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The fate of bromine after temperature-induced dehydrogenation of on-surface synthesized bisheptahelicene.
Journal article

The fate of bromine after temperature-induced dehydrogenation of on-surface synthesized bisheptahelicene.

  • Mairena A Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland . Email: christian.waeckerlin@empa.ch ; Email: karl-heinz.ernst@empa.ch.
  • Baljozovic M Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland . Email: christian.waeckerlin@empa.ch ; Email: karl-heinz.ernst@empa.ch.
  • Kawecki M Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland . Email: christian.waeckerlin@empa.ch ; Email: karl-heinz.ernst@empa.ch.
  • Grenader K Department of Chemistry , Institute of Inorganic and Analytical Chemistry , Goethe-University , 60438 Frankfurt , Germany.
  • Wienke M Department of Chemistry , University of Hamburg , 20146 Hamburg , Germany.
  • Martin K Laboratoire Moltech-Anjou , CNRS-Université d'Angers , 49045 Angers , France.
  • Bernard L Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland . Email: christian.waeckerlin@empa.ch ; Email: karl-heinz.ernst@empa.ch.
  • Avarvari N Laboratoire Moltech-Anjou , CNRS-Université d'Angers , 49045 Angers , France.
  • Terfort A Department of Chemistry , Institute of Inorganic and Analytical Chemistry , Goethe-University , 60438 Frankfurt , Germany.
  • Ernst KH Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland . Email: christian.waeckerlin@empa.ch ; Email: karl-heinz.ernst@empa.ch.
  • Wäckerlin C Empa, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf , Switzerland . Email: christian.waeckerlin@empa.ch ; Email: karl-heinz.ernst@empa.ch.
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  • 2019-04-19
Published in:
  • Chemical science. - 2019
General Chemistry
English The on-surface synthesis of bisheptahelicene by Ullmann coupling of 9-bromoheptahelicene on Au(111) and its temperature-induced dehydrogenation is studied using temperature-programmed reaction spectroscopy and time-of-flight secondary ion mass spectrometry. Specific dehydrogenation products of bisheptahelicene after loss of 6, 8 and 10 hydrogen atoms are identified, corresponding to molecules having undergone Diels-Alder transformations and intramolecular C-C coupling reactions. By combining with atomic hydrogen produced by dehydrogenation, the Ullmann coupling side-product bromine desorbs as HBr. H2 desorption emerges only after all Br has desorbed. Such characteristic behavior is explained by a kinetic model which explicitly considers the coverage of transient atomic H on the surface. Heating experiments performed with saturated layers of different Br-containing molecules reveal that the onset of HBr desorption depends strictly on the dehydrogenation step and therefore on the structure of the molecules.
Language
  • English
Open access status
gold
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Persistent URL
https://sonar.ch/global/documents/13585
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