Abstract: Metal organic frameworks (MOFs) are being increasingly considered as promising materials for gas separation and storage, yet specific interactions between gas molecules and the inner surface of pores are still not well understood. In this work, we propose a new approach for investigation of such interactions by Electron Paramagnetic Resonance (EPR). We use stable nitroxide radicals as multifunctional agents embedded into the pores of a MOF prior to the gas sorption. They act as EPR-active reporters, and simultaneously as competitor molecules during the gas adsorption process. We exemplify this approach using a ZIF-8 framework, nitroxide TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl), and CO2, N-2, and O-2 gases. The mobility of nitroxide monitored by continuous wave EPR behaves differently upon adsorption of each of these gases. In particular, a noticeable increase of mobility in the presence of CO2 reveals the weakening of guest host interactions TEMPO MOF induced by CO2, which was qualitatively supported by molecular dynamic calculations. The nitroxides can be embedded in MOFs postsynthetically, and their negligible amounts (<= 1 per 1000 cells) are required due to a high sensitivity of EPR Therefore, the proposed approach is sufficiently versatile and might fmd broad applications for various MOFs.

Cite: Sheveleva A.M. , Anikeenko A.V. , Poryvaev A.S. , Kuzmina D.L. , Shundrina I.K. , Kolokolov D.I. , Stepanov A.G. , Fedin M.V.
Probing Gas Adsorption in Metal-Organic Framework ZIF-8 by EPR of Embedded Nitroxides
Journal of Physical Chemistry C. 2017. V.121. N36. P.19880-19886. DOI: 10.1021/acs.jpcc.7b06884 WOS Scopus РИНЦ

Dates:

Published online:	Sep 5, 2017
Published print:	Sep 14, 2017

Identifiers:

Web of science	WOS:000411171800035
Scopus	2-s2.0-85029536713
Elibrary	31062685
OpenAlex	W2747747429

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