Synthesis of two new Hf‐MOFs with UiO‐66 and CAU‐22 structure employing 2,5‐pyrazinedicarboxylic acid as linker molecule

Two different metal‐organic frameworks containing 2,5‐pyrazinedicarboxylate (PzDC2−) as linker molecule and hexanuclear {Hf6(μ3‐O)4(μ3‐OH)4} clusters were obtained under solvothermal reaction conditions at 120 °C. Formic acid as the solvent leads to the formation of Hf‐UiO‐66‐PzDC ([Hf6(μ3‐O)4(μ3‐OH...

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Published in:Zeitschrift für anorganische und allgemeine Chemie (1950) 2021-11, Vol.647 (22), p.2029-2034
Main Authors: Poschmann, Mirjam P. M., Waitschat, Steve, Reinsch, Helge, Stock, Norbert
Format: Article
Language:English
Subjects:
Clusters
crystal structure
Crystallization
Decomposition
Dehydration
Formic acid
Hafnium
high-throughput method
metal-organic framework
Metal-organic frameworks
NMR
Nuclear magnetic resonance
Rietveld refinement
Sorption
Structural analysis
Surface area
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Summary:Two different metal‐organic frameworks containing 2,5‐pyrazinedicarboxylate (PzDC2−) as linker molecule and hexanuclear {Hf6(μ3‐O)4(μ3‐OH)4} clusters were obtained under solvothermal reaction conditions at 120 °C. Formic acid as the solvent leads to the formation of Hf‐UiO‐66‐PzDC ([Hf6(μ3‐O)4(μ3‐OH)4(OH)4(H2O)4(PzDC)4]), while the reaction in a water/formic acid mixture resulted in the crystallisation of Hf‐CAU‐22‐PzDC ([Hf6(μ3‐O)4(μ3‐OH)4(μ‐OH)2(OH)4(H2O)4(PzDC)3]). The UiO‐66 compound is a new member of the large class of UiO‐66‐type MOFs. Hf‐CAU‐22 contains a chain of condensed {Hf6O4(OH)4(μ‐OH)4} clusters as the IBU, which is new to Hf‐MOF chemistry. For both MOFs, a detailed characterization, i. e. structure refinement from powder X‐ray diffraction data, 1H‐NMR‐spectroscopy, elemental and thermogravimetric analyses and N2 sorption measurements, was carried out. Hf‐UiO‐66‐PzDC undergoes a dehydration around 215 °C and framework decomposition starts at 315 °C. From N2 sorption measurements, a maximum BET surface area of 460 m2/g was determined. The dehydration of Hf‐CAU‐22‐PzDC starts at 200 °C and the framework decomposition at 325 °C. The BET surface area was determined to 170 m2/g.
ISSN:0044-2313
1521-3749
DOI:10.1002/zaac.202100184