Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 17: Scanning Probe Techniques: Method Development II

O 17.5: Vortrag

Montag, 20. März 2017, 16:45–17:00, TRE Phy

Imaging successive intermediate states of the on-surface Ullmann reaction — •Daniel Ebeling¹, Sören Zint¹, Tobias Schlöder², Sebastian Ahles³, Doreen Mollenhauer², Hermann A. Wegner³, and Andre Schirmeisen¹ — ¹Institute of Applied Physics, Justus Liebig University Giessen, Germany — ²Institute of Physical Chemistry, Justus Liebig University Giessen, Germany — ³Institute of Organic Chemistry, Justus Liebig University Giessen, Germany

Recently, different bottom-up approaches have been developed for the on-surface synthesis of covalently bonded organic frameworks. In order to use these structures for future applications, such as nanoelectronic or -optical devices, in-depth knowledge about the underlying reaction mechanisms has to be gained. This is crucial for establishing a basis for the design of new functional devices with tailor-made properties. Here, we are using low temperature atomic force microscopy (AFM) with CO functionalized tips together with density functional theory (DFT) calculations with dispersion correction to study the complete reaction pathway of the on-surface Ullmann-type coupling between bromotriphenylene molecules on a Cu(111) surface. All steps of the Ullmann reaction, i.e., bromotriphenylenes, triphenylene radicals, organometallic intermediates, and bitriphenylenes could be imaged with submolecular resolution. We can unambiguously identify the chemical structure and the adsorption geometry of each individual species and therewith provide deeper insight into the reaction process.