When using metal–organic frameworks (MOFs) as electric field-dependent sensor devices, understanding their dielectric response is crucial as the orientation of polar groups is largely affected by confinement. To shed light on this at the molecular level, the response to a static field was computationally investigated for two structurally related MOFs, depending on their loading with guest molecules. The pillared-layer MOFs differ in their pillar moiety, with one bearing a rotatable permanent dipole moment and the other being non-polar. Two guest molecules with and without polarity, namely, methanol and methane, were considered. A comprehensive picture of the response of the guest molecules could be achieved with respect to both the amount and polarity of the confined species. For both MOFs, the dielectric response is very sensitive to the introduction of methanol, showing an anisotropic and non-linear increase in the system’s relative permittivity expressed by a strongly increasing polarization response to external electric fields scaling with the number of confined methanol molecules. As expected, the effect of methane in the non-dipolar MOF is negligible, whereas subtle differences can be observed for the dipolar response of the MOF with rotatable dipolar linker groups. Taking advantage of these anisotropic and guest-molecule-specific confinement effects may open pathways for future sensing applications. Finally, methanol-induced global framework dynamics were observed in both MOFs.
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14 May 2024
Research Article|
May 13 2024
Dielectric response of metal–organic frameworks as a function of confined guest species investigated by molecular dynamics simulations
Special Collection:
Porous Solids for Energy Applications
Babak Farhadi Jahromi
;
Babak Farhadi Jahromi
(Conceptualization, Methodology, Writing – original draft, Writing – review & editing)
Computational Materials Chemistry Group, Lehrstuhl für Anorganische Chemie 2, Ruhr-Universität Bochum
, Bochum, Germany
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Rochus Schmid
Rochus Schmid
a)
(Conceptualization, Funding acquisition, Methodology, Supervision, Writing – original draft, Writing – review & editing)
Computational Materials Chemistry Group, Lehrstuhl für Anorganische Chemie 2, Ruhr-Universität Bochum
, Bochum, Germany
a)Author to whom correspondence should be addressed: rochus.schmid@rub.de
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a)Author to whom correspondence should be addressed: rochus.schmid@rub.de
J. Chem. Phys. 160, 184119 (2024)
Article history
Received:
February 16 2024
Accepted:
April 25 2024
Citation
Babak Farhadi Jahromi, Rochus Schmid; Dielectric response of metal–organic frameworks as a function of confined guest species investigated by molecular dynamics simulations. J. Chem. Phys. 14 May 2024; 160 (18): 184119. https://doi.org/10.1063/5.0203820
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