Comparison of the Effect of Functional Groups on Gas-Uptake Capacities by Fixing the Volumes of Cages A and B and Modifying the Inner Wall of Cage C in rht-Type MOFs

Adsorption of Polycyclic Aromatics on Crystal Surface of Coordination Cages: Photophysical Properties and Förster Resonance Energy Transfer

Self-assembly reactions of PdX2 (X- = NO3-, BF4-, ClO4-, ReO4-, PF6-, and CF3SO3-) with 9,10-bis((isoquinolin-5-yloxy)methyl)anthracene (L) in Me2SO give rise to single crystals of coordination cages, [X@Pd2L4]X3, irrespective of X- anions, in high yields. The intracage Pd···Pd distance is significantly sensitive to the nestled X- anion, which can serve as a gauge for recognition of ubiquitous polyatomic anions. One interesting feature is that, via π-π interactions, various polycyclic aromatics (PAs) are characteristically adsorbed on the crystal surface of designed coordination cages with a wall of anthranyl moiety. This unprecedented ensemble system shows an efficient Förster resonance energy transfer (FRET) process from the anthracene (ANT) to pyrene (PYR) via a large degree of spectral overlap between the ANT emission and PYR absorption bands, in contrast to a simple mixture of ANT and PYR.

Lewis acid sites in MOFs supports promoting the catalytic activity and selectivity for CO esterification to dimethyl carbonate

We studied the effect of Lewis acidity in metal–organic frameworks (MOFs) on their activity as catalyst supports for the esterification of CO to dimethyl carbonate.

A dual-emitting Tb(iii)&Yb(iii)-functionalized coordination polymer: a "turn-on" sensor for N-methylformamide in urine and a "turn-off" sensor for methylglyoxal in serum

Fluorescent materials with lanthanide cations encapsulated in MOFs are currently used in numerous applications, especially in biosensors. Therefore, herein, two novel composites were designed and developed based on a Tb(iii)&Yb(iii)-functionalized Cu(ii)-coordination polymer, possessing higher thermal and water stability and fascinating fluorescence properties. The first bimetallic composite Tb@Cu-Hcbpp demonstrated broad ligand-centered emission and weak typical Tb³⁺ ion emission; moreover, it was used as an excellent ratiometric fluorescent sensor for the metabolic product NMF of DMF in the human body (LOD = 0.02 μM). In addition, the Yb³⁺ ions were doped into Tb@Cu-Hcbpp to improve the fluorescence performance of the green Tb³⁺ ion emission. Among the series of Tb_1-xYb_x@Cu-Hcbpp samples (x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 and 0.40), Tb_0.85Yb_0.15@Cu-Hcbpp showed maximum enhanced fluorescence intensity (almost 9.6 times that of the pure terbium system), but exhibited high fluorescence quenching efficiency for methylglyoxal (MGO), which could be used for the sensitive detection of MGO (LOD = 0.25 μM). Furthermore, the developed biosensors were successfully applied for the detection of NMF and MGO in urine and serum samples, and satisfactory results were obtained, showing good potential of these biosensors in practical applications such as in disease diagnosis and biochemical research.

Two microporous CoII-MOFs with dual active sites for highly selective adsorption of CO2/CH4 and CO2/N2

Two microporous Co^II-MOFs exhibit highly CO₂/CH₄ and CO₂/N₂ selective adsorption owing to abundant dual active sites. GCMC theoretical simulations further verify the experimental results.

A ligand conformation preorganization approach to construct a copper–hexacarboxylate framework with a novel topology for selective gas adsorption

A ligand conformation preorganization strategy was employed to design a hexacarboxylate ligand, and its corresponding copper-based MOF was constructed, exhibiting a novel topological structure and the potential for the separation and purification of acetylene and natural gas.

Process Evaluation of the Metal-Organic Frameworks for the Application of Personal Protective Equipment with Filtration Function

Metal-organic frameworks (MOFs) have been regarded as an ideal material for the development of functional textiles with filtration function. Such functional textiles with filtration function can be further used to develop personal protective equipment, such as protective masks. This paper focuses on the comparisons of different processes when applying MOFs to conventional textiles. Two different processes existing in the literature, namely the electrospinning method and hot-pressing method, are discussed in this paper. Materials loaded with MOFs developed with these two processes are evaluated and compared, regarding the adsorption of dyes in water and the removal of pollutants. Experiment results indicate that the hot-pressing method is more advantageous when applying MOF to textiles, in terms of adsorption and removal efficiency.

An unprecedented water stable acylamide-functionalized metal–organic framework for highly efficient CH4/CO2 gas storage/separation and acid–base cooperative catalytic activity

HNUST-8 exhibits water stable, efficient CH₄/CO₂ storage and separation, acid–base cooperative catalytic activity in a tandem deacetalization Knoevenagel densation.

High methane storage and working capacities in a NbO-type metal-organic framework

To improve methane adsorption by pore structure optimization, we developed a new organic linker and used it to construct a NbO-type metal-organic framework ZJNU-53 that, after activation, exhibits exceptionally high methane storage and working capacities of 241 and 190 cm(3) (STP) cm(-3) at 298 K and 65 bar, respectively, if the packing loss is not considered, which are among the highest reported for MOF materials.

Magnetic properties and luminescence sensing of five coordination polymers based on a rigid terphenyl-tetracarboxylic acid

Five terphenyl-tetracarboxylic acid based on CPs with variable-temperature magnetic susceptibilities and luminescence sensing of small organic molecules.

Synthesis and characterization of metallo-supramolecular polymers from thiophene-based unimers bearing pybox ligands

A series of novel metallo-supramolecular polymers was prepared, based on 2,6-bis(2-oxazolinyl)pyridine chelating groups bridged with thiophene, bithiophene and thienothiophene as a linker, beginning from commercially available (chelidamic) acid.

Two microporous Fe-based MOFs with multiple active sites for selective gas adsorption

Two Fe-based porous MOFs have been constructed from dimeric Fe-clusters and rod-shaped heterobimetallic Fe/Na-chains as SBUs, respectively. Notably, both of them exhibit highly selective CO₂ uptake over CH₄ and N₂ owing to abundant multiple active sites.

Siloxane-based linkers in the construction of hydrogen bonded assemblies and porous 3D MOFs

A siloxane-based hexacarboxylic acid has been prepared and applied in the construction of new hybrid MOF materials.

Experimental and theoretical investigations of the gas adsorption sites in rht-metal–organic frameworks

This highlight article reviews the experimental and theoretical studies that have been implemented to investigate the sorption sites for gases in rht-metal–organic frameworks.

Synthesis, Crystal Structure, and Theoretical Calculations of Two Cobalt, Nickel Coordination Polymers with 5-Nitroisophthalic Acid and Bis(imidazol) Ligands

Two new complexes [Co(NIPH)(bimb)(H2O)]n (1) and [Ni(NIPH)(mbix)]n (2) (H2NIPH = 5-nitroisophthalic acid, bimb = 1,4-bis(imidazol-1-yl)butane, mbix = 1,3-bis(imidazol-1-ylmethyl)benzene) have been hydrothermally synthesised and structurally characterised by elemental analysis, IR spectroscopy, thermogravimetric analysis, UV spectroscopy, and single-crystal X-ray diffraction. Complex 1 exhibits a two-dimensional (2D) network, which was stabilised through O–H···O and C–H···O hydrogen-bonding interactions. Complex 2 shows a two-dimensional (2D) network structure, which was further extended into a three-dimensional supramolecular structure through C–H···O hydrogen bonds and π–π interactions. Moreover, we analysed the natural bond orbital (NBO) using the PBE0/LANL2DZ method in the Gaussian 03 program. The calculation results indicated the obvious covalent interactions between the coordinated atoms and the CoII or NiII ion.

Solvothermal Metal Metathesis on a Metal-Organic Framework with Constricted Pores and the Study of Gas Separation

Metal-organic frameworks (MOFs) with constricted pores can increase the adsorbate density of gas and facilitate effective CO2 separation from flue gas or natural gas due to their enhanced overlapping of potential fields of the pores. Herein, an MOF with constricted pores, which was formed by narrow channels and blocks of functional groups, was fabricated from the assembly of a methyl-functionalized ligand and Zn(II) centers (termed NPC-7-Zn). Structural analysis of the as-synthesized NPC-7-Zn reveals a series of zigzag pores with pore diameters of ∼0.7 nm, which could be favorable for CO2 traps. For reinforcing the framework stability, a solvothermal metal metathesis on the pristine MOF NPC-7-Zn was performed, and a new Cu(II) MOF (termed NPC-7-Cu) with an identical framework was produced. The influence of the reaction temperatures on the metal metathesis process was investigated. The results show that the constricted pores in NPC-7-Zn can induce kinetic issues that largely slow the metal metathesis process at room temperature. However, this kinetic issue can be solved by applying higher reaction temperatures. The modified MOF NPC-7-Cu exhibits significant improvements in framework stability and thus leads to a permanent porosity for this framework. The constricted pore structure enables enhanced potential fields for these pores, rendering this MOF with high adsorbate densities for CO2 and high adsorption selectivity for a CO2/N2 gas mixture. The adsorption kinetic studies reveal that CH4 has a faster diffusion rate constant than CO2, showing a surface diffusion controlled mechanism for CO2 and CH4 adsorption.

Methane storage in metal-organic frameworks

Natural gas (NG), whose main component is methane, is an attractive fuel for vehicular applications. Realization of safe, cheap and convenient means and materials for high-capacity methane storage can significantly facilitate the implementation of natural gas fuelled vehicles. The physisorption based process involving porous materials offers an efficient storage methodology and the emerging porous metal-organic frameworks have been explored as potential candidates because of their extraordinarily high porosities, tunable pore/cage sizes and easily immobilized functional sites. In this view, we provide an overview of the current status of metal-organic frameworks for methane storage.

Polar group and defect engineering in a metal-organic framework: synergistic promotion of carbon dioxide sorption and conversion

A sulfone-functionalized metal-organic framework (MOF), USTC-253, has been synthesized that exhibits a much higher CO2 uptake capacity (168-182 %) than the corresponding unfurnished MOFs. The introduction of trifluoroacetic acid (TFA) during the synthesis of USTC-253 affords defect-containing USTC-253-TFA with exposed metal centers, which has an increased CO2 uptake (167 %) compared to pristine USTC-253. USTC-253-TFA exhibits a very high ideal adsorption solution theory selectivity (S=75) to CO2 over N2 at 298 K. In addition, USTC-253-TFA demonstrates good catalytic activity and recyclability in the cycloaddition of CO2 and epoxide at room temperature under 1 bar CO2 pressure as a result of the presence of Lewis and Brønsted acid sites, which were evaluated by diffuse reflectance infrared Fourier transform spectroscopy with a CO probe molecule. We propose that the CO2 adsorption capability has a positive correlation with the catalytic performance toward CO2 conversion.

Filling pore space in a microporous coordination polymer to improve methane storage performance

A strategy that allows the tuning of pore size in microporous coordination polymers (MCPs) through modification of their organic linkers is presented. When large substituents are introduced onto the linker, these pendent groups partially occupy the pores, thus reducing pore size while serving as additional adsorption sites for gases. The approach takes advantage of the fact that, for methane storage materials, small pores (0.4-0.8 nm in diameter) are more desirable than large pores since small pores promote optimal volumetric capacity. This method was demonstrated with IRMOF-8, a MCP constructed from Zn4O metal clusters and 2,6-naphthalenedicarboxylate (NDC) linkers. The NDC was functionalized through the addition of substituents including tert-butylethynyl or phenylethynyl groups. High pressure methane uptake demonstrates that the IRMOF-8 derivatives have significantly better performance than the unfunctionalized material in terms of both excess volumetric uptake and deliverable capacity. Moreover, IRMOF-8 derivatives also give rise to stronger interactions with methane molecules as shown by higher heat of adsorption values.

A pyridyl-decorated MOF-505 analogue exhibiting hierarchical porosity, selective CO2 capture and catalytic capacity

An expanded pyridyl-decorated MOF-505 analogue[Cu₂(L)(H₂O)₂]·G_x (H₄L = 5,5′-(pyridine-2,5-diyl)diisophthalic acid, G = solvent molecule) has been solvothermally synthesized and reported.

A high-performance “sweeper” for toxic cationic herbicides: an anionic metal–organic framework with a tetrapodal cage

High efficiency adsorption and removal of toxic herbicides in an anionic metal–organic framework.

4-(4-Carboxyphenoxy)phthalate-based coordination polymers and their application in sensing nitrobenzene

Structural characterization of 4-(4-carboxyphenoxy)phthalate-based Cd²⁺ and Mn²⁺ coordination polymers are reported, and Cd²⁺ coordination polymer can serve as probe to sense nitrobenzene.

A series of coordination polymers based on varied polycarboxylates and different imidazole-containing ligands: syntheses, crystal structures and physical properties

To investigate the effect of organic ligands on the coordination frameworks, seven nickel(ii) coordination polymers, based on varied polycarboxylates and different imidazole-containing ligands, are synthesized under hydrothermal method.

A NbO-type metal–organic framework exhibiting high deliverable capacity for methane storage

A NbO-type MOF incorporating phenylethyne moieties exhibits high methane working capacity for methane storage at room temperature.

A metal–organic framework based on cyclotriphosphazene-functionalized hexacarboxylate for selective adsorption of CO2 and C2H6 over CH4 at room temperature

A new MOF constructed from a flexible cyclotriphosphazene-functionalized hexacarboxylate exhibits selective adsorption of CO₂ and C₂H₆ over CH₄ at room temperature.

Improving the porosity and catalytic capacity of a zinc paddlewheel metal-organic framework (MOF) through metal-ion metathesis in a single-crystal-to-single-crystal fashion

Zinc paddlewheel metal-organic frameworks (MOFs) frequently exhibit low stability or complete collapse upon the removal of axial ligands. Hence, there are very few reports on gas adsorption of zinc paddlewheel MOFs. In this work, the N2 and H2 adsorption measurements were carried out for a zinc MOF (namely, SDU-1) based on two types of paddlewheel secondary building units (SBUs): [Zn2(COO)3] and [Zn2(COO)4]. Because of the existence of inherent surface instability upon removal of solvates in zinc paddlewheel SBU, SDU-1 possesses a very low surface area. Through metal-ion metathesis in a single-crystal-to-single-crystal fashion, the Zn(2+) ions in SDU-1 were exchanged by Cu(2+) ions to generate Cu-SDU-1. Through the measurements of gas adsorption and catalytic test, the porosity and catalytic capacity of Cu-SDU-1 have been improved significantly, compared to SDU-1.

Synthesis and Crystal Structure of the Bioinorganic Complex [Sb(Hedta)]·2H2O

The antimony(III) complex [Sb(Hedta)]·2H2O was synthesized with ethylenediaminetetraacetic acid (H4edta) and antimonous oxide as main raw materials in aqueous solution. The composition and structure of the complex were characterized by elemental analysis, infrared spectra, single crystal X-ray diffraction, X-ray powder diffraction, thermogravimetry, and differential scanning calorimetry. The crystal structure of the antimony(III) complex belongs to orthorhombic system, space group Pna2(1), with cell parameters of a = 18.4823(18) Å, b = 10.9408(12) Å, c = 7.3671(5) Å, V = 1489.7(2) Å(3), Z = 4, and D c = 1.993 g cm(-3). The Sb(III) ion is five-coordinated by two amido N atoms and three carboxyl O atoms from a single Hedta(3-) ligand, forming a distorted trigonal bipyramid geometry. The thermal decomposition processes of the complex include dehydration, oxidation, and pyrolysis of the ligand, and the last residue is Sb2O3 at the temperature of 570°C.