A theoretical study on the interaction between well curved conjugated systems and fullerenes smaller than C60or larger than C70

A large body of data exists about the interaction between curved π systems and C60 or C70. However, little is known about the interaction with fullerenes smaller than C60 or larger than C70. To fill that gap, we studied, by means of density functional theory (M06-2X), the interaction between corannulene, pentaindenocorannulene, C60H28 buckycatcher and the following fullerenes: C44, C50, C80, C90, C100, C180 and C240. For fullerenes smaller than C60, their high reactivity facilitated the covalent addition to the hosts assayed. Yet, the reaction energies determined for the covalent addition were comparable to those calculated for the formation of supramolecular complexes. Thus, the receptor may host a fullerene and at least have another one attached. As expected, for fullerenes larger than C70, supramolecular complexes were preferred over covalent assemblies. The binding energies with bowls increased with the size of the fullerenes in a non-monotonic fashion since they depended on the shape of the fullerene. Indeed, for one C80 isomer, it is possible to find a region which forms a complex with corannulene that is stronger than C60@corannulene, while another region exists whose interaction with corannulene is weaker. As the size of the fullerene becomes larger, ball–socket interactions are weakened, and CH–π interactions become important, accounting for the large interaction determined for corannulene and graphene. Finally, for the buckycatcher, the maximum encapsulation energy among the fullerenes assayed was displayed by C90. The fullerenes C80, C90 and C100 formed complexes with the buckycatcher which are stronger than in C60@buckycatcher. Copyright © 2014 John Wiley & Sons, Ltd.