Encapsulating functional guests in metal–organic frameworks: from strategies to performances

Encapsulation of various guest molecules into metal-organic frameworks (MOFs) to form host-guest composites has attracted increasing attention across diverse research fields. The encapsulated guest molecules achieve distinctive photophysical and photochemical properties through the confinement of the MOF caging effect. Using this concept as a starting point, this review provides a short but comprehensive account of this system. We first summarize the synthesis methods and design guidelines for Guest@MOF systems, where the main types of guests include organic fluorescent molecules, perovskites, metal nanoclusters, quantum dots, biomacromolecules and ionic liquids. In this section, we not only take into account traditional synthesis methods, but also innovatively incorporate new perspectives on data-driven design. Subsequent chapters systematically review recent local-scale characterization techniques for identifying guest locations and clarifying the underlying host-guest interactions. Following the introduction of the characterization methods in the previous section, the review finally focuses on the property changes of composites. By demonstrating in depth the performance gains brought by encapsulation, a coherent framework for understanding Guest@MOF systems is presented. We expect that this review will provide useful guidance for future research in this field.