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
✍ Scribed by Volkringer, Christophe; Meddouri, Mohamed; Loiseau, Thierry; Guillou, Nathalie; Marrot, Jérôme; Férey, Gérard; Haouas, Mohamed; Taulelle, Francis; Audebrand, Nathalie; Latroche, Michel
- Book ID
- 120060767
- Publisher
- American Chemical Society
- Year
- 2008
- Tongue
- English
- Weight
- 447 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0020-1669
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✦ Synopsis
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,Ndimethylformamide as a solvent (10 and 48 h, for Ga and In, respectively, at 100 °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 Kagome ´-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 °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 Å channels, is 3 wt % under 4 MPa.
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