Macrocycles and cyclic polymers have properties distinctly different from those of their linear counterparts. While effective approaches for their synthesis in solution remain scarce, on-surface synthesis under vacuum conditions has proven to be a viable alternative due to the inherent template effects of the metal surface. Due to the solvent-free conditions, solubility-enhancing side groups are not necessary and therefore the on-surface synthesis gives unprecedented access to the unsubstituted parent structures. In this contribution, we will discuss the controlled formation of conjugated, shape-persistent oligoarene macrocycles on (modified) metal single-crystal surfaces from various haloarenes through Ullmann type C-C coupling reactions. Examples that will be presented include phenylene, pyrrole and azulene based polymers and oligomers. Structural and chemical characterization of the adsorbed products was achieved by scanning tunnelling microscopy (STM) in combination with photoelectron spectroscopy (PES) and related techniques.

On-surface synthesis of polymers and macrocycles

255th National Meeting (2018)

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