A Combined Pulsed Electron Paramagnetic Resonance Spectroscopic and DFT Analysis of the (CO2)-C-13 and (CO)-C-13 Adsorption on the Metal-Organic Framework Cu2.97Zn0.03(btc)(2)

Journal article
(Original article)


Publication Details

Author(s): Jee B, Petkov PS, Vayssilov GN, Heine T, Hartmann M, Poeppl A
Journal: Journal of Physical Chemistry C
Publisher: American Chemical Society
Publication year: 2013
Volume: 117
Journal issue: 16
Pages range: 8231-8240
ISSN: 1932-7447


Abstract


Cu-3(btc)(2) (btc = 1,3,5-benzenetricarboxylate), also called HKUST-1, is one of the well-known representatives of the metal organic framework (MOF) compounds. It exhibits a large surface area and a high pore volume. Due to the coordinatively unsaturated metal centers as preferential adsorption sites, Cu-3(btc)(2) is particularly interesting for the separation of CO2 and CO in gaseous mixtures. We studied the interactions of C-13-enriched carbon dioxide ((CO2)-C-13) and carbon monoxide ((CO)-C-13) with the Cu2+ centers in the zinc-substituted homologue Cu2.97Zn0.03(btc)(2) using continuous wave (cw) and pulsed electron paramagnetic resonance (EPR) spectroscopy (Davies or Mims electron nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE)). Upon adsorption of (CO2)-C-13 and (CO)-C-13, the coordination geometry of the Cu2+ centers changed from square planar to square pyramidal The cupric ion g-tensor and the Cu-63/65 hyperfine coupling tensor A(Cu) show the changes in the ligand field of Cu2+. Moreover, the interaction with the C-13 nuclei of the gas molecules is reflected in the isotropic coupling constant A(iso)(C) and the dipolar coupling parameter T-perpendicular to(C) which are derived from the C-13 hyperfine coupling tensor A(C) obtained by the pulsed EPR experiments. From the experimentally obtained parameters, we derived a geometrical model for the adsorption of (CO2)-C-13 and (CO)-C-13) at the Cu2+ ions that is consistent with our DFT calculations. The (CO)-C-13 molecule is found to coordinate linearly at the Cu2+ center via the C-13 atom and perpendicular to the CuO4 plane with a Cu-C distance of r(CuC) = 2.57(10) angstrom (DFT, 2.42 angstrom). The (CO2)-C-13 molecule is coordinated slightly tilted via the O atom with a Cu-C distance of r(CuC) = 3.34(10) angstrom (DFT, 3.27 angstrom). The Cu-O distance for adsorbed (CO2)-C-13 is not directly accessible to EPR measurements but could be estimated from geometrical considerations in the range of r(Cuo) = 2.53-2.73 angstrom (DFT, 2.39 angstrom). The results provide detailed insight into the geometry of adsorbed CO2 and CO in porous materials and show the potential of EPR spectroscopy for analyzing adsorption complexes.



FAU Authors / FAU Editors

Hartmann, Martin Prof. Dr.
Professur für Katalyse


Additional Organisation
Interdisziplinäres Zentrum Erlangen Catalysis Resource Center (ECRC)


External institutions
Jacobs University Bremen gGmbH
Sofia University "St. Kliment Ohridski" / Софийски университет "Св. Климент Охридски"
Universität Leipzig


How to cite

APA:
Jee, B., Petkov, P.S., Vayssilov, G.N., Heine, T., Hartmann, M., & Poeppl, A. (2013). A Combined Pulsed Electron Paramagnetic Resonance Spectroscopic and DFT Analysis of the (CO2)-C-13 and (CO)-C-13 Adsorption on the Metal-Organic Framework Cu2.97Zn0.03(btc)(2). Journal of Physical Chemistry C, 117(16), 8231-8240. https://dx.doi.org/10.1021/jp4003033

MLA:
Jee, Bettina, et al. "A Combined Pulsed Electron Paramagnetic Resonance Spectroscopic and DFT Analysis of the (CO2)-C-13 and (CO)-C-13 Adsorption on the Metal-Organic Framework Cu2.97Zn0.03(btc)(2)." Journal of Physical Chemistry C 117.16 (2013): 8231-8240.

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Last updated on 2018-10-08 at 06:56