Mobility of the host framework and the guest molecules in nanoporous materials investigated by deuterium solid-state NMR and 1H MAS PFG NMR

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In the industrial application of nanoporous adsorbents in separation processes and in the chemical conversion by heterogeneous catalysis, the intracrystalline diffusivity is one of the key indicators for the efficiency of the process. Of particular importance is the diffusivity in mixtures, since separation and catalysis include a mass transport under the conditions of mixture adsorption. Metal-organic frameworks (MOFs) as compared with conventional zeolites exhibit a strong flexibility of the organic framework, which requires the study of the mobility of the framework in addition to the study of the mobility of the molecules and molecular groups. For exploring the molecular dynamics in mixtures, the 1H MAS PFG NMR diffusometry has proven to be suitable, as the preliminary investigations have shown in Leipzig. For the investigation of the dynamics of molecular groups and the flexibility of the organic framework the static solid-state 2H NMR spectroscopy of deuterated materials is particularly suitable and has been used very successfully in Novosibirsk on these systems. Therefore, in the proposed project, a merge of the know-how of both partners with the complementary methods is proposed, whereby the cooperation should enable the elucidation of the mechanisms of adsorption, diffusivity and separation of molecular mixtures taking into account the flexibility of the framework.