Tailoring the Adsorption and Reaction Chemistry of the Metal–Organic Frameworks UiO-66, UiO-66-NH₂, and HKUST‑1 via the Incorporation of Molecular Guests

Metal–organic frameworks (MOFs) are versatile materials highly regarded for their porous nature. Depending on the synthetic method, various guest molecules may remain in the pores or can be systematically loaded for various reasons. Herein, we present a study that explores the effect of guest molecules on the adsorption and reactivity of the MOF in both the gas phase and solution. The differences between guest molecule interactions and the subsequent effects on their activity are described for each system. Interestingly, different effects are observed and described in detail for each class of guest molecules studied. We determine that there is a strong effect of alcohols with the secondary building unit of UiO MOFs, while Lewis bases have an effect on the reactivity of the −NH₂ group in UiO-66-NH₂ and adsorption by the coordinatively unsaturated copper sites in HKUST-1. These effects must be considered when determining synthesis and activation methods of MOFs toward various applications

Facile Synthesis and Direct Activation of Zirconium Based Metal–Organic Frameworks from Acetone

In recent years much emphasis has been placed on the synthesis of highly novel metal–organic frameworks (MOFs) with general disregard to development of sustainable synthesis techniques. A novel synthesis of UiO-66 and UiO-66-NH₂, two highly stable MOFs that have shown much promise in the area of catalysis and reactive removal of small molecules, from acetone is demonstrated here. Using this method, the MOFs can be activated by simple heating under vacuum without the need for solvent exchange, which can be a timely processing step that requires the use of large amounts of solvent. The activity of the series of MOFs synthesized at various temperatures was determined by the rate of hydrolysis of methyl paraoxon and the reactive capacity of UiO-66-NH₂ with chlorine gas. Direct correlations were observed between synthesis temperature, crystallinity, BET surface area, and activity of the MOFs

Direct Surface Growth Of UIO-66-NH₂ on Polyacrylonitrile Nanofibers for Efficient Toxic Chemical Removal

Direct solvothermal growth of the metal–organic framework (MOF) UiO-66-NH₂ on polymer surface was successfully demonstrated. By using acetone as the solvent for synthesis instead of <i>N</i>,<i>N</i>-dimethylformamide, polymers like polyacrylonitrile (PAN) can be used directly in the solvothermal synthesis step to grow MOF on the polymer surface. We use X-ray diffraction and FT-IR to confirm our method produces crystalline UiO-66-NH2 on the surface of electrospun PAN nanofibers. Characterization of this type of composite revealed up to 50 wt % MOF loading according to nitrogen isotherms. Since the MOFs are located on the surface of the polymer fibers, the composites are capable of high loadings of chlorine gas. Compared to electrospun composites made with preformed UiO-66-NH₂, the in situ method is a simple alternative that produces composites with higher MOF loading

Polymer–Metal–Organic Frameworks (polyMOFs) as Water Tolerant Materials for Selective Carbon Dioxide Separations

Recently, polymer–metal–organic frameworks (polyMOFs) were reported as a new class of hybrid porous materials that combine advantages of both organic polymers and crystalline MOFs. Herein, we report a bridging coligand strategy to prepare new types of polyMOFs, demonstrating that polyMOFs are compatible with additional MOF architectures besides that of the earlier reported IRMOF-1 type polyMOF. Gas sorption studies revealed that these polyMOF materials exhibited relatively high CO₂ sorption but very low N₂ sorption, making them promising materials for CO₂/N₂ separations. Moreover, these polyMOFs demonstrated exceptional water stability attributed to the hydrophobicity of polymer ligands as well as the cross-linking of the polymer chains within the MOF

Polymer–Metal–Organic Frameworks (polyMOFs) as Water Tolerant Materials for Selective Carbon Dioxide Separations

Recently, polymer–metal–organic frameworks (polyMOFs) were reported as a new class of hybrid porous materials that combine advantages of both organic polymers and crystalline MOFs. Herein, we report a bridging coligand strategy to prepare new types of polyMOFs, demonstrating that polyMOFs are compatible with additional MOF architectures besides that of the earlier reported IRMOF-1 type polyMOF. Gas sorption studies revealed that these polyMOF materials exhibited relatively high CO₂ sorption but very low N₂ sorption, making them promising materials for CO₂/N₂ separations. Moreover, these polyMOFs demonstrated exceptional water stability attributed to the hydrophobicity of polymer ligands as well as the cross-linking of the polymer chains within the MOF