Linear Non-benzenoid\nIsomer of Acene Fusing Chrysene\nwith Azulene Units

Non-benzenoid polycyclic aromatic hydrocarbons (PAHs)\nhave received\nconsiderable attention owing to their distinctive optical and electrical\nproperties. Nevertheless, the synthesis and optoelectronic application\nof non-benzenoid PAHs remain challenging. Herein, we present a facile\nsynthesis of linear non-benzenoid PAH with an armchair edge, <b>diACh</b>, by fusing chrysene with two azulene units. We systematically\ninvestigated the optical and electrical properties, which were also\ncompared to its isomers, including benzenoid and non-benzenoid zigzag\nedge isomers. <b>diACh</b> exhibits global aromaticity, good\nplanarity, and suitable highest occupied molecular orbital/lowest\nunoccupied molecular orbital energy levels. The protonation of <b>diACh</b> in solution successively forms a stable tropylium cation\nand dication. Moreover, the neutral, cationic, and dicationic states\nof <b>diACh</b> can be transformed with remarkable reversibility\nduring the protonation–deprotonation process, as confirmed\nby ultraviolet–visible absorptions, fluorescence spectra, <sup>1</sup>H nuclear magnetic resonance, and theoretical calculations.\nAdditionally, we fabricate p-type organic field-effect transistor\n(OFET) devices based on <b>diACh</b> with hole mobility up to\n0.026 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>,\nand we further develop OFET-based acid vapor sensors with good sensitivity,\nrecyclability, and selectivity. These findings underscore the unique\nproperties of linear non-benzenoid PAHs with an armchair edge engendered\nby the fusion of azulene with the acene backbone, showcasing prospective\napplications in organic optoelectronics.