Inter-cage dynamics in structure I, II, and H fluoromethane hydrates as studied by NMR and molecular dynamics simulations

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DOIResolve DOI: http://doi.org/10.1063/1.4874636
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TypeArticle
Journal titleJournal of Chemical Physics
ISSN0021-9606
Volume140
Issue21
Article number214703
SubjectDefects; Hydration; Hydrogen bonds; Industrial applications; Molecular dynamics; Molecules; Nuclear magnetic resonance spectroscopy; Clathrate hydrate; Gas separations; Guest-host interactions; Hydrogen-bond formation; Molecular dynamics simulations; NMR chemical shifts; Temperature analysis; Temperature conditions; Gas hydrates
AbstractProspective industrial applications of clathrate hydrates as materials for gas separation require further knowledge of cavity distortion, cavity selectivity, and defects induction by guest-host interactions. The results presented in this contribution show that under certain temperature conditions the guest combination of CH3F and a large polar molecule induces defects on the clathrate hydrate framework that allow intercage guest dynamics. 13C NMR chemical shifts of a CH3F/CH4/TBME sH hydrate and a temperature analysis of the 2H NMR powder lineshapes of a CD3F/THF sII and CD3F/TBME sH hydrate, displayed evidence that the populations of CH4 and CH3F in the D and D′ cages were in a state of rapid exchange. A hydrogen bonding analysis using molecular dynamics simulations on the TBME/CH3F and TBME/CH4 sH hydrates showed that the presence of CH3F enhances the hydrogen bonding probability of the TBME molecule with the water molecules of the cavity. Similar results were obtained for THF/CH3F and THF/CH4 sII hydrates. The enhanced hydrogen bond formation leads to the formation of defects in the water hydrogen bonding lattice and this can enhance the migration of CH3F molecules between adjacent small cages. © 2014 AIP Publishing LLC.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Steacie Institute for Molecular Sciences (SIMS-ISSM)
Peer reviewedYes
NPARC number21272190
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Record identifiera690e2b4-888e-40c2-a04f-ac9b024d4473
Record created2014-07-23
Record modified2017-03-23
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