Pyridine, with formula C₅H₅N, can be viewed as a benzene molecule after substitution of a nitrogen atom for a methyne (C-H) group. The hexagonal symmetry is slightly distorted by the substituted nitrogen, represented in blue in the figure. The length of the C-N bonds is 2 pm shorter than the C-C bonds (0.139 nm), the bond angle at the N position is 117°. The molecule possesses a dipole moment having its negative charge on the nitrogen side.

Pyrrole is another aromatic compound incoporating a nitrogen atom, here in a pentagonal ring. The chemical formula is C₄NH₅. Like in benzene, there are six electrons delocalized around the ring, four come the carbon atoms, the two others are provided by the nitrogen. In the context of electrochromism, pyrrole is widely used in the form of polypyrrole polymers.