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Examination of the microstructure of metal-organic frameworks (MOFs) after postsynthetic exchange (PSE) reveals that the exchanged ligand is concentrated at the edges of the crystal and decreases in concentration with crystal depth, resulting in a core-shell arrangement. Diffusion studies of the carboxylate ligand into MOF-5 indicate that diffusion is limiting to the exchange process and may ultimately be responsible for the observed core-shell structure. Examination of PSE in UMCM-8 and single crystals of UiO-66 shows a similar trend, illustrating the applicability of PSE as a method for the creation of core-shell MOFs. [ABSTRACT FROM AUTHOR]

The use of microporous coordination polymers with coordinatively unsaturated metal centers in the removal of dimethyl ether from chloromethane via flow was explored as an alternative to current industrial methods. Three different materials examined, Co/DOBDC, MIL-100(Fe), and HKUST-1, were able to efficiently purify chloromethane through selective adsorption of dimethyl ether. The recyclability of Co/DOBDC after separation was also examined, and little loss of capacity for dimethyl ether over the course of multiple regeneration cycles was observed. [ABSTRACT FROM AUTHOR]

Airdrying is a widespread and critical industrial process. Removalof water from air is commonly accomplished by passage through a desiccantsuch as alumina; modestwater capacity and energy intensive regeneration are limitations ofcurrently used sorbents. Microporous coordination polymers (MCPs)are demonstrated here to be efficient desiccants for the dehumidificationof air, and a comparison of their capacity, regenerability, and efficiencywith commercial activated alumina is conducted. Complete regenerationusing dry air with mild heating is achieved. The attainment of highcapacity for the adsorption of water coupled to facile regenerationindicates that gas dehumidification may be an important applicationfor MCPs. [ABSTRACT FROM AUTHOR]

Because of their high surface areas,crystallinity, and tunableproperties, metal–organic frameworks (MOFs) have attractedintense interest as next-generation materials for gas capture andstorage. While much effort has been devoted to the discovery of newMOFs, a vast catalog of existing MOFs resides within the CambridgeStructural Database (CSD), many of whose gas uptake properties havenot been assessed. Here we employ data mining and automated structureanalysis to identify, “cleanup,” and rapidly predictthe hydrogen storage properties of these compounds. Approximately20 000 candidate compounds were generated from the CSD usingan algorithm that removes solvent/guest molecules. These compoundswere then characterized with respect to their surface area and porosity.Employing the empirical relationship between excess H2uptakeand surface area, we predict the theoretical total hydrogen storagecapacity for the subset of ∼4000 compounds exhibiting nontrivialinternal porosity. Our screening identifies several overlooked compoundshaving high theoretical capacities; these compounds are suggestedas targets of opportunity for additional experimental characterization.More importantly, screening reveals that the relationship betweengravimetric and volumetric H2density is concave downward,with maximal volumetric performance occurring for surface areas of3100–4800 m2/g. We conclude that H2storagein MOFs will not benefit from further improvements in surface areaalone. Rather, discovery efforts should aim to achieve moderate massdensities and surface areas simultaneously, while ensuring frameworkstability upon solvent removal. [ABSTRACT FROM AUTHOR]

This paper describes the heterogenization of single-site transition-metal catalysts in metal–organic frameworks (MOFs) via cation exchange. A variety of cationic complexes of Pd, Fe, Ir, Rh, and Ru have been incorporated into ZJU-28, and the new materials have been characterized by optical microscopy, inductively coupled plasma optical emission spectroscopy, and powder X-ray diffraction. MOF-supported [Rh(dppe)(COD)]BF4 catalyzes the hydrogenation of 1-octene to n-octane. The activity of this supported catalyst compares favorably to its homogeneous counterpart, and it can be recycled at least four times. Overall, this work provides a new and general approach for supporting transition-metal catalysts in MOFs. [ABSTRACT FROM AUTHOR]

Isolated successes of coordination copolymerization for the production of microporous coordination polymers (MCPs) have been reported recently; the logic for this synthetic approach has not been established nor have the key features of the synthetic conditions needed to generalize the method. Here, we establish guidelines for application of the copolymerization technique by exploring coordination modes and report, in addition to details on two previous coordination copolymers with exceptional properties, three new MCPs: UMCM-3 (Zn4O(2,5-thiophenedicaboxylate)1.2(1 ,3,5-tris(4- carboxyphenyl)benzene)1.2) UMCM-4 (Zn40(1,4-benzenedicarboxylate)3/2(4,4′,4″-tricarboxytriphenyl-amine)), and UMCM-5 (Zn4O(1,4-naphthalenedicarboxylate)(1,3,5-tris(4-carboxyphenyl)benzene)4/3). The MCPs prepared by the copolymerization technique demonstrate Brunauer-Emmett-Teller (BET) surface areas between 3500-5200 m2/g and high pore volumes (1 .64-2.37 cm3/g). In addition, the alignment of poly(3-hexylthiophene) within mesoporous channels of UMCM-1 is reported as a demonstration of the unique properties of these hosts. [ABSTRACT FROM AUTHOR]

Microporous coordination polymers (MCPs) are demonstrated to be efficient adsorbents for the removal of the organosulfur compounds dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) from model diesel fuel and diesel fuel. For example, packed bed breakthrough experiments utilizing UMCM-150 find capacities of 25.1 g S/kg MCP for DBT and 24.3 g S/kg MCP for DMDBT from authentic diesel indicating that large amounts of fuel are desulfurized before the breakthrough point. Unlike activated carbons, where selectivity has been a problem, MCPs selectively adsorb the organosulfur compounds over other, similar components of diesel. Complete regeneration using toluene at modest temperatures is achieved. The attainment of high selectivities and capacities, particularly for the adsorption of the refractory compounds that are difficult to remove using current desulfurization techniques, in a reversible sorbent indicates that fuel desulfurization may be an important application for MCPs. [ABSTRACT FROM AUTHOR]

The combination of zinc(II) nitrate with 1,3,5-(triscarboxyphenyl)benzene (H3BTB) leads to five different microporous coordination polymers (MCPs). Two of these were previously known (MOF-177 and MOF-39), whereas polymer-induced heteronucleation was used in the discovery of three phases that have not been previously reported (Zn/BTB ant, Zn/BTB tsx, and Zn/BTB dia). Modification of crystallization conditions allows for the bulk-scale synthesis of each of these MCPs. Zn/BTB ant and Zn/BTB tsx are each interpentrated 6,3-connected nets composed of the basic zinc carboxylate secondary building unit (SBU) and the tritopic linker BTB. The underlying noninterpenetrated net of Zn/BTB ant is derived for the net of anatase, whereas that of Zn/BTB tsx is the previously unreported "tsx" framework. Zn/BTB dia consists of an underlying diamondoid net in which four linear, trinuclear zinc hourglass SBUs are arranged about a central μ4-oxo anion as the tetrahedral unit in the net and BTB further links the hourglass SBUs. Zn/BTB ant, Zn/BTB tsx, and MOF-177 are here defined as polymorphic frameworks in that each is composed of the same SBU and linker but differ in topology and thus pore structure. These frameworks may be called a polyreticular series by analogy to several reported isoreticular series. The effect of linker-linker interactions are discussed. [ABSTRACT FROM AUTHOR]

A 2D zirconium-based microporous coordination polymer derived from the tritopic linker 1,3,5-(4-carboxylphenyl)benzene, UMCM-309a, has been synthesized. This noninterpenetrated material possesses a Zr6(μ3-O)4(μ3-OH)4(RCO2)6(OH)6(H2O)6 cluster with six hexagonal-planar-coordinated linkers. UMCM-309a is stable in an aqueous HCl solution for over 4 months. The use of different monocarboxylates as modulators leads to similar 2D structures with different layer spacings; moreover, removal of the modulator yields the parent UMCM-309a. [ABSTRACT FROM AUTHOR]

Flowing supercritical CO2 was used to activate a cross section of microporous coordination polymers (MCPs) directly from DMF, thus avoiding exchange with a volatile solvent. Most MCPs displayed exceptional surface areas directly after treatment although those with coordinatively unsaturated metals benefit from heating. The method presents an advance in efficiency of activation and quality of material obtained. [ABSTRACT FROM AUTHOR]

Mixing two different linkers with the same topology has been applied to make metal-organic frameworks (MOFs) either in one batch or sequentially to generate coordination copolymers with either a randomly mixed or a core-shell composition of linkers. [ABSTRACT FROM AUTHOR]

Mixing two different linkers with the same topology has been applied to make metal–organic frameworks (MOFs) either in one batch or sequentially to generate coordination copolymers with either a randomly mixed or a core–shell composition of linkers. [ABSTRACT FROM AUTHOR]

The article presents the coordination of theno[3.2-b]thiophene-2,5-dicarboxylate (T2DC) and bromothymol blue (BTB) linkers with zinc in producing a new porous material with microporous and mesoporous cages. It notes that the University of Michigan Crystalline Material (UMCM)-2 exceeds the materials derived from the pure linkers and illustrates the highest values. It also demonstrates the highest values which suggests a very high bright future for coordination copolymerization.

The article investigates the physisorptive methods for carbon dioxide separation using a porous material with a high uptake of carbon dioxide displaying reversible adsorption. According to the authors, Mg/2,5-dioxido-1,4-benzene-dicarboxylate was found to outperform all other physisorptive materials in low pressure physisorption of carbon dioxide. They add that physisorptive materials can achieve affinities and capacities competitive with amine sorbents.

The article discusses the result of a study concerning liquid phase adsorption by microporous coordination polymers (MCP) and removal of organosulfur compounds. MCP can adsorb large quantities of organosulfur compounds from the liquid phase and the exceptional levels of uptake suggests that liquid phase adsorption is an important application in this class of materials.

The article presents a study that investigated the use of tricarboxylate with two distinct binding motifs in generating highly porous crystalline material. The linker with carboxylate groups diffused in an unsymmetrical fashion has resulted to the coordination polymer with trinuclear copper(II) clusters. The porous crystalline material called University of Michigan crystalline material (UMCM-150) containing two clusters reveals a relatively high excess volumetric and gravimetric hydrogen uptake.

The article examines the H2 saturation uptake in microporous metal-organic frameworks (MOF). The gravimetric and volumetric storage densities of H2 in MOF are approaching the limits of practical utility. Surface area values show a significant correlation with gravimetric uptake.

Catalysts based on the C-H bond activation reaction show potential for the development of new, selective, hydrocarbon oxidation chemistry. A central consideration in the design of such C-H activation based catalysts is the choice of ligands. The ligands generally acceptable for C-H activation reactions range from C-donor. This article demonstrates that well-defined, late-metal, oxygen-ligated (O-ligated) complexes are competent for alkane C-H bond activation, exhibit high thermal and protic stability, and are efficient catalysts for H/D exchange reactions with alkanes. Authors of this article are currently investigating the oxidative functionalization of O-donor M-R complexes and new O-donor complexes that activate C-H bonds.

Exploratory research into the critical steps in metal-organic framework (MOF) activation involving solvent exchange and solvent evacuation are reported. It is discovered that solvent exchange kinetics are extremely fast, and minutes rather days are appropriate for solvent exchange in many MOFs. It is also demonstrated that choice of a very low surface tension solvent is critical in successfully activating challenging MOFs. MOFs that have failed to be activated previously can achieve predicted surface areas provided that lower surface tension solvents, such as n-hexane and perfluoropentane, are applied. The insights herein aid in the efficient activation of MOFs in both laboratory and industrial settings and provide best practices for avoiding structural collapse. [ABSTRACT FROM AUTHOR]

Exploratory research into the critical steps in metal-organic framework (MOF) activation involving solvent exchange and solvent evacuation are reported. It is discovered that solvent exchange kinetics are extremely fast, and minutes rather days are appropriate for solvent exchange in many MOFs. It is also demonstrated that choice of a very low surface tension solvent is critical in successfully activating challenging MOFs. MOFs that have failed to be activated previously can achieve predicted surface areas provided that lower surface tension solvents, such as n-hexane and perfluoropentane, are applied. The insights herein aid in the efficient activation of MOFs in both laboratory and industrial settings and provide best practices for avoiding structural collapse. [ABSTRACT FROM AUTHOR]

The design, synthesis, and properties of the new microporous coordination polymer UMCM-310 are described. The unique electronic character of the perylene-based linker enables selective interaction with electron-poor aromatics leading to efficient separation of nitroaromatics. UMCM-310 possesses high surface area and large pore size and thus permits the separation of large organic molecules based on adsorption rather than size exclusion. [ABSTRACT FROM AUTHOR]

A coordination terpolymerization strategy is introduced to alter the connectivity within layers of a pillared-layer coordination polymer. Assembling two different dicarboxylate linkers around a metal cluster in the layer suppresses interpenetration while enabling formation of a rectangular 2D grid structure. [ABSTRACT FROM AUTHOR]

Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material-discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks. [ABSTRACT FROM AUTHOR]

Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material-discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks. [ABSTRACT FROM AUTHOR]

Moisture can cause irreversible structural collapse in metal-organic frameworks (MOFs) resulting in decreased internal surface areas and pore volumes. The details of such structural collapse with regard to pore size evolution during degradation are currently unknown due to a lack of suitable in situ probes of porosity. Here we acquire MOF porosity data under dynamic conditions by incorporating a flow-through system in tandem with positronium annihilation lifetime spectroscopy (PALS). From the decrease in porosity, we have observed an induction period for water degradation of some Zn4O-based MOFs that signals much greater stability than commonly believed to be possible. The sigmoidal trend in the degradation curve of unfunctionalized MOFs caused by water vapor has been established from the temporal component of pore size evolution as characterized by in situ PALS. IRMOF-3 is found to degrade at a lower relative humidity than MOF-5, a likely consequence of the amine groups in the structure, although, in contrast to MOF-5, residual porosity remains. The presence of an induction period, which itself depends on previous water exposure of the sample (history dependence), and sigmoidal temporal behavior of the moisture-induced degradation mechanism of MOFs was also verified using powder X-ray diffraction analysis and ex situ gas adsorption measurements. Our work provides insight into porosity evolution under application-relevant conditions as well as identifying chemical and structural characteristics influencing stability. [ABSTRACT FROM AUTHOR]

Microporous coordination polymers(MCPs) have emerged as strongcontenders for adsorption-based fuel storage and delivery in largepart because of their high specific surface areas. The strategy ofincreasing surface area by increasing organic linker length has shownonly sporadic success; as demonstrated by many members of the iconicZn4O-based IRMOF series, for example, accessible porosityis often limited by interpenetration or pore collapse upon guest removal.In this work, we focus on Zn4O(ndc)3(IRMOF-8,ndc = 2,6-naphthalene dicarboxylate), which exhibits typical surfaceareas of only 1000–2000 m2/g even though a surfacearea of more than 4000 m2/g is expected from geometricanalysis of the originally reported crystal structure. We recentlyshowed that a high surface area could be produced with zinc and ndcby room-temperature synthesis followed by activation with flowingsupercritical CO2. In this work, we investigate in detailthe porosity of both the low- and high-surface-area materials. Positronannihilation lifetime spectroscopy (PALS) is used to show that thelow-surface-area material suffers from near-complete interpenetration,explaining why traditional synthetic routes have failed to yield materialswith the expected porosity. Furthermore, the high-pressure hydrogenand methane sorption properties of noninterpenetrated Zn4O(ndc)3are examined, and PALS is used to show that porefilling is not operative during room-temperature CH4sorptioneven at pressures approaching 100 bar. These results provide insightinto how gas adsorbs in high-surface-area materials at high pressureand reinforce previous contentions that increasing surface area aloneis not sufficient for the simultaneous optimization of deliverablegravimetric and volumetric gas uptake in MCPs. [ABSTRACT FROM AUTHOR]

Reacting biphenyl-3,4',5-liicarboxylic ∙acid (H3BIITC) with the approptiate metal salt yields the microporous coordination polymers (MCPs Mn3(BHTC)2 (1) Mg3#x00E7;BHTC) (2), and Co3(BHTC)2 (3) containing hourglass metal clusters. The addition of Cu to reactions with CoIIeIII or Mn leads to the fomiation of heterobimelaltic UMCM-150 isoslnictural analogues Co1Cu2(BHTC)2 (4), Fe,Cu2(BHTC)2 (5), and Mn1Cu2(BHTC)2 (6) containing both paddlewheel and to nuclear metal clusters. X-ray diffraction analysis of the crystals of the heterobimelallic MCPs suggests that Cu on the lrinuclear site of UMCM-150 was replaced by the other metal, whereas Cu in paddlewheel sites remains unchanged. N2 sorption isothernis were measured for the mixed-metal UMCM-1 50 analogues, and it was confirmed that there is no structural collapse after the metal replacement. [ABSTRACT FROM AUTHOR]

N-Heteroarene substitution into biphenyl-based linkers enhances the uptake of electron-rich organosulfur molecules in a series of isostructural microporous coordination polymers. [ABSTRACT FROM AUTHOR]

Positronium (Ps) is shown to exist in a delocalized state in self-assembled metalorganic crystals that have large 1.3-1.5 nm cell sizes. Belonging to a class of materials with record high accessible specific surface areas, these highly porous crystals are the first to allow direct probing with simple annihilation lifetime techniques of the transport properties of long-lived triplet Ps in what is hypothesized to be a Bloch state. Delocalized Ps has unprecedented (high) Ps mobility driven primarily by weak phonon scattering with unusual and profound consequences on how Ps probes the lattice. [ABSTRACT FROM AUTHOR]

High reversibility during crystallization leads to relatively defect-free crystals through repair of nonperiodic inclusions, including those derived from impurities. Microporous coordination polymers (MCPs) can achieve a high level of crystallinity through a related mechanism whereby coordination defects are repaired, leading to single crystals. In this work, we discovered and exploited the fact that this process is far from perfect for MCPs and that a minority ligand that is coordinatively identical to but distinct in shape from the majority linker can be inserted into the framework, resulting in defects. The reaction of Zn(II) with 1,4-benzenedicarboxylic acid (H2BDC) in the presence of small amounts of 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) leads to a new crystalline material, MOF-5(Oh), that is nearly identical to MOF-5 but has an octahedral morphology and a number of defect sites that are uniquely functionalized with dangling carboxylates. The reaction with Pd(OAc)2 impregnates the metal ions, creating a heterogeneous catalyst with ultrahigh surface area. The Pd(II)-catalyzed phenylation of naphthalene within Pd-impregnated MOF-5(Oh) demonstrates the potential utility of an MCP framework for modulating the reactivity and selectivity of such transformations. Furthermore, this novel synthetic approach can be applied to different MCPs and will provide scaffolds functionalized with catalytically active metal species. [ABSTRACT FROM AUTHOR]

Five non-interpenetrated microporous coordination polymers (MCPs) are derived by vertex desymmetrization using linkers with symmetry inequivalent coordinating groups, and these MCPs include properties such as rare metal clusters, new network topologies, and supramolecular isomerism. Gas sorption in polymorphic frameworks, UMCM-152 and UMCM-153 (based upon a copper-coordinated tetracarboxylated triphenylbenzene linker), reveals nearly identical properties with BET surface areas in the range of 3300-3500 m2/g and excess hydrogen uptake of 5.7 and 5.8 wt % at 77 K. In contrast, adsorption of organosulfur compounds dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) shows remarkably different capacities, providing direct evidence that liquid-phase adsorption is not solely dependent on surface area or linker/metal cluster identity. Structural features present in MCPs derived from these reduced symmetry linkers include the presence of more than one type of Cu-paddlewheel in a structure derived from a terphenyl tricarboxylate (UMCM-151) and a three-bladed zinc paddlewheel metal cluster in an MCP derived from a pentacarboxylated triphenylbenzene linker (UMCM-154). [ABSTRACT FROM AUTHOR]

The application of a core–shell architecture allows the formation of a polymer-coated metal–organic framework (MOF) maintaining high surface area (2289–2857 m2 g−1). The growth of a MOF shell from a MOF core was used to spatially localize initiators by post-synthetic modification. The confinement of initiators ensures that polymerization is restricted to the outer shell of the MOF. [ABSTRACT FROM AUTHOR]