title: From Au-Thiolate Chains to Thioether Sierpiński Triangles: The Versatile Surface Chemistry of 1,3,5-Tris(4-mercaptophenyl)benzene on Au(111).
abstract: Self-assembly of 1,3,5-tris(4-mercaptophenyl)benzene (TMB), a 3-fold symmetric, thiol-functionalized aromatic molecule, was studied on Au(111) with the aim of realizing extended Au-thiolate-linked molecular architectures. The focus lay on resolving thermally activated structural and chemical changes by a combination of microscopy and spectroscopy. Thus, scanning tunneling microscopy (STM) provided submolecularly resolved structural information, while the chemical state of sulfur was assessed by X-ray photoelectron spectroscopy (XPS). Directly after room-temperature deposition, only less well ordered structures were observed. Mild annealing promoted the first structural transition into ordered molecular chains, partly organized in homochiral molecular braids. Further annealing led to self-similar Sierpiński triangles, while annealing at even higher temperatures again resulted in mostly disordered structures. Both the irregular aggregates observed at room temperature and the chains were identified as metal-organic assemblies, whereby two out of the three intermolecular binding motifs are energetically equivalent according to density functional theory (DFT) simulations. The emergence of Sierpiński triangles is driven by a chemical transformation, i.e., the conversion of coordinative Au-thiolate to covalent thioether linkages, and can be further understood by Monte Carlo simulations. The great structural variance of TMB on Au(111) can on one hand be explained by the energetic equivalence of two binding motifs. On the other hand, the unexpected chemical transition even enhances the structural variance and results in thiol-derived covalent molecular architectures.
authors.affiliation: Department of Physics, Technische Universität München , James-Franck-Strasse 1, 85748 Garching, Germany.|Nanosystems Initiative Munich and Center for NanoScience (CeNS) , Schellingstrasse 4, 80799 Munich, Germany.|Deutsches Museum , Museumsinsel 1, 80538 Munich, Germany.
authors.forename: Atena
authors.initials: A
authors.lastname: Rastgoo-Lahrood
authors.affiliation: Department of Chemistry, University of Sheffield , Sheffield S3 7HF, U.K.
authors.forename: Natalia
authors.initials: N
authors.lastname: Martsinovich
authors.affiliation: Department of Physics, Technische Universität München , James-Franck-Strasse 1, 85748 Garching, Germany.|Nanosystems Initiative Munich and Center for NanoScience (CeNS) , Schellingstrasse 4, 80799 Munich, Germany.|Deutsches Museum , Museumsinsel 1, 80538 Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lischka
authors.affiliation: Department of Physics, Technische Universität München , James-Franck-Strasse 1, 85748 Garching, Germany.|Nanosystems Initiative Munich and Center for NanoScience (CeNS) , Schellingstrasse 4, 80799 Munich, Germany.|Deutsches Museum , Museumsinsel 1, 80538 Munich, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Eichhorn
authors.affiliation: Department of Theoretical Chemistry, Maria Curie-Skłodowska University , Pl. M.C. Skłodowskiej 3, 20-031 Lublin, Poland.
authors.forename: Pawel
authors.initials: P
authors.lastname: Szabelski
authors.affiliation: Supramolecular Chemistry Laboratory, University of Warsaw, Biological and Chemical Research Centre , Zwirki i Wigury 101, 02-089 Warsaw, Poland.
authors.forename: Damian
authors.initials: D
authors.lastname: Nieckarz
authors.affiliation: Institute for Materials Science - Multicomponent Materials, Christian-Albrechts-Universität zu Kiel , Kaiserstrasse 2, 24143 Kiel, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Strunskus
authors.affiliation: Center of Micro- and Nanochemistry and Engineering, Organische Chemie I, Universität Siegen , Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany.
authors.forename: Kalpataru
authors.initials: K
authors.lastname: Das
authors.affiliation: Center of Micro- and Nanochemistry and Engineering, Organische Chemie I, Universität Siegen , Adolf-Reichwein-Strasse 2, 57068 Siegen, Germany.
authors.forename: Michael
authors.identifier: 0000-0001-8622-2883
authors.initials: M
authors.lastname: Schmittel
authors.affiliation: Department of Physics, Technische Universität München , James-Franck-Strasse 1, 85748 Garching, Germany.|Nanosystems Initiative Munich and Center for NanoScience (CeNS) , Schellingstrasse 4, 80799 Munich, Germany.|Deutsches Museum , Museumsinsel 1, 80538 Munich, Germany.
authors.forename: Wolfgang M
authors.initials: WM
authors.lastname: Heckl
authors.affiliation: Department of Physics, Technische Universität München , James-Franck-Strasse 1, 85748 Garching, Germany.|Nanosystems Initiative Munich and Center for NanoScience (CeNS) , Schellingstrasse 4, 80799 Munich, Germany.|Deutsches Museum , Museumsinsel 1, 80538 Munich, Germany.
authors.forename: Markus
authors.identifier: 0000-0003-4226-4795
authors.initials: M
authors.lastname: Lackinger
keywords: DFT; Monte Carlo; STM; XPS; fractals; on-surface synthesis; surface chemistry; thioether; thiolate