Insight into the Oriented Growth of Surface-Attached Metal–Organic Frameworks: Surface Functionality, Deposition Temperature, and First Layer Order

The layer-by-layer growth of a surface-attached metal–organic framework (SURMOF), [Cu₂­(F₄bdc)₂­(dabco)] (F₄bdc = tetrafluorobenzene-1,4-dicarboxylate and dabco = 1,4-diazabicyclo-[2.2.2]­octane), on carboxylate- and pyridine-terminated surfaces has been investigated by various surface characterization techniques. Particular attention was paid to the dependency of the crystal orientation and morphology on surface functionality, deposition temperature, and first layer order. For the fully oriented deposition of SURMOFs, not only a suitable surface chemistry but also the appropriate temperature has to be chosen. In the case of carboxylate-terminated surfaces, the expected [100] oriented [Cu₂(F₄bdc)₂(dabco)] SURMOF can be achieved at low temperatures (5 °C). In contrast, the predicted [001] oriented SURMOF on pyridine-terminated surface was obtained only at high deposition temperatures (60 °C). Interestingly, we found that rearrangement processes in the very first layer determine the final orientation (distribution) of the growing crystals. These effects could be explained by a surprisingly hampered substitution at the apical position of the Cu₂-paddle wheel units, which requires significant thermal activation, as supported by quantum-chemical calculations

A Hafnium-Based Metal–Organic Framework as an Efficient and Multifunctional Catalyst for Facile CO₂ Fixation and Regioselective and Enantioretentive Epoxide Activation

Porous heterogeneous catalysts play a pivotal role in the chemical industry. Herein a new Hf-based metal–organic framework (Hf-NU-1000) incorporating Hf₆ clusters is reported. It demonstrates high catalytic efficiency for the activation of epoxides, facilitating the quantitative chemical fixation of CO₂ into five-membered cyclic carbonates under ambient conditions, rendering this material an excellent catalyst. As a multifunctional catalyst, Hf-NU-1000 is also efficient for other epoxide activations, leading to the regioselective and enantioretentive formation of 1,2-bifuctionalized systems via solvolytic nucleophilic ring opening

Single-Site Organozirconium Catalyst Embedded in a Metal–Organic Framework

A structurally well-defined mesoporous Hf-based metal–organic framework (Hf-NU-1000) is employed as a well-defined scaffold for a highly electrophilic single-site d⁰ Zr–benzyl catalytic center. This new material Hf-NU-1000-ZrBn is fully characterized by a variety of spectroscopic techniques and DFT computation. Hf-NU-1000-ZrBn is found to be a promising single-component catalyst (i.e., not requiring a catalyst/activator) for ethylene and stereoregular 1-hexene polymerization

Targeted Single-Site MOF Node Modification: Trivalent Metal Loading via Atomic Layer Deposition

Postsynthetic functionalization of metal organic frameworks (MOFs) enables the controlled, high-density incorporation of new atoms on a crystallographically precise framework. Leveraging the broad palette of known atomic layer deposition (ALD) chemistries, <u>A</u>LD <u>i</u>n <u>M</u>OFs (AIM) is one such targeted approach to construct diverse, highly functional, few-atom clusters. We here demonstrate the saturating reaction of trimethylindium (InMe₃) with the node hydroxyls and ligated water of NU-1000, which takes place without significant loss of MOF crystallinity or internal surface area. We computationally identify the elementary steps by which trimethylated trivalent metal compounds (ALD precursors) react with this Zr-based MOF node to generate a uniform and well characterized new surface layer on the node itself, and we predict a final structure that is fully consistent with experimental X-ray pair distribution function (PDF) analysis. We further demonstrate tunable metal loading through controlled number density of the reactive handles (−OH and −OH₂) achieved through node dehydration at elevated temperatures

A Hafnium-Based Metal–Organic Framework as a Nature-Inspired Tandem Reaction Catalyst

Tandem catalytic systems, often inspired by biological systems, offer many advantages in the formation of highly functionalized small molecules. Herein, a new metal–organic framework (MOF) with porphyrinic struts and Hf₆ nodes is reported. This MOF demonstrates catalytic efficacy in the tandem oxidation and functionalization of styrene utilizing molecular oxygen as a terminal oxidant. The product, a protected 1,2-aminoalcohol, is formed selectively and with high efficiency using this recyclable heterogeneous catalyst. Significantly, the unusual regioselective transformation occurs only when an Fe-decorated Hf₆ node and the Fe–porphyrin strut work in concert. This report is an example of concurrent orthogonal tandem catalysis

Correction to “A Hafnium-Based Metal–Organic Framework as a Nature-Inspired Tandem Reaction Catalyst”

Correction to “A Hafnium-Based Metal–Organic Framework as a Nature-Inspired Tandem Reaction Catalyst