Cyclodextrin inclusion complex is a special type of molecular complex composed of cyclodextrin monomer (host molecule) and inclusion molecule (guest molecule). The holes or holes formed by cyclodextrin molecule contain or insert guest molecule to form a capsule-like structure, so it is also called "molecular capsule". The guest molecule is dispersed into the host through a certain inclusion method. The host-guest molecule complexes are formed by the van der Waals force and the so-called Allinger configuration energy association between the host and guest molecule. The formation process of inclusion complex is a physical process without the formation or breaking of chemical bonds. The size and shape of cyclodextrin remain unchanged during this process.
Common methods of preparing inclusion compounds are saturated solution, grinding, freeze-drying, spray drying, liquid-liquid or gas-liquid, solid phase packing. Because the preparation process of cyclodextrin inclusion complex is usually not complex, some drawbacks of many guest molecules can be changed by the change of molecular micro-environment. At present, cyclodextrin inclusion complex has been widely used in medicine, food, cosmetics, pesticides and environmental protection.