Self-assembly and surface-mediated reactions of 1,3,5-tris(4-mercaptophenyl)benzene--a three-fold symmetric aromatic trithiol--are studied on Cu(111) by means of scanning tunneling microscopy (STM) under ultrahigh-vacuum (UHV) conditions. In order to reveal the nature of intermolecular bonds and to understand the specific role of the substrate for their formation, these studies were extended to Ag(111). Room-temperature deposition onto either substrate yields densely packed trigonal structures with similar appearance and lattice parameters. Yet, thermal annealing reveals distinct differences between both substrates: on Cu(111) moderate annealing temperatures (~150 °C) already drive the emergence of two different porous networks, whereas on Ag(111) higher annealing temperatures (up to ~300 °C) were required to induce structural changes. In the latter case only disordered structures with characteristic dimers were observed. These differences are rationalized by the contribution of the adatom gas on Cu(111) to the formation of metal-coordination bonds. Density functional theory (DFT) methods were applied to identify intermolecular bonds in both cases by means of their bond distances and geometries.

Self-assembly of 1,3,5-tris(4-mercaptophenyl)benzene (TMB) -a three-fold symmetric, thiol functionalized aromatic molecule -was studied on Au(111) with the aim to realize extended Authiolate linked molecular architectures. The focus lay on resolving thermally activated structural and chemical changes by a combination of microscopy and spectroscopy. Thereby Scanning Tunneling Microscopy provided submolecularly resolved structural information, while the chemical state of sulfur was assessed by X-ray Photoelectron Spectroscopy. 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 Sierpi ski 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 metalorganic assemblies, whereby two out of the three intermolecular binding motifs are energetically equivalent according to Density Functional Theory simulations. The emergence of Sierpi ski 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.3 KEYWORDS surface chemistry, on-surface synthesis, thiolate, thioether, fractals, STM, XPS, DFT, Monte CarloThe notorious affinity of thiols to gold is beneficial for molecular nano-science. 1 Important examples include ligation of gold nanoparticles, 2, 3 two probe conductance measurements of single molecules, [4][5][6][7] and surface functionalization of Au(111) by Self-Assembled Monolayers (SAMs). 8,9 All of these applications rely on anchoring via strong Au-thiolate bonds. Even though thiolate SAMs are widespread, structural details of the anchor bond were discussed controversially for a long time. Yet, a consensus seems to be reached insofar as Au-thiolate complexes formed with gold adatoms play an important role. 10 The promising properties of RSAu-SR linkages, in particular their electric conductance and their ability to form spontaneously on Au(111) motivated the present study with the aim to utilize these linkages for extended molecular nanostructures. To this end 1,3,5-tris(4-mercaptophenyl)benzene (TMB) as a threefold functionalized and suitable model compound for network formation is studied on Au(111).Owing to both the extended triphenylbenzene backbone and the three-point anchoring via thiolate-surface bonds, planar adsorption is anticipated as an important prerequisite for extended networks. In contrast to SAMs, where the prevalent monothiols adopt upri...

Direct amination of unactivated allylic alcohols with aqueous ammonia was catalyzed by a Pt/phosphine complex to give the corresponding allylamines along with water as the sole by‐product. Under optimized reaction conditions, primary allylamines were obtained as major products with excellent monoallylation selectivity. cod=1,5‐cyclooctadiene.