Single-crystalline covalent organic frameworks

Covalent organic frameworks (COFs) are a useful class of crystalline porous materials assembled from organic molecular precursors via covalent bonds. Single-crystalline COFs have gained increasing attention because of their unique advantages, such as well-defined structures and improved performance, compared with their polycrystalline counterparts. However, the development of such materials has been severely hampered due to the lack of general synthetic strategies and effective characterization methods. This review surveys recent advances in the preparation of single-crystalline COFs, provides a perspective on the current challenges, and proposes future directions for the exploration of this promising class of crystalline polymers.