Hierarchical Porous Metal-organic Framework Research Articles

Facile Construction of Stable Hierarchical Porous Metal–Organic Frameworks for In Situ Immobilization of β-Glucosidase Based on Competitive Coordination and Selective Etching Strategies

Facile Construction of Stable Hierarchical Porous Metal–Organic Frameworks for In Situ Immobilization of β-Glucosidase Based on Competitive Coordination and Selective Etching Strategies

A linker selective retention strategy to construct hierarchical porous metal-organic frameworks with high catalytic activity for oxidative desulfurization.

In order to improve the oxidative desulfurization (ODS) performance of MOF materials, an effective way is to convert a microporous MOF into a hierarchical porous MOF (HP-MOF) by utilizing the linker selective retention strategy. Herein, UiO-66 with the introduction of an unstable linker ligand (dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate, dhtz) can selectively remove dhtz ligands to form HP-MOF (HP-UiO-66-dhtz) through heat treatment at high temperature. While maintaining the original structure of UiO-66, HP-UiO-66-dhtz features mesopores and abundant Lewis acid sites, showing excellent ODS performance for diphenylthiophene (DBT).

Trimodal Hierarchical Porous Metal–Organic Frameworks with Tunable Mesoporous Core–Shell Architectures

Trimodal Hierarchical Porous Metal–Organic Frameworks with Tunable Mesoporous Core–Shell Architectures

Hierarchically porous amino-functionalized nanoMOF network anchored phosphomolybdic acid for oxidative desulfurization and shaping application

The applications of hierarchically porous metal–organic frameworks (HP-MOFs) against traditional microporous counterparts for oxidative desulfurization (ODS) have triggered wide research interests due to their highly exposed accessible active sites and fast mass transfer of substrate molecules, particularly for the large-sized refractory sulfur compounds. Herein, a series of hierarchically porous amino-functionalized Zr-MOFs (HP-UiO-66-NH2-X) network with controllable mesopore sizes (3.5–9.2 nm) were firstly prepared through a template-free method, which were further utilized as anchoring support to bind the active phosphomolybdic acid (PMA) via the strong host–guest interaction to catalyze the ODS reaction. Benefitting from the hierarchically porous structure, accessible active sites and the strong host–guest interaction, the resultant PMA/HP-UiO-66-NH2-X exhibited excellent ODS performance, of which, the PMA/HP-UiO-66-NH2-9 with an appropriate mesopore size (4.0 nm) showed the highest catalytic activity, achieving a 99.9% removal of dibenzothiophene (DBT) within 60 min at 50 °C, far exceeding the microporous sample and PMA/HP-UiO-66. Furthermore, the scavenger experiments confirmed that •OH radical was the main reactive species and the density functional theory (DFT) calculations revealed that electron transfer (from amino group to PMA) made PMA react more easily with oxidant, thereby generating more •OH radical to promote the ODS reaction. Finally, from the industrial point of view, the powdered MOF nanoparticles (NPs) were in situ grown on the carboxymethyl cellulose (CMC) substrates and shaped into monolithic MOF-based catalysts, which still exhibited satisfying ODS performance in the case of model real fuel with good reusability, indicating its potential industrial application prospect.

Spray synthesis of hierarchical porous metal-organic framework HKUST-1 with soft templates and methylene blue adsorption performance

We synthesize hierarchical porous HKUST-1 (HP-HKUST-1) with micropores, mesopores, and macropores using the spray synthesis and soft template methods. We utilize two types of structure-directing agents (SDAs), namely cetyltrimethylammonium bromide and citric acid for C-HKUST-1 and triblock copolymer P123 for P-HKUST-1. Paq-HKUST-1 is successfully synthesized using only water as the solvent. The volumes of the mesopores and macropores are changed by the amounts of SDAs. The highest values are: 0.78 and 0.30 cm3/g for C-HKUST-1; 0.44 and 0.38 cm3/g for P-HKUST-1; and 0.30 and 0.23 cm3/g for Paq-HKUST-1, respectively. HP-HKUST-1 shows high methylene blue (MB) adsorption rates and capacities of over 700 mg/g owing to its HP structure. In particular, C-HKUST-1 exhibits a rate constant of 19.7 mg/mg min for MB adsorption based on the pseudo-second-order adsorption kinetic model. This rate constant is 10 times higher than that of batch-synthesized HKUST-1. Furthermore, HP-HKUST-1 exhibits good stability for reuse as an MB adsorbent.

Fabrication of a bifunctional fluorescent chiral composite based on magnetic Fe3O4/chiral carbon dots@hierarchical porous metal-organic framework

Considering the selective pharmacological activity and ecotoxicity of chiral drugs, the development of chiral materials with the dual functions of enantiomeric recognition and adsorption is of great significance. Herein, a novel bifunctional chiral composite (Fe3O4/CCDs@HP-ZIF-8) which does not contain expensive and rare fluorescent chiral ligands or metal ions, was constructed for the first time by encapsulating chiral carbon dots (CCDs) and magnetic Fe3O4 nanoparticles into hierarchical porous metal-organic frameworks (HP-MOFs). Fe3O4/CCDs@HP-ZIF-8, which integrates fluorescent chiral property, magnetism, and hierarchical porosity, shows enormous potential in enantiomeric recognition and adsorption. Fluorescence detection results demonstrate that Fe3O4/CCDs@HP-ZIF-8 presents different fluorescence quenching for naproxen enantiomers. The limits of detection are determined to be 0.05 μM for S-naproxen (S-Nap) and 0.30 μM for R-naproxen (R-Nap), respectively. Furthermore, the isothermal, kinetic, and thermodynamic adsorption behaviors of Fe3O4/CCDs@HP-ZIF-8 to naproxen enantiomers were systematically studied. Due to its hierarchical porosity, the composite exhibits higher adsorption capacity to naproxen enantiomers compared to the non-hierarchical porous composite. Studies of enantiomeric recognition and adsorption mechanisms affirm that the synergistic effect of multiple mechanisms exists between Fe3O4/CCDs@HP-ZIF-8 and naproxen enantiomers. Finally, the satisfactory recoveries and relative standard deviations in the actual sample assays demonstrate the practicality of Fe3O4/CCDs@HP-ZIF-8 for S-Nap detection. This non-destructive functionalization method creates an innovative pathway for developing advanced multifunctional chiral materials, holding great promise for enantiomeric recognition and adsorption.

Template-Free Synthesis and Multifunctional Application of Foam HKUST-1.

Hierarchically porous metal-organic frameworks (HP-MOFs) have attracted a lot of attention in recent years because their hierarchical pores have critical importance in strengthening their performance, including guest diffusion kinetics, catalytic activity, and selectivity, especially with reference to large molecules. However, the preparation method for simple, controllable, and stable HP-MOFs at a micro-/meso-/macroscopic scale is still lacking. Herein, we showed several forms of HKUST-1 (HKUST = Hong Kong University of Science and Technology) by simply changing the copper source and solvent type, including original micron HKUST-1 (O-HKUST-1), half-foam HKUST-1 (HF-HKUST-1), and fully foam HKUST-1 (F-HKUST-1). Compared to O-HKUST-1, HF-HKUST-1 and F-HKUST-1 possessed an apparent hierarchically porous structure due to the high fusion of HKUST-1 nanocrystals. Especially in F-HKUST-1, all of the HKUST-1 nanocrystals were tightly integrated into each other, which formed a holistic hollow foam structure. Hence, F-HKUST-1 exhibited the highest adsorption capacity toward large molecules, including proteases, phosphotungstic acid, and organic dyes. Meanwhile, F-HKUST-1 presented the highest photocatalytic degradation capability for rhodamine B. Furthermore, F-HKUST-1, loaded with phosphotungstic acid (F-HKUST-1@PTA), which was used as a catalyst, indicated a catalytic capacity comparable to that of a homogeneous catalyst (pure phosphotungstic acid).

Facile synthesis of hierarchical porous MOFs via competition coordination strategy: A sustainable adsorbent for efficient removal of fluorine-containing drugs

Construction of hierarchically porous structure of metal–organic frameworks (MOFs) can improve the accessibility of active sites and mass transfer rate to improve practical applications effects such as adsorption efficiency. Rapid synthesis of hierarchically porous MOFs (HP-MOFs) at an industrial scale is extremely important from the perspective of sustainable development and economical practicality. Here, we propose a strategy to rapidly synthesize HP-MOFs at room temperature, using hydroxy double salts (HDS) as an intermediate to combine two ligands with different electronegativity to generate competitive coordination during the nucleation stage. Using this method, we can obtain HP-Zn-MOFs within 20 min at room temperature, with larger pores (average pore size > 8 nm) and higher space–time yield (STY > 3000 kg m−3 d−1). All the raw materials are low cost and low toxicity, which is consistent with the concept of green chemistry. More than that, the as-synthesized HP-Zn-MOFs have an excellent adsorption effect in removing fluorine-containing drugs (FCDs) through multiple interactions, showing good reusability, practical application, and good adsorption for other drugs. This work demonstrates the feasibility of the green synthesis of HP-MOFs through competition coordination methods at room temperature, which highlights the potential for the elimination of contaminants.

Hierarchical Porous Metal-Organic Framework as Biocatalytic Microreactor for Enzymatic Biofuel Cell-Based Self-Powered Biosensing of MicroRNA Integrated with Cascade Signal Amplification.

Enzymatic biofuel cells have become powerful tools in biosensing, which however generally suffer from the limited loading efficiency as well as low catalytic activity and poor stability of bioenzymes. Herein, the hierarchical porous metal-organic frameworks (MOFs) are synthesized using tannic acid (TA) for structural etching, which realizes co-encapsulation of glucose dehydrogenase (GDH) and nicotinamide adenine dinucleotide (NAD+ ) cofactor in zeolitic imidazolate framework (ZIF-L) and are further used as the biocatalytic microreactors to modify bioanode. In this work, the TA-controlled etching can not only expand the pore size of microreactors, but also achieve the reorientation of enzymes in their lower surface energy form, therefore enhancing the biocatalysis of cofactor-dependent enzyme. Meanwhile, the topological DNA tetrahedron is assembled on the microreactors, which acts as the microRNA-responsive "lock" to perform the cascade signal amplification of exonuclease III-assisted target recycling on bioanode and hybridization chain reaction (HCR) on biocathode. The proposed self-powered biosensor has achieved a detection limit as low as 2 aM (6 copies miRNA-21 in a 5µL of sample), which is further successfully applied to identify cancer cells and clinical serums of breast cancer patients based on the different levels of miRNA-21, holding great potential in accurate disease identification and clinical diagnosis.

Construction of dual-hydrophilic metal-organic framework with hierarchical porous structure for efficient glycopeptide enrichment

As an important role in life activities, it is necessary and important to study protein glycosylation. The pre-enrichment of N-glycopeptides is a significant step in glycoproteomics research. According to the inherent size, hydrophilicity and other properties of N-glycopeptides, affinity materials designed to match them will be able to separate N-glycopeptides from complex samples. In this work, we designed and prepared dual-hydrophilic hierarchical porous metal-organic frameworks (MOFs) nanospheres by metal-organic assembly (MOA) based template method and post-synthesis modification strategy. The hierarchical porous structure significantly improved the diffusion rate and binding sites for N-glycopeptide enrichment. Furthermore, the combination of hydrophilic MOFs and small molecules endowed the as-prepared MOFs nanospheres excellent hydrophilicity, which is conducive to the enrichment of N-glycopeptides based on hydrophilic interaction liquid chromatography (HILIC). Therefore, the nanospheres showed surprising enrichment ability for N-glycopeptides such as excellent selectivity (1/500, human serum immunoglobulin G/bovine serum albumin, m/m) and extremely low detective limitation (0.5 fmol). Meanwhile, 550 N-glycopeptides were identified from rat liver samples, proving its application potential in glycoproteomics research and providing design idea for porous affinity materials.

Hierarchical porous metal organic framework aerogel for highly efficient CO2 adsorption

Sustainable low-carbon economy has attracted global attention, and the development of advanced CO2 capture technology has become an important undertaking. Metal organic frameworks (MOFs) featured with high specific surface area and large porosity have held the promise for CO2 adsorption, but the micron scale make them difficult to handle, leading to easily be blown away, pipeline blockage, and the decline of adsorption capacity. Here, we demonstrate a novel strategy to develop a nanoporous HKUST-1 aerogel with hierarchical pore structure by combining HKUST-1 and aramid nanofiber for promoting CO2 adsorption. The resultant HKUST-1 aerogel has a low density of 5.86 mg/cm3, high specific surface area of 636.62 m2g−1, and hierarchical porosity of 99.33 %. The meso-/macropores of HKUST-1 aerogel can act as gas transfer channels to facilitate the transport CO2 into the HKUST-1, and the micropores of HKUST-1 provide active sites for CO2 adsorption. Benefitting from the synergistic effect of the hierarchical pore structure, the HKUST-1 aerogel demonstrates high CO2 adsorption capacity of 7.29 mmol/g, and high adsorption selectivity of 39 for CO2/N2 and 42 for CO2/O2. This novel design may provide a reliable theoretical and experimental basis for the development of MOF aerogel as CO2 adsorbent candidate for environmental purification.

Advances in enzyme immobilization based on hierarchical porous metal-organic frameworks

As an excellent hosting matrices for enzyme immobilization, metal-organic framework (MOFs) provides superior physical and chemical protection for biocatalytic reactions. In recent years, the hierarchical porous metal-organic frameworks (HP-MOFs) have shown great potential in enzyme immobilization due to their flexible structural advantages. To date, a variety of HP-MOFs with intrinsic or defective porous have been developed for the immobilization of enzymes. The catalytic activity, stability and reusability of enzyme@HP-MOFs composites are significantly enhanced. This review systematically summarized the strategies for developing enzyme@HP-MOFs composites. In addition, the latest applications of enzyme@HP-MOFs composites in catalytic synthesis, biosensing and biomedicine were described. Moreover, the challenges and opportunities in this field were discussed and envisioned.

Macro‐/mesoporous Metal–Organic Frameworks Templated by Amphiphilic Block Copolymers Enable Enhanced Uptake of Large Molecules

AbstractThe first synthesis of hierarchical porous metal–organic frameworks (HP‐MOFs) is reported through a solvent evaporation‐induced co‐assembly of polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) and MOF building blocks. The growth of MOFs is restricted to confined spaces formed by self‐assembled PS‐b‐PEO, and mesopores and/or macropores are created after removing PS‐b‐PEO by solvent rinsing. This approach avoids phase separation and competitive interactions between templates and MOF building blocks. Both amorphous and crystalline HP‐MOFs can be synthesized by finely controlling MOF growth conditions. Additionally, HP‐MOFs (ZIF‐L sheets) with honeycomb‐like channels show significantly enhanced incorporation of large guest molecules compared to microporous MOFs. This study establishes an efficient synthetic strategy for preparing HP‐MOFs with highly accessible mesopores and macropores for applications involving large molecules.

CO2-Switchable Hierarchically Porous Zirconium-Based MOF-Stabilized Pickering Emulsions for Recyclable Efficient Interfacial Catalysis.

Stimuli-responsive Pickering emulsions are recently being progressively utilized as advanced catalyzed systems for green and sustainable chemical conversion. Hierarchically porous metal-organic frameworks (H-MOFs) are regarded as promising candidates for the fabrication of Pickering emulsions because of the features of tunable porosity, high specific surface area and structure diversity. However, CO2-switchable Pickering emulsions formed by hierarchically porous zirconium-based MOFs have never been seen. In this work, a novel kind of the amine-functionalized hierarchically porous UiO-66-(OH)2 (H-UiO-66-(OH)2) has been developed using a post-synthetic modification of H-UiO-66-(OH)2 by (3-aminopropyl)trimethoxysilane (APTMS), 3-(2-aminoethylamino)propyltrimethoxysilane (AEAPTMS) and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AEAEAPTMS), and employed as emulsifiers for the construction of Pickering emulsions. It was found that the functionalized H-UiO-66-(OH)2 could stabilize a mixture of toluene and water to give an emulsion even at 0.25 wt % content. Interestingly, the formed Pickering emulsions could be reversibly transformed between demulsification and re-emulsification with alternate addition or removal of CO2. Spectral investigation indicated that the mechanism of the switching is attributed to the reaction of CO2 with amino silane on the MOF and the generation of hydrophilic salts, leading to a reduction in MOF wettability. Based on this strategy, a highly efficient and controlled Knoevenagel condensation reaction has been gained by using the emulsion as a mini-reactor and the emulsifier as a catalyst, and the coupling of catalysis reaction, product isolation and MOF recyclability has become accessible for a sustainable chemical process.

Nanoporous Zeolitic Imidazolate Framework-8 Nanoparticles for Arsenic Removal

Herein, we report a solvent-free self-templating strategy for rapid synthesis of nanoscale hierarchically porous zeolitic imidazolate framework-8 (HP-ZIF-8) with micro-, meso-, and macropores. ZIF-8 crystals were produced in situ on ZnO nanoparticles via vapor deposition of 2-methylimidazole, and hierarchical nanopores were obtained after selectively etching ZnO. ZnO nanoparticles acted as both a Zn source and a meso-/macropore template for HP-ZIF-8. Systematic arsenic adsorption experiments showed that the presence of meso-/macropores can effectively enhance and accelerate arsenic removal via chemisorption. As a result, HP-ZIF-8 exhibited an As(III) adsorption capacity of 104.9 mg/g, nearly double that of traditional ZIF-8 nanoparticles, despite having remarkably more micropores. This study provides a highly adsorbable strategy to fabricate hierarchical porous metal–organic frameworks for pollutant removal.

Hierarchically Porous Metal–Organic Frameworks: Synthetic Strategies and Applications

Hierarchically Porous Metal-Organic Frameworks The development of hierarchically porous metal-organic frameworks (HP-MOFs) has attracted considerable interest because these materials have exceptional advantages associated with the strengths of micropores and meso-/macropores. In article number 2200187, Banglin Chen, Xiaoyu Yang, Ganggang Chang, and co-workers review recent advances and breakthroughs in the synthesis and applications of HP-MOFs, emphasizing the relationships that exist between structure and applications.

A new ligand-regulated strategy of highly mesoporous metal–organic framework assembled in ionic liquid/ethanol solvent

The hierarchical porous metal–organic frameworks catalysts were synthesized by ligand regulation in ionic liquid/ethanol system for the first time. The porosity and morphology could be tuned by the mass fraction...

Co@ZIF‐8/TiO2 heterojunction for green hydrogen generation

A wet‐incipient impregnation method was reported to synthesize hierarchical porous bimetallic (Co, Zn)‐zeolitic imidazolate frameworks (ZIF‐8)/TiO2 (Co@ZIF‐8/TiO2) for green hydrogen generation via photocatalytic water splitting. Co@ZIF‐8/TiO2 showed higher photocatalytic efficiency than TiO2, with a hydrogen generation rate (HGR) of 13 mmol·h−1·g−1 with a 151‐fold increase in the catalytic performance of TiO2. The photocatalytic HGR of Co@ZIF‐8/TiO2 was superior to that of the ZIF‐8/TiO2 heterostructure. Co@ZIF‐8 showed a hierarchical porous structure containing micropores and mesopores regimes, providing a proficient transport channel for charge transfer. This study presents new prospects for using hierarchical porous metal–organic frameworks (MOFs) as support and promoter in photocatalytic applications of semiconductor such as TiO2.

Hierarchical porous metal-organic framework composite with inorganic fillers for high-performance Li+ ions transport

A quasi-solid-state electrolyte (QSSE) based on the hierarchical porous metal-organic framework (MOF) materials mixed with inorganic fillers Zeolite Socony Mobil-5 (ZSM-5) have been prepared for application of lithium ion battery, exhibiting effective storage and transportation capacity for lithium ions. The as-prepared lithium ion transports material demonstrated high ion conductivity (σ = 1.51 ×10−3 S/cm) and Li+ transference number (tLi+ = 0.80). Additionally, the electrolyte displays a wide electrochemical window with excellent electrochemical stability. Importantly, the lithium ion battery of LiFePO4 as the cathode has excellent rate capability and cycle durability, showing a new prospect of high-performance lithium-ion batteries.

Hierarchically Ultrasmall Hf-Based MOF: Mesopore Adjustment and Reconstruction by Recycle Using Acid Etching Strategy

Benefiting from their unique properties including faster mass transfer, more exposed active sites and large molecule recognition, hierarchically porous metal–organic frameworks (HP-MOFs), in the form of ultrasmall nanoparticles (NPs) and having self-assembled interparticle mesopores, have garnered greater attention in recent years that given to typical MOFs. However, controllable synthesis of HP-MOFs on the nanoscale remains a significant challenge. Herein, for the first time, a facile top-down acid etching strategy was developed to fabricate a series of nanosized (∼15 nm) mesoporous MOF, HP-UiO-66-NH2(Hf). The sizes of mesopores in this material can be effectively tuned by simply controlling the concentration of propionic acid (PA) utilized in the preparation solution. Interestingly, the generated mesoporous HP-UiO-66-NH2(Hf) has excellent stability and can be readily constructed by using PA etching solution that has been recycled at least four times. Remarkably, HP-UiO-66-NH2(Hf) displays a high size-selectivity for adsorption of enzymes. Associated with its highly matched mesopore size, the nanocomposite generated by complexation with glucose oxidase (GOD), GOD@HP-UiO-66-NH2(Hf) has a higher catalytic activity and a significantly enhanced stability (recycled at least 7 times) in promoting oxidation of glucose compared to its MOF counterpart, GOD@UiO-66-NH2(Hf) and native GOD.