Idea (2008): The π-electrons take the form of Torus Links for cycles with EVEN linking number, and adhere to 4n+2.
L0a1: Benzene
L2a1: Bernoulli Lemniscate in 3D!
L4a1: Roman mosaics
L6a1: Star of David necklaces.

The Knot atlas and the Knotilus Gallery