Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 51: Metal Substrates: Adsorption of Organic/Bio Molecules III

O 51.9: Talk

Wednesday, February 27, 2008, 17:15–17:30, MA 041

Ordered 2D assemblies of phenoxy substituted phthalocyanines as hosts for further guest molecules — Tomas Samuely¹, Shi-Xia Liu², Nikolai Wintjes¹, Marco Haas², Silvio Decurtins², Thomas A. Jung^1,3, and •Meike Stöhr¹ — ¹Institute of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland — ²Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012-Bern, Switzerland — ³Laboratory for Micro- and Nanostructures, Paul-Scherrer-Institute, 5232 Villigen, Switzerland

Symmetrically substituted phthalocyanines (Pcs) with eight peripheral di-(tert-butyl)phenoxy (DTPO) groups self-organize on Ag(111) and Au(111) substrates into various phases. These phases coexist due to a retardation of the thermodynamic optimization of the conformations, caused by the proximity of the Pc core to the metal substrate together with the steric entanglement between neighboring DTPO substituents. The rotational degrees of freedom allow all the DTPO substituents to be arranged above the plane of the Pc core, forming a bowl-like structure, which enables the interaction of the Pc core with the metal substrate. Moreover, this bowl-like shape predetermines such assemblies to serve as a host accommodating guest molecules. As an example, C60 molecules, upon deposition on an ordered layer of the DTPO substituted Pcs, bind to two clearly distinguishable sites, exhibiting different morphologic and electronic properties. Since Pcs are well-known electron donors and C60 molecules are good electron acceptors, such ordered guest-host systems allow addressable STM/STS investigations of individual donor-acceptor complexes.