Single-molecule imaging is challenging but highly beneficial for investigating intermolecular interactions at the molecular level^1,2,3,4,5,6. Van der Waals interactions at the sub-nanometre scale strongly influence various molecular behaviours under confinement conditions^7,8,9,10,11. Inspired by the traditional compass¹², here we use a para-xylene molecule as a rotating pointer to detect the host–guest van der Waals interactions in the straight channel of the MFI-type zeolite framework. We use integrated differential phase contrast scanning transmission electron microscopy^13,14,15 to achieve real-space imaging of a single para-xylene molecule in each channel. A good correlation between the orientation of the single-molecule pointer and the atomic structure of the channel is established by combining the results of calculations and imaging studies. The orientations of para-xylene help us to identify changes in the van der Waals interactions, which are related to the channel geometry in both spatial and temporal dimensions. This work not only provides a visible and sensitive means to investigate host–guest van der Waals interactions in porous materials at the molecular level, but also encourages the further study of other single-molecule behaviours using electron microscopy techniques.

单分子成像具有挑战性，但对于研究分子水平^1,2,3,4,5,6的分子间相互作用非常有益。亚纳米尺度的范德瓦尔斯相互作用强烈影响限制条件下的各种分子行为^7,8,9,10,11。受传统指南针¹²的启发，我们在这里使用对二甲苯分子作为旋转指针来检测 MFI 型沸石骨架直通道中的主客体范德华相互作用。我们使用集成的微分相衬扫描透射电子显微镜^13,14,15来实现单个对位的真实空间成像- 每个通道中的二甲苯分子。通过结合计算和成像研究的结果，建立了单分子指针的方向与通道原子结构之间的良好相关性。对二甲苯的方向帮助我们识别范德瓦尔斯相互作用的变化，这些变化与空间和时间维度上的通道几何形状有关。这项工作不仅提供了一种可见且灵敏的方法来在分子水平上研究多孔材料中的主客体范德瓦尔斯相互作用，而且还鼓励使用电子显微镜技术进一步研究其他单分子行为。