Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 6: Organic molecules on inorganic substrates: Adsorption and growth I

O 6.4: Talk

Monday, March 9, 2026, 11:15–11:30, TRE/PHYS

Orientational Order of Phenyl Rotors on Triangular Platforms on Ag and Au(111) — Richard Berndt¹, Richard Berndt², Richard Berndt², Richard Berndt³, and •Richard Berndt¹ — ¹Institut für Experimentelle und Angewandte Physik, CAU Kiel, Germany — ²Otto-Diels-Institut für Organische Chemie, CAU Kiel, Germany — ³Centro de Física de Materiales, Donostia-San Sebastián, Spain

We investigated trioxatriangulenium functionalized with phenyl on Ag(111) and Au(111) using low-temperature scanning tunneling microscopy (STM). On Ag, the molecules form hexagonal arrays and the orientations of the phenyl moieties are resolved. Moreover, STM images suggest a dimerization of the molecules. Density functional theory calculations reproduce the experimental data. Van der Waals interaction is the dominant binding mechanism. The apparent dimerization results from an asymmetry of the phenyl wavefunction, which reflects intramolecular hydrogen bonding between the ligand and an oxygen atom of the triangulenium platform. Direct long-range interaction between phenyl moieties across molecules and the intramolecular H bonding are decisive for the orientations of the phenyl moieties. Similar experimental results were obtained on Au(111).

Keywords: self-assembly; van der Waals interaction; dimerization; trioxatriangulenium; scanning tunneling microscopy