Question

How many aromatic rings does it take for helicity to arise?

Answer 1

Helicity: The arrangement of fused aromatic ring in specific manner gives rise to the different configuration due to lack of line of point of symmetry in system as whole this gives rise to asymmetry in fused aromatics which is termed as helicity.

3 ring systems is the maximum ring numbered system that exist in highly planar form beyond it the helicity phenomenon start appearing and with increasing number of ring it becomes stronger and stronger. We can some helical structures in diagram.