Semiconducting single crystals comprising segregated arrays of complexes of C₆₀

Although pristine C₆₀ prefers to adopt a face-centered cubic packing arrangement in the solid state, it has been demonstrated that noncovalent-bonding interactions with a variety of molecular receptors lead to the complexation of C₆₀ molecules, albeit usually with little or no control over their long-range order. Herein, an extended viologen-based cyclophane-ExBox₂⁴⁺-has been employed as a molecular receptor which, not only binds C₆₀ one-on-one, but also results in the columnar self-assembly of the 1:1 inclusion complexes under ambient conditions. These one-dimensional arrays of fullerenes stack along the long axis of needle-like single crystals as a consequence of multiple noncovalent-bonding interactions between each of the inclusion complexes. The electrical conductivity of these crystals is on the order of 10^-7 S cm^-1, even without any evacuation of oxygen, and matches the conductivity of high-quality, unfunctionalized C₆₀-based materials that typically require stringent high-temperature vaporization techniques, along with the careful removal of oxygen and moisture, prior to measuring their conductance.