Dithieno-Fused Polycyclic Aromatic Hydrocarbon with a Pyracylene Moiety: Strong Antiaromatic Contribution to the Electronic Structure

A synthetic route
to dithieno-fused CP-PAHs with a pyracylene segment
is reported. A combination of experimental and theoretical studies
revealed a strong contribution of antiaromatic character to the electronic
structure of this dithieno-fused CP-PAH. Anisotropy of current-induced
density (ACID) calculations indicated a significantly increased paramagnetic
ring current on the two pentagonal rings, which is more prominent
than that of the dibenzo-fused analogue. Furthermore, enhanced electron
affinity and a consequently decreased HOMO–LUMO gap were observed
for this dithieno-fused CP-PAH.