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

  • 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.

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Author:Anaïs Mairena, Milos Baljozovic, Maciej Kawecki, Konstantin Grenader, Martin Wienke, Kévin Martin, Laetitia Bernard, Narcis Avarvari, Andreas TerfortORCiDGND, Karl-Heinz Ernst, Christian Wäckerlin
Pubmed Id:
Parent Title (English):Chemical science
Place of publication:Cambridge
Document Type:Article
Year of Completion:2019
Date of first Publication:2019/01/15
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2019/05/02
Page Number:7
First Page:2998
Last Page:3004
This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Institutes:Biochemie, Chemie und Pharmazie / Biochemie und Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Licence (German):License LogoCreative Commons - Namensnennung 3.0