Illustrated Glossary of Organic Chemistry

Aromatic-aromatic interaction (aromatic stacking, pi stacking): A noncovalent attractive force between two aromatic rings. Alignment of positive electrostatic potential on one ring with negative electrostatic potential on another ring forms an offset stack, or in pure benzene, a T-shaped stack. Also called 'pi stacking' but this label is misleading because it implies that stacking might occur in any structure with pi electrons.


Offset stacking


T-stacking


Stacked base pairs cause aromatic-aromatic interactions in DNA.