cryptand

Also contains definition of: cryptate
https://doi.org/10.1351/goldbook.C01426
A @M03986@ comprising a cyclic or polycyclic assembly of @B00649@ that contains three or more binding sites held together by @C01384@, and which defines a molecular cavity in such a way as to bind (and thus 'hide' in the cavity) another molecular entity, the @G02711@ (a @C00907@, an @A00358@ or a neutral species), more strongly than do the separate parts of the assembly (at the same total concentration of binding sites). The @A00138@ thus formed is called a 'cryptate'. The term is usually restricted to bicyclic or oligocyclic molecular entities. Example:
C01426.png
Corresponding monocyclic ligand assemblies @C01421@ are sometimes included in this group, if they can be considered to define a cavity in which a @G02711@ can hide. The terms 'podand' and 'spherand' are used for certain specific ligand assemblies. Coplanar cyclic polydentate @L03518@, such as @P04765@, are not normally regarded as cryptands.
See also:
host
Sources:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1102 [Terms] [Paper]
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1329 [Terms] [Paper]