Macrocycle

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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, organic chemists may consider any molecule containing a ring of twelve or more atoms to be a macrocycle.[2] 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.

IUPAC definition

A cyclic macromolecule or a macromolecular cyclic portion of a macromolecule.

Notes

1. A cyclic macromolecule has no end-groups but may nevertheless be regarded as a chain.

2. In the literature, the term macrocycle is sometimes used for molecules of low relative molecular
mass that would not be considered macromolecules. [1]

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] 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] This property of coordinating macrocyclic molecules is the macrocycle effect. It is a special example of the chelate effect.

Synthesis[edit]

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]

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.

References[edit]

  1. ^ Parker, S.P. (2002). McGraw-Hill Science & Technology Dictionary. McGraw-Hill. ISBN 978-0070423138. 
  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.)
  4. ^ D. K. Cabbines and D. W. Margerum (1969). "Macrocyclic effect on stability of copper(II) tetramine complexes". J. Am. Chem. Soc. 91: 6540-6541. http://dx.doi.org/10.1021/ja01051a091
  5. ^ Melson, G.A., Ed. (1979). Coordination Chemistry of Macrocyclic Compounds. New York: Plenum Press. ISBN 0-306-40140-1. 
  6. ^ Jung, J.E.; Seung, S.Y., Bulletin of the Korean Chemical Society 2002, 23(10) 1483-1486.

See also[edit]

Further reading[edit]