A Triply Negatively Curved Graphenic Macrocycle

Negatively curved nanographenes have attracted extensive research interest due to their unique topological characteristics. Although various saddle-shaped negatively curved nanographenes have been successfully synthesized, macrocycles with multiple negative curvatures remain rarely investigated. Herein, we present the synthesis and physical properties of a novel triply negatively curved graphenic macrocycle (TNM), which contains three negative curvature regions within its cyclic framework. Single-crystal X-ray diffraction unambiguously confirmed the triangular cyclic topology incorporating 12 heptagonal rings. Theoretical calculations of aromaticity reveal that the heptagonal rings exhibit nonaromatic character, while the TNM macrocycle possesses localized aromaticity. Furthermore, the electron-rich cavity of TNM enables stable host-guest interactions with C60 and C70, affording significantly stronger binding affinities than those of the parent negatively curved nanographene monomer. The present TNM macrocycle exhibits a distinctive topological architecture defined by multiple negative curvature regions, serving as a well-defined conjugated segment of carbon nanotori.