Translational and rotational mobility of methanol-d4 molecules in NaX and NaY zeolite cages: A deuteron NMR investigation

Recent Advances in Solid State NMR of Small Molecules in Confinement

“…Polar molecules such as methanol,38–39 water,40–46 tert ‐butyl alcohol,47 and isobutyric acid,48–49 exhibit strong interactions with silanol (SiOH) groups on the surface of porous materials, due to the formation of hydrogen bonding networks. Thus, they show very different phase behavior in confinement compared to molecules in the bulk phase.…”

“…Lalowicz and Stoch et al. 38–39 focused their works on the interaction of zeolite cages of the types NaX and NaY. These aluminosilicates had pore diameters of approximately 12 Å and were filled with deuterated methanol.…”

Small Molecules, Non-Covalent Interactions, and Confinement

“…Polar molecules such as water [ 36 , 40 , 197 , 198 , 199 , 200 , 201 , 202 ], alcohols like methanol [ 166 , 167 ], tert.-butyl alcohol [ 165 ] or octanol [ 203 , 204 ] and carboxylic acids, such as isobutyric acid [ 38 , 42 ], can form hydrogen bonds among themselves and also with the surface’s silanol groups (Si–OH).…”

“…An extensive recent overview about this fascinating class of materials is given in the recent special issue on zeolite chemistry Owing to their narrow pore diameters and importance as catalysts for organic chemistry, most confinement studies employing zeolites use small molecules [163,164]. Typical recent examples are the deuterium NMR studies by Nishchenko et al [165] and Lalowicz et al [166,167] who analyzed the dynamics of tert.-butyl alcohol-d 9 and methanol-d 4 inside zeolites, respectively. Moreover, NMR field-gradient approaches yielded valuable insights into the diffusion of various small molecules in zeolites, including information about diffusion anisotropy, transport resistance at crystal surfaces, and pore connectivities [168][169][170][171][172][173][174].…”

Recent developments in solid-state NMR spectroscopy of crystalline microporous materials

“…From 2 H relaxation measurements there was also evidence for the formation of small clusters (usually trimers) of methanol within the pores. 106 More recent work has involved the study of MOFs, including a study by Ueda et al of deuterated cyclohexane confined in IRMOF-1, which found a number of different motional regimes as a function of temperature, 107 and work by Wright and co-workers on deuterated benzene incorporated into MOF-5 (IRMOF-1), where the incorporated molecules exhibit rotation around their C 6 axis at lower temperature, but isotropic motion as the temperature increases. 84 Motion of guests within the framework can also be detected indirectly, i.e., by the effect this causes upon the framework.…”