Search for: All records

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) containing open metal sites are advantageous for wide applications. Here, carboxylate linkers are replaced with triazolate coordination in pre-formed Zn-MOF-74 via solvent-assisted linker exchange (SALE) to prepare the novel NU-250, within the known hexagonal channel-based MAF-X25 series that has not previously been synthesized de novo . 

Boron trifluoride (BF₃) is a highly corrosive gas widely used in industry. Confining BF₃in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF₃corrosion. Herein, we designed and synthesized a Lewis basic single‐crystalline hydrogen‐bond crosslinked organic framework (H_COF‐50) for BF₃storage and its application in catalysis. Specifically, we introduced self‐complementaryortho‐alkoxy‐benzamide hydrogen‐bonding moieties to direct the formation of highly organized hydrogen‐bonded networks, which were subsequently photo‐crosslinked to generate H_COFs. The H_COF‐50 features Lewis basic thioether linkages and electron‐rich pore surfaces for BF₃uptake. As a result, H_COF‐50 shows a record‐high 14.2 mmol/g BF₃uptake capacity. The BF₃uptake in H_COF‐50 is reversible, leading to the slow release of BF₃. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF₃ ⋅ Et₂O. The elucidation of the structure–property relationship, as provided by the single‐crystal X‐ray structures, combined with the high BF₃uptake capacity and controlled sorption, highlights the molecular understanding of framework‐guest interactions in addressing contemporary challenges.

 

Boron trifluoride (BF₃) is a highly corrosive gas widely used in industry. Confining BF₃in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF₃corrosion. Herein, we designed and synthesized a Lewis basic single‐crystalline hydrogen‐bond crosslinked organic framework (H_COF‐50) for BF₃storage and its application in catalysis. Specifically, we introduced self‐complementaryortho‐alkoxy‐benzamide hydrogen‐bonding moieties to direct the formation of highly organized hydrogen‐bonded networks, which were subsequently photo‐crosslinked to generate H_COFs. The H_COF‐50 features Lewis basic thioether linkages and electron‐rich pore surfaces for BF₃uptake. As a result, H_COF‐50 shows a record‐high 14.2 mmol/g BF₃uptake capacity. The BF₃uptake in H_COF‐50 is reversible, leading to the slow release of BF₃. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF₃ ⋅ Et₂O. The elucidation of the structure–property relationship, as provided by the single‐crystal X‐ray structures, combined with the high BF₃uptake capacity and controlled sorption, highlights the molecular understanding of framework‐guest interactions in addressing contemporary challenges.