Two new dihydroxybenzoquinone-based metal-organic frameworks, ((CH3)2NH2)3[Al4(L1)3(L1(•))3]·3DMF (1, denoted CAU-20) and ((CH3)2NH2)3[Al4(L2)3(L2(•))3]·9DMF (2, denoted CAU-20-Cl2), were synthesized at 120 °C in DMF using 2,5-dihydroxy-p-benzoquinone ((C6H2(OH)2(O)2), H2L1) and 2,5-dichloro-3,6-dihydroxy-p-benzoquinone ((C6Cl2(OH)2(O)2), H2L2), respectively. Compared to other Al-MOFs, which contain carboxylate or phosphonate groups that connect the metal sites, in 1 and 2 the Al(3+) are coordinated by oxido groups. The metal ions are octahedrally surrounded by oxygen atoms of the deprotonated linker molecules to generate honeycomb layers with a metal to linker ratio of Al: L1/L2 = 2:3. The layers contain L1(2-) and L2(2-) ions as well as linker radical ions L1(•3-) and L2(•3-) in a molar ratio of 1 to 1. The presence of radical ions was confirmed by EPR and UV-vis-spectroscopic measurements, and the composition was determined from a combination of PXRD, (1)H NMR, TG, and elemental analyses. Charge balance is accomplished through intercalation of (CH3)2NH2(+) ions which are formed by partial hydrolysis of DMF. In the structures of 1 and 2 the eclipsed layers are AA and ABAB stacked, respectively, and one-dimensional hexagonal channels with diameters of ca. 9 and 6 Å are formed. Both compounds exhibit permanent porosity and have specific surface areas of 1440 and 1430 m(2) g(-1), respectively.
Highly porous three-dimensional Al- and Ga-MOFs with radical catecholate linker molecules were synthesized and characterized by electron diffraction, molecular simulation, Rietveld refinement and N2 sorption measurements.
Two new squarate complexes based on aluminum and gallium, [Al2(OH)2(C4O4)2(H2O)4]·2H2O (1) and [Ga2(OH)2(C4O4)2(H2O)4]·2H2O (2) were hydrothermally synthesized and characterized by infrared spectroscopy and thermogravimetric measurements. The structure of 1 was determined by single‐crystal X‐ray diffraction and the structure of 2 was refined from PXRD data. The dinuclear squarate complexes consist of two MO6 polyhedra (M = Al or Ga) interconnected by two squarate ions in axial and two hydroxyl groups in equatorial position. Two water molecules are coordinating to each central metal atom in equatorial position to complete the coordination spheres. Furthermore, a non‐coordinating water molecule is located between the dinuclear units. Hydrogen bonding leads to the interconnection of the molecular complexes to a three‐dimensional network.
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