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O: Fachverband Oberflächenphysik
O 11: Surface Reactions
O 11.9: Talk
Monday, March 27, 2023, 17:00–17:15, CHE 91
The role of aromaticity in the cyclization and polymerization of alkyne-substituted porphyrins on Au(111) — •Nan Cao1, Jonas Björk2, Eduardo Corral-Rascon1, Zhi Chen3,4, Mario Ruben3, Mathias O. Senge5, Johannes V. Barth1, and Alexander Riss1 — 1Technical University of Munich, Germany — 2Linköping University, Sweden — 3Karlsruhe Institute of Technology, Germany — 4Shenzhen University, China — 5Institute for Advanced Study, TUM, Germany
Aromaticity is one of the most practical and versatile concepts for the assessment of the reactivity of organic molecules. However, in on-surface chemistry - where the interaction with the substrate can significantly alter the electronic and geometric structure of the adsorbates - the role of aromaticity is not understood. Here we investigate how aromaticity affects the reactivity of alkyne-substituted porphyrin molecules in cyclization and coupling reactions on a Au(111) surface.[1] We examine and quantify the regioselectivity of the reactions by scanning tunneling microscopy and bond-resolved atomic force microscopy at the single-molecule level. Our experiments show a substantially lower reactivity of carbon atoms that are stabilized by the aromatic diaza[18]annulene pathway of free-base porphyrins. The results are corroborated by density functional theory calculations, revealing a direct correlation between aromaticity and thermodynamic stability of the reaction products. These insights will help to design and understand reactions in on-surface chemistry and heterogeneous catalysis. 1. https://doi.org/10.21203/rs.3.rs-1271465/v1