Synthesis and Crystal Structure of a [70]Fullerene–Pentacene Monoadduct

We succeeded in the first isolation of a single pure regioisomer of a C70–acene monoadduct. 1,9-Diels–Alder monoadducts of C70 with pentacene derivatives were obtained by not only the Diels–Alder reaction but also a one-pot reaction using stable dihydropentacene derivatives, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and C70. The X-ray crystallographic study of a single pure regioisomer 2b confirmed positions of the linkage between C70 and acenes for the first time, and revealed unique columnar stacks.