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.