Substituent effects in the π⋯π interaction between graphene and benzene: An indication for the noncovalent functionalization of graphene

The origin of the substituent effects in the π⋯π interaction between graphene and benzene has been uncovered by using large-scale symmetry adapted perturbation theory computations (up to 210 atoms and 3174 basis functions). The results show that the substituent effects in the π⋯π interaction between graphene and benzene are quite different from those reported for the benzene dimer. No correlation was found between the interaction energies and the Σσm values or the Σ|σm| values of the substituted benzenes. In most cases, the substituent effects in the π⋯π interaction between graphene and benzene can be explained by the differences in the dispersion interactions or the van der Waals surface areas of the substituted benzenes. However, for the dimers accompanied by efficient interfacial charge transfer which is a necessary condition for the aromatic molecules to tailor the electronic properties of graphene through noncovalent π⋯π stacking interaction, electrostatic, induction, and exchange-repulsion contributions are all significant to the total interaction energy although the dispersion interaction is still the major source of attraction.