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.