To follow current strategies to synthesize materials for organic semiconductors one has to decide between two categories of molecules: Either small molecules with high performance and low solubility or polymeric materials with generally lower conductivity but better material properties.[1] In our approach we seek to combine the advantages of both types of molecules by incorporating the conductive structural part into the side chain of a polymer. Therefore, N-Heteroacenes with a polymerizable functional unit have to be developed and synthesized. To achieve an easy-to-vary synthesis of different molecules a modular system is used to build up the monomers. Each monomer can be fragmented into three main parts: The conductive unit, a polymerizable part and a flexible alkoxy chain, which links the former parts together. The linker is crucial to the future conductivity of the material since the conductive unit needs to be able to develop a pi-stacking structure despite being linked to a tangled polymer chain. The conductive unit is build up from an aromatic diamine and a functionalized diketone. This allows easy variation of size and electronic nature of the conductive unit by using different diamines. To prove the polymerizability and the usability of the concept first, a monomer with a rather small conductive unit is synthesized. The polymerization was carried out free radically and anionically. Then a monomer with a bigger aromatic system was synthesized, so that conductivity can be expected. Both monomers and polymers were analyzed by NMR, UV/Vis, cyclovoltammetry and size exclusion chromatography.
[1] Acc. Chem. Res. 2001, 34, 359-369