Inclusion Compound
Definition and meaning of Inclusion Compound in chemistry.
An inclusion compound is a chemical complex in which a host structure with a cavity or channel physically traps a guest molecule inside itself, without forming a covalent bond between host and guest.
In more detail
The guest is held in place by noncovalent forces such as van der Waals attractions, hydrogen bonding, and simple shape fit, so the host lattice or macrocycle must be sized and shaped to match the guest. This selectivity makes inclusion compounds useful for separating similarly sized molecules, protecting unstable or volatile compounds from oxidation and evaporation, and controlling the release of drugs or fragrances over time. A related but more specific term is clathrate, used when the guest is fully enclosed within a closed cage of host molecules.
Key facts
| Bonding type | Noncovalent (van der Waals, hydrogen bonding, shape fit) |
|---|---|
| Common hosts | Cyclodextrins, zeolites, urea, water cages |
| Related term | Clathrate (guest fully enclosed in a cage) |
| Field | General Chemistry |
Beta-cyclodextrin, a ring-shaped sugar molecule with a hydrophobic interior, encloses a vitamin or flavor molecule inside its cavity to form a stable inclusion complex that shields the guest from air and light.
Frequently asked questions
How does an inclusion compound differ from a solution?
In an inclusion compound the guest occupies a specific, shaped cavity within the host structure, while in a solution the solute is dispersed randomly among solvent molecules with no defined binding site.
Is every inclusion compound a clathrate?
No. Clathrate describes the specific case where the guest is completely caged by the host lattice, such as methane trapped inside a water-cage clathrate hydrate; many inclusion compounds instead hold the guest in an open channel or partly exposed cavity.