Simple aromatic rings
In the basic aromatic rings, the lone pair of electrons is not part of the aromatic system and extends in the plane of the ring. This lone pair is responsible for the basicityof these nitrogenous bases, similar to the nitrogen atom in amines. In these compounds, the nitrogen atom is not connected to a hydrogen atom. Examples of basic aromatic rings are pyridine or quinoline. Several aromatic rings contain basic as well as non-basic nitrogen atoms, e.g., imidazole and purine.