In
chemistry,
pi stacking (also called p–p stacking) refers to attractive, noncovalent interactions between
aromatic rings, since they contain
pi bonds. These interactions are important in
nucleobase stacking within
DNA and
RNA molecules, protein folding, template-directed synthesis, materials science, and molecular recognition, although new research suggests that pi stacking may not be operative in some of these applications. Despite intense experimental and theoretical interest, there is no unified description of the factors that contribute to pi stacking interactions.