Synthesis and Properties of Large Polycyclic Aromatic Hydrocarbons with Planar and Non-Planar Structural Motifs

Implementation of non-planar aromatic motifs in the molecular design of π-conjugated materials represents a paradigm shift that is interesting from a fundamental research viewpoint but remains largely underdeveloped. To further facilitate this cause, we report on the synthesis and properties of two large polycyclic aromatic compounds (38 carbon atoms). In one compound the planar π-system pyrene is linked to bowl-shaped hydrocarbon corannulene through a C=C bond, which is referred to as “corannulene–vinylpyrene”. Photochemical treatment of this compound results in annulation of both aromatic nuclei and formation of the other large fused structure with ten six-membered aromatic rings, referred to as “corannulene–benzopyrene”. Photophysical and electrochemical studies reveal that the properties of these two structurally related hybrid materials arise from an extended π-conjugation between the planar and non-planar motifs and varies depending upon their molecular structure.