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.