AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP30
Formation of Supramolecular Cavitands on Electrode Surfaces

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: P. Broekmann, University of Bonn, Germany
Authors: C. Safarowsky, University of Bonn, Germany
A. Rang, University of Bonn, Germany
C.A. Schalley, University of Bonn, Germany
K. Wandelt, University of Bonn, Germany
P. Broekmann, University of Bonn, Germany
Correspondent: Click to Email
Supramolecular host-guest recognition is one the most challenging topics in modern chemistry and physics as well. Combining supramolecular approaches with state of the art surface science techniques allows to gain new insights about the structure and dynamics of supramolecular assemblies which are adsorbed at surfaces. In this contribution we present two approaches to realize supramolecular architectures at electrode surfaces in an electrochemical environment. The most prominent property of these architectures is their molecular host-cavity in which smaller guest molecules can be incorporated. Our method of choice to investigate these electrochemically fabricated arrays of host assemblies is the in-situ scanning tunnelling microscopy. Our first approach is based on the selforganization of small monomers to supramolecular assemblies at the surface. For this purpose we use redox-active dibenzyl-viologen cations which arrange on a chloride modified Cu(100) surface with the formation of square-shaped host assemblies consisting of 4 individual molecules. Characteristically, these assemblies are chiral and, hence, occur in two mirror-domains on the electrode surface. Our second approach is based on the direct adsorption of pre-assembled supramolecular units at the electrode surface from the solution phase. For this purpose we use so called Fujita-squares which are characterized by a fourfold-symmetric arrangement of 4 Pt(II)-cations stabilized by 4 bipyridine ligands and 4 further ethylenediamine molecules. These cationic molecules can also be adsorbed on a chloride modified Cu(100) electrode surface. In both cases we end up with molecular cavities which are oriented towards the solution phase and can, thus, be directly imaged by in-situ STM. The size of these cavities amounts to 1 nm in both cases.