Macrocycle-based metal-organic and covalent organic framework membranes

Membranes are a disruptive technology that can reduce the energy consumption of chemical separation processes. There are many remarkable materials that can be used for membrane building blocks; for example, covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) are emerging porous materials with uniform, tunable pores, ultrahigh surface areas, and accessible active sites. However, the aggregation of COF and MOF layers can affect the application properties of the material. Supramolecular macrocyclic hosts with welldefined cavities are easy to functionalize. In addition, it is beneficial to adjust the interpenetration effect, porosity, stability, and functionalities of MOF or COF materials, broadening their scope of applications. Therefore, macrocycle-based MOFs (M-MOFs) and COFs (M-COFs) are attractive candidates for building blocks for the construction of precise separation membranes and multifunctional membranes. This review focuses on the development and fabrication strategies of M-MOF and M-COF membranes and their emerging applications. The remaining challenges and proposals for M-MOF and M-COF membranes are also summarized. It is anticipated that this review will inspire further research in supramolecular chemistry and membrane separations.