworks (MOFs) are crystalline coordination polymers constructed through the directional bonding of metal ions and polydentate organic linkers, forming often porous networks. Over the last decade, MOFs have increasingly been investigated because of their highly tunable porosity and large density of accessible metal sites, making them suitable for catalytic applications, gas separation and storage. [1-4] However, developing chemically and thermally robust materials remains challenging. This has fueled interest in using oxophilic group IV elements such as Zr IV and Ti IV , which tend to form stable structures based on their strong metal-carboxylate bonds. In this context, numerous Zr MOFs have been reported, [5] but only 15 Ti IV MOFs have been described to date, of which 5 in the last year, even though Ti precursors are cheap, non-toxic and Ti MOFs show good redox-and photoactivity. [6-8] The much higher tendency of Ti IV to form ill-defined oxyhydroxides lies at the basis of this discrepancy and makes the synthesis of Ti MOFs extremely challenging.