Acene

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The general structural formula of acenes (n ≥ 1)

In chemistry, acenes belong to a class of organic compounds , more precisely the polycyclic aromatic hydrocarbons , consisting of linearly fused (fused) benzene rings. According to the nomenclature, anthracene is the main body of the series, and naphthalene is also occasionally counted among the acenes. The larger representatives are potentially interesting for optoelectronic applications and are currently the subject of chemical and electronic research. Pentacene has been incorporated into organic transistors with charge mobilities up to 5 cm 2 · V −1 · s −1 .

Minor acenes

The first five unsubstituted acenes are listed in the table:

Surname Molecular formula Number of rings Molecular weight
( g · mol -1 ) 		CAS number Structural formula
Anthracene C 14 H 10 3 178.23 120-12-7 Anthracene.svg
Tetracene C 18 H 12 4th 228.29 92-24-0 Tetracenes 200.svg
Pentacene C 22 H 14 5 278.35 135-48-8 Pentacene 200.svg
Hexacene C 26 H 16 6th 328.41 258-31-1 Hexacene 200.svg
Heptacene C 30 H 18 7th 378.46 258-38-8 Heptacene 200.svg

The higher representatives, hexacene and heptacene , are very reactive (unstable) and can only be isolated in a matrix. However, bis (trialkylsilyl) ethynylated derivatives of hexacene and heptacene are more stable and can be isolated as crystalline solids.

Larger acenes

Because of the increasing size of the conjugated π-electron system, larger acenes are a current research topic. Acenes can also be starting materials for the production of nanotubes etc. Unsubstituted octacene (general structural formula, n = 6) contains eight rings, nonacene (n = 7) nine rings. They have only been isolated and characterized in a matrix. A stable substituted nonacene has also been reported.

Isomers

Structural similarity to the linearly structured acenes have 1,2-fused helical helicenes .

Nomenclature / definition of the compound class

Acenes are polycyclic aromatic hydrocarbons that are built up from linearly condensed benzene units. While according to the IUPAC Gold Book, anthracene is the first link in the acene series, according to Römpp, naphthalene is the smallest acene. According to Römpp, the basis of the definition is the nomenclature proposal made by Clar in 1939.

Contrary to what the definition in Römpp suggests, however, the key point of Clar's proposal was to distinguish the class of linearly condensed from that of angularly condensed hydrocarbons, by defining the respective representatives based on the basic substances anthracene (referred to as triacene in Clar ) and phenanthrene ( called Triphen at Clar).

"Just as the series of acenes can be derived from anthracene, one can also derive a series of angular hydrocarbons, which would be called" phenes ", from phenanthrene: [...]"

Although only the term acene has found its way into the systematic nomenclature, Clar's statements clearly show that naphthalene or even benzene in the sense of the nomenclature do not belong to the acene class.

Individual evidence

  1. ↑ a b Entry on acenes . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.A00061 Version: 2.3.3.
  2. ^ A b J. Falbe, M Regitz (Ed.): Römpp Chemie Lexikon , keyword Acene , p. 20, 9th expanded and revised edition, 1995 , Georg Thieme Verlag, Stuttgart.
  3. ^ A b John E. Anthony: The Larger Acenes: Versatile Organic Semiconductors . In: Angewandte Chemie International Edition . 47, 2008, p. 452. doi : 10.1002 / anie.200604045 .
  4. ↑ Sanjio S. Zade, Michael Bendikov: heptacenes and Beyond: the Longest Characterized Acenes . In: Angewandte Chemie International Edition . 2010, pp. 4012-4015. doi : 10.1002 / anie.200906002 .
  5. ↑ Christina Tönshoff, Holger F. Bettinger: Photogeneration of Octacene and Nonacene . In: Angewandte Chemie International Edition . 2010, pp. 4125-4128. doi : 10.1002 / anie.200906355 .
  6. ↑ Irvinder Kaur, Mikael Jazdzyk, Nathan N. Stein, Polina Prusevich, Glen P. Miller: Design, Synthesis, and Characterization of a Persistent Nonacene Derivative . In: Journal of the American Chemical Society . 132, 2010, p. 1261. doi : 10.1021 / ja9095472 .
  7. ↑ Erich Clar: Suggestions for the nomenclature of condensed ring systems (Aromatic Hydrocarbons, XXVI. Communication). In: Reports of the German Chemical Society (A and B Series). Vol. 72, Edition 12, Wiley-VCH Verlag, Weinheim December 6, 1939, doi : 10.1002 / cber.19390721219 , pp. 2137-2139.
  8. ↑ Erich Clar: Aromatic hydrocarbons - polycyclic systems. 2. verb. Ed., Springer, Berlin / Heidelberg 1952, ISBN 978-3-642-85659-4 , doi : 10.1007 / 978-3-642-85658-7 , p. 6. ( limited preview in Google book search).