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Magnetic core-shell microspheres were developed to extract rare earth elements (REEs) from aqueous and brine solutions with up to 99.99% removal efficiency. The shell, composed of a thermally and chemically stable functionalized metal-organic framework (MOF), is grown over a synthesized Fe3O4 magnetic core (magnetite@MOF). The composite particles can be removed from the mixture under an applied magnetic field, offering a practical, and efficient REE-removal process. [ABSTRACT FROM AUTHOR]

Continuous ZIF-8 membranes effectively separated air/Xe gas mixtures. These membranes showed air permeances as high as 3.94 × 10−8 mol m−2 s−1 Pa−1 and separation selectivities as high as 12.4 for an air/Xe molar feed composition of 9 : 1. These membranes separated air from Xe via molecular sieving, preferential adsorption, and diffusivity differences. [ABSTRACT FROM AUTHOR]

A series of microporous metal–organic frameworks (MOFs) constructed by using a V-shaped linker, 4,4′-sulfonyldibenzoic acid, were evaluated for their Xe gas adsorption properties. In particular, a cadmium-based MOF exhibits noteworthy Xe adsorption and separation properties in the presence of other gases under nuclear reprocessing conditions. The outstanding Xe adsorption capacity was attributed to the close pore size matching of the MOF with the kinetic diameter of the Xe atom. [ABSTRACT FROM AUTHOR]

Technetium mainly forms during artificial nuclear fission; it exists primarily as TcO4− in nuclear waste, and it is among the most hazardous radiation-derived contaminants because of its long half-life (t1/2 = 2.13 × 105 years) and environmental mobility. The high water solubility of TcO4− (11.3 mol L−1 at 20 °C) and its ability to readily migrate within the upper layer of the Earth's crust make it particularly hazardous. Several types of materials, namely resins, molecular complexes, layered double hydroxides, and pure inorganic and metal–organic materials, have been shown to be capable of capturing TcO4− (or other oxoanions) from solution. In this review, we give a brief description about the types of materials that have been used to capture TcO4− and closely related oxyanions so far and discuss the possibility of using metal–organic frameworks (MOFs) as next-generation ion-exchange materials for the stated application. In particular, with the advent of ultra-stable MOF materials, in conjunction with their chemical tunability, MOFs can be applied to capture these oxyanions under real-life conditions. [ABSTRACT FROM AUTHOR]

Capture of CO2 from flue gas is considered to be a feasible approach to mitigate the effects of anthropogenic emission of CO2. Herein we report that an isostructural family of metal organic materials (MOMs) of general formula [M(linker)2(pillar)], linker = pyrazine, pillar = hexaflourosilicate and M = Zn, Cu, Ni and Co exhibits highly selective removal of CO2 from dry and wet simulated flue gas. Two members of the family, M = Ni and Co, SIFSIX-3-Ni and SIFSIX-3-Co, respectively, are reported for the first time and compared with the previously reported Zn and Cu analogs. [ABSTRACT FROM AUTHOR]

The metal organic framework, MOF-74(Ni), was synthesized in a continuous flow microwave-assisted reactor obtaining a high space-time yield (~90 g h−1 L−1) and 96.5% conversion of reagents. Separation of the nucleation and growth steps was performed by using uniform and rapid microwave heating to induce nucleation, which allowed a substantial increase in conversion for shorter reaction times under mild pressure. High yields were achieved in minutes, as opposed to days for typical batch syntheses, with excellent control over the material's properties due to more uniform nucleation, and the separation of the nucleation and growth steps. Optimization of the microwave reactor parameters led to improvements in MOF-74(Ni) crystallinity, reagent conversion, and production rates. Differences in MOF-74(Ni) crystallinity were observed as smaller grains were formed when higher microwave zone temperatures were used. Crystallinity differences led to different final adsorption properties and surface areas. Herein we show that a continuous high space-time yield synthesis of MOF-74(Ni) allows control over nucleation using microwave heating. [ABSTRACT FROM AUTHOR]

Chiral metal–organic frameworks are considered a useful platform in heterogeneous catalysis for enantioselective chemical transformations. However, it has been observed that the enantioselectivity is sensitive to the site at which the reaction takes place, even in a single crystal, since the chiral environment of the catalytic site varies according to its location, e.g., that of the surface is anisotropic, whereas that of the interior is isotropic. [ABSTRACT FROM AUTHOR]

A flexible metal–organic framework constructed from a flexible linker is shown to possess the capability of separating mixtures of polar compounds (propanol isomers) by exploiting the differences in the saturation capacities of the constituents. Transient breakthrough simulations show that these sorption-based separations are in favor of the component with higher saturation capacity. [ABSTRACT FROM AUTHOR]

The tetragonal apohost phase of p-tert-butyltetramethoxythiacalix-[4]arene absorbs hydrochloric acid and iodine. These guest molecules occupy different sites in the solid-state structure - either within the small intrinsic voids of themacrocycle or within the interstitial spaces between the hostmolecules. This study illustrates the dynamic deformation of the host, providing strong mechanistic insight into the diffusion of guests into this seemingly non-porous material. [ABSTRACT FROM AUTHOR]

Efficient and cost-effective removal of radioactive 137Cs and 90Sr found in spent fuel is an important step for safe, long-term storage of nuclear waste. Solid-state materials such as resins and titanosilicate zeolites have been assessed for the removal of Cs and Sr from aqueous solutions, but there is room for improvement in terms of capacity and selectivity. Herein, we report the Cs+ and Sr2+ exchange potential of an ultra stable MOF, namely, MIL-101-SO3H, as a function of different contact times, concentrations, pH levels, and in the presence of competing ions. Our preliminary results suggest that MOFs with suitable ion exchange groups can be promising alternate materials for cesium and strontium removal. [ABSTRACT FROM AUTHOR]

Various amounts of Ag nanoparticles were successfully deposited in porous MOF-74Ni (or Ni/DOBDC) by an auto-reduction method. An optimized silver-loaded MOF-74Ni was shown to have an improved Xe adsorption capacity (15% more) at STP compared to the MOF without silver nanoparticles. The silver-loaded sample also has a higher Xe/Kr selectivity. These results are explained by the stronger interactions between polarizable Xe molecules and the well-dispersed Ag nanoparticles. [ABSTRACT FROM AUTHOR]

The reaction conditions for the synthesis of Cu–BTC (BTC = benzene-1,3,5-tricarboxylic acid) were elucidated using a continuous-flow microreactor-assisted solvothermal system to achieve crystal size and phase control. A high-rate synthesis of Cu–BTC metal–organic frameworks with a BET surface area of more than 1600 m2 g−1 (Langmuir surface area of more than 2000 m2 g−1) and with a 97% production yield could be achieved with a total reaction time of 5 minutes. [ABSTRACT FROM AUTHOR]

A highly porous porphyrin-based organic polymer, PCPF-1, was constructed via homo-coupling reaction of the custom-designed porphyrin ligand, 5,10,15,20-tetrakis(4-bromophenyl)porphyrin. PCPF-1 possesses a large BET surface area of over 1300 m2 g−1 (Langmuir surface area of over 2400 m2 g−1) and exhibits strong hydrophobicity with a water contact angle of 135°, and these features afford it the highest adsorptive capacities for saturated hydrocarbons and gasoline among sorbent materials reported thus far, as well as render it the capability to remove oil from water. [ABSTRACT FROM AUTHOR]

The chiral 3D MOFs resulted from the packing of chiral 1D SBBs were studied. It was demonstrated that the final packing pattern is sensitively dependent on the dimension of SBBs. In addition, we were able to identify a new plywood-like network from ligand 2H2exhibiting an unprecedented six-way chiral helical packing motif, which extends the list of invariant rod packings. [ABSTRACT FROM AUTHOR]

A metal–organic framework obtained from a flexible organic linker shows a breathing phenomenon upon adsorption of saturated hydrocarbons. [ABSTRACT FROM AUTHOR]

Two novel cadmium–organic frameworks containing achiral helical nanotubular channels, [Cd(HImDC)(S)]n(S = Im(1) and Py(2)), have been synthesized and characterized using single crystal X-ray diffraction, in which 1converts to 2upon refluxing 1 in pyridine solution with noticeable porosity and hydrogen uptake at medium pressure. [ABSTRACT FROM AUTHOR]

Nanosized zeolitic imidazolate frameworks [nZIF-8] with excellent chemical and thermal stability have been synthesized at room temperature by simple mixing of 2-methylimidazole and zinc nitrate hexahydrate in methanol/1% high molecular weight poly(diallyldimethylammonium chloride) solution for 24 h. [ABSTRACT FROM AUTHOR]

Capture of CO2 from flue gas is considered to be a feasible approach to mitigate the effects of anthropogenic emission of CO2. Herein we report that an isostructural family of metal organic materials (MOMs) of general formula [M(linker)2(pillar)], linker = pyrazine, pillar = hexaflourosilicate and M = Zn, Cu, Ni and Co exhibits highly selective removal of CO2 from dry and wet simulated flue gas. Two members of the family, M = Ni and Co, SIFSIX-3-Ni and SIFSIX-3-Co, respectively, are reported for the first time and compared with the previously reported Zn and Cu analogs.

Chiral metal-organic frameworks are considered a useful platform in heterogeneous catalysis for enantioselective chemical transformations. However, it has been observed that the enantioselectivity is sensitive to the site at which the reaction takes place, even in a single crystal, since the chiral environment of the catalytic site varies according to its location, e.g., that of the surface is anisotropic, whereas that of the interior is isotropic.

Two well-known metal-organic frameworks (MOF-5, NiDOBDC) were synthesized and studied for facile xenon capture and separation. Our results indicate that NiDOBDC adsorbs significantly more xenon than MOF-5, and is more selective for xenon over krypton than activated carbon., (This journal is © The Royal Society of Chemistry 2012)

Cucurbit[7]uril (CB[7]), in its amorphous solid state, shows one of the highest CO(2) sorption capacities among known organic porous materials at 298 K and 0.1 and 1 bar. In addition to the highest CO(2) capacity, CB[7] also shows remarkable selectivity of CO(2) over N(2) and CH(4). These properties, along with the existence of readily available precursors, indicate amorphous CB[7] might find applications in recycling CO(2) particularly considering the easy synthesis and potentially low manufacturing costs.

Micro and mesoporous metal-organic frameworks were synthesized using a single tetrahedral building block and their catalytic properties towards alkylation of toluene and biphenyl showed high selectivity for the para oriented product using these porous materials.

Three interpenetrated metal-organic supramolecular isomers were synthesised using a flexible tetrahedral organic linker and Zn(2) clusters that sorb CO(2) preferably over N(2), H(2) and methane at room temperature.

The uptake of various nitrogen oxides was studied with the well known nonporous p-tert-butylcalix[4]arene under ambient conditions.

Large multicomponent nanospheroid arrays consisting of six C-pentylpyrogallol[4]arene molecules and 12 Ga3+ metal-ions which in turn enclose 1150 A3 of chemical space are reported.

We have studied the hydrogen sorption on three well-known organic hosts that possess vacant lattice voids large enough to accommodate H2 molecules.

The low density polymorph of the well-known host p-tert-butylcalix[4]arene absorbs more methane than p-tert-pentylcalix[4]arene at room temperature and 1 atm pressure, but the order of absorption is reversed at 38 atm with p-tert-pentylcalix[4]arene absorbing more.

A well-known host compound readily absorbs methane at room temperature and pressures of one atmosphere and lower.

A low-density polymorph of the well-known host compound p-tert-butylcalix[4]arene undergoes subtle structural changes when heated and cooled.

1,3-Dibromo-2,4,6-trinitrobenzene (DBTNB), a two-dimensional charge transfer hyperpolarisable chromophore, crystallizes in the non-centrosymmetric space group C2 in perfect polar order leading to an intense powder SHG signal at 1.06 microns.

The title molecule forms a honeycomb network of molecular and nitro-trimer synthons with guest species included in the hexagonal voids.

Conformational flexibility in a symmetrical tris-phenol leads to close packed structures that are also characterised by an extended though finite cooperative chain of hydrogen bonds.