5,14-Diaryldiindeno[2,1‑f:1′,2′-j]picene: A New Stable [7]Helicene with a Partial Biradical Character

5,14-Diaryldiindeno­[2,1-f:1′,2′-j]­picene (DDP, 1), a thermally and chemically stable helical arene, can be prepared from 1,4-bis­[2-(arylethynyl)­phenyl]­benzene in four synthetic steps. Its helical backbone, which incorporates an o-quinodimethane moiety, was verified by X-ray crystallography, and this structural feature results in a very high barrier to racemization (exceeding 50 kcal/mol). DDP possesses versatile and promising properties, including a small HOMO–LUMO energy gap (1.31 eV for the dimesityl-substituted derivative 1ab), an electron spin resonance (ESR)-active character, a small triplet–singlet energy gap (4.75 kcal/mol), broad photoabsorption covering the ultraviolet, visible, and near-infrared (NIR) regions, two-photon absorption in the NIR range, and respectable ambipolar charge-transport behavior in a solution-processed organic field-effect transistor.