Dibenzannulated peri -acenoacenes from anthanthrene derivatives.

A series of dibenzannulated phenyl-annulated [4,2] peri -acenoacenes have been synthesized in three straightforward steps from 4,10-dibromoanthanthrone (vat orange 3). The phenyl bisannulation of [4,2] peri -acenoacene provides extra stability by increasing the overall aromatic character of the molecules, and allows for a 45-80% increase of the molar extinction coefficient ( ε ) compared to their [5,2] peri -acenoacene isomers. Depending on the substituents attached to the π-conjugated core, some derivatives exhibit strong aggregation in the solid state with association constant ( K a ) up to 255 M -1 , resulting in a significant broadening of the absorption spectrum and a substantial decrease of the bandgap value (more than 0.3 V) from solution to the solid state. One [4,2] peri -acenoacene derivative was doubly reduced using cesium and the crystal structure of the resulting salt has been obtained. Field-effect transistors showing a temperature-dependent hole mobility have been tested.