Interaction between anions and substituted molecular bowls

Abstract

Complexes formed by anions and substituted molecular bowls were studied by means of computational methods. The bowls consisted of corannulene molecules substituted with five or ten F, Cl, or CN groups, whereas Cl⁻, Br⁻ and BF₄⁻ were the anions considered. Substitution with F, Cl and CN hardly affects the geometry of the bowl, but produces an inversion of the molecular electrostatic potential of the bowls, which becomes positive over the two faces of the bowl, therefore interacting favorably with anions. In all cases considered, the most stable complex presents the anion interacting with the concave side of the bowl. The strength of the interaction roughly follows the values of molecular electrostatic potential, being more stable as more positive is the potential. The preference of anions to interact with the concave side of the bowls has its origin in stronger electrostatic and dispersion interactions. Though the solvent produces an important decrease in the stability of the complexes, the results suggest the possibility of employing these substituted buckybowls as anion receptors with a preferential concave complexation, especially for large anions.