organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clay ...

, the acenes or polyacenes are a class of

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon- hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

s and

polycyclic aromatic hydrocarbon A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. ...

s made up of

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen ato ...

() rings which have been linearly fused. They follow the general

molecular formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. 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 In physics, a charge carrier is a particle or quasiparticle that is free to move, carrying an electric charge, especially the particles that carry electric charges in electrical conductors. Examples are electrons, ions and holes. The term is u ...

mobilities as high as 5 cm²/Vs. The first 5 unsubstituted members are listed in the following table: Hexacene is not stable in air, and dimerises upon isolation.

Heptacene Heptacene is an organic compound and a polycyclic aromatic hydrocarbon and the seventh member of the acene or polyacene family of linear fused benzene rings. This compound has long been pursued by chemists because of its potential interest in e ...

(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.

Larger acenes

Due to their increased

conjugation Conjugation or conjugate may refer to: Linguistics *Grammatical conjugation, the modification of a verb from its basic form * Emotive conjugation or Russell's conjugation, the use of loaded language Mathematics *Complex conjugation, the change ...

length the larger acenes are also studied. Theoretically, a number of reports are available on longer chains using density functional methods. They are also building blocks for nanotubes and

graphene Graphene () is an allotrope of carbon consisting of a Single-layer materials, single layer of atoms arranged in a hexagonal lattice nanostructure.

. Unsubstituted octacene (n=8) and nonacene (n=9) 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, an observation in violation of Kasha's rule. Subsequent work by others on different derivatives included crystal structures, with no such violations. The on-surface synthesis and characterization of unsubstituted, parent nonacene (n=9) and decacene (n=10) have been reported. In 2020, scientists reported about the creation of dodecacene (n=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

helicene In organic chemistry, helicenes are ortho-condensed polycyclic aromatic compounds in which benzene rings or other aromatics are angularly annulated to give helically-shaped chiral molecules. The chemistry of helicenes has attracted continuin ...

s have a helical structure. File:Heptacene 200.svg, Heptacene File:7-phenacene.svg, henacene File:M-heptahelicene.svg, ''M''-heptahelicene Benz nthracene, an isomer of tetracene, has three rings connected in a line and one ring connected at an angle.

References

{{PAHs Conductive polymers Organic semiconductors