https://doi.org/10.1351/goldbook.C01426
A
molecular entity
comprising a cyclic or polycyclic assembly of
binding sites
that contains three or more binding sites held together by
covalent bonds
, and which defines a molecular cavity in such a way as to bind (and thus 'hide' in the cavity) another molecular entity, the
guest
(a
cation
, an
anion
or a neutral species), more strongly than do the separate parts of the assembly (at the same total concentration of binding sites). The
adduct
thus formed is called a 'cryptate'. The term is usually restricted to bicyclic or oligocyclic molecular entities. Example:
Corresponding monocyclic ligand assemblies
crowns
are sometimes included in this group, if they can be considered to define a cavity in which a
guest
can hide. The terms 'podand' and 'spherand' are used for certain specific ligand assemblies. Coplanar cyclic polydentate
ligands
, such as
porphyrins
, are not normally regarded as cryptands.
See also:
host (in biotechnology)
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]