Title: macrocyclic component
Long Title: IUPAC Gold Book - macrocyclic component
DOI: 10.1351/goldbook.13965
Status: current

Definition
Molecule that has at least one ring (cycle) large enough to allow it to be threaded onto a linear subchain of another molecule.

Notes
1) To thread a simple hydrocarbon chain such as a polyethylene chain, at least a 24-membered ring is needed.
2) In a macromolecular rotaxane, a macrocyclic component can be a discrete macrocyclic molecule or a macromolecule that includes one or more threadable ring(s). Examples and structure representations of both are shown: 
3) The literature on rotaxanes frequently cites the word "macrocycle" as a contraction of (and an abbreviation for) macrocyclic component. A use of the word "macrocycle" in rotaxane terminology is incompatible with the IUPAC definition of a macrocycle, which is "a cyclic macromolecule or a macromolecular cyclic portion of a macromolecule":  Such a macrocycle is virtually never used as a macrocyclic component in a rotaxane assembly. Therefore, since the term "macrocycle" is ambiguous, its use should be avoided in the macromolecular rotaxane literature.

Related Terms
- macromolecular rotaxane: https://goldbook.iupac.org//terms/view/13968
- threadable ring(s): https://goldbook.iupac.org//terms/view/13984
- threading component: https://goldbook.iupac.org//terms/view/13985

Source
- PAC, 2012, 84, 2135. 'Terminology and nomenclature for macromolecular rotaxanes and pseudorotaxanes (IUPAC Recommendations 2012)' on page 2137 (https://doi.org/10.1351/PAC-REC-11-10-15)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/13965/html
- json: https://goldbook.iupac.org/terms/view/13965/json
- xml: https://goldbook.iupac.org/terms/view/13965/xml

Citation: Citation: 'macrocyclic component' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.13965
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Accessed: 2026-05-09T16:48:39+00:00