Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Inorganic/Organic Interfaces

O 41.14: Poster

Tuesday, March 17, 2015, 18:15–21:00, Poster B

Reactive Coupling and Self-Assembly of Tetraphenylporphyrins on Cu(111) — •Malte Zugermeier, Min Chen, Martin Schmid, and J. Michael Gottfried — Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany

Monolayer films of metalloporphyrins on metal substrates combine the chemical versatility of the tetrapyrrole macrocycle with a well ordered, quasi-crystalline arrangement of the molecules. The structural features and robustness of porphyrin layers may be further modified by the formation of strong chemical bonds between the individual molecules, for example by means of Ullmann coupling reactions. To understand the processes which are involved in the molecular arrangement before the formation of covalent porphyrin networks, we prepared (sub-)monolayers of nickel(II)-tetraphenylporphyrin (NiTPP) and its brominated counterpart nickel(II)-tetrakis-(4-bromophenyl)porphyrin (NiTBrPP) on Cu(111); the resulting layers were examined with XPS and STM. While the structure of NiTPP molecules on the Cu(111) surface is exclusively determined by van der Waals forces, the situation is more complex for NiTBrPP. There, the interaction with the Cu(111) surface results in the selective cleavage of all C-Br bonds already at room temperature, and accordingly, the coexistence of chemisorbed Br atoms and surface-stabilized radicalic moieties. The influence of the co-adsorbed Br atoms on the morphology and chemical state of the layers before and after Ullmann coupling will be discussed in comparison to the reference system NiTPP/Cu(111).