Functional Covalent Organic Frameworks: Design Principles to Potential Applications

Covalent organic frameworks (COFs) represent an emerging class of crystalline porous polymers synthesized by linking predesigned organic building units into targeted repetitive networks. The unique features of COFs stem from their modular synthesis, allowing for precise control over the chemical composition and functionalization on both the skeleton and the pore walls. Topologically, COFs are defined not by their chemical nature but by the symmetry and dimensions of the building units, resulting in 2D and 3D structures with distinct surface areas, pore architectures, and arrangements of functional moieties. The combination of predesigned organic units into geometries results in frameworks that can be precisely controlled and modified. This control is vital for applications requiring materials with specific pore sizes, surface areas, and functional group distributions. Particularly, COFs show great potential in the field of gas storage and separation, energy storage and conversion, catalysis, sensing, environmental remediation, and many more. Hence, an effective designed approach to incorporate various functional properties into the structures is pivotal to manipulate the functional properties and potential applications of COFs.