1,1′-Biaceanthrylene and 2,2′-Biaceanthrylene: Models for Linking Larger Polycyclic Aromatic Hydrocarbons via Five-Membered Rings

We show that polycyclic aromatic hydrocarbon (PAH) chromophores
that are linked between two five-membered rings can access planarized
structures with reduced optical gaps and redox potentials. Two aceanthrylene
chromophores were connected into dimer model systems with the chromophores
either projected outward (2,2′-biaceanthrylene) or inward (1,1′-biaceanthrylene),
and the optical and electronic properties were compared. Only the
planar 2,2′-biaceanthrylene system showed significant reductions
of the optical gaps (1 eV) and redox potentials in relation to the
aceanthrylene monomer. Organic field effect transistors based on 2,2′-biaceanthrylene
were prepared and were found to operate in the hole transport regime
with an average charge carrier mobilities of 1.8 × 10–4 cm2 V–1 s–1.