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Microwave-Assisted Synthesis of Defects Metal-Imidazolate-Amide-Imidate Frameworks and Improved CO2 Capture

  • In this work, we report three isostructural 3D frameworks, named IFP-11 (R = Cl), IFP-12 (R = Br), and IFP-13 (R = Et) (IFP = Imidazolate Framework Potsdam) based on a cobalt(II) center and the chelating linker 2-substituted imidazolate-4-amide-5-imidate. These chelating ligands were generated in situ by partial hydrolysis of 2-substituted 4,5-dicyanoimidazoles under microwave (MW)-assisted conditions in DMF. Structure determination of these IFPs was investigated by IR spectroscopy and a combination of powder X-ray diffraction (PXRD) with structure modeling. The structural models were initially built up from the single-crystal X-ray structure determination of IFP-5 (a cobalt center and 2-methylimidazolate-4-amide-5-imidate linker based framework) and were optimized by using density functional theory calculations. Substitution on position 2 of the linker (R = Cl, Br, and Et) in the isostructural IFP-11, -12, and -13 allowed variation of the potential pore window in 1D hexagonal channels (3.8 to 1.7 angstrom A). The potential of theIn this work, we report three isostructural 3D frameworks, named IFP-11 (R = Cl), IFP-12 (R = Br), and IFP-13 (R = Et) (IFP = Imidazolate Framework Potsdam) based on a cobalt(II) center and the chelating linker 2-substituted imidazolate-4-amide-5-imidate. These chelating ligands were generated in situ by partial hydrolysis of 2-substituted 4,5-dicyanoimidazoles under microwave (MW)-assisted conditions in DMF. Structure determination of these IFPs was investigated by IR spectroscopy and a combination of powder X-ray diffraction (PXRD) with structure modeling. The structural models were initially built up from the single-crystal X-ray structure determination of IFP-5 (a cobalt center and 2-methylimidazolate-4-amide-5-imidate linker based framework) and were optimized by using density functional theory calculations. Substitution on position 2 of the linker (R = Cl, Br, and Et) in the isostructural IFP-11, -12, and -13 allowed variation of the potential pore window in 1D hexagonal channels (3.8 to 1.7 angstrom A). The potential of the materials to undergo specific interactions with CO2 was measured by the isosteric heat adsorption. Further, we resynthesized zinc based IFPs, namely IFP-1 = Me), IFP-2 (R = Cl), IFP-3 (R = Br), and IFP-4 (R = Et), and cobalt based IFP-5 under MW-assisted conditions with higher yield. The transition from a nucleation phase to the pure crystalline material of IFP-1 in MW-assisted synthesis depends on reaction time. IFP-1, -3, and -5, which are synthesized by MW-assisted conditions, showed an enhancement of N-2 and CO2, compared to the analogous conventional electrical (CE) heating method based materials due to crystal defects.show moreshow less

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Metadaten
Author:Karsten Behrens, Suvendu Selchar Mondal, Robert Nöske, Igor A. Baburin, Stefano Leoni, Christina Günter, Jens Weber, Hans-Jürgen Holdt
DOI:https://doi.org/10.1021/acs.inorgchem.5b01952
ISSN:0020-1669 (print)
ISSN:1520-510X (online)
Pubmed Id:http://www.ncbi.nlm.nih.gov/pubmed?term=26447991
Parent Title (English):Inorganic chemistry
Publisher:American Chemical Society
Place of publication:Washington
Document Type:Article
Language:English
Year of first Publication:2015
Year of Completion:2015
Release Date:2017/03/27
Volume:54
Issue:20
Pagenumber:8
First Page:10073
Last Page:10080
Funder:Deutsche Forschungsgemeinschaft (SPP 1362 "Porous Metal-Organic Frameworks") [HO 1706/7-1, HO 1706/7-2]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie
Peer Review:Referiert