Rotational and Translational Motion of Benzene in ZIF-8 Studied by H-2 NMR: Estimation of Microscopic Self-Diffusivity and Its Comparison with Macroscopic Measurements | Sciact - CRIS-system of Boreskov Institute of Catalysis

Rotational and Translational Motion of Benzene in ZIF-8 Studied by H-2 NMR: Estimation of Microscopic Self-Diffusivity and Its Comparison with Macroscopic Measurements Full article

Journal

The Journal of Physical Chemistry C
ISSN: 1932-7447 , E-ISSN: 1932-7455

Output data

Year: 2014, Volume: 118, Number: 24, Pages: 12873-12879 Pages count : 7 DOI: 10.1021/jp5026834

Tags

Crystalline materials; Diffusion in liquids; Microporous materials; Molecular dynamics

Authors

Kolokolov Daniil I. ^1,2 , Diestel Lisa ³ , Caro Juergen ³ , Freude Dieter ⁴ , Stepanov Alexander G. ^1,2

Affiliations

1	Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
2	Faculty of Natural Sciences, Department of Physical Chemistry, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
3	Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstrasse 3A, 30167 Hannover, Germany
4	Universitat Leipzig, Fakultat fur Physik und Geowissenschaften, Linnestrasse 5, 04103 Leipzig, Germany

Funding (2)

1	Russian Foundation for Basic Research	14-03-91333
2	German Research Foundation	1362

In relation to unique properties of metal–organic framework (MOF) ZIF-8 to adsorb and separate hydrocarbons with kinetic diameters notably larger than the entrance windows of the porous system of this microporous material, the molecular dynamics of benzene adsorbed on ZIF-8 has been characterized and quantified with 2H nuclear magnetic resonance. We have established that within the ZIF-8 cage the benzene molecule undergoes fast rotations, hovering in the symmetric potential of the spherical cage and relatively slow isotropic reorientations by collisions with the walls. Benzene performs also translational jump diffusion between neighboring cages characterized by an activation barrier ED = 38 kJ mol–1 and a pre-exponential factor τD0 = 4 × 10–10 s. This microscopic measurement of benzene mobility allows us to estimate the self-diffusion coefficient for benzene in ZIF-8 (D0self ≈ 4 × 10–16 m2 s–1 at T = 323 K). Macroscopic measurements of diffusivities derived from membrane permeation studies (3.5 × 10–15 m2 s–1 at T = 298 K for fractional occupancy Θ ≈ 0.99) and sorption uptake (Di,MS ≈ 10–20 m2 s–1 at 323 K) are several orders of magnitude larger or smaller than the microscopic self-diffusion coefficient D0self, which was derived from relaxation time analysis. This experimental finding is attributed to the limits of macroscopic measurements.

Kolokolov D.I. , Diestel L. , Caro J. , Freude D. , Stepanov A.G.
Rotational and Translational Motion of Benzene in ZIF-8 Studied by H-2 NMR: Estimation of Microscopic Self-Diffusivity and Its Comparison with Macroscopic Measurements
The Journal of Physical Chemistry C. 2014. V.118. N24. P.12873-12879. DOI: 10.1021/jp5026834 WOS Scopus РИНЦ ANCAN OpenAlex

Submitted:	Mar 18, 2014
Accepted:	May 15, 2014
Published online:	Jun 11, 2014
Published print:	Jun 19, 2014

Web of science:	WOS:000337783900033
Scopus:	2-s2.0-84903184959
Elibrary:	24061605
Chemical Abstracts:	2014:880050
Chemical Abstracts (print):	161:77929
OpenAlex:	W2329225027

DB	Citing
Web of science	37
Scopus	37
Elibrary	37
OpenAlex	44