In organic chemistry, polyenes are polyunsaturated that contain multiple carbon–carbon ().
Conjugated polyenes contain a conjugated system of alternating single and double carbon–carbon bonds, with characteristic optical properties.
The following polyenes are used as antimycotics for humans: amphotericin B, nystatin, candicidin, pimaricin, methyl partricin, and trichomycin.
Optical properties
Some polyenes are brightly colored, an otherwise rare property for a hydrocarbon. Normally alkenes absorb in the
ultraviolet region of a spectrum, but the absorption energy state of polyenes with numerous conjugated double bonds can be lowered such that they enter the visible region of the spectrum, resulting in compounds which are coloured (because they contain a
chromophore). Thus many natural
contain linear polyenes.
Chemical and electrical properties
Polyenes tend to be more reactive than simpler alkenes. For example, polyene-containing
are reactive towards atmospheric oxygen.
Polyacetylene, which partially oxidized or reduced, exhibits high electrical conductivity. Most conductive polymers are polyenes, and many have conjugated structures. Poly(aza)acetylenes are readily prepared from
pyridine precursors without the necessity of a controlled atmosphere, simply by
ultraviolet irradiation of a mixture of pyridine and poly(4-vinyl) pyridine. Recent research at the Weizmann Institute and Aix-Marseille University showed a clear transition between ionic and electronic conductivity with increasing UV dose over 30 hours.
Occurrence
A few
are polyenes. Another class of important polyenes are polyene antimycotics.
File:Amphotericin B new.svg|Amphotericin B is an example of a polyene antifungal (antimycotic) agent.[Torrado, J. J.; Espada, R.; Ballesteros, M. P.; Torrado-Santiago, S. "Amphotericin B formulations and drug targeting", Journal of Pharmaceutical Sciences, 2008, volume 97, pp. 2405–2425. .]
File:Leukotriene A4.svg|Leukotriene A4 is a regulator of the immune response.
File:Trans-Polyacetylene.svg| are a synthetic polymer of theoretical interest because they exhibit metallic properties upon oxidation.[Lam, Jacky W. Y.; Tang, Ben Zhong. "Functional Polyacetylenes", Accounts of Chemical Research, 2005, volume 38, pp. 745–754. .]
