Aromatization of Benzannulated Perylene-3,9-diones: Unexpected Photophysical Properties and Reactivity

Highly
unusual properties of acene-based quinones 1A and 1T are reported. They undergo an unexpected combination
of Michael and carbonyl additions of aryllithium leading to new triarylated
benzoperylenes 3A and 3T. Uncharacteristically
for quinones, 1A and 1T display vibronically
split absorption bands and small Stokes shifts. The absorption/emission
spectra of the highly emissive 1A are almost indistinguishable
from those of the aromatized 3A. Additional benzene rings
cause a counterintuitive blue shift of the aromatic derivatives (2T/3T), but an expected red shift was observed
for the quinone (1T). This behavior is fully supported
by DFT calculations and rationalized by considering the longest conjugation
path.