Synthesis of 5,12-Diazapentacenes and Their Properties.

An efficient synthesis via a precursor route to a new class of linear dialkyldiaminoazapentacenes is reported. The synthetic route involves the coupling of 4-substituted aniline derivatives to 2,5-dibromoterephthalonitrile via Buchwald-Hartwig amination followed by an acid-mediated cyclization to furnish the diazapentacenes. These reactions occur under short reaction times (<2 h), provide high yields (77-99%), and do not require column chromatography for purification. The electrochemical and optical properties of the diazapentacenes were evaluated, and the values indicate that these molecules are promising n-type materials for organic electronic devices. The photostability of these molecules was significantly greater than unsubstituted acenes. Their method of degradation via endoperoxide generation was confirmed by X-ray crystallography and mass spectrometry.