Indeno[2,1-c]fluorene: a new electron-accepting scaffold for organic electronics.

A new class of fully conjugated indenofluorenes has been synthesized and confirmed by solid-state structure analysis. These indeno[2,1-c]fluorene molecules, containing an antiaromatic as-indacene core (in red), possess high electron affinities and show a broad absorption that reaches into the near-IR region of the electromagnetic spectrum. All of the featured compounds reversibly accept up to two electrons. Their electronic properties make this class of compounds attractive for applications in organic electronic devices.