This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)

Hybrid porous solids: past, present, future

New materials capable of storing hydrogen at high gravimetric and volumetric densities are required if hydrogen is to be widely employed as a clean alternative to hydrocarbon fuels in cars and other mobile applications. With exceptionally high surface areas and chemically-tunable structures, microporous metal–organic frameworks have recently emerged as some of the most promising candidate materials. In this critical review we provide an overview of the current status of hydrogen storage within such compounds. Particular emphasis is given to the relationships between structural features and the enthalpy of hydrogen adsorption, spectroscopic methods for probing framework–H2 interactions, and strategies for improving storage capacity (188 references).

/pdf/hydrogen-storage-in-metal-organic-frameworks-9ols7xj8jh.pdf

Hydrogen storage in metal–organic frameworks

Synthesis of metal-organic frameworks (MOFs): routes to various MOF topologies, morphologies, and composites.

In the domain of health, one important challenge is the efficient delivery of drugs in the body using non-toxic nanocarriers. Most of the existing carrier materials show poor drug loading (usually less than 5 wt% of the transported drug versus the carrier material) and/or rapid release of the proportion of the drug that is simply adsorbed (or anchored) at the external surface of the nanocarrier. In this context, porous hybrid solids, with the ability to tune their structures and porosities for better drug interactions and high loadings, are well suited to serve as nanocarriers for delivery and imaging applications. Here we show that specific non-toxic porous iron(III)-based metal-organic frameworks with engineered cores and surfaces, as well as imaging properties, function as superior nanocarriers for efficient controlled delivery of challenging antitumoural and retroviral drugs (that is, busulfan, azidothymidine triphosphate, doxorubicin or cidofovir) against cancer and AIDS. In addition to their high loadings, they also potentially associate therapeutics and diagnostics, thus opening the way for theranostics, or personalized patient treatments.

Porous metal–organic-framework nanoscale carriers as a potential platform for drug delivery and imaging

Metal Organic Frameworks in Biomedicine Patricia Horcajada,* Ruxandra Gref, Tarek Baati, Phoebe K. Allan, Guillaume Maurin, Patrick Couvreur, G erard F erey, Russell E. Morris, and Christian Serre* Institut Lavoisier, UMR CNRS 8180, Universit e de Versailles St-Quentin en Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France Facult e de Pharmacie, UMR CNRS 8612, Universit e Paris-Sud, 92296 Châtenay-Malabry Cedex, France Institut Charles Gerhardt Montpellier, UMR CNRS 5253, Universit e Montpellier 2, 34095 Montpellier cedex 05, France EaStChem School of Chemistry, University of St. Andrews Purdie Building, St Andrews, KY16 9ST U.K.

Metal-organic frameworks in biomedicine.

Hydrogen Storage in the Giant‐Pore Metal–Organic Frameworks MIL‐100 and MIL‐101

Microwave Synthesis of Chromium Terephthalate MIL-101 and Its Benzene Sorption Ability†

Recently, the domain of nanoporous materials has been enlarged very much to the development of porous hybrid materials designated as metal-organic frameworks (MOF), porous coordination polymers or organic-inorganic hybrids which are the most recently highlighted class of materials consisting of metal ions linked together by organic bridging ligands in the framework. The attraction of combining properties from both inorganic and organic components has led to a quest of research toward new hybrid materials with potential applications including gas storage, catalysis, separation, and molecular recognition. Very recently, Ferey and co-workers have reported a novel hybrid material, chromium trimesate (designated as MIL-100), which has a hierarchical pore system (micro: 5-9 A; mesoporous: 25-30 A) with a very high Langmuir surface area. Syntheses of the porous hybrid materials have been carried out mainly by hydrothermal or solvothermal synthesis generally in a period of several days. Microwave techniques have attracted growing attention for the rapid synthesis of nanoporous materials requiring several days to prepare under hydrothermal conditions. Potential advantages of this technique in the synthesis of porous materials include phase selectivity, narrow particle size distribution and facile morphology control besides fast crystallization. However, microwave technique has not been applied to the synthesis of nanoporous hybrid materials yet even though the microwave syntheses of not only organic molecules but also inorganic materials have been often studied. In this communication, we report the first successful result on the microwave synthesis of porous chromium trimesate as an organic-inorganic hybrid material. The porous chromium trimesate (MIL-100) was synthesized in aqueous media similar to the previous reported method except using microwave irradiation as a heating source. The molar composition of reactant mixture was 1.0 Cr: 0.67 H3BTC (benzene tricarboxylic acid): 2.0 HF: 290 H2O. The reactant mixture was loaded in a Teflon autoclave, which was sealed and placed in a microwave oven (Mars-5, CEM). The autoclave was heated to the reaction temperature of 220 C and kept for a predetermined time. The structure and crystallinity of the synthesized samples were determined by X-ray powder diffraction. The TGA pattern was obtained with a thermal analyzer in the air flow. The sorption experiments were carried out volumetrically. Figure 1 shows the XRD patterns of as-synthesized chromium trimesate obtained by varying crystallization time at 220 C under microwave irradiation. The XRD patterns of the samples obtained from microwave irradiation are well consistent with the pattern of MIL-100 synthesized for 4 days at 220 C using conventional hydrothermal heating. However, the chromium trimesate materials synthesized using microwave method contained unreacted metallic chromium species until 2 h of crystallization. The crystal yield of the chromium trimesate based on chromium from microwave synthesis for 4 h is 44%, which is comparable with the result of 45% in the conventional synthesis for 4 days. The TGA profile of Figure 2 reveals a stability of the title compound up to 270 C. The thermal stability determined with TGA are very similar to the previous results. The chromium trimesate synthesized by microwave heating shows nitrogen adsorption-desorption isotherm very similar to the isotherm of MIL-100 (Data not shown), representing the permanent porosity and similarity of the pore structure of the hybrid materials synthesized by both methods. For multiplayer coverage of N2, we estimate the apparent BET surface area and pore volume to be 1700 m/g and 0.97 mL/g, respectively. From H2 adsorption isotherm (Figure 3), the adsorption capacity of hydrogen at –196 C and 1 atm is estimated to be about 150 mL/g (STP), which is comparable with the results adsorbed on various MOFs and porous hybrid materials. The re-adsorption isotherm after the desorption at –196 C of the pre-adsorbed hydrogen is same as the adsorption isotherm on the fresh sample, representing that there is no chemisorption site in the chromium trimesate

/pdf/microwave-synthesis-of-a-nanoporous-hybrid-material-chromium-2tfznbjexb.pdf

Microwave synthesis of a nanoporous hybrid material, chromium trimesate

Microwave synthesis of two porous nickel glutarates was compared with conventional hydrothermal synthesis. The cubic nickel glutarate, [Ni20(C5H6O4)20(H2O)8] x 40 H2O (1), was synthesized by conventional electrical heating in several hours or days, depending on synthesis temperature. Crystallization was greatly accelerated by microwave irradiation, in which more stable, tetragonal nickel glutarate, [Ni22(C5H6O4)20(OH)4(H2O)10] x 38 H2O (2), was formed within a few minutes, suggesting the efficiency of the microwave technique in the synthesis of porous hybrid materials. The cubic phase 1 is formed preferentially at low pH, low temperature, and especially under conventional electrical heating. In contrast, the tetragonal phase 2 is obtained favorably at high pH, high temperature, and especially with microwave irradiation. This work demonstrates that the microwave method provides not only the very fast synthesis of a hybrid material, but also the possibility to discover a new porous hybrid material not yet identified by conventional hydrothermal synthesis. The hydrothermal formation of metal-organic hybrid materials in a matter of minutes is an important step towards developing commercially viable routes for producing this valuable class of materials.

Jin-Ho Lee

Papers

Hydrogen Storage in the Giant‐Pore Metal–Organic Frameworks MIL‐100 and MIL‐101

Microwave Synthesis of Chromium Terephthalate MIL-101 and Its Benzene Sorption Ability†

Microwave synthesis of a nanoporous hybrid material, chromium trimesate

Microwave Synthesis of Hybrid Inorganic–Organic Porous Materials: Phase‐Selective and Rapid Crystallization

A shape-selective catalyst for epoxidation of cyclic olefins: The nanoporous nickel phosphate VSB-5