Distance Measurement of a Noncovalently Bound Y@C₈₂ Pair with Double Electron Electron Resonance Spectroscopy

Paramagnetic endohedral fullerenes with long spin coherence times, such as N@C₆₀ and Y@C₈₂, are being explored as potential spin quantum bits (qubits). Their use for quantum information processing requires a way to hold them in fixed spatial arrangements. Here we report the synthesis of a porphyrin-based two-site receptor 1, offering a rigid structure that binds spin-active fullerenes (Y@C₈₂) at a center-to-center distance of 5.0 nm, predicted from molecular simulations. The spin-spin dipolar coupling was measured with the pulsed EPR spectroscopy technique of double electron electron resonance and analyzed to give a distance of 4.87 nm with a small distribution of distances.