Synthesis and properties of a new class of fully conjugated azahexacene analogues

Acenes are a traditional class of polycyclic aromatic hydrocarbons (PAHs) which attracted considerable interest during the last decade because of their outstanding p-channel semiconductor properties. More recently, N-heteroacenes have been prepared. These molecules have been shown to be more stable and can exhibit n-channel semiconductor properties. Inspired by these archetype PAHs, we synthesized a novel class of highly persistent azahexacene analogues 3 a-d. These molecules are composed of a core of four fused five-membered rings derived from their respective diketopyrrolopyrroles. These new π-conjugated scaffolds show broad and intense absorption in the visible region and possess low-lying HOMO and LUMO levels, leading to much better stability compared to that of acenes and most heteroacenes.