Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster: Crystallisation, Nucleation and Self assembly

CPP 17.4: Poster

Dienstag, 27. März 2012, 18:15–20:15, Poster A

Shape-persistent linear, kinked, and cyclic oligo(phenylene-ethynylene-butadiynylene)s: self-assembled monolayers — •Stefan-Sven Jester, Alisa Idelson, Daniela Schmitz, Friederike Eberhagen, and Sigurd Höger — Rheinische Friedrich-Wilhelms-Universität Bonn, Kekulé-Institut für Organische Chemie und Biochemie, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany

Self-assembled monolayers (SAMs) of shape-persistent rigid oligomers, particularly phenylene-ethynylene- butadiynylenes at the HOPG/TCB interface were studied by scanning tunneling microscopy (STM) with submolecular resolution. Substitution of the terminating acetylene functions of the linear oligomers with polar cyanopropyldimethylsilyl groups leads to 2D phase separation and defined rod-rod interactions, which determine the packing distances between the rigid rods. The results stimulated the connection of rigid rods via septiarylene clamp units. They covalently link two rigid rod units and define the intramolecular rod-rod distance that matches the alkoxy substituent chain lengths. The systems can be described as half-ring structures of two rigid rods connected via a rotatable joint unit. These acetylene-terminated half-ring structures were also oligomerized under Cu and Pd catalysis to yield defined acyclic and cyclic oligomers. Detailed STM studies decoded the molecular origin of the surface patterning of such systems. The dodecyloxy side chains are adsorbed along the HOPG main axes and, together with the alkoxy backbone angle, determine the adsorption direction of the adlayers. [1] S.-S. Jester, A. Idelson, D. Schmitz, F. Eberhagen, S. Höger, Langmuir 2011, 27, 8205.