A Twisted Aromatic Framework

  • Author: ChemistryViews.org
  • Published: 19 March 2017
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
  • Source / Publisher: Organic Letters/ACS Publications
  • Associated Societies: American Chemical Society (ACS), USA
thumbnail image: A Twisted Aromatic Framework

Polycyclic aromatic hydrocarbons (PAHs) are molecules composed of multiple aromatic rings. PAHs with a twisted structure and modified electronic features could be useful for organic electronics. Substituent-free PAHs are p-type semiconductors. Electron-withdrawing substituents can change the molecules' energy levels and make them n-type semiconductors.

Manuel Melle-Franco, University of Aveiro, Portugal, Luis E. Hueso, CIC Nanogune, Donostia-San Sebastián, Spain, Aurelio Mateo-Alonso, University of the Basque Country, Donostia-San Sebastián, Spain, and colleagues have synthesized pyrene-fused acenes with cyano groups in key positions, which induce a twist in the molecules. The team condensed 2,7-di-tert-butylpyrene-4,5-dione with tetracyanomethylbenzene under basic conditions to give a tetracyano-substituted tetrabenzoheptacene (pictured).

The resulting product is stable under a nitrogen atmosphere up to 460 °C. There is steric hindrance between the cyano groups and the tert-butyl groups, which forces the molecule out of planarity. The twisted structure improves the compound's solubility and changes its electronic properties. Additionally, the electron-withdrawing character of the CN groups lowers the molecules LUMO and decreases the HOMO-LUMO gap (LUMO = lowest unoccupied molecular orbital, HOMO = highest occupied molecular orbital). These properties allowed the researchers to build field-effect transistors using the substituted tetrabenzoheptacene, which showed behavior that is typical for n-type semiconductors.


Article Views: 1326

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more


ChemistryViews.org on Facebook

ChemistryViews.org on Twitter ChemistryViews.org on YouTube ChemistryViews.org on LinkedIn Sign up for our free newsletter

A product of ChemPubSoc Europe (16 European Chemical Societies)and Wiley-VCH