Constructing 1-Ethoxyphenanthro[9,10-e]acephenanthrylene for the Synthesis of a Polyaromatic Hydrocarbon Containing a Formal Azulene Unit

Abstract

peri-Acenoacenes are attractive synthetic targets, but their nonbenzenoid isomeric counterparts were unnoticed. 1-Ethoxyphenanthro[9,10e]acephenanthrylene 8 was synthesized and converted to azulene-embedded 9, which is a tribenzo-fused non-alternant isomeric motif of peri-anthracenoanthracene. Aromaticity and single-crystal analyses suggested a formal azulene core for 9, which showed a smaller highest occupied molecular orbital (HOMO)−lowest unoccupied molecular orbital (LUMO) energy gap with a charge-transfer absorption band and brighter fluorescence than 8 (quantum yield (Φ): 9 = 41.8%, 8 = 8.9%). The reduction potentials of 8 and 9 were nearly identical, and the observations were further supported by density functional theory (DFT) calculations.

Luminescent Chiral Furanol‐PAHs via Straightforward Ni‐Catalysed Csp2−F Functionalization: Mechanistic Insights into the Scholl Reaction

“…In order to have full control of the size and edge effects of these compounds, [8] tedious bottom‐up nanographene precursor synthesis has to be undertaken prior to final ring‐fusion graphitization via oxidative cyclodehydrogenation under acidic conditions (Scholl reaction) [9] . A large variety of methodologies have been published to reach valid pre‐Scholl precursors [9a,10] including cross‐coupling reactions, [11] annulative π‐extension (APEX), [12] cycloadditions [9a] and cross‐cyclotrimerization of arynes (Figure 1). [13]…”