Английская Википедия:Acene

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Файл:Acenes general structure.svg
The general structural formula for acenes

In organic chemistry, the acenes or polyacenes are a class of organic compounds and polycyclic aromatic hydrocarbons made up of benzene (Шаблон:Chem2) rings which have been linearly fused.[1][2] They follow the general molecular formula Шаблон:Chem2.

The larger representatives have potential interest in optoelectronic applications and are actively researched in chemistry and electrical engineering. Pentacene has been incorporated into organic field-effect transistors, reaching charge carrier mobilities as high as 5 cm2/Vs.

The first 5 unsubstituted members are listed in the following table:

Name Number of rings Molecular formula Structural formula
Anthracene 3 Шаблон:Chem2 Файл:Anthracen.svg
Tetracene 4 Шаблон:Chem2 Файл:Tetracene 200.svg
Pentacene 5 Шаблон:Chem2 Файл:Pentacene 200.svg
Hexacene 6 Шаблон:Chem2 Файл:Hexacene 200.svg
Heptacene 7 Шаблон:Chem2 Файл:Heptacene 200.svg

Hexacene is not stable in air, and dimerises upon isolation. Heptacene (and larger acenes) is very reactive and has only been isolated in a matrix. However, bis(trialkylsilylethynylated) versions of heptacene have been isolated as crystalline solids.[3]

Larger acenes

Due to their increased conjugation length the larger acenes are also studied.[4] Theoretically, a number of reports are available on longer chains using density functional methods.[5][6] They are also building blocks for nanotubes and graphene. Unsubstituted octacene (n=8) and nonacene (n=9)[7] have been detected in matrix isolation. The first reports of stable nonacene derivatives claimed that due to the electronic effects of the thioaryl substituents the compound is not a diradical but a closed-shell compound with the lowest HOMO-LUMO gap reported for any acene,[8] an observation in violation of Kasha's rule. Subsequent work by others on different derivatives included crystal structures, with no such violations.[9] The on-surface synthesis and characterization of unsubstituted, parent nonacene (n=9)[10] and decacene (n=10)[11] have been reported. In 2020, scientists reported about the creation of dodecacene (n=12)[12] for the first time.

Related compounds

The acene series have the consecutive rings linked in a linear chain, but other chain linkages are possible. The phenacenes have a zig-zag structure and the helicenes have a helical structure.

Benz[a]anthracene, an isomer of tetracene, has three rings connected in a line and one ring connected at an angle.

References

Шаблон:Reflist

Шаблон:Hydrocarbons Шаблон:PAHs

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  12. Шаблон:Cite journal