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O: Fachverband Oberflächenphysik
O 20: Focus Session: Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation I
O 20.8: Talk
Tuesday, March 19, 2024, 12:30–12:45, HE 101
On-Surface Synthesis of Nanostructures With Non-Alternant Topology — •Lukas Heuplick1, Qitang Fan1, Alexander Ihle2, Pengcai Liu3, Miguel Wiche2, Xing-Yu Chen3, Jiawen Cao3, Jan Herritsch1, Daniel Ebeling2, Xiao-Ye Wang3, André Schirmeisen2, and J. Michael Gottfried1 — 1Department of Chemistry, University of Marburg, Marburg, Germany — 2Institute of Applied Physics (IAP), University of Gießen, Gießen, Germany — 3State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, China
In contrast to benzenoid and alternant structures, molecules with non-alternant binding motifs, such as azulene, show drastic changes in their electronic and optical properties. Acepleiadylene (APD), a constitutional isomer of pyrene, consists of 5-, 6-, and 7-membered rings and represents such a non-alternant structure. Here, we report the sucessful on-surface synthesis of nanostructures with non-alternant topology based on APD derivatives. Upon annealing 1,2-dibromoacepleiadylene on Ag(111), non-alternant nanographenes, most notably a covalent trimer, are formed by an Ullmann coupling. Annealing 1,2-dicyanoacepleiadylene on Cu(111), on the other hand, yields acepleiadylenocyanine - a phthalocyanine with non-alternant backbone - by cyclotetramerization. To characterize these reactions, we performed scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy (XPS) experiments. To provide further evidence of the actual structures, we used non-contact atomic force microscopy (nc-AFM).
Keywords: on-surface synthesis; non-alternant; nanographene; phthalocyanine; scanning probe