SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 45: Focus Session: Scanning Probe Microscopy with Quartz Sensors I
O 45.6: Talk
Wednesday, March 29, 2023, 12:00–12:15, CHE 89
On-surface synthesis of PAHs by strain and the concerted motion of adatoms. — •Benjamin Mallada1,2, Bruno de la Torre1,2, Jesus I. Mendieta-Moreno2, Adam Matej1,2, Mikulas Matousek3, Jiri Brabec3, Libor Veis3, Timothee Cadart3, Martin Kotora4, and Pavel Jelinek1,2 — 1Czech Advanced Technology and Research Institute (CATRIN), Olomouc, Czech Republic — 2Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic — 3J. Heyrovsky Institute of Physical Chemistry, Prague, Czech Republic — 4Department of Organic Chemistry, Charles University, Prague, Czech Republic
The kinetic control of the synthesis of polycyclic aromatic hydrocarbons (PAH) is one of the most desired features in organic synthesis. In this work, we report the synthesis and characterization by STM/nc-AFM of several PAHs from one single precursor in which two different kinetic-driven mechanisms control the possible products at high temperatures. In the first mechanism, we show that the surface-induced mechanical constraints on a strained helical reactant leads to the synthesis of planar objects with non-benzenoid rings. In the second mechanism, the chemical pathway is mediated by an unusual C-C bond cleavage of the helical reactant mediated by the concerted motion of individual gold adatoms. These observations, supported by DFT and state-of-the-art QM/MM calculations, render a scenario where the molecular internal stress and the adatoms' role enable routes to the kinetic control of selected chemical reactions.