Theoretical ab initio study of substituted benzene trimer: Interplay between hydrogen bonding and π-π interactions

The interplay between two important noncovalent interactions involving aromatic rings is studied by means of ab initio calculations (RI-MP2/aug-cc-pVTZ//RI-MP2/aug-cc-pVDZ level of theory). We demonstrate that synergetic effects are present in complexes where hydrogen bonding interactions and pi-pi interactions coexist and that these effects are transmitted through the space to a third aromatic ring. The pi-pi interaction is influenced by the presence/absence of hydrogen bonding interactions that are established in a third pi-system far from the stacking interaction. These synergetic effects have been studied using energetic and geometric criteria and the Bader's theory of atoms in molecules. (C) 2011 Elsevier B.V. All rights reserved.