1,2,3-Tri(9-anthryl)benzene: Photophysical Properties and Solid-State Intermolecular Interactions of Radially Arranged, Congested Aromatic π-Planes.

We report the Negishi coupling based synthesis of 1,2,3-tri(9-anthryl)benzene derivatives containing three radially arranged anthracenes in a π-cluster. In the crystalline state of the unsubstituted derivative, intermolecular π-π and CH-π interactions between the anthracene units drive the formation of the two-dimensional packing structure. Owing to though-space π-conjugation between anthracene units, the substances have unique electronic properties. The excited-state dynamic behavior occurring between the three anthracene moieties, such as exciton localization/delocalization, was elucidated by means of transient absorption measurements and quantum chemical calculations. Interestingly, even though the three anthracenes are closely oriented with approximately 3.0 Å between their C-9 positions, exciton localization on two anthracene units is energetically favorable because of the flexible nature of the radially arranged aromatic rings.