Organic Surface-Template Structures as Host-Systems for Metal Binding
In this continued project organic two-dimensional (2D) surface structures composed of heteroaromatic systems („oligopyridines“) shall be refined by tailored syntheses of further molecules thus leading to an improved template function for metal binding. Hence, additional nitrogen atoms will be built in to maintain the hydrogen bonding capability on one side and to optimise the complexation properties in solution on the other side. Further metal complexes shall function as guest molecules in the template structures and will be manipulated selectively with the STM tip. Besides a topographical investigation the spectroscopic characterisation of these structures is important. Further functional molecules (e.g. fluorescent dyes) shall be attached to the square-planar metal complexes. Their behaviour on the surface shall be compared with the properties in solution. In addition, these experiments at the liquid/solid interface will be completed by investigations under ultra-high vacuum (UHV) conditions (deposition of metals onto the template structures) and under electrochemical control in aqueous electrolytes, respectively. The aspired functions of the 2D systems are catalytical and optical ones. The experimental results shall be supported theoretically by a combination of Hartree-Fock and Density-Functional Theory (DFT) based electron structure methods with force field calculations. On one hand the interactions of the molecular functional units shall be calculated in order to obtain hints for the mechanisms behind structure formation. On the other hand the changes of the electronic and chemical properties due to metal complexation shall be determined. The catalytic properties will be evaluated through the interaction of the hybrid structures with appropriate probe molecules. Additionally, dynamic and kinetic simulations will help to understand the process of structure formation.