Komori Yoshihiko, Hayashi Shigenobu
Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
J Phys Chem B. 2006 Jan 12;110(1):90-6. doi: 10.1021/jp055130e.
Dynamics of deuterated p-nitroaniline (pNA-d) molecules in the micropores of AlPO4-5 has been investigated by means of solid-state NMR. The adsorbed amounts of pNA-d were 5.0 and 10.1 mass % of the total mass. We have measured 13C magic-angle-spinning (MAS) and 2H NMR spectra of the guest molecules and 31P and 27Al MAS NMR spectra of the host framework. The pNA-d molecules distribute rather inhomogeneously in the channel, and do not coordinate to Al strongly like H2O. The intermolecular hydrogen bonds are formed between a part of the guest molecules only when the loading level is high. The 2H NMR spectra are successfully analyzed, elucidating the orientation and the motion of the guest molecules. The molecular axis of pNA-d is inclined to the channel axis, and the molecular plane is perpendicular to the inner wall. The guest molecule jumps among 12 sites or 12 orientations. This motion is faster in the sample of 5.0 mass % than in the sample of 10.1 mass %, suggesting that the guest-guest interaction hinders the motion. The mean residence times of the molecules are estimated from the analysis of the 2H NMR spectra, which are affected by the size of the nanospace as well as the property of the adsorbed site.
通过固态核磁共振研究了氘代对硝基苯胺（pNA-d）分子在磷酸铝分子筛AlPO4-5微孔中的动力学。pNA-d的吸附量为总质量的5.0%和10.1%。我们测量了客体分子的13C魔角旋转（MAS）和2H核磁共振谱以及主体骨架的31P和27Al MAS核磁共振谱。pNA-d分子在通道中的分布相当不均匀，不像H2O那样与Al强烈配位。仅当负载水平较高时，部分客体分子之间才会形成分子间氢键。成功分析了2H核磁共振谱，阐明了客体分子的取向和运动。pNA-d的分子轴相对于通道轴倾斜，分子平面垂直于内壁。客体分子在12个位置或12种取向上跳跃。这种运动在5.0质量%的样品中比在10.1质量%的样品中更快，这表明客体-客体相互作用阻碍了运动。通过对2H核磁共振谱的分析估计了分子的平均停留时间，其受纳米空间大小以及吸附位点性质的影响。
