日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Behavior of molecules confined in a nanospace is much different from that of the bulk state, and affects the function of porous materials. This article presents our solid-state NMR research results on dynamics of molecules confined in a nanospace of porous materials. Solidstate NMR is a microscopic technique at atomic and molecular levels, and is very useful to study local structures and dynamics. It can cover a wide dynamic rage from subnanoseconds to seconds, and can give us information unavailable by other techniques. The melting point lowers when liquid is introduced in mesopores. By utilizing this phenomenon, NMR observation of the unfrozen water and benzene in FSM-16 gave us pore size distribution and properties of the inner surface. We studied dynamics of p-nitroaniline molecules confined in ZSM-5, AlPO₄-5 and FSM-16, which have different pore sizes with each other, and determined the motional mode and rate. The motions of the guest molecules are affected by the pore size, the properties of the inner surface, extra-framework cations and coexisting molecules. We studied dynamics of basic molecules such as acetonitrile in AlPO₄-5, and determined the motional mode and rate. This study suggested the presence of the adsorbed sites for acetonitrile molecules on the inner-surface of AlPO₄-5. In summary, detailed information on dynamics of molecules confined in a nanospace of porous materials have been obtained by applying solid-state NMR techniques.