Synthesis and Structural Evaluation of Closed-Shell Folded and Open-Shell Twisted Hexabenzo[5.6.7]quinarene

We describe the synthesis and characterization of hexabenzo[5.6.7]quinarene, which is composed of an anthraquinodimethane (AQD) central core that is end-capped with fluorenyl and dibenzosuberenyl groups. Due to strong intramolecular spin-spin interaction through the central AQD unit, this compound is obtained as a stable folded form. Isolation of the stable twisted dication by oxidation and reduction of the dication yields a twisted triplet species, which thermally reverts to the folded form. This is a spin-switching system based on a combination of chemical oxidation/reduction and thermal stimulation.