triyne

A triyne is a hydrocarbon that contains three carbon–carbon triple bonds (alkynes). It is the simplest member of the polyynes family with three C≡C units. Triynes can be linear, branched, or cyclic, and the three triple bonds may be arranged in various topologies within a given framework.

In the simplest case, a linear triyne such as 1,3,5-hexatriyne has three C≡C bonds separated by single bonds along a carbon chain (for example H–C≡C–C≡C–C≡CH). Substituted triynes replace terminal or internal carbons with groups, and more complex cyclic or polycyclic triynes can be assembled around various cores. The standard naming follows the polyynes convention, with the positions of the three triple bonds indicated in the parent chain.

Triynes generally exhibit higher reactivity than single or diynes because multiple triple bonds contribute to strain, conjugation, and potential cyclization pathways. They can participate in cyclization cascades and other transformations under photochemical or catalytic conditions, enabling rapid construction of cyclic and polycyclic products. Many triynes are sensitive to air, light, or heat and are typically prepared and handled under controlled conditions.

Synthesis of triynes relies on assembling alkynyl fragments through cross-coupling or sequential coupling strategies, and they also arise by oxidative processes or dehydrogenative coupling of precursors. In chemistry and materials science, triynes are explored for their electronic and optical properties and as precursors to more complex aromatic and nanostructured materials.