Ring-annelated corannulenes as fullerene receptors. A DFT-D study

Abstract

Stacking π⋯π interactions of ring-annelated corannulenes with fullerenes C₆₀ and C₇₀ were studied at the B97-D level. For this purpose three-, four-, and five-membered rings (saturated and unsaturated) were annelated to the five rim bonds of corannulene. Substitution effects with NH, O and S units on each one of the five saturated five-membered rings annelated to the rim of corannulene were also evaluated. In all cases, complexation energies were larger than that for the parent compound, corannulene C₂₀H₁₀; in the best case an increase of almost 90% is found. According to our results, the increase of complexation energy is directly related to the increase of the dispersion contribution, where CH⋯π interactions play a very important role. This kind of interaction has special relevance for compounds with saturated annelated rings, where the spatial disposition favours the interaction between hydrogen atoms of CH₂ groups and the π cloud of fullerene. For compounds with unsaturated annelated rings the increase of dispersion is not so pronounced; however, this is fairly offset by the increase of the electrostatic interaction. Finally, stacking interactions between ring-annelated corannulenes and fullerene C₇₀ show complexation energy values quite similar to those obtained with fullerene C₆₀.