Applications of metal-organic frameworks featuring multi-functional sites

Highly Stable Lanthanide Metal-Organic Framework as an Internal Calibrated Luminescent Sensor for Glutamic Acid, a Neuropathy Biomarker

Glutamic acid (Glu) is the most abundant excitatory neurotransmitter in the central nervous system, and an elevated level of Glu may indicate some neuropathological diseases. Herein, three isomorphic microporous lanthanide metal-organic frameworks (MOFs) [(CH₃)₂NH₂]₂[Ln₆(μ₃-OH)₈(BDC-OH)₆(H₂O)₆]·(solv)_x (ZJU-168; ZJU = Zhejiang University, H₂BDC-OH = 2-hydroxyterephthalic acid, Ln = Eu, Tb, Gd) were designed for the detection of Glu. ZJU-168(Eu) and ZJU-168(Tb) suspensions simultaneously produce the characteristic emission bands of both lanthanide ions and ligands. When ZJU-168(Eu) and ZJU-168(Tb) suspensions exposed to Glu, the fluorescence intensity of ligands increases while the emission of lanthanide ions is almost unchanged. By utilizing the emission of ligands as the detected signal and the emission of lanthanide ions as the internal reference, an internal calibrated fluorescence sensor for Glu was obtained. There is a good linear relationship between fluorescence intensity ratio and Glu concentration in a wide range with the detection limit of 3.6 μM for ZJU-168(Tb) and 4.3 μM for ZJU-168(Eu). Major compounds present in blood plasma have no interference for the detection of Glu. Furthermore, a convenient analytical device based on a one-to-two logic gate was constructed for monitoring Glu. These establish ZJU-168(Tb) as a potential turn-on, ratiometric, and colorimetric fluorescent sensor for practical detection of Glu.

A review on production of metal organic frameworks (MOF) for CO2 adsorption

The environment sustenance and preservation of global climate are known as the crucial issues of the world today. Currently, the crisis of global warming due to CO₂ emission has turned into a paramount concern. To address such a concern, diverse CO₂ capture and sequestration techniques (CCS) have been introduced so far. In line with this, Metal Organic Frameworks (MOFs) have been considered as the newest and most promising material for CO₂ adsorption and separation. Due to their outstanding properties, this new class of porous materials a have exhibited a conspicuous potential for gas separation technologies especially for CO₂ storage and separation. Thus, the present review paper is aimed to discuss the adsorption properties of CO₂ on the MOFs based on the adsorption mechanisms and the design of the MOF structures. In addition, the main challenge associated with using this prominent porous material has been mentioned.

Metalloporphyrinic metal-organic frameworks: Controlled synthesis for catalytic applications in environmental and biological media

Recently, as a new sub-family of porous coordination polymers (PCPs), porphyrinic-MOFs (Porph-MOFs) with biomimetic features have been developed using porphyrin macrocycles as ligands and/or pillared linkers. The control over the coordination of the porphyrin ligand and its derivatives however remains a challenge for engineering new tunable Porph-MOF frameworks by self-assembly methods. The key challenges exist in the following respects: (i) collapse of the large open pores of Porph-MOFs during synthesis, (ii) deactivation of unsaturated metal-sites (UMCs) by axial coordination, and (iii) the tendency of both coordinated moieties (at peripheral meso- and beta-carbon sites) and the N₄-pyridine core to coordinate with metal cations. In this respect, this review covers the advances in the design of Porph-MOFs relative to their counterpart covalent organic frameworks (Porph-COFs). The potential utility of custom-designed porphyrin/metalloporphyrins ligands is highlighted. Synthesis strategies of Porph-MOFs are also illustrated with modular design of hybrid guest@host composites (either Porph@MOFs or guest@Porph-MOFs) with exceptional topologies and stability. This review summarizes the synergistic benefits of coordinated porphyrin ligands and functional guest molecules in Porph-MOF composites for enhanced catalytic performance in various redox applications. This review shed lights on the engineering of new tunable hetero-metals open active sites within (metallo)porphyrin-MOFs as out-of-the-box platforms for enhanced catalytic processes in chemical and biological media.

Coordinated Water as New Binding Sites for the Separation of Light Hydrocarbons in Metal-Organic Frameworks with Open Metal Sites

Metal-organic frameworks with open metal sites are promising materials for gas separations. Particularly, the M₂(dobdc) (dobdc^4- = 2,5-dioxidobenzenedicarboxylate, M²⁺ = Co²⁺, Mn²⁺, Fe²⁺, ...) framework has been the Drosophila of this research field and has delivered groundbreaking results in terms of sorption selectivity. However, many studies focus on perfect two-component mixtures and use theoretical models, e.g., the ideal adsorbed solution theory, to calculate selectivities. Within this work, we shed light on the comparability of these selectivities with values obtained from propane/propene multicomponent measurements on the prototypical Co₂(dobdc) framework, and we study the impact of impurities like water on the selectivity. Despite the expected capacity loss, the presence of water does not necessarily lead to a decreased selectivity. Density functional theory calculations of the binding energies prove that the water molecules adsorbed to the metal centers introduce new binding sites for the adsorbates.

Reversed ethane/ethylene adsorption in a metal-organic framework via introduction of oxygen

Separation of ethane from ethylene is a very important but challenging process in the petrochemical industry. Finding an alternative method would reduce the energy needed to make 170 million tons of ethylene manufactured worldwide each year. Adsorptive separation using C2H6-selective porous materials to directly produce high-purity C2H4 is more energy-efficient. We herein report the "reversed C2H6/C2H4 adsorption" in a metal-organic framework Cr-BTC via the introduction of oxygen on its open metal sites. The oxidized Cr-BTC(O2) can bind C2H6 over C2H4 through the active Cr-superoxo sites, which was elucidated by the gas sorption isotherms and density functional theory calculations. This material thus exhibits a good performance for the separation of 50/50 C2H6/C2H4 mixtures to produce 99.99% pure C2H4 in a single separation operation.

Understanding Time Dependence on Zinc Metal-Organic Framework Growth Using in Situ Liquid Secondary Ion Mass Spectrometry

The abundance of novel metal-organic framework (MOF) materials continues to increase as more applications are discovered for these highly porous, well-ordered crystalline structures. The simplicity of constituents allows for the design of new MOFs with virtue of functionality and pore topology toward target adsorbates. However, the fundamental understanding of how these frameworks evolve during nucleation and growth is mostly limited to speculation from simulation studies. In this effort, we utilize a unique vacuum compatible system for analysis at the liquid vacuum interface (SALVI) microfluidic interface to analyze the formation and evolution of the benchmark MOF-74 framework using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Principal component analysis of the SIMS mass spectra, together with ex situ electron microscopy, powder X-ray diffractometry, and porosimetry, provides new insights into the structural growth, metal-oxide cluster formation, and aging process of Zn-MOF-74. Samples collected over a range of synthesis times and analyzed closely with in situ ToF-SIMS, transmission electron microscopy, and gas adsorption studies verify the developing pore structure during the aging process.

Design and Construction of a Metal-Organic Framework as an Efficient Luminescent Sensor for Detecting Antibiotics

We first design and synthesize a dendritic aromatic 6-carboxyl linker (H₆TDCPB), which is successfully assembled with Cd(II) ion to construct a porous metal-organic framework with a raw Cd₆ cluster, {[Cd₃(TDCPB)·2DMAc]·DMAc·4H₂O}_n (namely, complex 1). More interestingly, six adjacent linkers are packed together by π-π-stacking interactions to form an amazing six-molecule accumulation in the crystal structure. By virtue of high stability and luminescent properties, the as-synthesized sample not merely owns an excellent detectable ability but also possesses an outstanding selectivity for nitrofurans with remarkable recursitivity.

Synthesis and catalytic activities of a Zn(ii) based metallomacrocycle and a metal-organic framework towards one-pot deacetalization-Knoevenagel tandem reactions under different strategies: a comparative study

Solvothermal reactions between a pyridine based amide functionalized dicarboxylic acid, 4,4'-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L), and zinc(ii) nitrate in the absence and presence of a base produced the binuclear metallomacrocyclic compound [Zn2(L)2(H2O)4]·2(H2O)·6(DMF) (1) and the metallomacrocyclic based two dimensional MOF [Zn5(L)4(OH)2(H2O)4]n·8n(DMF)·4n(H2O) (2), respectively. Compound 1 bears two tetrahedral Zn(ii) centres, whereas the 2D framework 2 includes a penta-nuclear Zn(ii) cluster as a secondary building block unit, with two of the metal cations assuming a tetrahedral type geometry and the remaining three an octahedral type geometry. The topological analyses reveal that compound 1 has a 2-connected uninodal net and framework 2 has a 2, 8-connected binodal net. These compounds heterogeneously catalyse the tandem deacetalization-Knoevenagel condensation reactions carried out under conventional heating, microwave irradiation or ultrasonic irradiation. Comparative studies show that ultrasonic irradiation (final product yield of 99% after 2 h of reaction time) provides the most favourable method (e.g., microwave irradiation leads to a final product yield of 91% after 3 h of reaction time). Moreover, the catalysts can be reused at least for five consecutive cycles without losing activity significantly.

Polyoxometalate-based hydrogen-bonded organic frameworks as a new class of proton conducting materials

To develop new types of crystalline proton conducting materials for fuel cells, a polyoxometalate-based hydrogen-bonded organic framework (PHOF) based on Keggin-type [PMo₁₂O₄₀]³⁻ and phenylimidazole (PHOF 1) has been prepared.

Three 3D LnIII-MOFs based on a nitro-functionalized biphenyltricarboxylate ligand: syntheses, structures, and magnetic properties

Cluster, chain or layer-based 3D Ln-MOFs have been synthesized and they exhibit ferromagnetic or antiferromagnetic interactions. Furthermore, the Dy-MOF shows slow relaxation behavior.

Formation of CX Bonds in CO2 Chemical Fixation Catalyzed by Metal-Organic Frameworks

Transformation of CO₂ based on metal-organic framework (MOF) catalysts is becoming a hot research topic, not only because it will help to reduce greenhouse gas emission, but also because it will allow for the production of valuable chemicals. In addition, a large number of impressive products have been synthesized by utilizing CO₂ . In fact, it is the formation of new covalent bonds between CO₂ and substrate molecules that successfully result in CO₂ solidly inserting into the products, and only four types of new CX bonds, including CH, CC, CN, and CO bonds, are observed in this exploration. An overview of recent progress in constructing CX bonds for CO₂ conversion catalyzed by various MOF catalysts is provided. The catalytic mechanism of generating different CX bonds is further discussed according to both structural features of MOFs and the interactions among CO₂ , substrates, as well as MOFs. The future opportunities and challenges in this field are also tentatively covered.

Topological polymorphism and temperature-driven topotactic transitions of metal–organic coordination polymers

A facile crystal-to-crystal solid-state phase transition between a low-temperature phase and a high temperature phase changes the MOF topology and involves a significant rearrangement of bulky organic ligands.

IRMOF-74(n)-Mg: a novel catalyst series for hydrogen activation and hydrogenolysis of C-O bonds

Metal-Organic Frameworks (MOFs) that catalyze hydrogenolysis reactions are rare and there is little understanding of how the MOF, hydrogen, and substrate molecules interact. In this regard, the isoreticular IRMOF-74 series, two of which are known catalysts for hydrogenolysis of aromatic C-O bonds, provides an unusual opportunity for systematic probing of these reactions. The diameter of the 1D open channels can be varied within a common topology owing to the common secondary building unit (SBU) and controllable length of the hydroxy-carboxylate struts. We show that the first four members of the IRMOF-74(Mg) series are inherently catalytic for aromatic C-O bond hydrogenolysis and that the conversion varies non-monotonically with pore size. These catalysts are recyclable and reusable, retaining their crystallinity and framework structure after the hydrogenolysis reaction. The hydrogenolysis conversion of phenylethylphenyl ether (PPE), benzylphenyl ether (BPE), and diphenyl ether (DPE) varies as PPE > BPE > DPE, consistent with the strength of the C-O bond. Counterintuitively, however, the conversion also follows the trend IRMOF-74(III) > IRMOF-74(IV) > IRMOF-74(II) > IRMOF-74(I), with little variation in the corresponding selectivity. DFT calculations suggest the unexpected behavior is due to much stronger ether and phenol binding to the Mg(ii) open metal sites (OMS) of IRMOF-74(III), resulting from a structural distortion that moves the Mg2+ ions toward the interior of the pore. Solid-state 25Mg NMR data indicate that both H2 and ether molecules interact with the Mg(ii) OMS and hydrogen-deuterium exchange reactions show that these MOFs activate dihydrogen bonds. The results suggest that both confinement and the presence of reactive metals are essential for achieving the high catalytic activity, but that subtle variations in pore structure can significantly affect the catalysis. Moreover, they challenge the notion that simply increasing MOF pore size within a constant topology will lead to higher conversions.

Highly sensitive photoelectrochemical detection of bleomycin based on Au/WS2 nanorod array as signal matrix and Ag/ZnMOF nanozyme as multifunctional amplifier

An ultrasensitive photoelectrochemical (PEC) biosensor was constructed based on gold nanoparticles (Au NPs)/tungsten sulfide nanorod array (WS₂ NA) photoelectrode as the PEC matrix and silver nanoparticles/flake-like zinc metal-organic framework (Ag/ZnMOF) nanozyme with the peroxidase mimetic enzyme property for sensitive detection of bleomycin (BLM). In particular, Au/WS₂ and Ag/ZnMOF were linked by thiolate DNA₁ and DNA₂ strand, respectively, and the Au/WS₂-Ag/ZnMOF probe was prepared via hybridization reaction between the two DNAs. The introduction of Ag/ZnMOF in the probe offers two functions: i) the steric hindrance effect can effectively impede electron transport and reduce the photocurrent; ii) Ag/ZnMOF nanozyme can also be used as mimic peroxidase to effectively catalyze 3,3-diaminobenzidine (DAB) to produce the relevant precipitation, which will further reduce photocurrent and eliminate false positive signals. When BLM exists, BLM with Fe²⁺ as irreversible cofactor can specifically recognize and cleave of the 5'-GC-3' active site of DNA₂, resulting in reduced precipitation deposited on the electrode and recovery of PEC signal. The highly sensitive PEC biosensor exhibits a the linear strategy from 0.5 nM to 500 nM with a detection limit down to 0.18 nM. Further, the unique strategy was conducted in biological samples for BLM detection with satisfactory consequence, offering available and efficient pathway for disease diagnosis.

Rapid mechanochemical encapsulation of biocatalysts into robust metal-organic frameworks

Metal–organic frameworks (MOFs) have recently garnered consideration as an attractive solid substrate because the highly tunable MOF framework can not only serve as an inert host but also enhance the selectivity, stability, and/or activity of the enzymes. Herein, we demonstrate the advantages of using a mechanochemical strategy to encapsulate enzymes into robust MOFs. A range of enzymes, namely β-glucosidase, invertase, β-galactosidase, and catalase, are encapsulated in ZIF-8, UiO-66-NH₂, or Zn-MOF-74 via a ball milling process. The solid-state mechanochemical strategy is rapid and minimizes the use of organic solvents and strong acids during synthesis, allowing the encapsulation of enzymes into three prototypical robust MOFs while maintaining enzymatic biological activity. The activity of encapsulated enzyme is demonstrated and shows increased resistance to proteases, even under acidic conditions. This work represents a step toward the creation of a suite of biomolecule-in-MOF composites for application in a variety of industrial processes.

Metal–organic frameworks (MOFs) are attractive for encapsulating enzymes for industrial purposes because they can increase selectivity, stability, and/or activity of the enzymes. Here, the authors developed an economical solid-state mechanochemical method to encapsulate enzymes during MOF synthesis.

Membrane-supported 1D MOF hollow superstructure array prepared by polydopamine-regulated contra-diffusion synthesis for uranium entrapment

This work reports the architecture of a novel class of membrane-supported 1D MOF hollow superstructures, by using the bio-inspired polydopamine (PDA) mediated contra-diffusion synthetic strategy, for facile and efficient separation of uranium in a flow-through mode. PDA chemistry was firstly employed to modify the inner surfaces of the cylindrical pore channels of polycarbonate track-etched membrane (PCTM), thereby regulating the heterogeneous nucleation and interfacial growth of ZIF-8 crystals. ZIF-8 hollow superstructures embedded in membrane matrix with well-defined 1D channels were obtained. These membrane-supported MOF hollow superstructures then, for the first time, served as integrated chromatographic micro-column arrays for effective entrapment of uranium from aqueous solutions. It is highlighted that the PCTM supported ZIF-8 superstructures exhibited outstanding uranium entrapment ability in both traditional batch mode (capacity 62.3 mg/g) and fast flow-through mode (removal rate over 90% for 3 level). Moreover, new insights into the interaction between ZIF-8 and uranyl ions were obtained, suggesting that an ion-exchange mechanism involved synergistic effect was responsible for uranium binding, especially in a long-term exposure. The membrane-supported 1D MOF hollow superstructures developed in this work represent a new category of organic-inorganic composite membrane. And, it is envisioned that the methodology established in this work would be versatile for preparing more MOF superstructures with deployable form for separation applications. In summary, a novel class of membrane-supported ZIF-8 hollow superstructure was fabricated for effective separation of uranyl ions.

Trends in Solid Adsorbent Materials Development for CO2 Capture

A recent report from the United Nations has warned about the excessive CO₂ emissions and the necessity of making efforts to keep the increase in global temperature below 2 °C. Current CO₂ capture technologies are inadequate for reaching that goal, and effective mitigation strategies must be pursued. In this work, we summarize trends in materials development for CO₂ adsorption with focus on recent studies. We put adsorbent materials into four main groups: (I) carbon-based materials, (II) silica/alumina/zeolites, (III) porous crystalline solids, and (IV) metal oxides. Trends in computational investigations along with experimental findings are covered to find promising candidates in light of practical challenges imposed by process economics.

Thiazolothiazole-Based Luminescent Metal-Organic Frameworks with Ligand-to-Ligand Energy Transfer and Hg2+-Sensing Capabilities

Photoinduced electron and energy transfer through preorganized chromophore, donor, and acceptor arrays are key to light-harvesting capabilities of photosynthetic plants and bacteria. Mimicking the design principles of natural photosystems, we constructed a new luminescent pillared paddle wheel metal-organic framework (MOF), Zn₂(NDC)₂(DPTTZ), featuring naphthalene dicarboxylate (NDC) struts that served as antenna chromophores and energy donors and N,N'-di(4-pyridyl)thiazolo-[5,4-d]thiazole (DPTTZ) pillars as complementary energy acceptors and light emitters. Highly ordered arrangement and good overlap between the emission and absorption spectra of these two complementary energy donor and acceptor units enabled ligand-to-ligand Förster resonance energy transfer, allowing the MOF to display exclusively DPTTZ-centric blue emission (410 nm) regardless of the excitation of either chromophore at different wavelengths. In the presence of Hg²⁺, a toxic heavy metal ion, the photoluminescence (PL) of Zn₂(NDC)₂(DPTTZ) MOF underwent significant red-shift to 450 nm followed by quenching, whereas other transition metal ions (Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Cd²⁺) caused only fluorescence quenching but no shift. The free DPTTZ ligand also displayed similar, albeit less efficient, fluorescence changes, suggesting that the heavy atom effect and coordination of Hg²⁺ and other transition metal ions with the DPTTZ ligands were responsible for the fluorescence changes in the MOF. When exposed to a mixture of different metal ions, including Hg²⁺, the MOF still displayed the Hg²⁺-specific fluorescence signal, demonstrating that it could detect Hg²⁺ in the presence of other metal ions. The powder X-ray diffraction studies verified that the framework remained intact after being exposed to Hg²⁺ and other transition metal ions, and its original PL spectrum was restored upon washing. These studies demonstrated the light-harvesting and Hg²⁺ sensing capabilities of a new bichromophoric luminescent MOF featuring a seldom-used photoactive ligand, which will likely spark an explosion of TTZ-based MOFs for various optoelectronic applications in near future.

Post-imparting Brønsted acidity into an amino-functionalized MOF as a bifunctional luminescent turn-ON sensor for the detection of aluminum ions and lysine

A novel aldehyde- and amino-functionalized luminescent metal-organic framework, Cd-TCHO, was constructed through the solvothermal reaction of 4,4',4''-tricarboxytriphenylamine, 2-amino-3-pyridinecarboxaldehyde and cadmium nitrate and was characterized. Post-synthetically oxidizing the aldehyde groups into carboxylate groups afforded a new complex, Cd-TCOOH, and this successful conversion process was confirmed by FT-IR and ¹H NMR studies. With the Brønsted acidic sites inside the cavities of Cd-TCOOH, it could be used as a luminescent sensor for Al³⁺ detection with a high selectivity and sensitivity (LOD = 0.54 ppb), which could be attributed to the coordination between free Brønsted acidic sites and Al³⁺. Importantly, it could also detect Lys among 20 kinds of natural amino acids; the selectivity, sensitivity and the sensing mechanism are discussed in detail. Also, both of the sensing processes were carried out in the HEPES buffer.

Crystallographic Visualization of Postsynthetic Nickel Clusters into Metal-Organic Framework

Postsynthetic metalation (PSM) has been employed as a robust method for the postsynthetic modification of metal-organic frameworks (MOFs). However, the lack of relevant information that can be obtained for the postsynthetically introduced metallic ions has hindered the development of PSM applications. Thanks to the advancement in single-crystal X-ray diffraction (SCXRD) technology, there have been a few recent examples in which successful postsynthetic introduction of single metal ions into MOFs occurred at the defined chelating sites. These works have provided useful explanations about the complicated host-guest chemistry involved in PSMs. On the other hand, there are only limited examples with crystallographic snapshots of the postsynthetic installation of metal clusters into the pores of MOFs using an ordinary SCXRD due to the loss of crystallinity of parent matrix during the PSM process. Herein, by the careful selection of starting materials and controlling the reaction conditions, we report the first crystallographic visualization of metal clusters inserted into Zr-based MOFs via PSM. The structural advantages of the parent Zr-MOF, which are inherited from the stable Zr₆ cluster and triazole-containing dicarboxylate ligand, ensure both the preservation of high crystallinity and the presence of flexible coordination sites for PSM. Furthermore, PSM of metal clusters in a MOF pore space enhances stability of the final samples while also imparting the functionality of a successful catalyst toward ethylene dimerization reaction. The related construction ideas and structural information detailed in this work can help lay the foundation for further advancements using the postmodification of MOFs as well as open new doors for the utilization of SCXRD technology in the field of MOFs.

Persistent luminescent metal-organic frameworks with long-lasting near infrared emission for tumor site activated imaging and drug delivery

Luminescent porous materials have been widely used in biosensing, bioimaging and drug delivery by virtue of the special porous structure and luminescent property. The main obstacle for the application in biosensing and bioimaging is the background interference of external irradiation. Herein, we report a background interference-free persistent luminescent metal-organic framework (PLMOF) with persistent luminescent near infrared (NIR) luminescence for tumor site activated persistent luminescence imaging. The PLMOF (PLNPs@ZIF-8) was prepared by in-situ growth of MOF on the persistent luminescent nanoparticles (PLNPs) via a surface adsorption induced self-assembly method. The PLMOF possessed NIR persistent luminescence and renewable NIR luminescence and thus enabled deep-tissue and long-term imaging without external excitation. Specifically, the PLMOF showed acidic tumor site activated persistent luminescence for in vitro and in vivo tumor imaging, which was also help to reduce the background interference. The mechanism of acidic activation was attributed to the protonation of imidazole that induces disassembly of ZIF-8. In addition, the PLMOF presented a high anti-cancer drug loading capacity, acidity-responsive drug release behavior, and significant anti-tumor effect. All these results indicate that our PLMOF can serve as a promising theranostic platform for precision medicine.

Novel and Versatile Cobalt Azobenzene-Based Metal-Organic Framework as Hydrogen Adsorbent

A novel URJC-3 material based on cobalt and 5,5'-(diazene-1,2-diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC-3, with polyhedral morphology, crystallizes in the tetragonal and P4₃ 2₁ 2 space group, exhibiting a three-dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77-298 K) and pressures (1-170 bar). The hydrogen storage capacity of URJC-3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single-walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.

A Microporous Metal-Organic Framework Supramolecularly Assembled from a CuII Dodecaborate Cluster Complex for Selective Gas Separation

A novel 3D metal-organic framework BSF-1 based on the closo-dodecaborate cluster [B₁₂ H₁₂ ]^2- was readily prepared at room temperature by supramolecular assembly of CuB₁₂ H₁₂ and 1,2-bis(4-pyridyl)acetylene. The permanent microporous structure was studied by X-ray crystallography, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and gas sorption. The experimental and theoretical study of the gas sorption behavior of BSF-1 for N₂ , C₂ H₂ , C₂ H₄ , CO₂ , C₃ H₈ , C₂ H₆ , and CH₄ indicated excellent separation selectivities for C₃ H₈ /CH₄ , C₂ H₆ /CH₄ , and C₂ H₂ /CH₄ as well as moderately high separation selectivities for C₂ H₂ /C₂ H₄ , C₂ H₂ /CO₂ , and CO₂ /CH₄ . Moreover, the practical separation performance of C₃ H₈ /CH₄ and C₂ H₆ /CH₄ was confirmed by dynamic breakthrough experiments. The good cyclability and high water/thermal stability render it suitable for real industrial applications.

One-Step Construction of Hydrophobic MOFs@COFs Core-Shell Composites for Heterogeneous Selective Catalysis

The exploration of novel porous core-shell materials is of great significance because of their prospectively improved performance and extensive applications in separation, energy conversion, and catalysis. Here, mesoporous metal-organic frameworks (MOFs) NH2-MIL-101(Fe) as a core generate a shell with mesoporous covalent organic frameworks (COFs) NUT-COF-1(NTU) by a covalent linking process, the composite NH2-MIL-101(Fe)@NTU keeping retentive crystallinity with hierarchical porosity well. Importantly, the NH2-MIL-101(Fe)@NTU composite shows significantly enhanced catalytic conversion and selectivity during styrene oxidation. It is mainly due to the hydrophilic MOF nanocrystals readily gathering the hydrophobic reactants styrene and boosting the radical mechanism path after combining the hydrophobic COFs shell. The synthetic strategy in this systematic study develops a new rational design for the synthesis of other core-shell MOF/COF-based hybrid materials, which can expand the promising applications.