10.1021/ja403453g.s002
Linjiang Chen
Linjiang
Chen
John P.
S. Mowat
John P.
S.
Mowat
David Fairen-Jimenez
David
Fairen-Jimenez
Carole A. Morrison
Carole A.
Morrison
Stephen P. Thompson
Stephen P.
Thompson
Paul A. Wright
Paul A.
Wright
Tina Düren
Tina
Düren
Elucidating the Breathing of the Metal–Organic
Framework MIL-53(Sc) with ab Initio Molecular Dynamics Simulations
and in Situ X‑ray Powder Diffraction Experiments
American Chemical Society
2016
MIL
ab Initio Molecular Dynamics Simulations
framework
method
AIMD simulations
CO 2 pressure
CO 2 loadings
CO 2 adsorption
phase
response
MOF
2016-02-18 13:58:52
Dataset
https://acs.figshare.com/articles/dataset/Elucidating_the_Breathing_of_the_Metal_Organic_Framework_MIL_53_Sc_with_ab_Initio_Molecular_Dynamics_Simulations_and_in_Situ_X_ray_Powder_Diffraction_Experiments/2363440
Ab initio molecular dynamics (AIMD)
simulations have been used
to predict structural transitions of the breathing metal–organic
framework (MOF) MIL-53(Sc) in response to changes in temperature over
the range 100–623 K and adsorption of CO<sub>2</sub> at 0–0.9
bar at 196 K. The method has for the first time been shown to predict
successfully both temperature-dependent structural changes and the
structural response to variable sorbate uptake of a flexible MOF.
AIMD employing dispersion-corrected density functional theory accurately
simulated the experimentally observed closure of MIL-53(Sc) upon solvent
removal and the transition of the empty MOF from the <i>closed-pore</i> phase to the <i>very-narrow-pore</i> phase (symmetry change
from <i>P</i>2<sub>1</sub>/<i>c</i> to <i>C</i>2/<i>c</i>) with increasing temperature, indicating
that it can directly take into account entropic as well as enthalpic
effects. We also used AIMD simulations to mimic the CO<sub>2</sub> adsorption of MIL-53(Sc) in silico by allowing the MIL-53(Sc) framework
to evolve freely in response to CO<sub>2</sub> loadings corresponding
to the two steps in the experimental adsorption isotherm. The resulting
structures enabled the structure determination of the two CO<sub>2</sub>-containing <i>intermediate</i> and <i>large-pore</i> phases observed by experimental synchrotron X-ray diffraction studies
with increasing CO<sub>2</sub> pressure; this would not have been
possible for the <i>intermediate</i> structure via conventional
methods because of diffraction peak broadening. Furthermore, the strong
and anisotropic peak broadening observed for the <i>intermediate</i> structure could be explained in terms of fluctuations of the framework
predicted by the AIMD simulations. Fundamental insights from the molecular-level
interactions further revealed the origin of the breathing of MIL-53(Sc)
upon temperature variation and CO<sub>2</sub> adsorption. These simulations
illustrate the power of the AIMD method for the prediction and understanding
of the behavior of flexible microporous solids.