The packing motifs change for [11], and [12]helicene where there are π-stacked chains of alternating enantiomers (Fig. ). These motifs are most likely seen in these helicenes rather than mid-length helicenes as there is a (near) full rotation of the helix, which promotes end-to-end terminal ring π -π interactions. Comparing these motifs to those found in [6]helicene shows that [11] and [12]helicene contain structural motifs that are similar to motifs that consistently resulted in calculated hole mobilities greater than 1 cm 2 V -1 s -1 in [6]helicene. For [11]helicene, the racemic structure is substantially higher in energy than the global minimum enantiopure structure (above the polymorphic window), and so is unlikely to form. However, the racemic polymorph of [12]helicene is the global minimum and so perhaps a solid form of [12]helicene may exhibit a similar high hole mobility as calculated for the [6]helicene polymorphs, making it a good candidate for charge mobility testing.