Anisotropic Paramagnetic Properties of Metallofullerene Confined in a Metal-Organic Framework

Paramagnetic metallofullerenes have a spherical molecular structure and stable unpaired spin protected by a fullerene cage and have potential applications in quantum information processing, etc. For endohedral azafullerene Y₂@C₇₉N, the N atom on the cage endows the molecule with unpaired spin and is proposed to induce the molecule orientation within the MOF pore via host-guest interaction. Angular-dependent EPR spectroscopy was employed on the Y₂@C₇₉N∪MOF-177 complex to detect the anisotropic paramagnetic properties. These results experimentally confirmed the trend of molecule orientation of Y₂@C₇₉N within MOF-177 under certain conditions, which also induces the presence of several conformers of Y₂@C₇₉N. The additional EPR splittings in Y₂@C₇₉N∪MOF-177 are proposed to originate from partially disordered molecules as well as the N-coupling of Y₂@C₇₉N upon implanting it into the MOF-177 pore. The N-defect on the fullerene cage of Y₂@C₇₉N is expected to be utilized as an anchor to build a three-dimensional spin array within MOF matrix.