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http://dx.doi.org/10.18419/opus-14590
Autor(en): | Grunenberg, Lars Keßler, Christopher Teh, Tiong Wei Schuldt, Robin Heck, Fabian Kästner, Johannes Groß, Joachim Hansen, Niels Lotsch, Bettina V. |
Titel: | Probing self-diffusion of guest molecules in a covalent organic framework : simulation and experiment |
Erscheinungsdatum: | 2024 |
Dokumentart: | Zeitschriftenartikel |
Seiten: | 16091-16100 |
Erschienen in: | ACS nano 18 (2024), S. 16091-16100 |
URI: | http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-ds-146096 http://elib.uni-stuttgart.de/handle/11682/14609 http://dx.doi.org/10.18419/opus-14590 |
ISSN: | 1936-086X 1936-0851 |
Zusammenfassung: | Covalent organic frameworks (COFs) are a class of porous materials whose sorption properties have so far been studied primarily by physisorption. Quantifying the self-diffusion of guest molecules inside their nanometer-sized pores allows for a better understanding of confinement effects or transport limitations and is thus essential for various applications ranging from molecular separation to catalysis. Using a combination of pulsed field gradient nuclear magnetic resonance measurements and molecular dynamics simulations, we have studied the self-diffusion of acetonitrile and chloroform in the 1D pore channels of two imine-linked COFs (PI-3-COF) with different levels of crystallinity and porosity. The higher crystallinity and porosity sample exhibited anisotropic diffusion for MeCN parallel to the pore direction, with a diffusion coefficient of Dpar = 6.1(3) × 10-10 m2 s-1 at 300 K, indicating 1D transport and a 7.4-fold reduction in self-diffusion compared to the bulk liquid. This finding aligns with molecular dynamics simulations predicting 5.4-fold reduction, assuming an offset-stacked COF layer arrangement. In the low-porosity sample, more frequent diffusion barriers result in isotropic, yet significantly reduced diffusivities (DB = 1.4(1) × 10-11 m2 s-1). Diffusion coefficients for chloroform at 300 K in the pores of the high- (Dpar = 1.1(2) × 10-10 m2 s-1) and low-porosity (DB = 4.5(1) × 10-12 m2 s-1) samples reproduce these trends. Our multimodal study thus highlights the significant influence of real structure effects such as stacking faults and grain boundaries on the long-range diffusivity of molecular guest species while suggesting efficient intracrystalline transport at short diffusion times. |
Enthalten in den Sammlungen: | 04 Fakultät Energie-, Verfahrens- und Biotechnik |
Dateien zu dieser Ressource:
Datei | Beschreibung | Größe | Format | |
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nn3c12167.pdf | 3,33 MB | Adobe PDF | Öffnen/Anzeigen |
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