Diels–Alder Reaction of C60 and C70 Fullerenes Confined in a Nanohoop: A Theoretical Study

The reactivity of the bonds in fullerenes plays an important role in the chemical modification of their structures. It has been proved that fullerenes can be included as a guest molecule in the conjugated [n]cyclodibenzopentalene nanohoop to form intriguing host–guest systems with potential organic material applications. Experimental results show that the strength of the interaction between fullerenes and [n]cyclodibenzopentalenes is very high. Here, we theoretically investigated the effect of encapsulating C60 and C70 fullerenes in the [4]cyclodibenzopentalene nanohoop on the reactivity of the bonds in C60 and C70. The calculated results indicate that the binding energy between the nanohoop and C60 is 2.7 kcal mol−1 higher than that between the nanohoop and C70. Compared with the isolated fullerenes, the differences between the reactivities of the bonds in C60 and C70 enclosed in the nanohoop are smaller because of their interaction with the nanohoop. The distortion/interaction model was used to analyze the underlying reasons. We believe that the results of this study will aid in the research fields of supramolecular chemistry and fullerene chemistry.