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 present invention relates to a method for preparing an MOF solid of a crystallised and porous aluminium aromatic azocarboxylate, in a non-aqueous organic medium. The invention also relates to solids made up of metal-organic frameworks (MOF) of aluminium aromatic azocarboxylates capable of being obtained by the method of the invention, as well as to the uses thereof for the storage of liquid or gaseous molecules, for selective separation of gas and for catalysis.

Method for preparing metal-organic framework crystallised and porous aluminium aromatic azocarboxylates

Chapter 7 – Oxyfluorinated Open Frameworks

Crystal structures of tetravalent uranium fluorides obtained in the presence of hydrazine from uranyl source

Crystals of the title hydrated rubidium gallium phosphate, rubidium aqua-μ3-hydroxo-di-μ-phosphato-digallium hydrate, were synthesized hydro­thermally at 453 K under autogenous pressure. The solid crystallizes in the monoclinic system and its structure was determined from single-crystal X-ray diffraction analysis. It is similar to dihydrated gallium phosphate, GaPO4·2H2O, which is isostructural with the mineral leucophosphite. The structure is built up from a three-dimensional anionic framework composed of corner-linked octameric Ga4(PO4)4(OH)2(H2O)2 units. The Ga atom is in an octahedral coordination. Connection of the Ga4P4 species generates eight-ring channels, in which are encapsulated the Rb+ cations and water mol­ecules.

Rb(GaPO4)2(OH)(H2O).H2O: a hydrated rubidium gallium phosphate analogue of GaPO4.2H2O and leucophosphite.

The title compound, bis(μ-phosphato-O:O')bis[(hydrogenphosphato-O)(hydroxo)gallium] tris(2-aminoethyl)-amine hydrate, was hydrothermally synthesized, in the presence of tris(2-aminoethyl)amine (tren), from a nonaqueous mixture in which dimethyl sulfoxide was used as solvent (423K, 24h, autogeneous pressure). Its structure consists of isolated hexameric units composed of two GaO 4 and four PO 4 tetrahedra, these units being separated by the tren and water molecules.

Thierry Loiseau

Papers

Method for preparing metal-organic framework crystallised and porous aluminium aromatic azocarboxylates

Chapter 7 – Oxyfluorinated Open Frameworks

Crystal structures of tetravalent uranium fluorides obtained in the presence of hydrazine from uranyl source

Rb(GaPO4)2(OH)(H2O).H2O: a hydrated rubidium gallium phosphate analogue of GaPO4.2H2O and leucophosphite.

A New Gallium Phosphate Templated by Tris(2-aminoethyl)amine: [Ga(HPO4)(PO4)(OH)].[(C2H7N)3N].H2O