Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

The Chemistry and Applications of Metal-Organic Frameworks

Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

Selective gas adsorption and separation in metal–organic frameworks

1. INTRODUCTION Among the classes of highly porous materials, metalÀorganic frameworks (MOFs) are unparalleled in their degree of tunability and structural diversity as well as their range of chemical and physical properties. MOFs are extended crystalline structures wherein metal cations or clusters of cations (\" nodes \") are connected by multitopic organic \" strut \" or \" linker \" ions or molecules. The variety of metal ions, organic linkers, and structural motifs affords an essentially infinite number of possible combinations. 1 Furthermore, the possibility for postsynthetic modification adds an additional dimension to the synthetic variability. 2 Coupled with the growing library of experimentally determined structures, the potential to computationally predict, with good accuracy, affinities of guests for host frameworks points to the prospect of routinely predesigning frameworks to deliver desired properties. 3,4 MOFs are often compared to zeolites for their large internal surface areas, extensive porosity, and high degree of crystallinity. Correspondingly, MOFs and zeolites have been utilized for many of the same applications

Metal–Organic Framework Materials as Chemical Sensors

Metal–Organic Frameworks for Separations

Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

The hydrothermal synthesis and the structure determination from powder or single crystals X-ray diffraction of 3 new metallophosphonates are presented. Crystal data: Ga(OH) 0.28 F 0.72 PO 3 (CH 3 ): P 2 1 / c (n∘ 14), a = 7.7912(7) A, b = 7.2310(6) A, c = 9.3114(8) A, β = 106.873(2) °, V = 502.00(8) A 3 , Z = 4, R 1 ( F ) = 0.0409, wR 2 ( F 2 ) = 0.0933 for 1 266 reflections I > 2 σ ( I ) with 77 parameters. Ga 3 (OH) 3 F 3 (MePO 3 ) 2 H 2 N(CH 2 ) 3 NH 3 : P -3 (No. 147), a = b = 7.2514(2) A, c = 7.9413(2) A, V = 361.6(3) A 3 , Z = 6, R F = 7.95, R Bragg = 7.18, R wp = 17.3, R p = 12.0. (V IV O(H 2 O))(Cu II (H 2 O))O 3 P-CH 2 -PO 3 : P 2 1 2 1 2 1 (No. 19), a = 6.3884(3) A, b = 10.7284(4) A, c = 11.2762(5) A, V = 772.84(6) A 3 , Z = 4, R 1 (F) = 0.0395, wR 2 ( F 2 ) = 0.0861 for 2 012 reflections I > 2 σ ( I ) and 128 parameters.

Hybrid open-frameworks (MIL-n) : Syntheses and structures of 2-dimensional gallium methylphosphonates (MIL-23) and 3-dimensional copper vanadium methyldiphosphonate (MIL-24)

Open-Framework Fluorinated Gallium and Aluminum Phosphates: An in situ Study of the Hydrothermal Synthesis by X-Ray Diffraction Using Synchrotron Radiation.

PROBLEM TO BE SOLVED: To provide a production method for a metal-organic structure (MOF) solid of porous crystal aluminum aromatic azo-carboxylate used as liquid or gas molecule storage, selective gas separation and catalyst.SOLUTION: A method for producing a crystalline porous aluminum aromatic azo-carboxylate MOF solid represented in Figure 5, comprises the steps of: (i) mixing a metal-inorganic precursor represented by metal salt Al3+, and an organic precursor of ligand represented by azobenzene-4,4'-dicarboxylic acid, in a non-aqueous organic solvent represented by N,N-dimethyl formamide; and (ii) heating the mixture at temperature of at least 50°C to obtain a solid.

Production method for metal-organic structure-type crystalline porous aluminum aromatic azo-carboxylate

106Ru is a radioactive isotope usually generated by the nuclear industry within power plant reactors. During a nuclear accident, 106Ru reacts with oxygen, leading to the production of highly volatile ruthenium tetroxide RuO4. The combination of volatility and radioactivity makes 106RuO4, one of the most radiotoxic species and justifies the development of a specific setup for its capture and immobilization. In this study, we report for the first time the capture and immobilization of gaseous RuO4 within a porous metal-organic framework (UiO-66-NH2). We used specific installation for the production of gaseous RuO4 as well as for the quantification of this gas trapped within the filtering medium. We proved that UiO-66-NH2 has remarkable affinity for RuO4 capture, as this MOF exhibited the worldwide highest RuO4 decontamination factor (DF of 5745), hundreds of times higher than the DF values of sorbents daily used by the nuclear industry (zeolites or activated charcoal). The efficiency of UiO-66-NH2 can be explained by its pore diameters well adapted to the capture and immobilization of RuO4 as well as its conversion into stable RuO2 within the pores. This conversion corresponds to the reactivity of RuO4 with the MOF organic sub-network, leading to the oxidation of terephthalate ligands. As proved by powder X-ray diffraction and NMR techniques, these modifications did not decompose the MOF structure.

Capture and immobilization of gaseous ruthenium tetroxide RuO4 in the UiO-66-NH2 metal-organic framework.

Two Chain Gallium Fluorodiphosphates: Synthesis, Structure Solution, and Their Transient Presence During the Hydrothermal Crystallization of a Microporous Gallium Fluorophosphate.

Thierry Loiseau

Papers

Hybrid open-frameworks (MIL-n) : Syntheses and structures of 2-dimensional gallium methylphosphonates (MIL-23) and 3-dimensional copper vanadium methyldiphosphonate (MIL-24)

Open-Framework Fluorinated Gallium and Aluminum Phosphates: An in situ Study of the Hydrothermal Synthesis by X-Ray Diffraction Using Synchrotron Radiation.

Production method for metal-organic structure-type crystalline porous aluminum aromatic azo-carboxylate

Capture and immobilization of gaseous ruthenium tetroxide RuO4 in the UiO-66-NH2 metal-organic framework.

Two Chain Gallium Fluorodiphosphates: Synthesis, Structure Solution, and Their Transient Presence During the Hydrothermal Crystallization of a Microporous Gallium Fluorophosphate.