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A macrocycle is, as defined by IUPAC, "a cyclic macromolecule or a macromolecular cyclic portion of a molecule."[1] In the chemical literature, macrocycles varyingly include molecules containing rings of 8 or more atoms,[1][2] or 12 or more atoms.[2][page needed] In general, coordination chemists define a macrocycle more narrowly as a cyclic molecule with three or more potential donor atoms that can coordinate to a metal center. A well-known example is the group of drugs known as macrolides. The IUPAC definition notes that a "cyclic macromolecule has no end-groups but may nevertheless be regarded as a chain," and that "macrocycle is sometimes used [in the literature] for molecules of low relative molecular mass that are not considered 'macromolecules.[3]

Macrocycle effect[edit]

Crystal structure of a Zn(II) ion coordinated to cyclen and ethanol reported in Inorg. Chem., 1997, 4579-4584.

The macrocyclic effect was discovered in 1969.[3][non-primary source needed] Coordination chemists study macrocycles with three or more potential donor atoms in rings of greater than nine atoms, as these compounds often have strong and specific binding with metals.[4][page needed] This property of coordinating macrocyclic molecules is termed the macrocycle effect, and is a special example of the chelate effect.[citation needed]


In general, macrocycles are synthesized from smaller, usually linear, molecules.

Historical uses[edit]

Macrocycles have been in use for several decades as synthetic dyes. Phthalocyanine is a porphyrin analogue, which is arguably the most useful, in uses as dyes and pigments since their discovery in 1928, due to their dark-blue colour. However, there are many other uses for them. Their name comes from their synthetic precursor, phthalodinitrile.[5][page needed]

Biological macrocycles[edit]

Related molecular categories[edit]

  • Ligand: an atom, ion, or functional group that is bonded to one or more central atoms or ions.
  • Chelate: a multidentate ligand, containing more than one donor atom.
  • Cryptand: a macrocycle with multiple loops (e.g., bicyclic).
  • Rotaxane: macrocycle(s) stuck on a stick, generally freely
  • Catenane: interlocked molecular rings (like a chain).
  • Molecular knot: a molecule in the shape of a knot such as a trefoil knot.


  1. ^ Still, W. C.; Galynker, I. Tetrahedron 1981, 37, 3981-3996.
  2. ^ J. D. Dunitz. Perspectives in Structural Chemistry (Edited by J. D. Dunitz and J. A. Ibers), Vol. 2, pp. l-70; Wiley, New York (1968)
  3. ^ "Glossary of basic terms in polymer science (IUPAC Recommendations 1996)" (PDF). Pure and Applied Chemistry 68 (12): 2287–2311. 1996. doi:10.1351/pac199668122287. 
  1. ^ Parker, S.P. (2002). McGraw-Hill Science & Technology Dictionary. McGraw-Hill. ISBN 978-0070423138. [page needed]
  2. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "macrocycle".
  3. ^ Milgrom, L.R (1997). The Colours of Life: An Introduction to the Chemistry of Porphyrins and Related Compounds. New York: Oxford University Press. ISBN 0-19-855380-3.  (hardbound) ISBN 0-19-855962-3 (pbk.)[page needed]
  4. ^ Cabbines, D. K.; Margerum, D. W. (1969). "Macrocyclic effect on stability of copper(II) tetramine complexes". J. Am. Chem. Soc. 91 (23): 6540–6541. doi:10.1021/ja01051a091. [non-primary source needed]
  5. ^ Melson, G.A., Ed. (1979). Coordination Chemistry of Macrocyclic Compounds. New York: Plenum Press. ISBN 0-306-40140-1. [page needed]
  6. ^ Jung, J.E.; Seung, S.Y. (2002). Bulletin of the Korean Chemical Society 23 (10): 1483–1486. doi:10.5012/bkcs.2002.23.10.1483.  Missing or empty |title= (help)[better source needed][non-primary source needed]

See also[edit]

Further reading[edit]