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Macrocycles

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Macrocycles

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 nine or more atoms to be a macrocycle. Coordination chemists generally 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

The macrocyclic effect was discovered in 1969.[2] 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.[3] This property of coordinating macrocyclic molecules is the macrocycle effect.

Synthesis

Macrocycles are generally synthesized from smaller, usually linear, molecules.

Historical uses

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. There are however many other uses for them. Their name comes from their synthetic precursor, phthalodinitrile.[4]

Biological macrocycles

Related molecular categories

  • 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

  1. macrocycle".
  2. ^ (hardbound) ISBN 0-19-855962-3 (pbk.)
  3. http://dx.doi.org/10.1021/ja01051a091
  4. ^
  5. ^ Jung, J.E.; Seung, S.Y., Bulletin of the Korean Chemical Society 2002, 23(10) 1483-1486.

See also

Further reading

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