Theoretical insight into complexation between cyclocarbons and C60 fullerene

This work conducts the comprehensive theoretical study on the non-covalent complexation between cyclocarbons of different sizes and C60 fullerene for the first time. The binding energy between cyclocarbons and C60 fullerene is observed to be significantly stronger than that between two C18 or two C60 fullerenes, indicating a particularly strong affinity between them. The cyclocarbons and C60 fullerene can spontaneously assemble into non-covalent complexes characterized by - stacking in the gas phase at room temperature, and the hydrophobic effect caused by the solvent environment can promote this binding. From C18 to C34, the binding strength with C60 fullerene increases almost linearly with the increase of cyclocarbon size, and the C34@C60 dimer exhibits a perfect nano-Saturn structure. By studying the trimers of 2:1 form between cyclocarbons and C60 fullerene, it is observed that as the ring size increases, the angle between the two cyclocarbons gradually decreases. In the largest trimer we studied, C60@2C34, the fullerene is symmetrically surrounded by two cyclocarbons. The results on the trimers formed by cyclocarbon and C60 fullerenes in a 1:2 ratio showed when the size of the cyclocarbon sandwiched between two fullerenes is not quite large, the trimers exhibit an ideal dumbbell-like structure, and the presence of the first fullerene has a significant synergistic effect on the binding of the second one. Combined with the analysis of interaction energy and van der Waals potential, we found that the cyclocarbon greatly promotes the non-covalent dimerization of fullerenes, which acted as a “molecular glue”.