Parallel interactions of aromatic and heteroaromatic molecules

Abstract

Parallel interactions of aromatic and heteroaromatic molecules are very important in chemistry and biology. In this review, recent findings on preferred geometries and interaction energies of these molecules are presented. Benzene and pyridine were used as model systems for studying aromatic and heteroaromatic molecules, respectively. Searches of Cambridge Structural Database show that both aromatic and heteroaromatic molecules prefer interacting at large horizontal displacements, even though previous calculations showed that stacking interactions (with offsets of about 1.5 angstrom) are the strongest. Calculations of interaction energies at large horizontal displacements revealed that the large portion of interaction energy is preserved even when two molecules do not overlap. These substantial energies, as well as the possibility of forming larger supramolecular structures, make parallel interactions at large horizontal displacements more frequent in crystal structures than stacking interactions.