4nπ Stable Multitasking Azapentacene: Acidochromism, Hole Mobility, and Visible Light Photoresponse.

Herein, we describe the synthesis, characterization, and optoelectronic investigation of a stable 4nπ dihydrotetraazapentacene derivative. The neutral dihydrotetraazapentacene contains a 24π-conjugated -heteroacene core with two phenyl pendants appended thereof. The exceptional stability of this formally antiaromatic π-system is attributed to the fused dihydropyrazine ring, which has ethenamine (enamine) conjugations, and hence, the π-electrons delocalize over the nearly planar azapentacene core to endow with a global aromatic characteristic.