Insights into the pores of microwave-assisted metal-imidazolate frameworks showing enhanced gas sorption
- Microwave heating (MW)-assisted synthesis has been widely applied as an alternative method for the chemical synthesis of organic and inorganic materials. In this work, we report MW-assisted synthesis of three isostructural 3D frameworks with a flexible linker arm of the chelating linker 2-substituted imidazolate- 4-amide-5-imidate, named IFP-7-MW (M = Zn, R = OMe), IFP-8-MW (M = Co; R = OMe) and IFP-10-MW (M = Co; R = OEt) (IFP = Imidazolate Framework Potsdam). These chelating ligands were generated in situ by partial hydrolysis of 2-substituted 4,5-dicyanoimidazoles under MW-and also conventional electrical heating (CE)-assisted conditions in DMF. The structure of these materials was determined by IR spectroscopy and powder X-ray diffraction (PXRD) and the identity of the materials synthesized under CE-conditions was established. Materials obtained from MW-heating show many fold enhancement of CO2 and H-2 uptake capacities, compared to the analogous CE-heating method based materials. To understand the inner pore-sizes of IFPMicrowave heating (MW)-assisted synthesis has been widely applied as an alternative method for the chemical synthesis of organic and inorganic materials. In this work, we report MW-assisted synthesis of three isostructural 3D frameworks with a flexible linker arm of the chelating linker 2-substituted imidazolate- 4-amide-5-imidate, named IFP-7-MW (M = Zn, R = OMe), IFP-8-MW (M = Co; R = OMe) and IFP-10-MW (M = Co; R = OEt) (IFP = Imidazolate Framework Potsdam). These chelating ligands were generated in situ by partial hydrolysis of 2-substituted 4,5-dicyanoimidazoles under MW-and also conventional electrical heating (CE)-assisted conditions in DMF. The structure of these materials was determined by IR spectroscopy and powder X-ray diffraction (PXRD) and the identity of the materials synthesized under CE-conditions was established. Materials obtained from MW-heating show many fold enhancement of CO2 and H-2 uptake capacities, compared to the analogous CE-heating method based materials. To understand the inner pore-sizes of IFP structures and variations of gas sorptions, we performed positron annihilation lifetime spectroscopy (PALS), which shows that MW-assisted materials have smaller pore sizes than materials synthesized under CE-conditions. The "kinetically controlled" MW-synthesized material has an inherent ability to trap extra linkers, thereby reducing the pore sizes of CE-materials to ultra/micropores. These ultramicropores are responsible for high gas sorption.…
Author details: | Suvendu Sekhar MondalORCiD, Subarna Dey, Ahmed G. Attallah, Reinhard Krause-Rehberg, Christoph Janiak, Hans-Jürgen HoldtORCiD |
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DOI: | https://doi.org/10.1039/c7dt00350a |
ISSN: | 1477-9226 |
ISSN: | 1477-9234 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/28349137 |
Title of parent work (English): | Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry |
Publisher: | Royal Society of Chemistry |
Place of publishing: | Cambridge |
Publication type: | Article |
Language: | English |
Year of first publication: | 2017 |
Publication year: | 2017 |
Release date: | 2020/04/20 |
Volume: | 46 |
Number of pages: | 10 |
First page: | 4824 |
Last Page: | 4833 |
Funding institution: | German Research Foundation (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 |