As a kind of three-dimensional molecule with permanent cavity, organic molecular cages (OMCs) have gained intensive attention of the researchers in recent years, mainly due to their significant role in supramolecular chemistry as host molecules. Firstly, most of OMCs were synthesized via irreversible bond formation. However, the irreversible nature of these reactions usually caused serious problems, such as quite complex purification process and low overall yields. As an alternative approach, dynamic covalent chemistry has shown its power in the construction of OMCs from simple precursors with high yields. In recent years, by using various dynamic covalent reactions, a series of OMCs have been successfully synthesized in large scale, which facilitates their interesting applications. It is found that OMCs can not only show great potential applications in the fields of molecular recognition and molecular flask, but also form crystalline porous materials through self-assembly, which have shown interesting applications in gas absorption and separation. In this review, we will summarize the research progress of OMCs, highlight the synthesis of these OMCs by using various dynamic covalent reactions and also discuss their interesting applications in different areas. Perspectives of OMCs are also mentioned, regarding to their remaining challenging issues.

Contents
1 Introduction
2 Synthesis of organic molecular cages
2.1 Boronic acid condensation
2.2 Imine condensation reaction
2.3 Alkyne/alkene metathesis
2.4 Other dynamic covalent reactions
3 Applications of organic molecular cages
3.1 Molecular recognition
3.2 Molecular flask
3.3 Porous materials
4 Conclusion and outlook