A study on the aromaticity of [n]phenacenes and [n]helicenes (n = 3-9)

- Both the global and local aromaticity of helicenes and phenacenes is analyzed and discussed.
- Their outer rings are more aromatic than their inner rings.
- The π-sextets in the Clar structure are the primary sources of aromaticity.
- The two terminal rings make the largest aromatic contribution to the whole molecule.