Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 64: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures IV

O 64.5: Vortrag

Mittwoch, 14. März 2018, 16:00–16:15, MA 004

Resolving molecular products of surface induced chemical reactions of 9-Azidophenanthrene — •Aleš Cahlík¹, John Hellerstedt¹, Pingo Mutombo¹, Oleksander Stetsovych¹, Ivo Starý², Irena Stará², Martin Švec¹, and Pavel Jelínek¹ — ¹Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic — ²Institute of Chemistry and Biochemistry, Czech Academy of Sciences, Praha, Czech Republic

The preparation of suitable systems for controllable, light-driven molecular switches presently remains an appealing experimental challenge. Recently, azo-compounds have proven to be an auspicious choice for such purpose. We report the on-surface synthesis and identification of azo-phenanthrene isomers, a prospective molecular switch, using azide-based 9-Azidophenanthrene (APT) as a molecular precursor. Due to the high reactivity of APT, a broad variety of reaction pathways exist which results in an extensive mixture of products. Such chemical diversity is hard to grasp by means of a conventional chemical analysis tools owing to the subtle structural differences with nearly identical bond environments. In our experiment, we went beyond the limits of these techniques by employing non-contact atomic force microscopy to achieve submolecular resolution of the product species. We speculate that the precursor decomposes into highly reactive nitrene species, that subsequently form a diverse mixture of products. By close comparison with theoretical calculations we are able to distinguish between covalently (N=N) bonded azo-phenanthrene isomers and other non-covalently bonded molecular structures.