The application of continuous-flow hyperpolarized 129Xe NMR spectroscopy to investigate the pores of three shape-persistent organic macrocycles is described. Peaks with xenon chemical shifts between 160 and 200 ppm are assigned to xenon atoms trapped in highly confined pores while NMR peaks with chemical shifts of 100 to 140 ppm are assigned to xenon present in channels that exist through the centre of the stacked macrocycles. With the aid of molecular dynamics simulations, connections between the 129Xe NMR spectra and the X-ray diffraction structure of one of the solvated macrocycles, 1, have been made. The similarities in the 129Xe NMR spectra of the three compounds containing hyperpolarized xenon suggest that all three hosts possess comparable pore structures. The 129Xe NMR data provide information about the porous nature of the two compounds for which X-ray crystallographic analysis was not possible. Data obtained from two-dimensional 129Xe NMR exchange spectroscopy experiments, variable-temperature 129Xe NMR and molecular dynamics simulations suggest a mechanism whereby the xenon gains access to the highly confined sites via the channels.
描述了应用连续流超极化 129Xe NMR 光谱研究三种形状持久有机大环的孔。
氙化学位移在 160 至 200 ppm 之间的峰被指定为被捕获在高度受限的孔中的
氙原子,而
化学位移为 100 至 140 ppm 的 NMR 峰被指定为存在于通过堆叠大环中心存在的通道中的
氙。借助分子动力学模拟,129Xe NMR 谱与其中一种溶剂化大环化合物 1 的 X 射线衍射结构之间建立了联系。三种含有超极化
氙的化合物的 129Xe NMR 谱的相似性表明所有三种主体都具有相当的孔结构。 129Xe NMR 数据提供了有关无法进行 X 射线晶体学分析的两种化合物的多孔性质的信息。从二维 129Xe NMR 交换光谱实验、变温 129Xe NMR 和分子动力学模拟获得的数据表明,
氙可以通过通道进入高度受限的位点。