Programmed Pore Architectures in Modular Quaternary Metal–Organic Frameworks

To generate metal–organic frameworks (MOFs) that are complex and modular yet well ordered, we present a strategy employing a family of three topologically distinct linkers that codes for the assembly of a highly porous quaternary MOF. By introducing substituted analogues of the ligands, a set of eight isoreticular frameworks is delivered, with the MOF structure systematically varied while the topology is maintained. To combat randomness and disorder, the substitution patterns of the ligands are designed to be compatible with their crystallographic site symmetries. MOFs produced in this way feature “programmed pores”multiple functional groups compartmentalized in a predetermined array within a periodic latticeand are capable of complex functional behavior. In these examples unconventional CO₂ sorption trends, including capacity enhancements close to 100%, emerge from synergistic effects. Future PP-MOFs may be capable of enzyme-like heterogeneous catalysis and ultraselective adsorption

Programmed Pore Architectures in Modular Quaternary Metal–Organic Frameworks

To generate metal–organic frameworks (MOFs) that are complex and modular yet well ordered, we present a strategy employing a family of three topologically distinct linkers that codes for the assembly of a highly porous quaternary MOF. By introducing substituted analogues of the ligands, a set of eight isoreticular frameworks is delivered, with the MOF structure systematically varied while the topology is maintained. To combat randomness and disorder, the substitution patterns of the ligands are designed to be compatible with their crystallographic site symmetries. MOFs produced in this way feature “programmed pores”multiple functional groups compartmentalized in a predetermined array within a periodic latticeand are capable of complex functional behavior. In these examples unconventional CO₂ sorption trends, including capacity enhancements close to 100%, emerge from synergistic effects. Future PP-MOFs may be capable of enzyme-like heterogeneous catalysis and ultraselective adsorption

Sulfonated Metal–Organic Framework Mixed-Matrix Membrane toward Direct Lithium Extraction

Lithium supply has been limited by time-consuming and energy-intensive processing. Membranes are an attractive alternative as a low energy, timely, and continuous process to facilitate ion–ion separations. However, recent metal–organic framework (MOF) membranes are difficult to prepare and scale. Here, we realize an electrochemical LiCl/NaCl selectivity of 1.21 by use of a flexible, low-cost, and simple solution cast mixed-matrix membrane comprised of cellulose triacetate and UiO-66-SO3H MOF. Compatible chemical interactions between the MOF and polymer allowed for high loadings of up to 100% (mMOF/mpolymer) consistently, minimizing interfacial defects and aggregation. Single salt transport measurements confirmed that the selectivity of the membrane arises from high lithium diffusion (1.6 cf sodium diffusion) across the membrane overcoming high sodium solubility (1.3 cf lithium solubility). Incorporating a combination of confined sub-nanoporous (6.3 and 9.5 Å) pore windows in UiO-66-SO3H and chemically compatible high diffusivity SO3– groups achieve flexible, low-cost, and scalable membranes with desirable selectivity towards refining lithium

Performance evaluation of CuBTC composites for room temperature oxygen storage

Oxygen is commonly separated from air using cryogenic liquefaction.</p

Efficient delivery of oxygen via magnetic framework composites

Efficient delivery of oxygen via magnetic framework composite

Visible Light-Triggered Capture and Release of CO₂ from Stable Metal Organic Frameworks

The ability to expose MOF pores on demand using visible light has been demonstrated and exploited for the capture and release of carbon dioxide. Coating of <b>Mg-MOF-74</b> or <b>MIL-53(Al)</b> with methyl red dye afforded composite materials that became able to adsorb carbon dioxide after exposure to visible light. The <b>Mg-MOF-74</b> series can be tailored to an 84% uptake change upon irradiation, which is an attractive low-energy alternative for CO₂ capture, where the reliance on coal-based power for materials generation is reduced. Kinetic and temperature dependent studies highlighted the mechanism behind this new effect in MOFs, which varied according to the structural rigidity of the framework

Porous Aromatic Frameworks Impregnated with Fullerenes for Enhanced Methanol/Water Separation

Molecular simulation techniques have revealed that the incorporation of fullerenes within porous aromatic frameworks (PAFs) remarkably enhances methanol uptake while inhibiting water uptake. The highest selectivity of methanol over water is found to be 1540 at low pressure (1 kPa) and decreases gradually with increasing pressure. The adsorption of water is very small compared to methanol, a useful material property for membrane and adsorbent-based separations. Grand canonical Monte Carlo (GCMC) simulations are utilized to calculate the pure component and mixture adsorption isotherms. The water and methanol mixture simulations show that water uptake is further inhibited above the pure component results because of the dominant methanol adsorption. Molecular dynamics (MD) simulations confirm that water diffusivity is also inhibited by strong methanol adsorption in the mixture. Overall, this study reveals profound hydrophobicity in C60@PAF materials and recommends C60@PAFs as suitable applicants for adsorbent and membrane-based separations of methanol/water mixtures and other alcohol/water separation applications

Charge Carrier Molecular Sieve (CCMS) Membranes with Anti-aging Effect for Long-Life Vanadium Redox Flow Batteries

Vanadium crossover hinders widespread commercial adoption of vanadium redox flow batteries (VRFBs). Superglassy polymers have the potential to offer high selectivity needed to control the crossover but as yet do not possess the requisite proton conductivity and stability. Here, we explore nanocomposite separators that can improve this selectivity. We report a dual-function charge carrier molecular sieve (CCMS) membrane, consisting of a high free volume microporous glassy polymer, poly­[1-(trimethylsilyl)-1-propyne] (PTMSP)/sulfonated PAF (PAF-1-SO3H), that effectively hinders the migration of hydrated vanadium ions. Furthermore, ideally placed PAF-1-SO3H pores not only proved excellent for developing proton conductive channels but also suppressed physical aging within the separator. Experiments then linked this to an increased battery cycle life. As a consequence of achieving higher and more stable VRFB performance compared to benchmarked Nafion (Coulombic efficiencies of 97 vs 87% and capacity retention values of 85 vs 58% at a current density of 60 mA cm–2, respectively), our integrated design heralds a class of stable separators for hydrogen-based energy technologies

Iodobenzene-Catalyzed Oxabicyclo[3.2.1]octane and [4.2.1]Nonane Synthesis via Cascade C–O/C–C Formation

Iodobenzene-catalyzed 1,2-olefin functionalization via C–C and C–O bond formation has been achieved with electron rich aromatic groups and vinylogous esters acting as independent nucleophiles. The reaction provides oxabicyclo[3.2.1]octanes and [4.2.1]nonanes from commercially available 3-alkoxy cycohexen-2-ones in three steps

Finely Tuning the Free Volume Architecture in Iptycene-Containing Polyimides for Highly Selective and Fast Hydrogen Transport

Iptycene-based polyimides have attracted extensive attention recently in the membrane gas separation field due to their unique structural hierarchy and chemical characteristics that enable construction of well-defined yet tailorable free volume architecture for fast and selective molecular transport. We report here a new series of iptycene-based polyimides that are exquisitely tuned in the monomer structure to afford preferred microcavity architecture for hydrogen transport. In particular, a triptycene-containing dianhydride (TPDAn) was prepared to react with two iptycene-containing diamines (i.e., TPDAm and PPDAm) or 2,2′-bis­(3-amino-4-hydroxy­phenyl)­hexa­fluoropropane (6FAP) to produce entirely or partially iptycene-based polyimides. The incorporation of iptycene units effectively disrupted chain packing, which resulted in ultrafine microporosity in the membranes with a desired bimodal size distribution with maxima at ∼3 and ∼7 Å, respectively. Depending on the combination of diamine and dianhydride, the microporosity was feasibly tuned and optimized to meet the needs of challenging H₂ separations, especially for H₂/N₂ and H₂/CH₄ gas pairs. Particularly, a H₂ permeability of 27 barrers and H₂/N₂ and H₂/CH₄ selectivities of 142 and 300, respectively, were obtained for TPDAn-6FAP