Defibrillation of soft porous metal-organic frameworks with electric fields

Gas transport through metal-organic framework membranes (MOFs) was switched in situ by applying an external electric field (E-field). The switching of gas permeation upon E-field polarization could be explained by the structural transformation of the zeolitic imidazolate framework ZIF-8 into polymor...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2017-10, Vol.358 (6361), p.347-351
Main Authors: Knebel, A., Geppert, B., Volgmann, K., Kolokolov, D. I., Stepanov, A. G., Twiefel, J., Heitjans, P., Volkmer, D., Caro, J.
Format: Article
Language:English
Subjects:
Deformation
Deformation mechanisms
Deoxidizing
Deuterium
Electric fields
Gas mixtures
Gas permeation
Gas transport
Lattices
Membranes
Metal-organic frameworks
Metals
NMR
Nuclear magnetic resonance
Penetration
Polarization
Porosity
Spectroscopy
Stiffening
Switching
X-ray diffraction
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Summary:Gas transport through metal-organic framework membranes (MOFs) was switched in situ by applying an external electric field (E-field). The switching of gas permeation upon E-field polarization could be explained by the structural transformation of the zeolitic imidazolate framework ZIF-8 into polymorphs with more rigid lattices. Permeation measurements under a direct-current E-field poling of 500 volts per millimeter showed reversibly controlled switching of the ZIF-8 into polar polymorphs, which was confirmed by x-ray diffraction and ab initio calculations. The stiffening of the lattice causes a reduction in gas transport through the membrane and sharpens the molecular sieving capability. Dielectric spectroscopy, polarization, and deuterium nuclear magnetic resonance studies revealed low-frequency resonances of ZIF-8 that we attribute to lattice flexibility and linker movement. Upon E-field polarization, we observed a defibrillation of the different lattice motions.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aal2456