An Azulene-Fused Tetracene Diimide with a Small HOMO-LUMO Gap.

A newly prepared tetraazulene-fused tetracene diimide (TA-fused TDI) showed absorption in the near-IR region owing to the effective extension of the π-conjugated system as well as a large two-photon absorption cross-section (σ(2) =2140 GM) at 950 nm. Four reversible reduction processes and n-type semiconductivity were also confirmed as attractive electronic properties of this compound.