Atomic Real-Space Imaging of Molecular Statics and Dynamics at Confined States

Atomic imaging of molecules and intermolecular interactions is important for obtaining a deeper understanding of the related physics and chemistry. At a confined state in reticular matrix, molecular architecture can be stabilized for studying its static and dynamic behaviors, which is a milestone for molecular science but is still challenging in real space. Here, we use the coordination interactions between reticular building units of UiO-66 framework to maintain small molecules in a quasistatic structure. Low-dose electron microscopy is applied to resolving the atomic structures of these confined-state molecules. Meanwhile, the UiO-66 framework allows us modifying metal node structures for a controlled molecular manipulation by stretching and compressing. Then, the molecular statics and dynamics during stretching and compressing can be unraveled by directly measuring projected atomic positions, bond lengths, and peak widths via intensity profile analysis. These results perfectly support the predictions from our first-principles calculations, indicating the elastic deformation of coordination bonds and the varied vibration of C_{6} rings. This Letter not only represents an efficient strategy for atomically controlling and imaging the molecular statics and dynamics in reticular chemistry, but also opens up a new pathway for studying other molecular behaviors and interactions at confined states from new perspectives of atoms and bonds.