Engineering the interactions between metal-organic frameworks and modifying agents: Design, structures, and applications

Because of their high porosity and abundant binding sites, metal–organic frameworks (MOFs) can be modified by a variety of modifying agents to obtain composites. Typically, non-covalent interactions, coordination bonds, and covalent bonds are introduced to connect the MOF and the modifying agent without changing the topology and the crystallinity of the composite. For the modifying agent, macromolecules and organo-macrocycles are widely applied to modify the exterior and/or interior of the MOF to form composites with enhanced properties and functionalities. It was found that the MOF-composites exhibited advances in various applications, such as gas separation, catalysis, imaging, drug delivery, sensing, and membrane fabrication. Even, MOF-composites are gradually commercialized in capacitors, generators, electronic equipment, etc. In this review, engineering different interactions between MOFs and modifying agents to obtain composites with extended functionalities and enhanced performance has been the topic of discussion. More importantly, the "interaction-property-relationship" of specific interactions and their functionalities have been elucidated for guiding people in future research.