Direct Through‐Space Substituent‐π Interactions in Noncovalent Arene–Fullerene Assemblies

Abstract

The arene–arene interactions between electron‐rich and deficient aromatics have been less understood. Herein, we focus on a [60]fullerene π‐surface as an electron‐deficient aromatics. Using a 1H signal of H2O@C60 as a magnetic probe, the presence of benzene–fullerene interactions was confirmed. To investigate substituent effects on the noncovalent arene–fullerene interactions, NMR titration experiments were carried out using an open‐[60]fullerene and a series of substituted benzenes, i.e., PhX (X = NO2, CN, Cl, OMe, H, CH3, and NH2), demonstrating a 1:2 stoichiometry with a positive correlation between stabilization energies upon the first association (ΔG1) and Hammet constants (σm). The destabilization of the self‐assembled structure for X = OMe with a σ‐withdrawing nature clearly showed direct through‐space substituent–π interactions describable by the Wheeler–Houk model while the second association was suggested to be considerably perturbed by the secondary effects.