polyeneihin

Polyeneihin, Finnish for polyenes, denotes a class of organic compounds characterized by two or more carbon–carbon double bonds arranged in a conjugated system. In such compounds the double bonds are separated by single bonds, allowing delocalization of π electrons across the chain or ring. Polyenes can be linear (acyclic) or cyclic and may vary in chain length from butadiene (two double bonds) to longer systems such as hexatriene, extending to numerous conjugated units used in dyes and pigments. The extent of conjugation governs optical properties: longer chains absorb longer wavelengths, giving colors from yellow to deep red, and underpin applications in dyes, pigments, and organic electronics.

Chemically, polyenes arise by various synthetic routes, including polymerization of dienes, Wittig-type coupling, and cross-coupling approaches that build conjugated backbones. They play key roles in biology and medicine: retinal and other visual chromophores are polyenes; carotenoids are long-studied natural polyenes; polyene antibiotics, such as amphotericin B, consist of polyene chains within macrocyclic frameworks and act by interacting with membrane sterols.

Stability and reactivity increase with chain length and degree of conjugation, though extended polyenes can be prone to oxidation and isomerization. In materials science, conjugated polyenes form the basis of conducting polymers and organic semiconductors, with performance tied to planarity and substituent effects.

The term polyeneihin is used primarily in Finnish-language contexts to refer to polyenes; in English-language literature, polyenes is the standard term.