Supramolecular Complexes of C80-Based Metallofullerenes with [12]Cycloparaphenylene Nanoring and Altered Property in a Confined Space

Metallofullerenes have a cage-shaped molecular structure and special properties derived from encapsulated metal atoms. Owing to the ball-like fullerene cage, it is still a challenge to manipulate the metallofullerene molecule and to control its properties. Herein, we use the molecular carbon nanoring of [12]­cycloparaphenylene to hoop the C80-based metallofullerene Y3N@C80 and azafullerene Y2@C79N, resulting in a stable supramolecular complex, induced molecule orientation, changed assembly behavior, and tunable spin state. These supramolecular complexes and their host–guest interactions were systematically characterized by DFT-calculations, spectroscopy, NMR, and electrochemical analysis. Scanning tunneling microscopy was employed to reveal that the metallofullerene guests dominate the assembly process on the Au(111) surface and the [12]­CPP nanoring can change the weak van der Waals forces and influence self-assembly. Moreover, the electron spin in paramagnetic Y2@C79N was employed to percept the host–guest interaction, and it showed anisotropic spin–metal couplings due to its insufficient rotational averaging in a confined space of the nanoring. The special spin character of Y2@C79N⊂[12]­CPP was also investigated in its solid state, and it exhibits the independent spin of Y2@C79N separated by a nanoring. This study provides a strategy to hoop the ball-like C80-based metallofullerenes and modulate their electronic and magnetic properties using a circular nanoring. Metal-induced orientation, self-assembly characters, and susceptible electron spin for these supramolecular complexes reveal a great significance in molecule science and nanotechnology.