Advancing Membrane Technology: Ordered Macroporous ZIF-67 as a Filler in Mixed Matrix Membranes for Enhanced Propylene/Propane Separation

Conventional separation technologies for valuable commodities require substantial energy, accounting for 10%-15% of global consumption. Mixed-matrix membranes (MMMs) offer a promising solution by combining processable polymers with selective inorganic fillers. Here, the potential of using ordered microporous structured materials is demonstrated as MMM fillers. The use of ordered macroporous ZIF-67 in combination with the well-known 6FDA-DAM polymer leads to superior performance in the important separation of propylene from propane. The enhanced performance can be rationalized with the help of advanced microscopy, which demonstrates that the polymer is able to penetrate the macroporous network around which the MOF (Metal-Organic Framework) is synthesized, resulting in a much better interphase between the two components and the homogeneous distribution of the filler, even at high loadings.

Morphology Control of Zr-Based Luminescent Metal-Organic Frameworks for Aflatoxin B1 Detection

Metal-organic frameworks (MOFs) have gained significant prominence as sensing materials owing to their unique properties. However, understanding the correlation between the morphology, properties, and sensing performance in these MOF-based sensors remains a challenge, limiting their applications and potential for improvement. In this study, Zr-MOF was chosen as an ideal model to explore the impact of the MOF morphology on the sensing performance, given its remarkable stability and structural variability. Three luminescent MOFs (namely rod-like Zr-LMOF, prismoid-like Zr-LMOF, and ellipsoid-like Zr-LMOF) were synthesized by adjusting the quantities of the benzoic acid and the reaction time. More importantly, the sensing performance of these Zr-LMOFs in response to aflatoxin B1 (AFB1) was thoroughly examined. Notably, the ellipsoid-like Zr-LMOF exhibited significantly higher sensitivity compared to other Zr-LMOFs, attributed to its large specific surface area and pore volume. Additionally, an in-depth investigation into the detection mechanism of AFB1 by Zr-LMOFs was conducted. Building upon these insights, a ratiometric fluorescence sensor was developed by coordinating Eu3+ with ellipsoid-like Zr-LMOF, achieving a remarkably lower detection limit of 2.82 nM for AFB1. This study contributes to an improved comprehension of the relationship between the MOF morphology and the sensing characteristics while presenting an effective approach for AFB1 detection.

Dynamical and electronic properties of anion-pillared metal-organic frameworks for natural gas separation

The increasing demand for natural gas as a clean energy source has emphasized the need for efficient gas separation technologies. Metal-organic frameworks (MOFs) have emerged as a promising class of materials for gas separation, with anion-pillared MOFs (APMOFs) gaining attention for their fine-tuned pore design and shape/size selectivity. In this study, we investigate the dynamical and electronic properties of three APMOFs, SIFSIX-3-Cu, SIFSIX-2-Cu-i, and SIFSIX-2-Cu, for the separation of methane from ethane, ethene, propane, propene, and N using computational simulations. Our simulations employ Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) techniques combined with Density Functional Theory (DFT) calculations. We find that that all three APMOFs exhibit promising separation capabilities for methane from propane and propene based on both thermodynamics and kinetics parameters. In addition, we use Noncovalent Interaction (NCI) analysis to investigate intermolecular interactions and find that the fluorine atoms in the MOF can polarize gas molecules and establish electrostatic interactions with hydrogen atoms in the molecule. Finally, we show that SIFSIX-2-Cu-i is a potential candidate for separating N2/CH4 due to its interpenetration.

UiO-66 derived ZrO2@C catalysts for the double-bond isomerization reaction of 2-butene

1-Butene, as one of the widely used chemical raw materials, can be produced by the double bond isomerization of 2-butene. However, the current yield of the isomerization reaction is only up to 20% or so. It is therefore an urgent issue to develop novel catalysts with higher performances. In this work, a high-activity ZrO₂@C catalyst that is derived from UiO-66(Zr) is fabricated. The catalyst is prepared by calcining the precursor UiO-66(Zr) at high temperature in nitrogen, and characterized by XRD, TG, BET, SEM/TEM, XPS and NH₃-TPD. The results demonstrate that the calcination temperature has significant influences on the catalyst structure and performance. Regarding the catalyst ZrO₂@C-500, the selectivity and yield of 1-butene are 94.0% and 35.1%, respectively. The high performance is due to multiple aspects, including the inherited octahedral morphology from parent UiO-66(Zr), suitable medium-strong acidic active sites and high surface area. The present work will lead to a better understanding of the ZrO₂@C catalyst and guide the rational design of high-activity catalysts for the double bond isomerization of 2-butene to 1-butene.

Integrating Self-Partitioned Pore Space and Amine Functionality into an Aromatic-Rich Coordination Framework with Ph Stability for Effective Purification of C2 Hydrocarbons

A great demand for high-purity C₂ hydrocarbons calls for the development of chemically stable porous materials for the effective isolation of C₂ hydrocarbons from CH₄ and CO₂. However, such separations are challenged by their similar physiochemical parameters and have not been systematically studied to date. In this work, we reported a cadmium-based rod-packing coordination framework compound ZJNU-140 of a new 5,6,7-c topology built up from a custom-designed tricarboxylate ligand. The metal-organic framework (MOF) features an aromatic-abundant pore surface, uncoordinated amine functionality, and self-partitioned pore space of suitable size. These structural characteristics act synergistically to provide the MOF with both selective recognition ability and the confinement effect toward C₂ hydrocarbons. As a result, the MOF displays promising potential for adsorptive separation of C₂-CH₄ and C₂-CO₂ mixtures. The IAST-predicted C₂/CH₄ and C₂/CO₂ adsorption selectivities, respectively, fall in the ranges of 7.3-10.2 and 2.1-2.9 at 298 K and 109 kPa. The real separation performance was also confirmed by dynamic breakthrough experiments. In addition, the MOF can maintain skeleton intactness in aqueous solutions with a wide pH range of 3-11, as confirmed by powder X-ray diffraction (PXRD) and isotherm measurements, showing no loss of framework integrity and porosity. The excellent hydrostability, considerable uptake capacity, impressive adsorption selectivity, and mild regeneration make ZJNU-140 a promising adsorbent material applied for the separation and purification of C₂ hydrocarbons.

Substituent Engineering-Enabled Structural Rigidification and Performance Improvement for C2/CO2 Separation in Three Isoreticular Coordination Frameworks

Construction of porous solid materials applied to the adsorptive removal of CO₂ from C₂ hydrocarbons is highly demanded thanks to the important role C₂ hydrocarbons play in the chemical industry but quite challenging owing to the similar physical parameters between C₂ hydrocarbons and CO₂. In particular, the development of synthetic strategies to simultaneously enhance the uptake capacity and adsorption selectivity is very difficult due to the trade-off effect frequently existing between both of them. In this work, a combination of the dicopper paddlewheel unit and 4-pyridylisophthalate derivatives bearing different substituents afforded an isoreticular family of coordination framework compounds as a platform. Their adsorption properties toward C₂ hydrocarbons and CO₂ were systematically investigated, and subsequent IAST and density functional theory calculations combined with column breakthrough experiments verified their promising potential for C₂/CO₂ separations. Furthermore, the substituent engineering endowed the resulting compounds with simultaneous enhancement of uptake capacity and adsorption selectivity and thus better C₂/CO₂ separation performance compared to their parent compound. The substituent introduction not only mitigated the framework distortion via fixing the ligand conformation for establishment of better permanent porosity required for gas adsorption but also polarized the framework surface for host-guest interaction improvement, thus resulting in enhanced separation performance.

Exceptionally high selectivity in the separation of light hydrocarbons by adsorption on MIL-127(Fe) and on a (9,9) carbon nanotube

Porous solids with channel sizes that are not much above the size of small hydrocarbons can yield extremely large adsorption selectivity. Our Grand Canonical Monte-Carlo simulations indicate exceptionally high selectivity for the separation of methane, ethane and propane from natural gas. At 250 K the C₃H₈/CH₄ separation on MIL-127 at low pressure has a selectivity of more than 1000 and the C₃H₈/CH₄ separation on CNT (9,9) is even above 2000. This is due to the strong molecule lattice interaction in narrow channels which leads to large enthalpies of adsorption. The Arrhenius law for the Henry coefficients is analysed in order to show that the effect is due to this enthalpy rather than to steric reasons.

A Coordination Network Featuring Two Distinct Copper(II) Coordination Environments for Highly Selective Acetylene Adsorption

Single crystals of 2D coordination network {Cu2 L2  ⋅ (DMF)3 (H2 O)3 }n (1-DMF) were prepared by reaction of commercial reagents 3-formyl-4-hydroxybenzoic acid (H2 L) and Cu(NO3 )2 in dimethylformamide (DMF). The single-crystal structure shows two distinct Cu(II) coordination environments arising from the separate coordination of Cu(II) cations to the carboxylate and salicylaldehydato moieties on the linker, with 1D channels running through the structure. Flexibility is exhibited on solvent exchange with ethanol and tetrahydrofuran, while porosity and the unique overall connectivity of the structure are retained. The activated material exhibits type I gas sorption behaviour and a BET surface area of 950 m2  g-1 (N2 , 77 K). Notably, the framework adsorbs negligible quantities of CH4 compared with CO2 and the C2 Hn hydrocarbons. It exhibits exceptional selectivity for C2 H2 /CH4 and C2 H2 /C2 Hn , which has applicability in separation technologies for the isolation of C2 H2 .

Recent progress on porous MOFs for process-efficient hydrocarbon separation, luminescent sensing, and information encryption

Metal-organic frameworks (MOFs), as an emerging class of porous materials, excel in designability, regulatability, and modifiability in terms of their composition, topology, pore size, and surface chemistry, thus affording a huge potential for addressing environment and energy-related challenges. In particular, MOFs can be applied as porous adsorbents for the purification of industrially important hydrocarbons through certain process-efficient separation schemes based on selectivity-reversed adsorption and multicomponent separation. Moreover, the vast combination possibilities and controllable and engineerable luminescent units of MOFs make them a versatile platform to develop functionally tailored materials for luminescent sensing and optical data encryption. In this feature article, we summarize the recent progress in the use of porous MOFs for the separation and purification of acetylene (C₂H₂) and ethylene (C₂H₄) based on selectivity-reversed adsorption and multicomponent separation strategies. Moreover, we highlight the advances over the past three years in the field of MOF-based luminescent materials for thermometry, turn-on sensing, and information encryption.

Stabilization of CO2 as Zwitterionic Carbamate within a Coordination Polymer (CP): Synthesis, Structure and Anions Sensing Behaviour of Tb-CP composite

A new gadolinium (III) based coordination polymer (CP), [Gd(3,5-pydc)1.5(CO2)0.5(H2O)4].3H2O (where 3,5-pydc =3,5-pyridinedicarboxylate) , 1, has been successfully synthesized using slow diffusion method at room temperature. Single crystal X-ray diffraction study...

Porous Metal-Organic Frameworks for Hydrogen Storage

The high gravimetric energy density and environmental benefit place hydrogen as a promising alternative to the widely used fossil fuel, which is however impeded by the lack of safe, energy-saving...

Efficient Separation of Acetylene-Containing Mixtures Using ZIF-8 Membranes

Metal-organic framework (MOF) membranes show great potential in the separation of acetylene mixtures. In this work, we have prepared ZIF-8 membranes on polyamide (PA) substrates for the highly selective separation of acetylene/methane and acetylene/carbon dioxide mixtures. The C₂H₂/CH₄ and C₂H₂/CO₂ mixtures can be successfully separated using the ZIF-8 membranes, with separation factors of 12.1 and 1.8, respectively. Based on the results of the cross-permeation tests of C₂H₂/CH₄, CO₂/CH₄, and C₂H₂/CO₂, the separation mechanism of C₂H₂/CH₄ in our ZIF-8 membrane can be attributed to a higher affinity for acetylene and molecular sieving effect, while C₂H₂/CO₂ separation is related to thermodynamic factors. It is worth noting that this is the first example of MOF membranes to successfully separate C₂H₂ from CH₄ and CO₂.

Lanthanide-Organic Frameworks Featuring Three-Dimensional Inorganic Connectivity for Multipurpose Hydrocarbon Separation

Implementation of lanthanide-organic frameworks (LOFs) as solid adsorbents has been frequently handicapped by their permanent porosity being difficult to establish owing to the remarkable flexibility and diversity of lanthanide ions in terms of coordination number and geometry. Construction of robust LOFs with permanent porosity for industrially important hydrocarbon separation will greatly expand their application potential. In this work, by distributing N and O donors into an m-terphenyl skeleton, we rationally synthesized a heterofunctional linker, and constructed a pair of isostructural LOFs. Due to the inclusion of a rarely observed three-dimensional metal-carboxylate backbone serving as a highly connected inorganic secondary building unit, their permanent porosities were successfully established by diverse gas isotherms. They can be applied as separating media not only for natural gas purification and removal of carbon dioxide from C₂ hydrocarbons but also more importantly for single-step ethylene (C₂H₄) purification from a three-component C₂H_n mixture during the adsorption process. The latter separation is very challenging and has been less reported in the literature. This work provides a unique example of LOFs featuring three-dimensional inorganic connectivity applied to multipurpose hydrocarbon separations.

Ligand Bent-Angle Engineering for Tuning Topological Structures and Acetylene Purification Performances of Copper-Diisophthalate Frameworks

To enrich structural chemistry and widen the application prospects of MOFs (metal-organic frameworks), the development of a synthetic strategy to realize structural and functional modulation is highly demanded. By implementation of the linker bent-angle engineering strategy, three banana-like diisophthalate linkers with distinct bent angles were designed and synthesized. The inclusion of the targeted linkers into MOFs through solvothermal assembly with CuCl₂·2H₂O under identical conditions yielded three crystalline solids featuring diversified topological structures as revealed by X-ray crystallographic studies. Furthermore, functional explorations indicated that they are promising solid adsorbents for acetylene (C₂H₂) purification application with structurally dependent separation potentials. The results reported in this study illustrated a rare example of modulating the topological structures and separation efficiencies of MOFs by engineering the ligand bent angles.

Response of a Zn(II)-based metal-organic coordination polymer towards trivalent metal ions (Al3+, Fe3+ and Cr3+) probed by spectroscopic methods

A new zinc-based two-dimensional coordination polymer, [Zn(5-AIP)(Ald-4)]·H2O (5-AIP = 5-amino isophthalate, Ald-4 = aldrithiol-4), 1, has been synthesized at room temperature by the layer diffusion technique. Single-crystal X-ray diffraction analysis of 1 showed a two-dimensional bilayer structure. An aqueous suspension of 1 upon excitation at 300 nm displayed an intense blue emission at 403 nm. The luminescence spectra were interestingly responsive and selective to Al3+, Cr3+ and Fe3+ ions even in the presence of other interfering ions. The calculated detection limits for Al3+, Cr3+ and Fe3+ were 0.35 μM ([triple bond, length as m-dash]8.43 ppb), 0.46 μM ([triple bond, length as m-dash]22.6 ppb) and 0.30 μM ([triple bond, length as m-dash]15.85 ppb), respectively. Notably, with the cumulative addition of Al3+ ions, the luminescence intensity at 403 nm decreased steadily with a gradual red shift up to 427 nm. Afterward, this red shifted peak showed a turn-on effect upon further addition of Al3+ ions. On the other hand, for Cr3+ and Fe3+ ions, there was only drastic luminescence quenching and a large red shift up to 434 nm. This indicated the formation of a complex between 1 and these metal ions, which was also supported by the UV-Visible absorption spectra of 1 that showed the appearance of a new band at 280 nm in the presence of these three metal ions. The FTIR spectra revealed that these ions interacted with the carboxylate oxygen atom of 5-AIP and the nitrogen atom of the Ald-4 ligand in the structure. The luminescence lifetime decay analysis manifested that a charge-transfer type complex was formed between 1 and Cr3+ and Fe3+ ions that resulted in huge luminescence quenching due to the efficient charge transfer involving the vacant d-orbitals, whereas for Al3+ ions having no vacant d-orbital, turn-on of luminescence occurred because of the increased rigidity of 1 upon complexation.

High Working Capacity Acetylene Storage at Ambient Temperature Enabled by a Switching Adsorbent Layered Material

Unlike most gases, acetylene storage is a challenge because of its inherent pressure sensitivity. Herein, a square lattice (sql) coordination network [Cu(4,4'-bipyridine)₂(BF₄)₂]_n (sql-1-Cu-BF₄) is investigated with respect to its C₂H₂ sorption behavior from 189 to 298 K. The C₂H₂ sorption studies revealed that sql-1-Cu-BF₄ exhibits multistep isotherms that are temperature-dependent and consistent with the transformation from "closed" (nonporous) to four "open" (porous) phases induced by the C₂H₂ uptake. The Clausius-Clapeyron equation was used to calculate the performance of sql-1-Cu-BF₄ for C₂H₂ storage at pressures >1 bar, which revealed that its volumetric working capacity at 288 K is slightly superior to acetone (174 vs 170 cm³ cm^-3) over a safer pressure range (1-3.5 vs 1-15 bar). Molecular simulations provided insights into the observed switching phenomena, revealing that the layer expansion of sql-1-Cu-BF₄ occurs via intercalation and inclusion of C₂H₂. These results indicate that switching adsorbent layered materials offer promise for utility in the context of C₂H₂ storage and delivery.

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.

A turn-on luminescence probe based on amino-functionalized metal-organic frameworks for the selective detections of Cu2+, Pb2+ and pyrophosphate

A "turn-on" fluorescent probe based on amino-functionalized metal-organic frameworks (MOF-5-NH₂) is developed for the detection of Cu²⁺, Pb²⁺ and pyrophosphate (P₂O₇^4-, PPi). The fluorescence emission of fluorescent materials obtained by one-step synthesis is attributed to organic ligands. Cu²⁺ and Pb²⁺ coordinate with the amino group on the surface of the MOF-5-NH₂, which is ascribed to the host-guest electron transfer between analyte and probe, giving rise to the fluorescence quenching. After adding PPi, the intense affinity between Cu²⁺ and PPi remove Cu²⁺ from the MOF-5-NH₂, blocking of the electron transfer process, and the fluorescence can be recovered. The limit of detection is 0.057, 0.25 and 0.32 μmol L^-1 for the detection of Cu²⁺, Pb²⁺ and PPi, respectively. This turn-on mode based fluorescent probe shows preferable sensitivity and specificity to detect Cu²⁺, Pb²⁺ and PPi. These results demonstrate that the fluorescent MOF-5-NH₂ as a sensing platform displays remarkably performance.

An aromatic-rich cage-based MOF with inorganic chloride ions decorating the pore surface displaying the preferential adsorption of C2H2 and C2H6 over C2H4

An aromatic-rich chloride-embedded nanocage-based MOF displayed an unusual adsorption relationship towards C₂ hydrocarbons, with the potential for C₂H₄ separation and purification application.

Analysis of the effects of Cu-MOFs on fungal cell inactivation

Three dimensional (3D) copper metal organic frameworks (Cu-MOFs) containing glutarates and bipyridyl ligands (bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethylene, or bpp = 1,3-bis(4-pyridyl)propane) were synthesized by using previously reported hydrothermal reactions or a layering method. All three Cu-MOFs contained well-defined one dimensional (1D) channels with very similar pore shapes and different pore dimensions. The bulk purities of the Cu-MOFs were confirmed using powder X-ray diffraction (PXRD) and infrared spectroscopy (IR) spectra. When the three types of Cu-MOFs were applied to Candida albicans cells and Aspergillus niger spores, an average of about 50-80% inactivation was observed at the highest concentration of Cu-MOFs (2 mg mL^-1). The efficiency of the fungal inactivation was not significantly different among the three different types (bpa, bpe, bpp). Treatment of the fungi using Cu-MOFs induced an apoptosis-like death and this was more severe in A. niger than C. albicans. This may be due to elevation of the intracellular level of reactive oxygen species (ROS) in A. niger. Generation of the reactive species in solution by Cu-MOFs was observed. However, there was a dramatic variation in the levels observed among the three types. Our results suggest that Cu-MOFs can produce antifungal effects and induce apoptosis-like death of the fungi, which was probably caused by the elevated level of intracellular reactive species.

Isolable 1-Butene Copper(I) Complexes and 1-Butene/Butane Separation Using Structurally Adaptable Copper Pyrazolates

Non-porous small molecule adsorbents such as {[3,5-(CF₃ )₂ Pz]Cu}₃ (where Pz=pyrazolate) are an emerging class of materials that display attractive features for ethene-ethane separation. This work examines the chemistry of fluorinated copper(I) pyrazolates {[3,5-(CF₃ )₂ Pz]Cu}₃ and {[4-Br-3,5-(CF₃ )₂ Pz]Cu}₃ with much larger 1-butene in both solution and solid state, and reports the isolation of rare 1-butene complexes of copper(I), {[3,5-(CF₃ )₂ Pz]Cu(H₂ C=CHC₂ H₅ )}₂ and {[4-Br-3,5-(CF₃ )₂ Pz]Cu(H₂ C=CHC₂ H₅ )}₂ and their structural, spectroscopic, and computational data. The copper-butene adduct formation in solution involves olefin-induced structural transformation of trinuclear copper(I) pyrazolates to dinuclear mixed-ligand systems. Remarkably, larger 1-butene is able to penetrate the dense solid material and to coordinate with copper(I) ions at high molar occupancy. A comparison to analogous ethene and propene complexes of copper(I) is also provided.

Tuning the Pore Surface of an Ultramicroporous Framework for Enhanced Methane and Acetylene Purification Performance

Both methane (CH₄) and acetylene (C₂H₂) are important energy source and raw chemicals in many industrial processes. The development of an energy-efficient and environmentally friendly separation and purification strategy for CH₄ and C₂H₂ is necessary. Ultramicroporous metal-organic framework (MOF) materials have shown great success in the separation and purification of small-molecule gases. Herein, the synergy effect of tritopic polytetrazolate and ditopic terephthalate ligands successfully generates a series of isoreticular ultramicroporous cadmium tetrazolate-carboxylate MOF materials (SNNU-13-16) with excellent CH₄ and C₂H₂ purification performance. Except for the uncoordinated tetrazolate N atoms serving as Lewis base sites, the pore size and pore surface of MOFs are systematically engineered by regulating dicarboxylic acid ligands varying from OH-BDC (SNNU-13) to Br-BDC (SNNU-14) to NH₂-BDC (SNNU-15) to 1,4-NDC (SNNU-16). Benefiting from the ultramicroporous character (3.8-5.9 Å), rich Lewis base N sites, and tunable pore environments, all of these ultramicroporous MOFs exhibit a prominent separation capacity for carbon dioxide (CO₂) or C2 hydrocarbons from CH₄ and C₂H₂. Remarkably, SNNU-16 built by 1,4-NDC shows the highest ideal adsorbed solution theory CO₂/CH₄, ethylene (C₂H₄)/CH₄, and C₂H₂/CH₄ separation selectivity values, which are higher than those of most famous MOFs with or without open metal sites. Dynamic breakthrough experiments show that SNNU-16 can also efficiently separate the C₂H₂/CO₂ mixtures with a gas flow rate of 4 mL min^-1 under 1 bar and 298 K. The breakthrough time (18 min g^-1) surpasses most best-gas-separation MOFs and nearly all other metal azolate-carboxylate MOF materials under the same conditions. The above prominently CH₄ and C₂H₂ purification abilities of SNNU-13-16 materials were further confirmed by the Grand Canonical Monte Carlo (GCMC) simulations.

Overcoming Fundamental Limitations in Adsorbent Design: Alkene Adsorption by Non-porous Copper(I) Complexes

Purifying alkenes from alkanes requires cryogenic distillation. This consumes energy equivalent to countries of ca. 5 million people. Replacing distillation with adsorption processes would significantly increase energy efficiency. Trade-offs between kinetics, selectivity, capacity, and heat of adsorption have prevented production of an optimal adsorbent. We report adsorbents that overcome these trade-offs. [Cu-Br]₃ and [Cu-H]₃ are air-stable trinuclear complexes that undergo reversible solid-state inter-molecular rearrangements to produce dinuclear [Cu-Br⋅(alkene)]₂ and [Cu-H⋅(alkene)]₂ . The reversible solid-state rearrangement, confirmed in situ using powder X-ray diffraction, allows adsorbent design trade-offs to be overcome, coupling low heat of adsorption (-10 to -17 kJ mol^-1 _alkene ), high alkene:alkane selectivity (47; 29), and uptake capacity (>2.5 mol_alkene  mol^-1 _Cu3 ). Most remarkably, [Cu-H]₃ displays fast uptake and regenerates capacity within 10 minutes.

Construction and selective gas adsorption properties of two heteroSBU MOFs based on unsymmetrical tetracarboxylate linkers

Two homometallic pure-carboxylate hetero-SBU MOFs were constructed, displaying selective C₂H₂/CH₄ and CO₂/CH₄ separation potential.

A hydrostable cage-based MOF with open metal sites and Lewis basic sites immobilized in the pore surface for efficient separation and purification of natural gas and C2H2

Design and construction of stable adsorbents for efficient separation and purification of natural gas and C2H2 is fundamentally important in the chemical industry, and hierarchical cage-based MOFs are attractive in this regard due to their intrinsic structural advantages. In this work, a cage-based MOF (termed ZJNU-15) assembled from a tetranuclear Cu4O-based SBU and an amine-functionalized N,O-mixed donor ligand was solvothermally constructed. Single-crystal X-ray diffraction studies showed that the resulting MOF incorporates two different types of polyhedral cages in the entire network and bears incompatible open copper sites and uncoordinated amine groups immobilized in the pore surface. In view of its intriguing structural features, its gas adsorption properties with respect to C2 hydrocarbons, CO2, and CH4 were systematically investigated, revealing that it could achieve efficient removal of C2 hydrocarbons and CO2 from CH4 as well as separation of a binary C2H2-CO2 mixed gas, which is associated with natural gas and C2H2 separation and purification. At 298 K and 1 atm, for equimolar binary components, the IAST-predicted adsorption selectivities for C2 hydrocarbons over CH4 are above 17.7, while the CO2/CH4 and C2H2/CO2 adsorption selectivities are 5.0 and 4.4, respectively. Notably, stability studies showed that the framework maintained its structural integrity after being immersed in HCl/NaOH aqueous solutions within a pH range of 4-11 at ambient temperature for 24 h, indicating its good hydrolytic stability under harsh chemical conditions, which might lay a solid foundation for its practical applications.

Two Co-based MOFs assembled from an amine-functionalized pyridinecarboxylate ligand: inorganic acid-directed structural variety and gas adsorption properties

A pair of Co-based MOFs exhibited inorganic acid-driven structural diversities, and one of them displayed the C₂H₂ separation and purification potential.

Dramatic luminescence signal from a Co(ii)-based metal–organic compound due to the construction of charge-transfer bands with Al3+ and Fe3+ ions in water: steady-state and time-resolved spectroscopic studies

A Co(ii)-based metal–organic compound exhibits luminescence turn-on by Al³⁺ and quenching by Fe³⁺ due to the formation of charge-transfer complexes/adducts.

Cobalt(II)-coordination polymers containing glutarates and bipyridyl ligands and their antifungal potential

Three new Co^II-coordination polymers (Co-CPs) containing glutarates and bipyridyl ligands, formulated as [Co₂(Glu)₂(µ-bpa)₂]·(H₂O)₄ (1), [Co₄(Glu)₄(µ-bpp)₂] (2), and [Co₂(Glu)₂(µ-bpe)₂]·(H₂O)_0.5 (3), were prepared, and their structures were determined by X-ray crystallography. Glutarates bridge Co^II ions to form 2D sheets, and the sheets are connected either by bpa or by bpp ligands to form 3D networks 1 and 2, respectively. Both frameworks 1 and 2 are two-fold interpenetrated, and there is no significant void volume in either network. Four glutarates bridge two Co^II ions to form chains, and these chains are connected by bpe ligands to form the 2D sheet 3. The antifungal properties of these new Co-CPs were tested against two model fungal pathogens, Candida albicans and Aspergillus niger. Under the maximum concentration of Co-CPs, 2.0 mg mL^-1, the inhibition rates of Co-CPs against A. niger were much lower (44-62%) than those (90-99.98%) observed in C. albicans. The results indicate that 1-3 can inactivate C. albicans cells more efficiently than A. niger spores in the same treatment time, and the greater inactivation of C. albicans can be explained by dramatic changes in the morphology of C. albicans cells. We also found that Co-CPs could generate the reactive species NO and H₂O₂, and these species might play a role in inactivating fungal cells. Additionally, degradation tests confirmed that the leaching of Co^II ions from Co-CPs was not significant. The small amount of leached Co^II ions and the robust Co-CPs themselves as well as the reactive species generated by Co-CPs can actively participate in fungal inactivation.

Self-assembly of two robust 3D supramolecular organic frameworks from a geometrically non-planar molecule for high gas selectivity performance

The synthesis of highly porous frameworks has received continuous research interest, but achieving the ability to target stable and selective materials remains challenging. Herein, by utilizing a 'direction-oriented' strategy and modulating reaction conditions, two novel 3D porous supramolecular organic framework (SOF) materials (JLU-SOF2 and JLU-SOF3, as isomers) are assembled from a non-planar building block (TMBTI = 2,4,6-trimethyl benzene-1,3,5-triyl-isophthalic acid) and they display permanent porosity, high thermal stability, and good recyclability. It is worth mentioning that the CO2 uptake values of JLU-SOF2 and JLU-SOF3 rank among the highest values for SOF-based materials under ambient conditions. Furthermore, these two materials exhibit preferential adsorption of CO2 over N2 and CH4, and can effectively separate the mixtures of light hydrocarbons. These studies indicate the possible application of JLU-SOF2 and JLU-SOF3 in trapping greenhouse gases and upgrading natural gas. In addition, this synthetic strategy introduces an effective method for developing remarkable 3D SOFs among other framework materials.

Mixed matrix membranes for hydrocarbons separation and recovery: a critical review

The separation and purification of light hydrocarbons are significant challenges in the petrochemical and chemical industries. Because of the growing demand for light hydrocarbons and the environmental and economic issues of traditional separation technologies, much effort has been devoted to developing highly efficient separation techniques. Accordingly, polymeric membranes have gained increasing attention because of their low costs and energy requirements compared with other technologies; however, their industrial exploitation is often hampered because of the trade-off between selectivity and permeability. In this regard, high-performance mixed matrix membranes (MMMs) are prepared by embedding various organic and/or inorganic fillers into polymeric materials. MMMs exhibit the advantageous and disadvantageous properties of both polymer and filler materials. In this review, the influence of filler on polymer chain packing and membrane sieving properties are discussed. Furthermore, the influential parameters affecting MMMs affinity toward hydrocarbons separation are addressed. Selection criteria for a suitable combination of polymer and filler are discussed. Moreover, the challenges arising from polymer/filler interactions are analyzed to allow for the successful implementation of this promising class of membranes.