Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 14: Metal substrates: Adsorption of organic / bio molecules II

O 14.4: Talk

Monday, March 22, 2010, 15:45–16:00, H36

Thiolate based 2D Metal-Organic-Frameworks — •Georg Eder, Hermann Walch, Jürgen Dienstmaier, and Markus Lackinger — LMU Munich, Department of Earth and Environmental Sciences

Self-assembled monolayers of the organic compound 1,3,5-tris(4-mercaptophenyl)benzene on Cu(111) are studied by Scanning Tunneling Microscopy under ultrahigh vacuum conditions. The molecular structure of this threefold symmetric compound aims at the synthesis of open pore networks through symmetric interconnection via their functional groups. Thiol groups can interact via weak hydrogen bonds, whereas deprotonated thiolate groups can form covalent disulphur bridges or metal coordination bonds. After room temperature deposition on Cu(111) we observe a close packed arrangement of deprotonated molecules that do not interact directly via their functional groups. Yet, annealing the sample up to 200°C induces phase transitions which result in two distinctly different phases where molecules bond through their functional groups. Depending on the initial coverage, we observe predominance of one of these phases. In both cases molecules coordinate with metal adatoms, thereby forming S-Cu-S metal coordination bonds. Preliminary results obtained on a Ag(111) surface suggest a similar behavior. Since the thiolate metal coordination bond provides better electronic coupling than for instance carboxylate analogues, this novel type of networks is of particular interest for molecular electronics.