High Methane Storage Capacity in Aluminum Metal–Organic Frameworks

The use of porous materials to store natural gas in vehicles requires large amounts of methane per unit of volume. Here we report the synthesis, crystal structure and methane adsorption properties of two new aluminum metal–organic frameworks, MOF-519 and MOF-520. Both materials exhibit permanent porosity and high methane volumetric storage capacity: MOF-519 has a volumetric capacity of 200 and 279 cm³ cm^–3 at 298 K and 35 and 80 bar, respectively, and MOF-520 has a volumetric capacity of 162 and 231 cm³ cm^–3 under the same conditions. Furthermore, MOF-519 exhibits an exceptional working capacity, being able to deliver a large amount of methane at pressures between 5 and 35 bar, 151 cm³ cm^–3, and between 5 and 80 bar, 230 cm³ cm^–3

Crystalline Fibers of Metal–Peptide Double Ladders

Despite remarkable progress in the field of MOFs, structures based on long-flexible organic linkers are scarce and the majority of such materials rely on rigid linkers. In this work, crystals of a new metal–organic double ladder (MODL) are obtained by linking a pentapeptide (NH₂-Glu-<i>p</i>CO₂Phe-<i>p</i>CO₂Phe-Ala-Gly-OH) with cadmium acetate to produce a Cd­(2-pyrrolidone<i>-p</i>CO₂Phe-<i>p</i>CO₂Phe-Ala-Gly)­(H₂O)₃ framework. SEM and TEM analyses show the fibrous nature of the crystals and show that the infinite cadmium oxide rod secondary building units (SBUs) are aligned with the longitudinal axis of the nanofibers

Crystalline Fibers of Metal–Peptide Double Ladders

Despite remarkable progress in the field of MOFs, structures based on long-flexible organic linkers are scarce and the majority of such materials rely on rigid linkers. In this work, crystals of a new metal–organic double ladder (MODL) are obtained by linking a pentapeptide (NH₂-Glu-<i>p</i>CO₂Phe-<i>p</i>CO₂Phe-Ala-Gly-OH) with cadmium acetate to produce a Cd­(2-pyrrolidone<i>-p</i>CO₂Phe-<i>p</i>CO₂Phe-Ala-Gly)­(H₂O)₃ framework. SEM and TEM analyses show the fibrous nature of the crystals and show that the infinite cadmium oxide rod secondary building units (SBUs) are aligned with the longitudinal axis of the nanofibers

Tunable Catalytic Activity of Solid Solution Metal–Organic Frameworks in One-Pot Multicomponent Reactions

The aim of this research is to establish how metal–organic frameworks (MOFs) composed of more than one metal in equivalent crystallographic sites (solid solution MOFs) exhibit catalytic activity, which is tunable by virtue of the metal ions ratio. New MOFs with general formula [In_<i>x</i>Ga_1–<i>x</i>(O₂C₂H₄)_0.5(hfipbb)] were prepared by the combination of Ga and In. They are isostructural with their monometal counterparts, synthesized with Al, Ga, and In. Differences in their behavior as heterogeneous catalysts in the three-component, one pot Strecker reaction illustrate the potential of solid solution MOFs to provide the ability to address the various stages involved in the reaction mechanism

Superacidity in Sulfated Metal–Organic Framework-808

Superacids, defined as acids with a Hammett acidity function <i>H</i>₀ ≤ −12, are useful materials, but a need exists for new, designable solid state systems. Here, we report superacidity in a sulfated metal–organic framework (MOF) obtained by treating the microcrystalline form of MOF-808 [MOF-808-P: Zr₆O₅­(OH)₃­(BTC)₂­(HCOO)₅(H₂O)₂, BTC = 1,3,5-benzene­tricar­box­ylate] with aqueous sulfuric acid to generate its sulfated analogue, MOF-808-2.5SO₄ [Zr₆O₅­(OH)₃­(BTC)₂­(SO₄)_2.5(H₂O)_2.5]. This material has a Hammett acidity function <i>H</i>₀ ≤ −14.5 and is thus identified as a superacid, providing the first evidence for superacidity in MOFs. The superacidity is attributed to the presence of zirconium-bound sulfate groups structurally characterized using single-crystal X-ray diffraction analysis

Tunable Catalytic Activity of Solid Solution Metal–Organic Frameworks in One-Pot Multicomponent Reactions

The aim of this research is to establish how metal–organic frameworks (MOFs) composed of more than one metal in equivalent crystallographic sites (solid solution MOFs) exhibit catalytic activity, which is tunable by virtue of the metal ions ratio. New MOFs with general formula [In_<i>x</i>Ga_1–<i>x</i>(O₂C₂H₄)_0.5(hfipbb)] were prepared by the combination of Ga and In. They are isostructural with their monometal counterparts, synthesized with Al, Ga, and In. Differences in their behavior as heterogeneous catalysts in the three-component, one pot Strecker reaction illustrate the potential of solid solution MOFs to provide the ability to address the various stages involved in the reaction mechanism

Tunable Catalytic Activity of Solid Solution Metal–Organic Frameworks in One-Pot Multicomponent Reactions

The aim of this research is to establish how metal–organic frameworks (MOFs) composed of more than one metal in equivalent crystallographic sites (solid solution MOFs) exhibit catalytic activity, which is tunable by virtue of the metal ions ratio. New MOFs with general formula [In_<i>x</i>Ga_1–<i>x</i>(O₂C₂H₄)_0.5(hfipbb)] were prepared by the combination of Ga and In. They are isostructural with their monometal counterparts, synthesized with Al, Ga, and In. Differences in their behavior as heterogeneous catalysts in the three-component, one pot Strecker reaction illustrate the potential of solid solution MOFs to provide the ability to address the various stages involved in the reaction mechanism

Tunable Catalytic Activity of Solid Solution Metal–Organic Frameworks in One-Pot Multicomponent Reactions

The aim of this research is to establish how metal–organic frameworks (MOFs) composed of more than one metal in equivalent crystallographic sites (solid solution MOFs) exhibit catalytic activity, which is tunable by virtue of the metal ions ratio. New MOFs with general formula [In_<i>x</i>Ga_1–<i>x</i>(O₂C₂H₄)_0.5(hfipbb)] were prepared by the combination of Ga and In. They are isostructural with their monometal counterparts, synthesized with Al, Ga, and In. Differences in their behavior as heterogeneous catalysts in the three-component, one pot Strecker reaction illustrate the potential of solid solution MOFs to provide the ability to address the various stages involved in the reaction mechanism

Synthesis and Characterization of Metal–Organic Framework-74 Containing 2, 4, 6, 8, and 10 Different Metals

Metal–organic frameworks (MOFs) containing more than two kinds of metal ions mixed in one secondary building unit are rare because the synthesis often yields mixed MOF phases rather than a pure phase of a mixed-metal MOF (MM-MOF). In this study, we use a one-pot reaction to make microcrystalline MOF-74 [M₂(DOT); DOT = dioxidoterephthalate] with 2 (Mg and Co), 4 (Mg, Co, Ni, and Zn), 6 (Mg, Sr, Mn, Co, Ni, and Zn), 8 (Mg, Ca, Sr, Mn, Fe, Co, Ni, and Zn), and 10 (Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Zn, and Cd) different kinds of divalent metals. The powder X-ray diffraction patterns of MM-MOF-74 were identical with those of single-metal MOF-74, and no amorphous phases were found by scanning electron microscopy. The successful preparation of guest-free MM-MOF-74 samples was confirmed by N₂ adsorption measurements. Elemental analysis data also support the fact that all metal ions used in the MOF synthesis are incorporated within the same MOF-74 structure. Energy-dispersive X-ray spectroscopies indicate that metal ions are heterogeneously distributed within each of the crystalline particles. This approach is also employed to incorporate metal ions (i.e., Ca, Sr, Ba, and Cd) from which the parent MOF structure could not be made as a single-metal-containing MOF

A Titanium–Organic Framework as an Exemplar of Combining the Chemistry of Metal– and Covalent–Organic Frameworks

A crystalline material with a two-dimensional structure, termed metal–organic framework-901 (MOF-901), was prepared using a strategy that combines the chemistry of MOFs and covalent–organic frameworks (COFs). This strategy involves <i>in situ</i> generation of an amine-functionalized titanium oxo cluster, Ti₆O₆(OCH₃)₆(AB)₆ (AB = 4-aminobenzoate), which was linked with benzene-1,4-dialdehyde using imine condensation reactions, typical of COFs. The crystal structure of MOF-901 is composed of hexagonal porous layers that are likely stacked in staggered conformation (<b>hxl</b> topology). This MOF represents the first example of combining metal cluster chemistry with dynamic organic covalent bond formation to give a new crystalline, extended framework of titanium metal, which is rarely used in MOFs. The incorporation of Ti­(IV) units made MOF-901 useful in the photocatalyzed polymerization of methyl methacrylate (MMA). The resulting polyMMA product was obtained with a high-number-average molar mass (26 850 g mol^–1) and low polydispersity index (1.6), which in many respects are better than those achieved by the commercially available photocatalyst (P-25 TiO₂). Additionally, the catalyst can be isolated, reused, and recycled with no loss in performance