Removal of Trace Benzene from Cyclohexane Using a MOF Molecular Sieve.

Cyclohexane (Cy), commonly produced by the catalytic hydrogenation of benzene (Bz), is used in large quantities as a solvent or feedstock for nylon polymers. Removing trace unreacted Bz from the Cy product is technically difficult due to their similar molecular structures and physical properties. Herein, we report that a metal-organic framework (MOF) adsorbent shows a molecular sieving effect for Bz and Cy with record-high Bz/Cy adsorption selectivities (216, 723, and 1027) in their liquid mixtures (v/v = 1:1, 1:10, and 1:20), and traps Bz molecules effectively even at low partial pressure in the vapor phase (e.

Rare-Earth Metal-Organic Framework with Nonplanar Porphyrin Groups for High-Efficiency Photocatalysis.

Nonplanar porphyrins play crucial roles in many biological processes and chemical reactions as catalysts. However, the preparation of artificial nonplanar porphyrins suffers from complicated organic syntheses. Herein, we present a new rare-earth porphyrinic metal-organic framework (RE-PMOF), BUT-233, which is a three-dimensional (3D) framework structure with the topology consisting of 4-connected BBCPPP-Ph ligands HBBCPPP-Ph = 5',5⁗-(10,20-diphenylporphyrin-5,15-diyl)bis([1,1':3',1″-terphenyl]-4,4'' dicarboxylic acid) and 8-connected Eu clusters.

Interior and Exterior Surface Modification of Zr-Based Metal-Organic Frameworks for Trace Benzene Removal.

The emission of volatile organic compounds (VOCs) significantly contributes to air pollution and poses a serious threat to human health. Benzene, one of the most toxic VOCs, is difficult for the human body to metabolize and is classified as a Group 1 carcinogen. The development of efficient adsorbents for removing trace amounts of benzene from ambient air is thus of great importance.

Highly Efficient Propyne/Propylene Separation in a "Flexible-Robust" and Hydrolytically Stable Cu(II)-MOF.

Propyne/propylene separation is important in the petrochemical industry but challenging due to their similar physical properties and close molecular sizes. Metal-organic frameworks (MOFs) are a class of promising adsorbents for light hydrocarbon separations. Among them, the so-called "flexible-robust" MOFs combine the advantages of flexibility and rigidity in structure and could show enhanced gas separation selectivity as well as improved gas uptake at low pressure.

Expanding the Structural Topologies of Rare-Earth Porphyrinic Metal-Organic Frameworks through Ligand Modulation.

Expanding the structural diversity of porphyrinic metal-organic frameworks (PMOFs) is essential to develop functional materials with novel properties or enhanced performance in different applications. Herein, we establish a strategy to construct rare-earth (RE) PMOFs with unprecedented topology via rational functionalization of porphyrinic ligands. By introducing phenyl/pyridyl groups to the -positions of the porphyrin core, the symmetries and connectivities of the ligands are tuned, and three RE-PMOFs (BUT-224/-225/-226) with new topologies are successfully obtained.

Efficient Propylene/Ethylene Separation in Highly Porous Metal-Organic Frameworks.

Light olefins are important raw materials in the petrochemical industry for the production of many chemical products. In the past few years, remarkable progress has been made in the synthesis of light olefins (C2-C4) from methanol or syngas. The separation of light olefins by porous materials is, therefore, an intriguing research topic.

Catalytic ozone decomposition and adsorptive VOCs removal in bimetallic metal-organic frameworks.

Atmospheric ozone has long been a threat to human health, however, rational design of high-performance O-decomposition catalysts remains challenging. Herein, we demonstrate the great potential of a series of isomorphous bimetallic MOFs denoted as PCN-250(FeM) (M = Co, Ni, Mn) in catalytic O decomposition. Particularly, PCN-250(FeCo) showed 100% O removal efficiency for a continuous air flow containing 1 ppm O over a wide humidity range (0 ‒ 80% RH) at room temperature.

Construction and application of base-stable MOFs: a critical review.

Metal-organic frameworks (MOFs) are a new class of porous crystalline materials constructed from organic ligands and metal ions/clusters. Owing to their unique advantages, they have attracted more and more attention in recent years and numerous studies have revealed their great potential in various applications. Many important applications of MOFs inevitably involve harsh alkaline operational environments.

Trace removal of benzene vapour using double-walled metal-dipyrazolate frameworks.

In principle, porous physisorbents are attractive candidates for the removal of volatile organic compounds such as benzene by virtue of their low energy for the capture and release of this pollutant. Unfortunately, many physisorbents exhibit weak sorbate-sorbent interactions, resulting in poor selectivity and low uptake when volatile organic compounds are present at trace concentrations. Herein, we report that a family of double-walled metal-dipyrazolate frameworks, BUT-53 to BUT-58, exhibit benzene uptakes at 298 K of 2.

Construction of a mixed ligand MOF as "green catalyst" for the photocatalytic degradation of organic dye in aqueous media.

In the past few years, metal-organic frameworks (MOFs) have emerged as a class of fascinating materials for photocatalysis. Herein, a new MOF formulated as [Zn(bpe)(fdc)]·2DMF (BUT-206, bpe = 1,2-bis(4-pyridyl) ethylene, Hfdc = 2,5-furan dicarboxylic acid, DMF = ,-dimethylformamide) is reported, which was synthesized under solvothermal conditions and applied for photocatalytic degradation of dyes (crystal violet and rhodamine B). Noteworthily, BUT-206 exhibited high photocatalytic activity toward the degradation of crystal violet without using any photosensitizer or cocatalyst under UV-irradiation.

A Hydrolytically Stable Cu(II)-Based Metal-Organic Framework with Easily Accessible Ligands for Water Harvesting.

Water scarcity is a critical issue in desert and arid regions, and atmospheric water harvesting is a potential solution. The challenge is lacking ideal adsorbents that can efficiently capture water from low-humidity air and be regenerated readily. Herein, we report a hydrolytically stable metal-organic framework (MOF), [Cu(AD)(SA)] (Cu-AD-SA), with excellent performance in water harvesting.

Linker Desymmetrization: Access to a Series of Rare-Earth Tetracarboxylate Frameworks with Eight-Connected Hexanuclear Nodes.

The exploration of metal-organic frameworks (MOFs) through the rational design of building units with specific sizes, geometries, and symmetries is essential for enriching the structural diversity of porous solids for applications including storage, separation, and conversion. However, it is still a challenge to directly synthesize rare-earth (RE) MOFs with less connected clusters as a thermodynamically favored product. Herein, we report a systematic investigation on the influence of size, rigidity, and symmetry of linkers over the formation of RE-tetracarboxylate MOFs and uncover the critical role of linker desymmetrization in constructing RE-MOFs with eight-connected hexanuclear clusters.

A Series of Mesoporous Rare-Earth Metal-Organic Frameworks Constructed from Organic Secondary Building Units.

Further development of metal-organic frameworks (MOFs) requires an establishment of hierarchical interaction within the framework. Herein, we report a series of mesoporous rare-earth (RE) MOFs that are constructed from an unusual 12-connected π-stacked pyrene secondary building unit (SBU) and a typical 12-connected RE cluster (RE=Eu, Y, Yb, Tb, Ce). The judicious design of a butterfly-shape pyrene ligand with a tert-butyl substituent enables the formation of the disordered 12-connected organic SBUs on its strong intermolecular π-π interactions.

A Green-Emission Metal-Organic Framework-Based Nanoprobe for Imaging Dual Tumor Biomarkers in Living Cells.

The modular nature of metal-organic frameworks (MOFs) permits their tunable structure and function for target application, such as in biomedicine. Herein, a green-emission Zr(IV)-MOF (BUT-88) was constructed from a customized luminescent carbazolyl ligand. BUT-88 represents the first bcu-type MOF with both organic linker and metal node in eight connections and shows medium-sized pores, rich accessible linking sites, and good water stability and biocompatibility.

Microporous Hydrogen-Bonded Organic Framework for Highly Efficient Turn-Up Fluorescent Sensing of Aniline.

A microporous three-dimensional (3D) hydrogen-bonded organic framework (HOF-20) has been constructed from an aromatic-rich tetratopic carboxylic acid, 5-(2,6-bis(4-carboxyphenyl)pyridin-4-yl)isophthalic acid (HBCPIA). The activated HOF-20a has a moderately high Brunauer-Emmett-Teller (BET) surface area of 1323 m g and excellent stability in water and HCl aqueous solution. HOF-20 exhibits highly efficient turn-up fluorescent sensing of aniline in water with a detection limit of 2.

Selective adsorption and separation of C hydrocarbons in a "flexible-robust" metal-organic framework based on a guest-dependent gate-opening effect.

The selective adsorption/separation of C hydrocarbons has been realized in a "flexible-robust" MOF, Zn(Atz)Ox. Owing to the distinctive guest-dependent multistep adsorption behaviors and suitable guest-framework interactions, this MOF shows outstanding separation performance for CH/CH mixtures in a wide range of temperature confirmed by a column breakthrough experiment.

Hydrophobic Metal-Organic Frameworks: Assessment, Construction, and Diverse Applications.

Tens of thousands of metal-organic frameworks (MOFs) have been developed in the past two decades, and only ≈100 of them have been demonstrated as porous and hydrophobic. These hydrophobic MOFs feature not only a rich structural variety, highly crystalline frameworks, and uniform micropores, but also a low affinity toward water and superior hydrolytic stability, which make them promising adsorbents for diverse applications, including humid CO capture, alcohol/water separation, pollutant removal from air or water, substrate-selective catalysis, energy storage, anticorrosion, and self-cleaning. Herein, the recent research advancements in hydrophobic MOFs are presented.

A stable zirconium based metal-organic framework for specific recognition of representative polychlorinated dibenzo-p-dioxin molecules.

Polychlorinated dibenzo-p-dioxins (PCDDs), as a class of persistent and highly toxic organic pollutants, have been posing a great threat to human health and the environment. The sensing of these compounds is important but challenging. Here, we report a highly stable zirconium-based metal-organic framework (MOF), ZrO(OH)(HCOO)(CPTTA) (BUT-17) with one-dimensional hexagonal channels and phenyl-rich pore surfaces for the recognition and sensing of two representative PCDDs, 2,3-dichlorodibenzo-p-dioxin (BCDD) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), based on the fluorescence quenching.

Metal-Organic Frameworks for Food Safety.

Food safety is a prevalent concern around the world. As such, detection, removal, and control of risks and hazardous substances present from harvest to consumption will always be necessary. Metal-organic frameworks (MOFs), a class of functional materials, possess unique physical and chemical properties, demonstrating promise in food safety applications.

Ligand Rigidification for Enhancing the Stability of Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) have been developing at an unexpected rate over the last two decades. However, the unsatisfactory chemical stability of most MOFs hinders some of the fundamental studies in this field and the implementation of these materials for practical applications. The stability in a MOF framework is mostly believed to rely upon the robustness of the M-L (M = metal ion, L = ligand) coordination bonds.

Reaction duration-dependent formation of two Cu(ii)-MOFs with selective adsorption properties of CH over CH.

The formation of metal-organic frameworks (MOFs) under given reaction conditions depends on various factors including reaction duration, temperature, used solvent, system pH, and others. Among them, the reaction duration is relatively less investigated. In this work, based on a Cu(ii)-MOF system, the reaction duration was found to play an important role in directing the formation of two different products, (NH2(CH3)2)[Cu12(DDPN)6(H2O)10Cl] (BUT-301) on shorter reaction time and (NH2(CH3)2)2[Cu(DDPN)] (BUT-302) on longer reaction time, when CuCl2 reacted with 3,5-di(3,5-dicarboxylphenyl)nitrobenzene (H4DDPN) in a DMA/MeOH mixed solvent at 120 °C.

A Stable Zr(IV)-Based Metal-Organic Framework Constructed from C═C Bridged Di-isophthalate Ligand for Sensitive Detection of CrO in Water.

As the CrO anion is highly toxic, new sensors have been developing for its effective detection from water, among which metal-organic frameworks (MOFs) show distinct superiority over many other materials. Herein, a new fluorescent Zr(IV)-based MOF, [ZrO(OH)(HO)(sbtc)] (referred to as BUT-28), based on the di-isophthalate ligand with a central CH═CH moiety, trans-stilbene-3,3',5,5'-tetracarboxylate (sbtc), has been prepared and structurally determined. The MOF shows excellent stability in neutral, highly acidic, and weakly basic aqueous solutions.

Bidentate Phosphine-Assisted Synthesis of an All-Alkynyl-Protected Ag Nanocluster.

Determining the total structure of metal nanoparticles is vital to understand their properties. In this work, the first all-alkynyl-protected Ag nanocluster, Ag(C≡CPh), was synthesized and structurally characterized by single crystal diffraction. Ag atoms are arranged in a Ag@Ag@Ag three shell structure and all 44 phenylethynyl ligands coordinated with Ag in a μ mode.