title: Microwave-Assisted Synthesis of Defects Metal-Imidazolate-Amide-Imidate Frameworks and Improved CO2 Capture.
abstract: 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 Å). The potential of the materials to undergo specific interactions with CO2 was measured by the isosteric heat of adsorption. Further, we resynthesized zinc based IFPs, namely IFP-1 (R = 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 N2 and CO2, compared to the analogous conventional electrical (CE) heating method based materials due to crystal defects.
authors.affiliation: Institut für Chemie, Anorganische Chemie, Universität Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Behrens
authors.affiliation: Institut für Chemie, Anorganische Chemie, Universität Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany.
authors.forename: Suvendu Sekhar
authors.initials: SS
authors.lastname: Mondal
authors.affiliation: Institut für Chemie, Anorganische Chemie, Universität Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Nöske
authors.affiliation: Institut für Physikalische Chemie und Elektrochemie, Technische Universität Dresden , Dresden 01062, Germany.
authors.forename: Igor A
authors.initials: IA
authors.lastname: Baburin
authors.affiliation: Cardiff University , School of Chemistry, Cardiff CF10 3AT, United Kingdom.
authors.forename: Stefano
authors.initials: S
authors.lastname: Leoni
authors.affiliation: Institut für Erd- und Umweltwissenschaften, Universität Potsdam , 14476 Potsdam, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Günter
authors.affiliation: Department of Chemistry, Hochschule Zittau/Görlitz, University of Applied Science , 02763 Zittau, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Weber
authors.affiliation: Institut für Chemie, Anorganische Chemie, Universität Potsdam , Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Holdt