Dynamics in nanoporous materials probed by2H solid state NMR: estimation of self-diffusion coefficients

H-2 solid-state NMR represents a reliable method for probing the dynamics of the molecules in confined geometries, including microporous and mesoporous materials such as zeolites or metal-organic frameworks (MOFs). Dynamic characteristics derived from analyses of(2)H NMR line shape and spin relaxation for adsorbed deuterated molecules can be related with translational motions along the porous framework. This opens up the possibility to use(2)H NMR for probing self-diffusion within porous materials. Herein we discuss the basic principles and approaches that can be used to derive the information on diffusion coefficients based on analysis of the dynamics of confined molecules by(2)H NMR. We discuss the corresponding possibilities and limitations of(2)H NMR compared to other experimental methods, such QENS and PFG NMR. Several examples for estimation of diffusion coefficients by(2)H NMR for alkanes, olefins, alcohol, benzene, pyridine in zeolites and MOFs are provided.

Automated summary

H-2 solid-state NMR is a reliable method for probing the dynamics and self-diffusion of molecules in porous materials like zeolites and metal-organic frameworks. It can provide valuable information on diffusion coefficients of different molecules within confined geometries. Comparisons with other experimental methods such as QENS and PFG NMR reveal both possibilities and limitations of H-2 NMR.