Bowl-Shaped Polyarenes as Concave-Convex Shape Complementary Hosts for C60- and C70-Fullerenes

The X-ray crystal structures of two new cocrystals comprised of C-60 and C-70 fullerenes and a dibenzo[a,g]corannulene bowl, namely, (C28H14)center dot(C-60) and (C28H14)(2)center dot(C-70), are reported. A clear difference is observed between C-60 to C-70, with the latter fullerene molecule being fully ordered and lacking the orientational disorder found in many fullerene co-crystallized products. In the solid state structure of (C28H14)(2)center dot(C-70), two bowl-shaped C28H14 molecules encapsulate the C-70-cage and exhibit a preferential spatial alignment parallel to the longer axis of the fullerene. In this case, dibenzo[a,g]corannulene utilizes only its concave surface for binding, showing a staggered conformation of carbon atoms over the convex surface of C-70-fullerene. In the solid-state structure of (C28H14)center dot(C-60), both convex-convex and convex-concave pi center dot center dot center dot pi interactions are observed between the curved surfaces of C28H14 and C-60. The C-60-core is disordered showing no preferential orientation. In both cases, the formation of pi center dot center dot center dot pi adducts was not observed in solutions of chlorinated benzene solvents from which the co-crystals were grown.