2004 Volume 77 Issue 4 Pages 673-679
The dynamics of deuterated p-nitroaniline (pNA-d) molecules in zeolite ZSM-5 including Na+ (NaZSM-5) were investigated by means of 2H and 13C solid-state NMR to clarify the effects of Na+ and hydrated Na+. The adsorbed amount of pNA-d was four molecules per unit cell of NaZSM-5. 2H NMR spectra of a dehydrated sample indicated that the motion of pNA-d in the micropore is a 180°flip-flop around the C2 axis of the molecule. Another species with a faster flip-flop motion was distinguishable and assigned to pNA-d on the outer surface. When the sample adsorbed water molecules, 2H spectra showed that the flip-flop motion of pNA-d was largely suppressed in the micropore and that pNA-d on the outer surface underwent an isotropic motion. These results indicated that the dynamics of pNA-d in NaZSM-5 depended on the interactions with Na+ and hydrated Na+ as well as on the location.
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