Design and synthesis of metal–organic cycles/cages (MOCs) and their applications

Metal–organic cycles/cages (MOCs) are a class of nanoscale molecular entities that possess distinct shapes and sizes and are designed and synthesized through the predictable integration of organic and inorganic ligands. The diverse functionalities of MOCs render them valuable in the fields of biology, chemistry, and materials. First, the cavity renders them suitable for host–guest interactions, which are subsequently employed to induce conformational changes, and this approach is particularly advantageous for catalysis, sensing, and controlled loading and release. Furthermore, MOC- and polymer-based aggregates can be applied in biomedical research and cascaded light-harvesting systems. Benefiting from the high specific surface area, the initial exploration of MOC-based hierarchical assemblies indicates their potential applications in biomedicine and catalysis. MOC-based microsheets and centimeter films can be used for dual-mode catalysis and novel wound dressing for nonhealing wounds. In addition, the design and synthesis of novel MOCs with different shapes and sizes through various strategies are discussed. We summarized the latest progress in the past 5 years in this Review.