Structural design and determination of 3D covalent organic frameworks

3D covalent organic frameworks (COFs) represent a unique class of crystalline porous materials that allow the precise integration of organic molecular building blocks into 3D networks through the formation of covalent bonds. Considering their numerous open sites and hierarchical pore structures, 3D COFs have shown interesting potential in many areas, especially gas adsorption and catalysis. However, the chemistry of 3D COFs has been restrained largely due to their limited structural diversity and complicated structural determination. In this review, we summarize the key strategies and techniques used to diversify and determine the structure of 3D COFs. Finally, the remaining challenges and prospects concerning the structural design and determination of 3D COFs are presented.