Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 89: Inorganic/Organic Interfaces: Molecular Switches

O 89.7: Talk

Thursday, March 19, 2015, 16:30–16:45, MA 043

Self-assembly and thermally induced conformational changes of Ni(II)-meso-tetrakis (4-tert-butylphenyl) benzoporphyrin on Cu(111) studied by STM — •Michael Lepper, Michael Stark, Liang Zhang, Stefanie Ditze, Hans-Peter Steinrück, and Hubertus Marbach — Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058

A detailed scanning tunneling microscopy study of the self-assembly and thermally induced conformational changes of Ni(II)-meso-tetrakis (4-tert-butylphenyl) benzoporphyrin (Ni-TTBPBP) on Cu(111) will be presented. The coverage-dependent adsorption behavior at room temperature reveals that Ni-TTBPBP molecules can easily diffuse on the surface and self-assemble into islands with square order and a certain registry to the substrate. The role of molecule-molecule and molecule-substrate interactions for the formation of the well-ordered supramolecular structure will be discussed. Interestingly, upon moderate heating two successive, irreversible intramolecular conformational changes are observed. This is explained comprehensively by a thermally induced dehydrogenative, intramolecular aryl-aryl coupling reaction. In addition this intramolecular structural change is coverage dependent, exhibiting a lower rate at higher initial coverage. This modification and the overall adsorption behavior of Ni-TTBPBP on Cu(111) will be discussed and compared to the very different behavior of the similar Ni(II)-tetraphenylbenzoporphyrin on the same substrate.