Exploration Al-basierter Metallorganischer Netzwerke mit mehreren verschiedenen Linkern und Funktionalitäten - mikroskopische Strukturierung und Protonenleitung
Zusammenfassung der Projektergebnisse
Within the project a new temperature gradient high-throughput reactor was developed that will allow us to rapidly and systematically study the influence of reaction temperature on the product formation. It can be used at six different reaction temperatures (Tmax = of 180 °C). Another high-throughput reactor for vapor phase crystallization studies was developed and tested. Unfortunately, the current set-up is not very practical and reproducibility of the synthesis is often a problem. Thus, future work will focus on the use of the new temperature gradient oven. The synthetic exploration of linkers (functionalized and un-functionalized) and mixture of linkers with a different number and arrangement of carboxylic acid groups for the formation of new Al-MOFs was carried out using our high-throughput reactor systems. While the synthesis of new MOFs with a single linker as well as functionalized linkers was successful, we have not been able to obtain new mixed-linker Al-MOFs. Instead, phase mixtures were always isolated which could be identified as Al-MOFs containing only one of the linker molecules. New linker molecules or new solvents (mixtures) resulted in the formation of Al-MOFs, with new inorganic building units or framework structures and thus unique properties (CAU-21). The properties of known MOF structures could be modified by using smaller or flexible linker molecules or by changing the solvent. Thus, compounds crystallizing in the MIL-53 and MIL-68 structure were discovered. To understand the structural flexibility and sorption properties of these materials, the local structural ordering was studied by NMR spectroscopy. NMR spectroscopy was also employed to analyse host-guest interactions in postsynthetically modified Al-MIL-101 and Cr-MIL-101. Thus, improved water stability of Al-MIL-101 could be traced back to the shielding of the inorganic building blocks against attack by water molecules and effective separation of 2-amino pyridine and 3-amino pyridine from mixtures in dioxane solutions could be explained by the different hydrogen bonding interactions of the molecules. Through the introduction of sulfonic acid groups covalently bonded to Al-MIL-101 a compound exhibiting high proton conductivity could be obtained and NMR measurements could demonstrate that the water molecules are already mobile at temperatures below 273 K in this relatively large pore MOF (∅ > 1 nm). The influence of host-guest interactions in small pore Al-MOFs (∅ < 1 nm) on proton conductivity was systematically investigated by replacing -H atoms in the linkers terephthalic acid of fumaric acid by bulky and hydrophobic -CH3 groups. Ordering of guest molecules is observed in the first case, which directly influences the conductivity of the host-guest compounds. Thus, highest conductivity is found where no host-guest hydrogen bonding interactions are observed. These observations cannot be directly transferred to other hostguest systems. Finally, the size effects and interparticle interactions on the proton conductivity was studied using Al-MIL-53 and two of its post-synthetically modified frameworks, Al-MIL-53- NH2 and Al-MIL-53-OH. Depending on the functional groups, which also influence the framework flexibility, different proton conductivity mechanisms are likely.
Projektbezogene Publikationen (Auswahl)
- “Structure and Properties of Al-MIL-53-ADP, a Breathing MOF Based on the Aliphatic Linker Molecule Adipic Acid”, Dalt. Trans. 2016, 45, 4179–4186
H. Reinsch, R.S. Pillai, R. Siegel, J. Senker, A. Lieb, G. Maurin, N. Stock
(Siehe online unter https://doi.org/10.1039/C5DT03510D) - “Structure property relationships affecting the proton conductivity in imidazole loaded Al-MOFs”, Dalton Trans., 2016, 45, 15041-15047
T. Homburg, C. Hartwig, H. Reinsch, M. Wark und N. Stock
(Siehe online unter https://doi.org/10.1039/C6DT03048C) - “Polymorphous Al-MOFs based on V-shaped Linker molecules: Synthesis, Properties, and In-Situ investigation of their crystallization”, Inorg. Chem., 2017, 56, 5851-5862
M. Krüger, A. K. Inge, H. Reinsch, Y.-H. Li, M. Wahiduzzaman, C.-H. Lin, S.-L. Wang, G. Maurin, N. Stock
(Siehe online unter https://doi.org/10.1021/acs.inorgchem.7b00202) - „New Group 13 MIL-53 Derivates Based on 2,5-Thiophenedicarboxylic Acid.” Z. Anorg. Allg. Chem. 2017, 643 (21), 1600–1608
C.B.L. Tschense, N. Reimer, C.-W. Hsu, H. Reinsch, R. Siegel, W.-J. Chen, C.-H. Lin, A. Cadiau, C. Serre, J. Senker, N. Stock
(Siehe online unter https://doi.org/10.1002/zaac.201700260) - “Green Synthesis of a New Al-MOF Based on the Aliphatic Linker Mesaconic Acid: Structure, Properties and In Situ Crystallisation Studies of Al-MIL-68-Mes”, Chem Eur. J., 2018, 24, 2173-2181
H. Reinsch, T. Homburg, N. Heidenreich, D. Fröhlich, S. Henninger, M. Wark, N. Stock
(Siehe online unter https://doi.org/10.1002/chem.201704771) - „Probing Interactions of N-Donor Molecules with Open Metal Sites within Paramagnetic Cr-MIL-101: A Solid-State NMR Spectroscopic and Density Functional Theory Study”, J. Am. Chem. Soc. 2018, 140, 2135–2144
T. Wittmann, A. Mondal, C.B.L. Tschense, J.J. Wittmann, O. Klimm, R. Siegel, B. Corzilius, B. Weber, M. Kaupp, J. Senker
(Siehe online unter https://doi.org/10.1021/jacs.7b10148) - “Selective Host–Guest Interactions in Metal–Organic Frameworks via Multiple Hydrogen Bond Donor–Acceptor Recognition Sites”, J. Mater. Chem. A 2019, 7, 10379–10388
T. Wittmann, C.B.L. Tschense, L. Zappe, C. Koschnick, R. Siegel, R. Stäglich, B.V. Lotsch, J. Senker
(Siehe online unter https://doi.org/10.1039/C8TA12190G) - “Solvent Impact on the Framework Properties of Benchmark MOFs: Acetonitrile Based Synthesis of CAU-10, Ce-UiO- 66 and Al-MIL-53”, Chem. Eur. J., 2020, 26, 3877-3883
S. Leubner, R. Stäglich, J. Franke, J. Jacobsen, J. Gosch, R. Siegel, H. Reinsch, G. Maurin, J. Senker, P.G. Yot, N. Stock
(Siehe online unter https://doi.org/10.1002/chem.201905376) - „Design and Precursor-based Solid-State Synthesis of Mixed-Linker Zr-MIL-140A“, Inorg. Chem., 2020, 59, 15250–15261
S. Leubner, R. Siegel, J. Franke, M. T. Wharmby, C. Krebs, H. Reinsch, J. Senker, N. Stock
(Siehe online unter https://doi.org/10.1021/acs.inorgchem.0c02221)
