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Functional porous metal–organic frameworks (MOFs) have been explored for a number of potential applications in catalysis, chemical sensing, water capture, gas storage, and separation. MOFs are among the most promising candidates to address challenges facing our society related to energy and environment, but the successful implementation of functional porous MOF materials are contingent on their stability; therefore, the rational design of stable MOFs plays an important role towards the development of functional porous MOFs. In this Focus article, we summarize progress in the rational design and synthesis of stable MOFs with controllable pores and functionalities. The implementation of reticular chemistry allows for the rational top-down design of stable porous MOFs with targeted topological networks and pore structures from the pre-selected building blocks. We highlight the reticular synthesis and applications of stable MOFs: (1) MOFs based on high valent metal ions ( e.g. , Al 3+ , Cr 3+ , Fe 3+ , Ti 4+ and Zr 4+ ) and carboxylate ligands; (2) MOFs based on low valent metal ions ( e.g. , Ni 2+ , Cu 2+ , and Zn 2+ ) and azolate linkers. We envision that the synthetic strategies, including modulated synthesis and post-synthetic modification, can potentially be extended to other more complex systems like metal-phosphonate framework materials. 

Since the structure of supramolecular isomers determines their performance, rational synthesis of a specific isomer hinges on understanding the energetic relationships between isomeric possibilities. To this end, we have systematically interrogated a pair of uranium-based metal–organic framework topological isomers both synthetically and through density functional theory (DFT) energetic calculations. Although synthetic and energetic data initially appeared to mismatch, we assigned this phenomenon to the appearance of a metastable isomer, driven by levers defined by Le Châtelier's principle. Identifying the relationship between structure and energetics in this study reveals how non-equilibrium synthetic conditions can be used as a strategy to target metastable MOFs. Additionally, this study demonstrates how defined MOF design rules may enable access to products within the energetic phase space which are more complex than conventional binary ( e.g. , kinetic vs. thermodynamic) products. 

Metal–organic frameworks (MOFs) with Lewis acid catalytic sites, such as zirconium‐based MOFs (Zr‐MOFs), comprise a growing class of phosphatase‐like nanozymes that can degrade toxic organophosphate pesticides and nerve agents. Rationally engineering and shaping MOFs from as‐synthesized powders into hierarchically porous monoliths is essential for their use in emerging applications, such as filters for air and water purification and personal protection gear. However, several challenges still limit the production of practical MOF composites, including the need for sophisticated reaction conditions, low MOF catalyst loadings in the resulting composites, and poor accessibility to MOF‐based active sites. To overcome these limitations, a rapid synthesis method is developed to introduce Zr‐MOF nanozyme coating into cellulose nanofibers, resulting in the formation of processable monolithic aerogel composites with high MOF loadings. These composites contain Zr‐MOF nanozymes embedded in the structure, and hierarchical macro‐micro porosity enables excellent accessibility to catalytic active sites. This multifaceted rational design strategy, including the selection of a MOF with many catalytic sites, fine‐tuning the coating morphology, and the fabrication of a hierarchically structured monolithic aerogel, renders synergistic effects toward the efficient continuous hydrolytic detoxification of organophosphorus‐based nerve agent simulants and pesticides from contaminated water.

 

The interactions between uranium and non‐innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium‐based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self‐assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non‐innocent linkers. We report the synthesis of the MOFNU‐1700, assembled from U⁴⁺‐paddlewheel nodes and catecholate‐based linkers. We propose this highly unusual structure, which contains two U⁴⁺ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X‐ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations.

 

The interactions between uranium and non‐innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium‐based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self‐assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non‐innocent linkers. We report the synthesis of the MOFNU‐1700, assembled from U⁴⁺‐paddlewheel nodes and catecholate‐based linkers. We propose this highly unusual structure, which contains two U⁴⁺ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X‐ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations.

 

The synthesis of [1,1′-bis( o -carboranyl)]boranes was achieved through the deprotonation of 1,1′-bis( o -carborane) reagents followed by salt metathesis with ( i Pr) 2 NBCl 2 . X-ray crystallography confirms planar central BC 4 rings and Gutmann–Beckett studies reveal an increase in Lewis acidity at the boron center in comparison to their biphenyl congener, 9-borafluorene. 

Hierarchically ordered porous materials with tailored and inter‐connected macro‐, meso‐, and micro‐pores would facilitate the heterogeneous adsorption and catalysis processes for a wide range of applications but remain a challenge for synthetic chemists. Here, a general and efficient strategy for the synthesis of inverse opal metal–organic frameworks (IO MOFs) with a tunable size of macro‐, meso‐, and micro‐pores is reported. The strategy is based on the step‐wise template formation, precursor infiltration, solvo‐thermal reaction, and chemical etching. As a proof of the general applicability of this strategy, a series of inverse opal zirconium‐based MOFs with intrinsic micro‐ and/or meso‐pores, including UiO‐66, MOF‐808, NU‐1200, NU‐1000 and PCN‐777, and tunable macropores (1 µm, 2 µm, 3 µm, 5 µm, and 10 µm), have been prepared with outstanding yields. These IO MOFs demonstrate significantly enhanced absorption rates and faster initial hydrolysis rates for organophosphorus (OPs) aggregates compared to those of the pristine MOFs. This work paves the way for the further development of hierarchically ordered MOFs for advanced applications.