| Autor: |
Gosch J; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany., Guiotto V; Dipartimento di Chimica, Università degli Studi di Torino, Via Gioacchino Quarello 15a, 10135 Turin, Italy., Steinke F; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany., Svensson Grape E; Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden., Atzori C; European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble Cedex 9, France., Mertin K; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany., Otto T; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany., Ruser N; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany., Meier C; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany., Morelli Venturi D; Dipartimento di Chimica Biologia e Biotecnologia, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy., Inge AK; Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden., Lomachenko KA; European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble Cedex 9, France., Crocellà V; Dipartimento di Chimica, Università degli Studi di Torino, Via Gioacchino Quarello 15a, 10135 Turin, Italy., Stock N; Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany.; Kiel Nano, Surface and Interface Science KiNSIS, Christian-Albrechts-Universität zu Kiel, Christian-Albrechts-Platz 4, 24118 Kiel, Germany. |
| Abstrakt: |
We report the discovery and characterization of two porous Ce(III)-based metal-organic frameworks (MOFs) with the V-shaped linker molecules 4,4'-sulfonyldibenzoate (SDB 2- ) and 4,4'-(hexafluoroisopropylidene)bis(benzoate) (hfipbb 2- ). The compounds of framework composition [Ce 2 (H 2 O)(SDB) 3 ] ( 1 ) and [Ce 2 (hfipbb) 3 ] ( 2 ) were obtained by using a synthetic approach in acetonitrile that we recently established. Structure determination of 1 was accomplished from 3D electron diffraction (3D ED) data, while 2 could be refined against powder X-ray diffraction (PXRD) data using the crystal structure of an isostructural La-MOF as the starting model. Their framework structures consist of chain-like inorganic building units (IBUs) or hybrid-BUs that are interconnected by the V-shaped linker molecules to form framework structures with channel-type pores. The composition of both compounds was confirmed by PXRD, elemental analysis, as well as NMR and IR spectroscopy. Interestingly, despite the use of (NH 4 ) 2 [Ce IV (NO 3 ) 6 ] in the synthesis, cerium ions in both MOFs occur exclusively in the + III oxidation state as determined by X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS). Thermal analyses reveal remarkably high thermal stabilities of ≥400 °C for the MOFs. Initial N 2 sorption measurements revealed the peculiar sorption behavior of 2 which prompted a deeper investigation by Ar and CO 2 sorption experiments. The combination with nonlocal density functional theory (NL-DFT) calculations adds to the understanding of the nature of the different pore diameters in 2 . An extensive quasi-simultaneous in situ XANES/XRD investigation was carried out to unveil the formation of Ce-MOFs during the solvothermal syntheses in acetonitrile. The crystallization of the two Ce(III)-MOFs presented herein as well as two previously reported Ce(IV)-MOFs, all obtained by a similar synthetic approach, were studied. While the XRD patterns show time-dependent MOF crystallization, the XANES data reveal the presence of Ce(III) intermediates and their subsequent conversion to the MOFs. The addition of acetic acid in combination with the V-shaped linker molecule was identified as the crucial factor for the formation of the crystalline Ce(III/IV)-MOFs. |
