NMR relaxation and diffusion studies of methane and carbon dioxide in nanoporous ZIF-8 and ZSM-58

Intermolecular Force Field Parameters Optimization for Computer Simulations of CH4in ZIF-8

“…Since the CH 4 molecules are more close to the imidazolate ligands which are flexible, the movements of CH 4 molecules are additionally induced by the ligands, and locating around the cage windows increases the chance of cage-to-cage migration. By the way, these obtained values agree well with some experimental values that are in a range in the order between 10 −11 and 10 −9 m 2 /s [2,8,[20][21][22]. More comparative works between experiments and simulations are required for more discussions.…”

Combined Nuclear Magnetic Resonance and Molecular Dynamics Study of Methane Adsorption in M2(dobdc) Metal–Organic Frameworks

“…47 Previous work has also demonstrated that R 1 decreases linearly with increasing adsorbed-phase density of CH 4 in ZIF-8, a MOF with no coordinatively unsaturated metal sites. 26 It was proposed that the spin-rotation mechanism is influenced by interactions with the framework, and a surface relaxivity term, ρ s , was introduced to describe the slope of the observed spin-lattice relaxation rates with increasing adsorbed phase density in the frameworks. Thus, the relative difference in ρ s for similar MOF archetypes is proportional to the strength of interaction between the frameworks and the adsorbed gases.…”

Solid-State NMR Investigations of Carbon Dioxide Gas in Metal–Organic Frameworks: Insights into Molecular Motion and Adsorptive Behavior

“…In the case of adsorbed gases, there is an intermediate-to-high density regime, where the strength of the interaction with the surface is associated with the slope of the relaxation rate versus gaseous density. 39 The relaxation mechanism associated with adsorbed CO 2 is more commonly described in the context of adsorbed liquids. Here, reorientation mediated by translational displacements occurs when interactions with the surface of the pore result in hindered or incomplete reorientations about a preferential axis such as the PAS of the molecule or the surface.…”

“…Relaxation rates for CO 2 in ZIF-8 systems 74 determined the effect of loading or gas density (ρ) on the longitudinal relaxation rate (R 1 ) through quantification of the "surface relaxivity" of CO 2 in ZIF-8. Although methane in this system exhibited a linear dependence of R 1 on the density of the Figure 9.…”

“…This correction has only been found to be valid for R 1 correlated with low-to-moderate densities of CO 2 where intermolecular collisions are still dominating the reorientation rates of the molecules. The surface relaxivity arising from loading-dependent measurements 74 may be used to quantify the adsorbate−adsorbent interaction of gases in MOFs. In a follow-up article, these same authors used R 1 measurements to determine the local jump dynamics of CO 2 in Cu 3 (BTC) 3 .…”