Interlocked covalent organic cages: Design, synthesis, and self-assembly

Interlocked covalent organic cages have aesthetic skeletons endowed with structural and topological complexity. Their self-assembly provides a unique possibility to mimic the hierarchical self-assembly of biomacromolecules. In recent years, significant progresses in interlocked covalent organic cages have been witnessed. Different topological structures have been fabricated via various non-template induced methods, and diverse weak interactions are demonstrated to play critical roles in guiding the formation of interlocked structures. Therefore, this article systematically summarizes the recent advances in interlocked covalent organic cages, especially their design, synthesis, and self-assembly properties. Depending on different types of chemical reactions, irreversible and reversible reactions are separately introduced. In each section, proper monomer selection, critical topology design, key driving forces as well as detailed interlocked mechanisms for the formation of interlocked structures, and their self-assembly behaviors in single crystals are discussed detailedly. Finally, the challenge and future development of interlocked covalent organic cages are briefly prospected.