In comparison to their linear congeners, conjugated materials that are star-shaped, with oligothiophene side arms, have very different properties. This includes improved processability in solution, distinct electrochemistry, and favorable electrical transport properties. These types of materials, usually containing a (hetero)aromatic or triphenylamine core from which thiophene groups extend, also have optical properties and electrochemical features that can be applied for use in organic photovoltaic cells.
Alexander S. Fisyuk, Omsk State Technical University, Russia, Wojciech Pisula, Max Planck Institute for Polymer Research, Mainz, Germany, and Adam Pron, Warsaw University of Technology, Poland, and colleagues have synthesized solution-processable star-shaped molecules with a benzene central core. Symmetrically attached to this core are donor/acceptor-type side arms, consisting of either oxa- or thiadiazole bithiophene groups.
The molecules show blue photoluminescence and electroluminescence, as well as emission of either blue or green light from the oxadiazole or thiadiazole derivatives, respectively, when the molecules are in a host-guest scaffold. The three-fold symmetry allowed for easy self-assembly in monolayers with graphene. The derivatives can be processed into a highly ordered supramolecular organization or be electrochemically polymerized. The resulting polymer networks can be doped towards p- or n-type character and possess reversible electrochemical behavior.
- Star-Shaped Conjugated Molecules with Oxa- or Thiadiazole Bithiophene Side Arms,
Kamil Kotwica, Anastasia S. Kostyuchenko, Przemyslaw Data, Tomasz Marszalek, Lukasz Skorka, Tomasz Jaroch, Sylwia Kacka, Malgorzata Zagorska, Robert Nowakowski, Andrew P. Monkman, Alexander S. Fisyuk, Wojciech Pisula, Adam Pron,
Chem. Eur. J. 2016, 22, 11795–11806.