Straightforward supramolecular purification of C84 from a fullerene extract

Abstract

Selective purification of fullerene mixtures via supramolecular encapsulation is an appealing strategy to circumvent the tedious HPLC chromatographic purification protocols. In this work, we utilize tetragonal prismatic nanocapsules of different cavity sizes and shapes to selectively encapsulate C₈₄ from a mixture containing fullerenes ranging from C₆₀ to C₉₆ (fullerene extract), allowing the enrichment of the C₈₄ content from 0.7% to 86%. Moreover, terphenyl-based extra-large nanocapsules were prepared for the first time that can strongly bind the dumbbell-shaped azafullerene dimer (C₅₉N)₂ as a guest. Competition experiments between (C₅₉N)₂ and C₈₄ allowed the deduction of K_a > 1.0 × 10⁷ M⁻¹ for C₈₄ in nanocapsule 6·(BArF)₈. The preference of nanocapsule 7·(BArF)₈ to bind C₈₄-D₂(22) among all IPR-isomers is also discussed.