Probing Adsorption Interactions in Metal-Organic Frameworks using X-ray Spectroscopy

We explore the local electronic signatures of molecular adsorption at coordinatively unsaturated binding sites in the metal-organic framework Mg-MOF-74 using X-ray spectroscopy and first-principles calculations. In situ measurements at the Mg K-edge reveal distinct pre-edge absorption features associated with the unique, open coordination of the Mg sites which are suppressed upon adsorption of CO2 and N,N′-dimethylformamide. Density functional theory shows that these spectral changes arise from modifications of local symmetry around the Mg sites upon gas uptake and are strongly dependent on the metal-adsorbate binding strength. The expanded MOF Mg2(dobpdc) displays the same behavior upon adsorption of CO 2 and N,N′-dimethylethylenediamine. Similar sensitivity to local symmetry is expected for any open metal site, making X-ray spectroscopy an ideal tool for examining adsorption in such MOFs. Qualitative agreement between ambient-temperature experimental and 0 K theoretical spectra is good, with minor discrepancies thought to result from framework vibrational motion. © 2013 American Chemical Society.


Published in:
Journal of the American Chemical Society, 135, 48, 18183-18190
Year:
2013
ISSN:
0002-7863
Note:
Times Cited: 0
Drisdell, Walter S. Poloni, Roberta McDonald, Thomas M. Long, Jeffrey R. Smit, Berend Neaton, Jeffrey B. Prendergast, David Kortright, Jeffrey B.
Smit, Berend/B-7580-2009; EFRC, CGS/I-6680-2012
Smit, Berend/0000-0003-4653-8562;
0
J AM CHEM SOC
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