Term: host
https://doi.org/10.1351/goldbook.H02859

Definition:
A molecular entity that forms complexes with organic or inorganic guests, or a chemical species that can accommodate guests within cavities of its crystal structure. Examples include cryptands and crowns (where there are ion-dipole attractions between heteroatoms and positive ions), hydrogen-bonded molecules that form 'clathrates' (e.g. hydroquinone and water), and host molecules of inclusion compounds (e.g. urea or thiourea). van der Waals forces and hydrophobic interactions bind the guest to the host molecule in clathrates and inclusion compounds.

Related Terms:
1) molecular entity (http://doi.org/10.1351/goldbook.M03986).
2) complexes (http://doi.org/10.1351/goldbook.C01203).
3) cryptands (http://doi.org/10.1351/goldbook.C01426).
4) crowns (http://doi.org/10.1351/goldbook.C01421).
5) hydrogen-bonded (http://doi.org/10.1351/goldbook.H02899).
6) inclusion compounds (http://doi.org/10.1351/goldbook.I02998).
7) van der waals forces (http://doi.org/10.1351/goldbook.V06597).
8) hydrophobic interactions (http://doi.org/10.1351/goldbook.H02907).
9) clathrates (http://doi.org/10.1351/goldbook.C01097).
10) guest (http://doi.org/10.1351/goldbook.G02711).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1122 (https://doi.org/10.1351/pac199466051077)

Citation: 'host' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.H02859

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