Topological Analysis and Structural Determination of 3D Covalent Organic Frameworks

3D covalent organic frameworks (3D COFs) constitute a new type of crystalline materials that consist of a range of porous structures with numerous applications in the fields of adsorption, separation, and catalysis. However, because of the complexity of the three-periodic net structure, it is desirable to develop a thorough structural comprehension, along with a means to precisely determine the actual structure. Indeed, such advancements would considerably contribute to the rational design and application of 3D COFs. In this review, the reported topologies of 3D COFs are introduced and categorized according to the configurations of their building blocks, and a comprehensive overview of diffraction-based structural determination methods is provided. The current challenges and future prospects for these materials will also be discussed. The structure of covalent organic frameworks can be seen as periodic nets. First, some basic concepts about periodic nets and topology are introduced, and then the topological rules of reported 3D COFs are analyzed and summarized. Furthermore, the structural determination methods of 3D COFs is described, and finally, some prospects toward the structural problem of 3D COFs are proposed. image