Persistent Ambipolar Heptacenes and Their Redox Species.

Sixfold TIPS-ethynylation combined with fourfold bromination of the armchair edges furnishes a long-lived, soluble heptacene; π-extension via Stille coupling accesses a persistent tetrabenzononacene. Both types of acenes were stabilized best by double TIPS-ethynylation on every other benzene ring. Tetrabromoheptacene is an ambipolar transistor material (up to 0.036 cm2  V-1  s-1 n-channel), which was corroborated by generation of its monoanion and monocation.