Stabilization by Benzannulation: Butterfly Azaacenes

Abstract

Soluble butterfly-shaped tetraazapentacenes and tetraazaheptacenes were prepared by condensation or Stille coupling with a stannafluorene. The stability of the benzo-winged tetraazaheptacene is dramatically increased through the fourfold benzannulation, yet its acene character is retained to a significant extent.

Thiadiazolo‐Azaacenes

“…Reduction potentials are similar to that of A but absorption features are blueshifted. The thiadiazole moieties stabilize a heptacene‐type, very similar to the recently reported tetrabenzo‐stabilized tetraazaheptacene D (Table ; Figure ).…”

Recent progress in well-defined higher azaacenes (n≥ 6): synthesis, molecular packing, and applications

“…The pyrene unit is tilted from the plane, and the p-p overlap is prevented by steric stress from large substituents on the framework. Similar results have also been found in tetraazaheptacene ( 21) 5 and tetraazaoctacenes (5 64 and 7 39 ) that also have large steric hindrance substituents. All these three azaacene molecules packed in a herringbone-type mode without p-p overlapping.…”

“…2 This discovery made researchers realize the tremendous potential of hydroazaacenes/azaacenes in organic electronics. Since then, many synthetic methods such as condensation reactions, [3][4][5] Diels-Alder cycloaddition reactions, 6 palladium-catalysed coupling reactions, 7 etc. [8][9][10][11][12][13] have been developed to prepare a large number of azaacenes.…”

Potential Building Blocks for 1,4‐Dihydro‐N‐heteroacenes

“…They were capped with phenanthrenes at each end to stabilise them. [30] Dimers and trimers of phenylene bridged cyclic azaacenes can be prepared by multiple benzoin diamine condensations or by Buchwald-Hartwig-type palladium-catalysed couplings. [31] A computational comparison of the properties of dihydrotetraazapentacenes and their derivatives with those of acenes has been made.…”