We trace the evolution of crystal interface during the solvothermal synthesis of metal-organic frameworks (MOFs) in flow cell by in situ dark-field microscope. Precise measurement of the growth rate at specific crystal facets allows for the extraction of the key determining factors for the crystal growth of five typical MOFs, i.e., Cu-MOF-74 (1D), Co-ZIF, Cu-MOF-2-BDC, Cu-MOF-2-NDC (2D), and HKUST-1 (3D). Rather than strongly correlating to the corresponding chemical formulas, the compositional organic linker and metal ion play vital but separate roles for different MOFs, giving insight into the crystal growth mechanism. Moreover, upon interruption, retreat and recovery of the crystal interface are observed, unveiling the influence from interface to MOF crystal growth. This also leads to the discovery of a transition layer that mediates the linkage of molecular building blocks to form MOF single crystals at the interface.

我们通过原位追踪流动池中金属有机框架（MOF）的溶剂热合成过程中晶体界面的演变暗视野显微镜。精确测量特定晶面的生长速率允许提取五种典型 MOF 晶体生长的关键决定因素，即 Cu-MOF-74 (1D)、Co-ZIF、Cu-MOF-2-BDC 、Cu-MOF-2-NDC (2D) 和 HKUST-1 (3D)。组成有机连接剂和金属离子不是与相应的化学式密切相关，而是对不同的 MOF 起到重要但不同的作用，从而深入了解晶体生长机制。此外，观察到晶体界面的中断、后退和恢复，揭示了界面对 MOF 晶体生长的影响。这也导致发现了一种过渡层，该过渡层介导分子结构单元的连接以在界面处形成 MOF 单晶。