A DFT-D study of stacking interactions between substituted buckybowls with fullerenes

Stacking interactions between substituted buckybowls (corannulene and sumanene) with fullerenes (C₆₀ and C₇₀) were studied at the B97-D2/TZVP level. Corannulene and sumanene monomers were substituted with five and six Br, Cl, CH₃, C₂H or CN units, respectively. This work was carried out for supplement our previous work of the study of substituent effects in corannulene dimers, in which C₆₀-like (‘fullerene copy’, corannulene with curvature of buckminsterfullerene, C₆₀) was employed to imitate the concave-convex interactions between substituted corannulenes and fullerene C₆₀. Despite the promising results using C₆₀-like, different trends of effects of substituent were obtained for our later calculations using C₆₀. So, C₆₀-like, does not seem representative for imitate the concave-convex interactions between substituted corannulenes and C₆₀. The calculations with fullerenes indicate that all substituents provide a substantial increase of the interaction energy compared with unsubstituted buckybowls, as observed previously. However, substitution with CH₃ groups is more favorable than substitution with CN groups, obtained using C₆₀-like. Sumanene substituted with six CH₃ groups caused the largest effect increasing the interaction energy about 11 kcal.mol^-1 compared with unsubstituted corannulene for both fullerenes. CH-π interactions seem the great responsible for this increase. Stacking interactions between buckybowls evaluated and fullerene C₇₀ show interaction energies quite similar to that obtained with C₆₀. Therefore, it is not expected that buckybowls evaluated to specifically bind one of the fullerenes when exposed to the C₆₀/C₇₀ mixture.