Three-dimensional Microporous Framework Research Articles

Assembly of a pyrene-based zinc(II)-organic framework with fluorescence property for selective sensing of nitroaromatic compounds

In this work, a zinc(II)-based metal–organic framework, namely [Zn2(TBAPy)(H2O)(DMF)]·4DMF·2H2O (JOU-34) (TBAPy = 1,3,6,8-tetrakis (p-benzoic acid) pyrene; DMF = N,N’-Dimethylformamide), has been solvothermally synthesized and characterized. Single-crystal X-ray diffraction shows that JOU-34 displays three-dimensional microporous framework with rare topology. Due to the introduction of pyrene groups, JOU-34 shows strong fluorescent emission cantered at about 470 nm. Furthermore, it shows a good fluorescence sensing performance toward nitroaromatic compounds, especially nitrobenzene (NB). Although the NB concentration was only 8.33 × 10−4 M, the quenching efficiency can reach 89 %. Further studies show that the quenching effect of JOU-34 in the presence of nitroaromatics may be attributed to the fluorescence resonant energy transfer and electron transfer between nitroaromatics and JOU-34. These results indicate that JOU-34 can be applied as a functional material for nitroaromatics detection.

Novel Multifunctional Samarium-Organic Framework for Fluorescence Sensing of Ag+, MnO4 -, and Cimetidine and Electrochemical Sensing of o-Nitrophenol in Aqueous Solutions.

A novel Sm-metal–organic framework (MOF) sensor with the molecular formula Sm8(HDBA)6·H2O has been prepared based on a penta-carboxyl organic ligand (H5DBA = 3,5-di(2′,4′-dicarboxylphenyl)benzoic acid) and samarium nitrate under solvothermal conditions. Sm-MOF is characterized by single-crystal X-ray diffraction analysis, elemental analysis, thermogravimetric analysis, and powder X-ray diffraction analysis. Structural analysis shows that the dimer metal units are alternately connected to form a one-dimensional chain, and this chain is connected by the bridging carboxyl oxygen of the ligand H5DBA to form a two-dimensional double-layer plane, which then expands into a three-dimensional microporous framework. Fluorescence detection studies show that Sm-MOF can detect Ag+ ions, MnO4– anions, and cimetidine tablets with high sensitivity and selectivity and can also be used to electrochemically detect o-nitrophenol in water. High-sensitivity detection capability of the Sm-MOF can enrich the application of samarium complexes in multifunctional sensors.

Enhanced Adsorption and Separation of Xenon over Krypton via an Unsaturated Calcium Center in a Metal-Organic Framework.

Krypton (Kr) and xenon (Xe) are nowadays widely applied in technical and industrial fields. Separating and collecting highly pure Xe from nuclear facilities are necessary and urgent. However, the technology is limited due to the inert nature of Xe and other interferential factors. In this work, a calcium-based metal-organic framework, Ca-SINAP-1, which comprises a three-dimensional microporous framework with a suitable pore width, was researched for xenon and krypton separation through both experimental and theoretical methods. Ca-SINAP-1, synthesized in solvothermal and gamma ray conditions, features accessible open-metal sites, exhibits a high Xe/Kr selectivity of 10.32, and owns a Xe adsorption capacity of 2.87 mmol/g at room temperature (1.0 bar). Particularly, its excellent chemical stability (from pH 2 to 13) and thermal stability (up to 550 °C), as well as radiation-resistance (up to 400 kGy β irradiations), render this material a promising candidate for radioactive inert gases treatment.

A Multifunctional Tb-MOF Detector for H2O2, Fe3+, Cr2O7 2-, and TPA Explosive Featuring Coexistence of Binuclear and Tetranuclear Clusters.

A novel three-dimensional microporous terbium(III) metal–organic framework (Tb-MOF) named as [Tb10 (DBA)6(OH)4(H2O)5]·(H3O)4 (1), was successfully obtained by a solvothermal method based on terbium nitrate and 5-di(2′,4′-dicarboxylphenyl) benzoic acid (H5DBA). The Tb-MOF has been characterized by single crystal X-ray diffraction, elemental analysis, thermogravimetry, and fluorescence properties, and the purity was further confirmed by powder X-ray diffraction (PXRD) analysis. Structural analysis shows that there are two kinds of metal cluster species: binuclear and tetranuclear, which are linked by H5DBA ligands in two μ7 high coordination fashions into a three-dimensional microporous framework. Fluorescence studies show that the Tb-MOF can detect H2O2, Fe3+, and Cr2O72– with high sensitivity and selectivity and can also be used for electrochemical detection of exposed 2,4,6-trinitrophenylamine (TPA) in water. The highly selective and sensitive detection ability of the Tb-MOF might make it a potential multifunctional sensor in the future.

Dynamic Covalent Synthesis of Crystalline Porous Graphitic Frameworks

Summary Porous graphitic framework (PGF) is a two-dimensional (2D) material that has emerging energy applications. An archetype contains stacked 2D layers, the structure of which features a fully annulated aromatic skeleton with embedded heteroatoms and periodic pores. Due to the lack of a rational approach in establishing in-plane order under mild synthetic conditions, the structural integrity of PGF has remained elusive and ultimately limited its material performance. Here, we report the discovery of the unusual dynamic character of the C=N bonds in the aromatic pyrazine ring system under basic aqueous conditions, which enables the successful synthesis of a crystalline porous nitrogenous graphitic framework with remarkable in-plane order, as evidenced by powder X-ray diffraction studies and direct visualization using high-resolution transmission electron microscopy. The crystalline framework displays superior performance as a cathode material for lithium-ion batteries, outperforming the amorphous counterparts in terms of capacity and cycle stability.

Series of 3d-4f heterometallic coordination polymers: Structures, near-infrared luminescence and magnetic properties

A series of 3d-4f heterometallic coordination polymers (CPs), namely, Ln2(CuL)2(nipt)3(H2O)]⋅nH2O (Ln = Sm 1, Nd 2, Gd 3, for 1–2 n = 2, for 3 n = 1.6), [Yb2(CuL)4(nipt)3]·3.5H2O (4), [Pr2(NiL)(nipt)3(H2O)]⋅1.5H2O (5), [Sm2(NiL)(nipt)3(H2O)2]CH3OH⋅H2O (6), [Er2(NiL)2(nipt)3(H2O)2]⋅3H2O (7) (ML, H2L = 2, 3-dioxo-5, 6, 14, 15-dibenzo-1, 4, 8, 12-tetraazacyclo-pentadeca-7, 13-dien; H2nipt = 5-nitroisophthalic acid) were obtained by a solvothermal method and structurally characterized. Complexes 1–3 have 3,3,4,5-connected (3.4.5)(32.42.5.63.72)(42.63.8)(42.6) topological structure consisting of two different chains. 4 exhibits a two-dimensional (2D) heterometallic structure with 3-connected (63) topology. 5 displays a 2D framework formed by four-strand meso-helical chains and characterized by 6,6,4,4,4-connected (411.64)(412.63)(43.62.8)(45.6)2 topology. Compound 6 has 3,4,4,3-connected (43)(44.62)(42.124)(42.6) topological structure formed by three-strand meso-helical chains. In 7, two kinds of μ3-bridged nipt2− ligands together with NiL connect the eight-coordinated Er3+ ions to form a 2D structure, and the 2D layers are extended by μ2-bridged nipt2− into a three-dimensional (3D) microporous framework with 4,4,3,3-connected (4.62.83)2(4.82)2 topology. Interestingly, for 1, 2 and 4, CuL-sensitized the near-infrared emissions form Sm(III), Nd(III) and Yb(III) were firstly found under visible light irradiation. Moreover, the magnetic properties of 1, 2, 4 and 5 are also discussed.

Correction: Bottom-up synthesis of fully sp2 hybridized three-dimensional microporous graphitic frameworks as metal-free catalysts

Correction for ‘Bottom-up synthesis of fully sp2 hybridized three-dimensional microporous graphitic frameworks as metal-free catalysts’ by S. N. Talapaneni et al., J. Mater. Chem. A, 2017, 5, 12080–12085.

Stable Tb(III)-Based Metal-Organic Framework: Structure, Photoluminescence, and Chemical Sensing of 2-Thiazolidinethione-4-carboxylic Acid as a Biomarker of CS2.

A novel three-dimensional microporous framework, [Tb(pddb)phen(ox)0.5] n (Tb-MOF), was synthesized hydrothermally with V-shaped 4,4'-(pyridine-2,6-diyl)dibenzoic acid (H2pddb), oxalate (ox), and 1,10-phenanthroline (phen). The framework of Tb-MOF features one-dimensional channels functionalized with pyridine-N Lewis base groups and the absence of coordinated and lattice water molecules in the structure. The Tb-MOF exhibits high thermostability (up to 385 °C) and chemical stability in a wide pH range (4-11) and common organic solvents as well as boiling water. The luminescence investigations of the Tb-MOF in common solvents, water with different pH values, and inorganic ions were performed. Results show that the Tb-MOF has high luminescence stability and the ability to probe Fe3+ ions. Significantly, the Tb-MOF with particularly high water stability can be first developed as a highly selective and sensitive luminescent sensor for the biomarker 2-thiazolidinethione-4-carboxylic acid (TTCA) via fluorescence quenching. The low detection limit (1 ppm), reusability, and high antidisturbance together make the Tb-MOF become a promising sensor for the practical detection of TTCA in urine systems, and for the first time realize the detection of urinary TTCA through fluorescence spectrometry based on an Ln-MOF sensor.

Two Series of Microporous Lanthanide-Organic Frameworks with Different Secondary Building Units and Exposed Lewis Base Active Sites: Sensing, Dye Adsorption, and Magnetic Properties.

Two series of new lanthanide complexes, {[Ln(L)1.5(H2O)]·DMA·4H2O} n (1-Ln, Ln = Tb, Gd, and Dy) and {[La2(L)3]·4H2O} n (2-La), were prepared successfully by Ln3+ ions and a N-heterocyclic dicarboxylic (2-pyrimidin-5-yl)terephthalic acid (H2L) ligand. The four complexes are three-dimensional (3D) microporous frameworks with different secondary building units (SBUs) and exposed Lewis base active sites. Topology analyses reveal that 1-Ln are the binodal (3,8)-connected tfz-d (43)2(46·618·84) nets and 2-La is a binodal (2,12)-connected (4)6(46·848·1212) net. The photoluminescence of 1-Tb, the dye adsorption of 1-Tb and 2-La, and the magnetism of 1-Dy have been well studied. The luminescent explorations indicate that 1-Tb is a highly efficient probe for sensing Fe3+ and Cr2O72-, respectively. Complexes 1-Tb and 2-La display the unique selective adsorption to Congo red (CR) dyes. Magnetic measurements further indicate that 1-Dy has a slow magnetic relaxation performance.

Three-dimensional porous carbon frameworks derived from mangosteen peel waste as promising materials for CO2 capture and supercapacitors

Abstract Business costs, environmental and energy concerns have increased interest in biomass materials for the production of porous carbon materials, especially as solid-state adsorbents for CO2 capture or as electrode materials for supercapacitors. We put forward an efficient and scalable approach to convert mangosteen peel (MP) waste into three-dimensional microporous carbon frameworks (3D-MP-CFW) for effective CO2 capture and supercapacitors. The MP waste is first subjected to a controllable hydrothermal treatment in alkaline solution and then a carbonization process. The resultant optimal carbon sample possesses a high surface area up to 1270 m2 g−1 and abundant micropores with fine micropore sizes below 1 nm. The typical sample has a well-tailored open 3D macroporous interconnected network structure, exhibiting an outstanding CO2 capture recyclability and high CO2 capture capacities of 6.93 and 4.77 mmol g−1 at 0 °C and 25 °C (1 bar), respectively. Simultaneously, benefiting from its high surface area and 3D interconnected porous structure, this optimal sample also exhibits a good supercapacitance performance with the specific capacitance of 240 F g−1 (in 6 M KOH, at 1 A g−1) in a three-electrode system. Our simple preparation method presents an efficient way to make promising carbon materials for high-performance CO2 capture and supercapacitors.

Improving Water-Stability and Porosity of Lanthanide Metal–Organic Frameworks by Stepwise Synthesis for Sensing and Removal of Heavy Metal Ions

Employing polynuclear cluster-based nodes can make metal–organic frameworks have higher porosity and good stability. In this work, by using compound [(Me2NH2)Eu(L)(DMA)(H2O)]n (1) as reactant, polynuclear cluster-based [(Me2NH2)Eu5(L)4(DMA)4(H2O)6]n (2) (H4L = 1,3-bis-[3,5-bis(carboxy)phenoxy]propane) can be synthesized successfully. Although two compounds are all three-dimensional microporous anionic frameworks, the water-stability and porosity of compound 2 is higher than that of compound 1. Compound 2 is assembled by two kinds of multinuclear metal units in which one Eu(III) ion center is hexa-coordinated. The luminescence studies exhibited that compound 2 performed a highly selective photoluminescence quenching toward nitrobenzene and Fe(III) ion. So, compound 2 can be possibly developed as a dual functional chemosensor for detecting Fe(III) ion and nitrobenzene. Furthermore, compound 2 also has the potential ability to absorb and remove toxic metal ions from aqueous solution.

Expression of concern: Bottom-up synthesis of fully sp2 hybridized three-dimensional microporous graphitic frameworks as metal-free catalysts

Expression of concern for ‘Bottom-up synthesis of fully sp2 hybridized three-dimensional microporous graphitic frameworks as metal-free catalysts’ by Siddulu Naidu Talapaneni et al., J. Mater. Chem. A, 2017, 5, 12080–12085.

Zeolite-templated carbons - three-dimensional microporous graphene frameworks.

Zeolite-templated carbons (ZTCs) are ordered microporous carbons synthesized by using zeolite as a sacrificial template. Unlike well-known ordered mesoporous carbons obtained by using mesoporous silica templates, ZTCs consist of curved and single-layer graphene frameworks, thereby affording uniform micropore size (ca. 1.2 nm), developed microporosity (∼1.7 cm3 g-1), very high surface area (∼4000 m2 g-1), good compatibility with chemical modification, and remarkable softness/elasticity. Thus, ZTCs have been used in many applications such as hydrogen storage, methane storage, CO2 capture, liquid-phase adsorption, catalysts, electrochemical capacitors, batteries, and fuel cells. Herein, the relevant research studies are summarized, and the properties as well as the performances of ZTCs are compared with those of other materials including metal-organic frameworks, to elucidate the intrinsic advantages of ZTCs and their future development.

Three microporous metal-organic frameworks assembled from dodecanuclear {NiLn} subunits: synthesis, structure, gas adsorption and magnetism.

Three isostructural heterometallic metal-organic frameworks (MOFs) {[Ln2Ni(OAc)5(HL)(L)]·solvent molecules}n (H2L = 2-hydroxyimino-N-[1-(2-pyrazinyl)ethylidene]-propanohydrazone, Ln = Dy for 1, Tb for 2 and Gd for 3) were solvothermally synthesized by varying rare-earth metal ions with different electron configurations. Their crystal structures, gas adsorption and magnetic behaviors were fully investigated. The three isomorphous MOFs exhibit three-dimensional microporous frameworks with two different orientated dodecane metallic {NiIILnIII(HL)}6 metallomacrocycles alternately connected by {LnIII(L)} connectors, in which an empty one-dimensional channel decorated by the basic hydrazone interior is generated. Due to their LnIII-independent microporous nature, the activated sample of 1 as a representative example has a significant CO2 uptake up to 42.2 cm3 g-1 and an unusually high CO2/N2 and CO2/CH4 adsorption selectivity of up to 98.8 and 16.8 at 298 K and 100 kPa. Magnetically, apparent antiferromagnetic interactions for both 1 and 2 as well as ferromagnetic coupling for 3 are respectively observed at low temperature resulting from the competition of magnetic anisotropy and intermetallic ferromagnetic superexchange. Additionally, 1 with highly anisotropic DyIII spin shows slow magnetization relaxation under zero dc field, whereas 3 possessing isotropic GdIII ions displays a significant cryogenic magnetocaloric effect with a maximum entropy change of 26.6 J kg-1 K-1 at 3.0 K and 70 kOe. These interesting results can provide valuable information on gas separation-based multifunctional 3d-4f MOF materials.

New Luminescent Three-Dimensional Zn(II)/Cd(II)-Based Metal–Organic Frameworks Showing High H2 Uptake and CO2 Selectivity Capacity

Three new three-dimensional (3D) luminescent metal–organic frameworks (MOFs), namely, [Zn2(L)2]·2DMA·3H2O (1), [Zn2(L)2]·H2O (2), and [Cd2(L)2]·H2O (3) [H2L = 2-(imidazol-1-yl)terephthalic acid], have been solvothermally synthesized by using d10 metal ions Zn(II)/Cd(II) and H2L in different solvent systems, which have been well characterized by elemental analysis, Fourier transform infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. As influenced by the different solvents and metal ions, single-crystal X-ray diffraction shows that 1 is a three-dimensional (3D) microporous framework with one-dimensional (1D) pores (10.85 × 8.79 A2) based on the [Zn2(μ2-COO)4] secondary building units, and 2 and 3 are two 3D isostructural networks composed by 1D zigzag chains, which are further connected by L2– ligands into dense packing structures. Topology analyses reveal that 1 can be simplified as a binodal (6,3)-connected ant topological net with a point symbol of (44·63·83)(48·62), and 2 a...

A new layer-stacked porous framework showing sorption selectivity for CO2 and luminescence.

A new metal-organic framework, [Zn3(μ3-OH)(tzba)2(bpy)(H2O)]OH·DMF (1), was solvothermally synthesized by employing tetrazolate-carboxylate 4-(1H-tetrazol-5-yl) benzoic acid (H2tzba) linker and 2,2'-bipyridine (bpy) chelating coligand. 1 contains novel Zn6(μ3-OH)2(μ2-H2O)2(COO)4(N4C)2 hexanuclear clusters and reveals a three-dimensional (3D) microporous supramolecular framework based on the stacked 2D layers. The highly polar pores cause not only strong affinity towards CO2 molecules but also a significant selective adsorption of CO2 over CH4. Meanwhile, the multiple binding sites for CO2 in the framework were determined by Grand Canonical Monte Carlo (GCMC) simulations. 1 also shows strong blue luminescence from ligand-to-metal charge transfer (LMCT).

Bottom-up synthesis of fully sp2 hybridized three-dimensional microporous graphitic frameworks as metal-free catalysts

We demonstrated template-free inclusion of the third dimension into the graphitic frameworks while retaining π-conjugation and conductivity, which was verified by their activity as metal-free electrocatalysts for the hydrogen evolution reaction.

High Capacity Rechargeable Magnesium-Ion Batteries Based on a Microporous Molybdenum–Vanadium Oxide Cathode

The three-dimensional microporous framework of the oxide Mo2.5+yVO9+δ (containing Mo5+/6+ and V4+/5+) is defined by three-, six-, and seven-membered ring channels. Due to the oxidation–reduction properties of Mo and V ions and the large open tunnels that can provide a diffusion pathway for small ions, Mo2.5+yVO9+δ has been found to intercalate both Li+ ions, reported previously, and also Mg2+ ions in Mg-ion batteries. Cathodes composed of Mo2.5+yVO9+δ were discharged and charged in Mg-ion cells at current densities ranging from 2 mA/g (C/70) to 10 mA/g (C/12). Mg2+ ions can be inserted into and extracted from MgxMo2.5+yVO9+δ between ∼3.33 and 1.73 V vs Mg/Mg2+ at room temperature, with up to 3.49 Mg2+ ions per formula unit intercalated into the framework, corresponding to a capacity of 397 mAh/g (1st discharge) which is among the highest capacities reported for Mg-based batteries. Powder X-ray diffraction was used to determine the lattice parameters of MgxMo2.5+yVO9+δ (0 < x ≤ 3) compositions prepared by ...

A highly stable multifunctional three-dimensional microporous framework: excellent selective sorption and visible photoluminescence

A Cd(II)-MOF [Cd(L)(DMF)] (1) (H2L = 5-(4-pyridyl)-isophthalic acid) featuring high thermal and chemical stability has been solvothermally synthesized and characterized. Complex 1 is a robust multifunctional three-dimensional (3D) microporous framework possessing an unusual (4,5)-connected topological net. Activated 1 shows high-efficiency for the selective capture of CO2 over N2 and CH4 under ambient conditions, which ranks it among MOFs with the highest selectivity. In addition, desolvated 1 exhibits good separation ratios of H2 over N2 at lower temperature, as well as alcohols from water. In particular, desolvated 1 demonstrates significantly higher adsorption enthalpies for CO2 and CH4 gas molecules, which are in the range of the highest Q(st) values reported to date. Furthermore, complex 1 displays visible photoluminescence in the solid state under UV irradiation.

A microporous Zn(II)-MOF with open metal sites: structure and selective adsorption properties.

A three-dimensional microporous framework, Zn(II)-MOF [Zn(HPyImDC)(DMA)]n (1) (H3PyImDC = 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic, DMA = N,N'-dimethylacetamide), with open metal sites and small-sized pores, exhibits excellent selective capture of CO2 over N2 and CH4 at 273 K, as well as alcohols from water. The excellent CO2 adsorption selectivity of 1 allows its potential use in the capture of CO2 from industrial flue gas or the removal of CO2 from natural gas. More interestingly, compound represents the rare case of porous materials separating propanol isomers, which may be caused by the relative flexibility of the linear n-propanol considering that both n-propanol and i-propanol have similar kinetic diameters.