Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Metal substrates: Adsorption of organic / bio molecules III

O 18.7: Vortrag

Dienstag, 24. März 2009, 12:00–12:15, SCH A118

Theoretical Investigation of Bis(terpyridine)-based Surface Structures — •Daniela Künzel and Axel Groß — Institute for Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany

Ordered organic layers of bis(terpyridine)-derived molecules (BTPs) adsorbed on graphite show a number of interesting properties that can easily be varied by slight modifications of the system such as the coverage [1]. In order to understand this dependence, structures of 3,3’-BTP and 2,4’-BTP on graphite were investigated using density functional theory (DFT) and several force field methods such as COMPASS, UFF, CVFF and Dreiding.

These calculations confirm that the formation of weak C-H⋯N hydrogen bonds controls the self-assembled adsorption of BTP molecules into ordered surface structures. Modifications with different surface coverages and surface structures can be obtained, depending on BTP isomer and adsorption conditions. In addition, chemical modifications of the adsorbate molecules and their consequences on structure formation have been addressed.

Due to its large cavities, the hexagonal structure of 3,3’-BTP is of special interest. These cavities can be used as a template for the adsorption of guest molecules such as phthalocyanine derivatives. At room temperature, the guest molecules can rotate within the cavities, as both STM experiments and force field calculations of the rotational barriers demonstrate [1]. Furthermore, the dependence of the rotational barriers on the size of the guest molecules will be discussed.

[1] C. Meier et al., Angew. Chem. Int. Ed. 47, 3821 (2008).