Shape switchable azo macrocycles

The present thesis is organized in three main chapters. The first section discusses a research project for the integration of azobenzene motives as a functional unit in macrocyclic molecular structures. The optically addressable switching units give access to two conformations with large differences in exterior form. Due to the rigid design with a m�terphenyl backbone and the integration of two azo units a considerable stabilization of the thermodynamically less favored cis�isomer is obtained.
In a second project the modification of platinum electrodes with different functional molecules, in order to obtain tailor made surfaces is investigated. By electrochemical grafting the electrodes with a suitable diazonium salt, an organic coated platinum electrode exposing iodoaryls is obtained. Subsequent Sonogashira cross-coupling chemistry with tailor made acetylene molecules allows substituting the exposed iodines with various functional groups. The new technique is improved in order to introduce a wide range of functional groups onto surfaces with a high surface coverage of functional subunits.
In a last project a bridged biphenyl as a novel molecular switch and memory device based on “mechanical” motion in a molecular biphenylic structure was synthesized. To alter the transport properties by an external stimulus, such as light, an azobenzene derivative as a bistable molecular subunit with state dependent length as the bridging system was integrated.