Polycyclic aromatic compounds containing fully unsaturated five-membered ring(s) have been intensively studied because of their unique properties, which include high electron affinity and reactivity. Reported herein is an efficient route for the synthesis of tetrabenzo-fused pyracylene, which comprises pyracylene and tetracene segments, using intramolecular oxidative C-H coupling. It was shown to possess high electron affinity and was found to undergo addition reactions with n-butyllithium or benzyne. These reactions led to either a 1,4-addition compound or triptycene-type adduct with a curved or planar π-system, respectively. Although these compounds exhibited similar sky-blue emissions in a dilute solution, the emission band of the 1,4-addition compound was significantly red-shifted in the solid state and exhibited intense yellow emission attributable to the excimer, while the triptycene-type adduct retained the intense blue color emission in the solid state.
Keywords: X-ray diffraction; fluorescence; fused-ring systems; hydrocarbons; π interactions.
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