Supramolecular Length-Dependent Encapsulation of C₉₀, C₁₀₀, C₁₂₀, and C₁₃₀: a Shape-Selective Approach to Fullertube Purification

There are no studies on the supramolecular encapsulation of the newly discovered [5,5]C₉₀, -C₁₀₀, -C₁₂₀, and -C₁₃₀ fullertubes, a family of fixed diameter allotropic carbons differing by symmetry and nanotubular length. This permits an opportunity to probe their supramolecular encapsulation and evaluate how fullertube length is influencing the former. We report a nanocapsule with an inner cavity height (14.1 Å) capable of selectively encapsulating fullertubes with a diameter of 7 Å. Results show an increased affinity for encapsulation in proportion to increasing tubular length following a trend of [5,5]C₉₀ < [5,5]C₁₀₀ < [5,5]C₁₂₀ < [5,5]C₁₃₀, as deduced from <i>K</i>_a values, inferred from competition experiments and corroborated by molecular dynamics simulations. This tubular shape selectivity could be leveraged for "tuning" the isolation of giant fullertubes of C₁₅₀-C₂₀₀.