Selective Sorption of Light Hydrocarbons on a Family of Metal–Organic Frameworks with Different Imidazolate Pillars

A Copper-Based Metal-Organic Framework for Selective Separation of C2 Hydrocarbons from Methane at Ambient Conditions: Experiment and Simulation

C2 hydrocarbon separation from methane represents a technological challenge for natural gas upgrading. Herein, we report a new metal-organic framework, [Cu2L(DEF)2]·2DEF (UNT-14; H4L = 4,4',4″,4‴-((1E,1'E,1″E,1‴E)-benzene-1,2,4,5-tetrayltetrakis(ethene-2,1-diyl))tetrabenzoic acid; DEF = N,N-diethylformamide; UNT = University of North Texas). The linker design will potentially increase the surface area and adsorption energy owing to π(hydrocarbon)-π(linker)/M interactions, hence increasing C2 hydrocarbon/CH4 separation. Crystallographic data unravel an sql topology for UNT-14, whereby [Cu2(COO)4]···[L]4- paddle-wheel units afford two-dimensional porous sheets. Activated UNT-14a exhibits moderate porosity with an experimental Brunauer-Emmett-Teller (BET) surface area of 480 m2 g-1 (vs 1868 m2 g-1 from the crystallographic data). UNT-14a exhibits considerable C2 uptake capacity under ambient conditions vs CH4. GCMC simulations reveal higher isosteric heats of adsorption (Qst) and Henry's coefficients (KH) for UNT-14a vs related literature MOFs. Ideal adsorbed solution theory yields favorable adsorption selectivity of UNT-14a for equimolar C2Hn/CH4 gas mixtures, attaining 31.1, 11.9, and 14.8 for equimolar mixtures of C2H6/CH4, C2H4/CH4, and C2H2/CH4, respectively, manifesting efficient C2 hydrocarbon/CH4 separation. The highest C2 uptake and Qst being for ethane are also desirable technologically; it is attributed to the greatest number of "agostic" or other dispersion C-H bond interactions (6) vs 4/2/4 for ethylene/acetylene/methane.

Modifying a partial corn-sql layer-based (3,3,3,3,4,4)-c topological MOF by substitution of OH- with Cl- and its highly selective adsorption of C2 hydrocarbons over CH4

Modifying VNU-18 (a MOF with a partial cone-sql layer pillared by the chains of pillars decorated with OH^-) by substitution of OH^- with Cl^-, a new isoreticular structure, [Cu₆(L)₅·(Cl^-)₂·H₂O·4DMF]·4DMF·6(H₂O) (SNNU-Bai67, SNNU-Bai = Shaanxi Normal University Bai's group), has been successfully synthesized. Furthermore, we deeply investigated the selective C2 hydrocarbon separation properties of SNNU-Bai67 and VNU-18 by single-component gas adsorption experiments, breakthrough experiments and simulation studies. They exhibit highly selective adsorption for C2 hydrocarbons over CH₄ compared to many reported MOFs for the separation of C2 hydrocarbons from CH₄, due to the suitable pore sizes of the partial corn sql-layer built from the isophthalic acid analogy and Cu-paddlewheel units. Interestingly, with the counterion of OH^- in VNU-18 tuned by Cl^- in SNNU-Bai67, the adsorption uptake values of C2 hydrocarbons were apparently improved by 15.0% for C₂H₂, 20.4% for C₂H₄ and 25.3% for C₂H₆, respectively, while the IAST selectivities of C2 hydrocarbons/CH₄ were still nearly the same, which may be because the synergistic effect of interactions of H_C2/1O_COO, H_C2/1N/C_Py, H_PyC_C2, ππ or H_C2C_C2 between the gas molecules and the framework is enhanced by the weaker polarity of Cl^- decorating the framework.

Nanoscale Metal-Organic Layers Detect Mitochondrial Dysregulation and Chemoresistance via Ratiometric Sensing of Glutathione and pH

Mitochondrial dysregulation controls cell death and survival by changing endogenous molecule concentrations and ion flows across the membrane. Here, we report the design of a triply emissive nanoscale metal-organic layer (nMOL), NA@Zr-BTB/F/R, for sensing mitochondrial dysregulation. Zr-BTB nMOL containing Zr₆ secondary building units (SBUs) and 2,4,6-tris(4-carboxyphenyl)aniline (BTB-NH₂) ligands was postsynthetically functionalized to afford NA@Zr-BTB/F/R by exchanging formate capping groups on the SBUs with glutathione(GSH)-selective (2E)-1-(2'-naphthyl)-3-(4-carboxyphenyl)-2-propen-1-one (NA) and covalent conjugation of pH-sensitive fluorescein (F) and GSH/pH-independent rhodamine-B (R) to the BTB-NH₂ ligands. Cell imaging demonstrated NA@Zr-BTB/F/R as a ratiometric sensor for mitochondrial dysregulation and chemotherapy resistance via GSH and pH sensing.

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.

Two new MOFs based on 5-((4-carboxypyridin-2-yl)oxy) isophthalic acid displaying unique selective CO2 gas adsorption and magnetic properties

The reaction of Cu(ii)/Co(ii) with a N-heterocyclic carboxylate ligand produced two new MOFs with different topologies. The Cu-MOF showed selective adsorption for CO₂ over CH₄, and the antiferromagnetic properties existed in the two MOFs.

Amino-functionalized Cu-MOF for efficient purification of methane from light hydrocarbons and excellent catalytic performance

Amino-functionalized Cu-MOF for the efficient purification of methane from light hydrocarbons and excellent catalytic performance.

Stable Lanthanide-Organic Framework Materials Constructed by a Triazolyl Carboxylate Ligand: Multifunction Detection and White Luminescence Tuning

Under hydrothermal conditions, we have successfully synthesized six isostructural lanthanide coordination polymers, [LnL_1.5(H₂O)₂]·1.75H₂O (1-6; Ln = Eu, La, Pr, Nd, Sm, Gd), by the reaction of 5-methyl-1-(4-carboxylphenyl)-1 H-1,2,3-triazole-4-carboxylic acid (H₂L) and Ln(NO₃)₃·6H₂O. Structural analysis shows that polymers 1-6 show novel three-dimensional supramolecular network structures. The luminescent properties for polymer 1 have been investigated at room temperature. The results have shown that polymer 1 can be used as a chemical sensor for multifunctional testing such as UO₂²⁺, Fe³⁺ ion detection, and small organic molecule detection because of its strong fluorescence properties. In particular, polymer 1 exhibits extremely high selectivity and sensitivity for the detection of Fe³⁺ ions. In addition, white-light emission is achieved through a reasonable tuning proportion by mixing Gd³⁺ and Eu³⁺.

Honeycomb Metal-Organic Framework with Lewis Acidic and Basic Bifunctional Sites: Selective Adsorption and CO2 Catalytic Fixation

Carrying out the strategy of incorporating rod secondary building units and polar functional groups in metal-organic frameworks (MOFs) to accomplish the separation of CO₂ and C₂ hydrocarbons over CH₄ as well as CO₂ fixation, an oxalamide-functionalized ligand N, N'-bis(isophthalic acid)-oxalamide (H₄BDPO) has been designed. The solvothermal reaction of H₄BDPO with the oxophilic alkaline-earth Ba²⁺ ion afforded a honeycomb Ba-MOF, {[Ba₂(BDPO)(H₂O)]·DMA} _n (1). Due to the existence of Lewis basic oxalamide groups and unsaturated Lewis acid metal sites in the tubular channels, the activated framework presents not only high C₂H₆, C₂H₄, and CO₂ uptakes and selective capture from CH₄, but also efficient CO₂ chemical fixation as a recyclable heterogeneous catalyst. Grand canonical Monte Carlo simulations were combined to explore the adsorption selectivities for C₂H₆-CH₄ and C₂H₄-CH₄ mixtures as well as the interaction mechanisms between the framework and epoxides.

Solvent-induced framework-interpenetration isomers of Cu MOFs for efficient light hydrocarbon separation

For a pair of Cu-paddlewheel framework-interpenetrating isomers, the interpenetrating framework exhibits a high adsorption and separation selectivity for light hydrocarbons.

An Uncommon Carboxyl-Decorated Metal-Organic Framework with Selective Gas Adsorption and Catalytic Conversion of CO2

A new three-dimensional (3D) framework, [Ni(btzip)(H₂ btzip)]⋅2 DMF⋅2 H₂ O (1) (H₂ btzip=4,6-bis(triazol-1-yl)isophthalic acid) as an acidic heterogeneous catalyst was constructed by the reaction of nickel wire and a triazolyl-carboxyl linker. Framework 1 possesses intersected 2D channels decorated by free COOH groups and uncoordinated triazolyl N atoms, leading to not only high CO₂ and C₂ H₆ adsorption capacity but also significant selective capture for CO₂ and C₂ H₆ over CH₄ and CO in 273-333 K. Moreover, 1 reveals chemical stability toward water. Grand Canonical Monte Carlo simulations confirmed the multiple CO₂ - and C₂ H₆ -philic sites. As a result of the presence of accessible Brønsted acidic COOH groups in the channels, the activated framework demonstrates highly efficient catalytic activity in the cycloaddition reaction of CO₂ with propylene oxide/4-chloromethyl-1,3-dioxolan-2-one/3-butoxy-1,2-epoxypropane into cyclic carbonates.

Microporous rod metal–organic frameworks with diverse Zn/Cd–triazolate ribbons as secondary building units for CO2 uptake and selective adsorption of hydrocarbons

Three rod MOFs exhibiting remarkable CO₂ uptake and high CO₂ and C₂-hydrocarbons over CH₄ selectivity, as well as high isosteric heat of adsorption for C₂H₂.

Selective adsorption of chlorinated volatile organic compound vapours by microcrystalline 1D coordination polymers

Microcrystalline 1D coordination polymers 1–3Pwd are able to adsorb vapours of chlorinated volatile organic compounds (Cl-VOCs), displaying interesting selectivity patterns, as demonstrated by ¹H-NMR and X-ray diffraction analyses.