Crystalline structure of UiO-like MOF compounds bearing thorium with azobenzene dicarboxylate linker

International audienc

Crystalline structure of UiO-like MOF compounds bearing thorium with azobenzene dicarboxylate linker

National audienc

Crystalline structure of UiO-like MOF compounds bearing thorium with azobenzene dicarboxylate linker

National audienc

Series of hydrated heterometallic uranyl-cobalt(II) coordination polymers with aromatic polycarboxylate ligands: Formation of U=O—Co bonding upon dehydration process

Five new heterometallic UO22+-Co2+ coordination polymers have been obtained by hydrothermal reactions of uranyl nitrate and metallic cobalt with aromatic polycarboxylic acids. Single-crystal X-ray diffraction reveals the formation of four 3D frameworks with the mellitate (noted mel) ligand and one 2D network with the isophthalate (noted iso) ligand. The compounds [(UO2(H2O))2Co(H2O)4(mel)]·4H2O (1), [UO2Co(H2O)4(H2mel)]·2H2O (2), and [(UO2(H2O))2Co(H2O)4(mel)] (4) consist of 3D frameworks built up from the connection of mellitate ligands and mononuclear metallic centers. These three compounds exhibit two types of geometry for the uranyl cation: pentagonal bipyramidal environment for 1 and 4, and hexagonal bipyramidal environment for 2. Using the mellitate ligand, the uranyl dinuclear unit is isolated in the compound [(UO2)2(OH)2(Co(H2O)4)2(mel)]·2H2O (3). Due to their 2D framework and the presence of uncoordinated cobalt(II) cations, the compound [(UO2)(iso)3][Co(H2O)6]·3(H2O) (5) is drastically different than the previous one. The thermal behavior of compounds 1, 2, and 3 has been studied by thermogravimetric analysis, X-ray thermodiffraction, and in situ infrared. By heating, the dehydration of compounds 1 and 2 promotes two structural transitions (1 → 1′ and 2 → 2′). The crystal structures of [(UO2(H2O))2Co(H2O)2(mel)] (1′) and [(UO2)Co(H2mel)] (2′) were determined by single-crystal X-ray diffraction; each of them presents a heterometallic interaction between uranyl bond and the Co(II) center. Due to the rarely reported coordination environment for the cobalt center in compound 2′ (square pyramidal configuration), the magnetic properties and EPR characterizations of the compounds 2 and 2′ were also investigated

Synthesis, crystal structure and 71Ga solid state NMR of a MOF-type gallium trimesate (MIL-96) with µ3-oxo bridged trinuclear units and a hexagonal 18-ring network

International audienceA new gallium trimesate Ga12O(OH)12({OH}4,{H2O}5)[btc]6 24H2O, called MIL-96, (btc = 1,3,5- benzenetricarboxylate or trimesate species) was hydrothermally synthesized under mild conditions (210 C, 5 h) in the presence of trimethyl 1,3,5-benzenetricarboxylate in water and characterized by single-crystal X-ray diffraction technique. The MIL-96 (Ga) structure exhibits a three-dimensional metal– organic framework containing isolated trinuclear l3-oxo-bridged gallium clusters and infinite chains of GaO4(OH)2 and GaO2(OH)4 octahedra generating a hexagonal network based on 18-membered ring. The two types of gallium groups are connected to each other through the trimesate species which induce corrugated chains of gallium octahedra, linked via l2-hydroxo bonds with the specific -cis–cis–trans- sequence. The 3D framework of MIL-96 reveals three kinds of cavities (two of them have estimated pore volumes of 480 and 860 A˚ 3), in which are encapsulated free water molecules. The latter species are removed upon heating at 150 C. The MIL- 96 (Ga) compound was characterized by 71Ga solid state NMR at different magnetic fields (14.1 and 17.6 T). 71Ga spectra of MIL-96 (Ga) show the gallium exhibits relatively weak quadrupolar interactions compared to those observed in other MOF-type gallium carboxylates that have very strong quadrupolar interactions (MIL-61 and MIL-53)

Capture of radionuclides in Metal-Organic Frameworks

International audienc

Etude de la précipitation quantitative de l’ion uranyle par des ligands organiques: cas de l’adamantane acétamide

International audienc