Thierry Loiseau

Open‐Framework Inorganic Materials

Aluminosilicate zeolites such as UTD-1 (structure shown) belong to a family of nanoporous inorganic materials that find utility in catalysis, separation, and ion exchange. During the last decade, the rate of discovery of new open-framework materials based, for example, on phosphates, sulfides, halides, nitrides, and coordination compounds has increased dramatically. The synthesis, structures, and properties of this remarkable class of materials are reviewed.

Hydrogen adsorption in the nanoporous metal-benzenedicarboxylate M(OH)(O2C–C6H4–CO2)(M = Al3+, Cr3+), MIL-53

Hydrogen adsorption has been studied in the nanoporous metal-benzenedicarboxylate M(OH)(O2C-C6H4-CO2) (M = Al3+, Cr3+); these solids show a hydrogen storage capacity of 3.8 and 3.1 wt.% respectively when loaded at 77 K under 1.6 MPa.

Comparative Study of Hydrogen Sulfide Adsorption in the MIL-53(Al, Cr, Fe), MIL-47(V), MIL-100(Cr), and MIL-101(Cr) Metal−Organic Frameworks at Room Temperature

Hydrogen sulfide gravimetric isotherm adsorption measurements were carried out on MIL-53(Al, Cr, Fe), MIL-47(V), MIL-100(Cr), and MIL-101(Cr) metal-organic frameworks (MOFs). A two-step adsorption mechanism related to a breathing effect was observed for MIL-53 terephthalate-based MOFs. Methane adsorption measurements highlighted the regenerability of MIL-53(Al, Cr) and MIL-47(V) MOFs after H(2)S treatment, whereas MIL-100 and MIL-101 CH(4) adsorption capacities were significantly decreased.

Synthesis and Modification of a Functionalized 3D Open-Framework Structure with MIL-53 Topology

Aluminum aminoterephthalate Al(OH)[H(2)N-BDC] x 0.3 (H(2)N-H(2)BDC (denoted MIL-53-NH(2)(as)) was synthesized under hydrothermal conditions. The activation of the compound can be achieved in two steps. The treatment with DMF at 150 degrees C leads to Al(OH)[H(2)N-BDC] x 0.95 DMF (MIL-53-NH(2)(DMF)). In the second step, DMF is thermally removed at 130 degrees C. Upon cooling in air, the hydrated form Al(OH)[H(2)N-BDC] x 0.9 H(2)O (MIL-53-NH(2)(lt)) is obtained. The dehydration leads to a porous compound that exhibits hysteresis behavior in the N(2) sorption experiments. The MIL-53-NH(2)(lt) can be modified by postsynthetic functionalization using formic acid, and the corresponding amide Al(OH)[HC(O)N(H)-BDC] x H(2)O (MIL-53-NHCHO) is formed. All four phases were thoroughly characterized by X-ray powder diffraction, solid-state NMR and IR spectroscopy, and sorption measurements, as well as thermogravimetric and elemental analysis. Based on the refined lattice parameter similar breathing behavior of the framework as found in the unfunctionalized MIL-53 can be deduced. Solid-state NMR spectra unequivocally demonstrate the presence of the guest species, as well as the successful postsynthetic functionalization.

Anorganische Materialien mit offenen Gerüsten

Die alumosilicatischen Zeolithe wie UTD-1 (siehe Bild) bilden eine bemerkenswerte Familie nanoporoser anorganischer Materialien, die in der Katalyse, in Trennverfahren und als Ionenaustauscher angewendet werden. Wahrend des letzten Jahrzehnts wurden mehr und mehr neue Materialien mit offenen Gerusten hergestellt. Diese basieren z. B. auf Phosphaten, Sulfiden, Halogeniden, Nitriden und Koordinationsverbindungen. Es wird eine Ubersicht uber die Synthesen, die Strukturen und die Eigenschaften dieser bemerkenswerten Klasse von Materialien gegeben.

[Al4(OH)2(OCH3)4(H2N‐bdc)3]⋅x H2O: A 12‐Connected Porous Metal–Organic Framework with an Unprecedented Aluminum‐Containing Brick

Al together now! A new stable aluminum aminoterephthalate system contains octameric building blocks that are connected by organic linkers to form a 12-connected net (see picture). The structure adopts a cubic centered packing motive in which octameric units replace individual atoms, thus forming distorted octahedral (red sphere) and tetrahedral cages (green spheres) with effective accessible diameters of 1 and 0.45 nm, respectively.

Hydrocarbon Adsorption in the Flexible Metal Organic Frameworks MIL-53(Al, Cr)

A general study of the adsorption of n-alkanes in the flexible metal organic framework (MOF) MIL-53 is presented. The roles of the length of the alkyl chain (n = 1-9), the nature of the metal (Al, Cr), and temperature were investigated. The shape of the adsorption curves is driven by the alkyl chain length of the n-alkanes. While traditional type-I isotherms are observed for short alkanes (n = 1, 2), adsorbates with longer chains induce clear substeps in the isotherm curves whose positions depend on the chain length. Such substeps are due to a breathing phenomenon, as proven by ex situ X-ray diffraction analysis. They strongly depend on the amount of adsorbate in the pores and on the nature of the metal (Al, Cr), which, for a given alkane, leads to a strong change in the substep positions despite the similar characteristics of the two metals. The adsorption kinetics are highly sensitive to small variations in temperature. Their detailed analysis in different regions of the isotherms shows in some cases the existence of distinct diffusion regimes and/or conformations within the flexible phases.

Al30: A Giant Aluminum Polycation

Simple hydrothermal treatment of the well-known aluminum polycation varepsilon-Al(13) produces the novel Al(30) structure (see picture), the largest polycation yet observed. Its characterization, by X-ray diffraction and NMR spectroscopy, also solved previously unassigned signals in (27)Al NMR spectra of other Al - O species.

The Kagomé Topology of the Gallium and Indium Metal-Organic Framework Types with a MIL-68 Structure: Synthesis, XRD, Solid-State NMR Characterizations, and Hydrogen Adsorption

The vanadium-based terephthalate analogs of MIL-68 have been obtained with gallium and indium (network composition: M(OH)(O(2)C-C(6)H(4)-CO(2)), M = Ga or In) by using a solvothermal synthesis technique using N,N-dimethylformamide as a solvent (10 and 48 h, for Ga and In, respectively, at 100 degrees C). They have been characterized by X-ray diffraction analysis; vibrational spectroscopy; and solid-state (1)H and (1)H-(1)H radio-frequency-driven dipolar recoupling (RFDR), (1)H-(1)H double quantum correlation (DQ), and (13)C{(1)H} cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The three-dimensional network with a Kagomé-like lattice is built up from the connection of infinite trans-connected chains of octahedral units MO(4)(OH)(2) (M = Ga or In), linked to each other through the terephthalate ligands in order to generate triangular and hexagonal one-dimensional channels. The presence of DMF molecules with strong interactions within the channels as well as their departure upon calcination (150 degrees C under a primary vacuum) of the materials has been confirmed by subjecting MIL-68 (Ga) to solid-state (1)H MAS NMR. The (1)H-(1)H RFDR and (1)H-(1)H DQ spectra revealed important information on the spatial arrangement of the guest species with respect to the hybrid organic-inorganic network. (13)C{(1)H} CPMAS NMR of activated samples provided crystallographically independent sites in agreement with X-ray diffraction structure determination. Brunauer-Emmett-Teller surface areas are 1117(24) and 746(31) m(2) g(-1) for MIL-98 (Ga) and MIL-68 (In), respectively. Hydrogen adsorption isotherms have been measured at 77 K, and the storage capacities are found to be 2.46 and 1.98 wt % under a saturated pressure of 4 MPa for MIL-68 (Ga) and MIL-68 (In), respectively. For comparison, the hydrogen uptake for the aluminum trimesate MIL-110, which has an open framework with 16 A channels, is 3 wt % under 4 MPa.

Breathing Transitions in MIL‐53(Al) Metal–Organic Framework Upon Xenon Adsorption

MOFs come alive: The combination of gas‐adsorption experiments at various temperatures with an osmotic thermodynamic model produced a generic temperature–loading phase diagram that displays unexpected re‐entrant behavior. The breathing effect in the metal–organic framework MIL‐53(Al) is predicted to be general and should be observed over a limited temperature range regardless of the guest adsorbate.