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Ionic metal-organic frameworks (MOFs) are a subclass of porous materials that have the ability to incorporate different charged species in confined nanospace by ion-exchange. To date, however, very few examples combining mesoporosity and water stability have been realized in ionic MOF chemistry. Herein, we report the rational design and synthesis of a water-stable anionic mesoporous MOF based on uranium and featuring tbo-type topology. The resulting tbo MOF exhibits exceptionally large open cavities (3.9 nm) exceeding those of all known anionic MOFs. By supercritical CO2 activation, a record-high Brunauer-Emmett-Teller (BET) surface area (2100 m2 g−1) for actinide-based MOFs has been obtained. Most importantly, however, this new uranium-based MOF is water-stable and able to absorb positively charged ions selectively over negatively charged ones, enabling the efficient separation of organic dyes and biomolecules. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) have gained considerable attention as hybrid materials-in part because of a multitude of potential useful applications, ranging from gas separation to catalysis and light harvesting. Unfortunately, de novo synthesis of MOFs with desirable function-property combinations is not always reliable and may suffer from vagaries such as formation of undesirable topologies, low solubility of precursors, and loss of functionality of the sensitive network components. The recently discovered synthetic approach coined solvent-assisted linker exchange (SALE) constitutes a simple to implement strategy for circumventing these setbacks; its use has already led to the generation of a variety of MOF materials previously unobtainable by direct synthesis methods. This Review provides a perspective of the achievements in MOF research that have been made possible with SALE and examines the studies that have facilitated the understanding and broadened the scope of use of this invaluable synthetic tool. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks-a class of porous hybrid materials built from metal ions and organic bridges-have recently shown great promise for a wide variety of applications. The large choice of building blocks means that the structures and pore characteristics of the metal-organic frameworks can be tuned relatively easily. However, despite much research, it remains challenging to prepare frameworks specifically tailored for particular applications. Here, we have used computational modelling to design and predictively characterize a metal-organic framework (NU-100) with a particularly high surface area. Subsequent experimental synthesis yielded a material, matching the calculated structure, with a high BET surface area (6,143 m2 g−1). Furthermore, sorption measurements revealed that the material had high storage capacities for hydrogen (164 mg g−1) and carbon dioxide (2,315 mg g−1)-gases of high importance in the contexts of clean energy and climate alteration, respectively-in excellent agreement with predictions from modelling. [ABSTRACT FROM AUTHOR]

The first tritopic carborane-based linker, H3BCA (C15B24O6H30), based on closo-1,10-C2B8H10, has been synthesized and incorporated into a metal–organic framework (MOF), NU-700 (Cu3(BCA)2). In contrast to the analogous MOF-143, NU-700 can be activated with retention of porosity, yielding a BET surface area of 1870 m2 g−1. [ABSTRACT FROM AUTHOR]

Four heterobimetallic U(vi)/M(ii) (M = Mn, Co, Cd) carboxyphosphonates have been synthesized. M2[(UO2)6(PO3CH2CO2)3O3(OH)(H2O)2]·16H2O (M = Mn(ii), Co(ii), and Cd(ii)) adopt cubic three-dimensional network structures with large cavities approximately 16 in diameter that are filled with co-crystallized water molecules. [Cd3(UO2)6(PO3CH2CO2)6(H2O)13]·6H2O forms a rhombohedral channel structure with hydrated Cd(ii) within the channels. The cubic compound (Co) displays differential gas absorption with a surface area for CO2uptake of 40 m2g−1at 273 K, and no uptake of N2at 77 K. [ABSTRACT FROM AUTHOR]

Separations of CO2/CH4, CO2/N2, and O2/N2mixtures were studied in three porous coordination polymers made of the same carborane ligand and Co(ii) nodes. High selectivities for CO2over CH4(∼47) and CO2over N2(∼95) were obtained, especially in the material with coordinated pyridine. Unusual selectivity for O2over N2(as high as 6.5) was demonstrated in the materials with open Co(ii) sites. [ABSTRACT FROM AUTHOR]

A diimide based porous organic polymer (POP) post-synthetically reduced with lithium metal demonstrates a drastic increase in selectivity for carbon dioxide over methane. [ABSTRACT FROM AUTHOR]

The article focuses on the Fabry—Pérot devices that was based on the metal—organic framework (MOF) which serves as chemical vapors and gasses selective sensors. It states that the sustainability of the device was relied on the fabrication of ZIF-8 films. It presents how energies of Fabry—Pérot interface peaks are optically monitored as an analyte exposure function. Meanwhile, it presents tunability as the key to chemical sensing of microporous MOF.

Enzymes that catalytically transform small molecules such as CO, formate, or protons are naturally composed of transition metal cluster units bound into a larger superstructure. Artificial biomimetic catalysts are often modeled after the active sites but are typically molecular in nature. We present here a series of fully integrated porous materials containing Fe4S4 clusters, dubbed "biomimetic chalcogels". We examine the effect of third metal cations on the electrochemical and electrocatalytic properties of the chalcogels. We find that ternary biomimetic chalcogels containing Ni or Co show increased effectiveness in transformations of carbon dioxide and can be thought of as solid-state analogues of NiFe or NiFeS reaction centers in enzymes. [ABSTRACT FROM AUTHOR]

Thin-film membranes have been made from cavity-containing supramolecular building blocks known as molecular squares and evaluated for simple test separations. Permeation properties of single components and binary gas mixtures were measured through membranes made of several different molecular squares. For a small square with pyrazine edges, permeation increased in the order cyclohexane, consistent with the selectivities predicted from the sorption coefficients. Diffusion rates also play an important role in the permeation selectivity. For a larger square with porphyrin edges, mixture selectivities for 4-picoline over toluene were observed to be around 7–9, depending on the partial pressure. Functionalization of the interior of the porpyrin square allowed a mixture selectivity of 7 for benzene over cyclohexane. Independently measured adsorption isotherms and effective diffusion coefficients proved very helpful in understanding the effects of sorption and diffusion on the observed permeabilities. [Copyright &y& Elsevier]

Since sulfur mustard was first used in World War I, significant efforts have been made in materials and methods development for the adsorption and detoxification of different classes of chemical warfare agents (CWAs). Considering the importance of efficiency and safety in this process, catalytic degradation is a viable approach for fast and complete detoxification of CWAs. To date, a variety of catalysts have been discovered to be active for the degradation of nerve agents and sulfur mustard. Among the most promising are a class of porous functional materials named metal-organic frameworks (MOFs). In the past few years, tremendous progress has been made in this field including the discovery of zirconium MOF catalysts for fast nerve agent hydrolysis. In this review, we summarize recent advances in the development of MOF catalysts for the hydrolysis of nerve agents as well as the oxidation of sulfur mustard. Dual function MOF catalysts, i.e. catalysts that can detoxify nerve agents and sulfur mustard simultaneously, are also discussed. [ABSTRACT FROM AUTHOR]

Conspectus: Metal-organic frameworks (MOFs) are periodic, hybrid, atomically well-defined porous materials that typically form by self-assembly and consist of inorganic nodes (metal ions or clusters) and multitopic organic linkers. MOFs as a whole offer many intriguing properties, including ultrahigh porosity, tunable chemical functionality, and low density. These properties point to numerous potential applications, including gas storage, chemical separations, catalysis, light harvesting, and chemical sensing, to name a few. Reticular chemistry, or the linking of molecular building blocks into predetermined network structures, has been employed to synthesize thousands of MOFs. Given the vast library of candidate nodes and linkers, the number of potentially synthetically accessible MOFs is enormous. Nevertheless, a powerful complementary approach to obtain specific structures with desired chemical functionality is to modify known MOFs after synthesis. This approach is particularly useful when incorporation of particular chemical functionalities via direct synthesis is challenging or impossible. The challenges may stem from limited stability or solubility of precursors, unwanted secondary reactivity of precursors, or incompatibility of functional groups with the conditions needed for direct synthesis. MOFs can be postsynthetically modified by replacing the metal nodes and/or organic linkers or via functionalization of the metal nodes and/or organic linkers. Here we describe some of our efforts toward the development and application of postsynthetic strategies for imparting desired chemical functionalities in MOFs of known topology. The techniques include methods for functionalizing MOF nodes, i.e., solvent-assisted ligand incorporation (SALI) and atomic layer deposition in MOFs (AIM) as well as a method to replace structural linkers, termed solvent-assisted linker exchange (SALE), also known as postsynthethic exchange (PSE). For each functionalization strategy, we first describe its chemical basis along with the requirements for its successful implementation. We then present a small number of examples, with an emphasis on those that (a) convey the underlying concepts and/or (b) lead to functional structures (e.g., catalysts) that would be difficult or impossible to access via direct routes. The examples, however, are only illustrative, and a significant body of work exists from both our lab and others, especially for the SALE/PSE strategy. We refer readers to the papers cited and to the references therein. More exciting, in our view, will be new examples and new applications of the functionalization strategies especially applications made possible by creatively combining the strategies. Underexplored (again, in our view) are implementations that impart electrical conductivity, enable increasingly selective chemical sensing, or facilitate cascade catalysis. It will be interesting to see where these strategies and others take this compelling field over the next few years. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of two thin films (DA-MOF and L2-MOF) of porphyrin-based MOFs on functionalized surfaces using a layer-by-layer (LbL) approach. Profilometry measurements confirm that the film thickness increases systematically with number of growth cycles. Polarization excitation and fluorescence measurements indicate that the porphyrin units are preferentially oriented, while X-ray reflectivity scans point to periodic ordering. Ellipsometry measurements show that the films are highly porous. Since there are currently few methods capable of yielding microporous MOFs containing accessible free-base porphyrins, it is noteworthy that the LbL growth permits direct MOF incorporation of unmetalated porphyrins. Long-range energy transfer is demonstrated for both MOF films. The findings offer useful insights for subsequent fabrication of MOF-based solar energy conversion devices. [ABSTRACT FROM AUTHOR]

A Cu–carborane-basedmetal–organic framework (MOF), NU-135, which containsa quasi-spherical para-carborane moiety, has beensynthesized and characterized. NU-135exhibits a porevolume of 1.02 cm3/g anda gravimetric BET surface area of ca. 2600 m2/g, and thusrepresents the first highly porous carborane-based MOF. As a consequenceof the unique geometry of the carborane unit, NU-135hasa very high volumetric BET surface area of ca. 1900 m2/cm3. CH4, CO2, and H2adsorptionisotherms were measured over a broad range of pressures and temperaturesand are in good agreement with computational predictions. The methanestorage capacity of NU-135at 35 bar and 298 K is ca.187 vSTP/v. At 298 K, the pressure required to achievea methane storage density comparable to that of a compressed naturalgas (CNG) tank pressurized to 212 bar, which is a typical storagepressure, is only 65 bar. The methane working capacity (5–65bar) is 170 vSTP/v. The volumetric hydrogen storage capacityat 55 bar and 77 K is 49 g/L. These properties are comparable to thoseof current record holders in the area of methane and hydrogen storage.This initial example lays the groundwork for carborane-based materialswith high surface areas. [ABSTRACT FROM AUTHOR]

Abstract: Separation of Xe/Kr mixtures was studied in two copper-paddlewheel metal-organic framework materials, MOF-505 and HKUST-1. For MOF-505, which has small pores with strong adsorption sites, high Xe/Kr selectivities (9–10) are obtained from breakthrough measurements and grand canonical Monte Carlo (GCMC) simulations. The consistent results from both techniques suggest that MOF-505 is a promising candidate for Xe/Kr separation. For HKUST-1, which has small octahedral pores, only modest Xe/Kr selectivities (4.5) are observed from breakthrough measurements, although the GCMC simulations predicted unusually high selectivities at low loadings. [Copyright &y& Elsevier]

Thermal treatment of highly stable porous organic polymersbased upon the Yamamoto polymerization of 2,2′,7,7′-tetrabromo-9,9′-spirobifluorenewas done. The polymers are shown to be thermally and chemically stable.Upon thermal treatment the polymers are shown to have BET surfaceareas of ca. 2,000 m2/g and 2,500 m2/g respectively. [ABSTRACT FROM AUTHOR]

Robust catechol-functionalized porous organic polymers(POPs) withtunable porosities (560–1050 m2/g) and degrees offunctionalization were synthesized using a cobalt-catalyzed acetylenetrimerization (CCAT) strategy. Post-synthesis metalation canbe readily carried out with a wide range of metal precursors (CuII, MgII, and MnIIsalts and complexes),resulting in metalated POPs with enhanced heat of hydrogen adsorptionscompared to the starting nonmetalated materials. [ABSTRACT FROM AUTHOR]