Synthesis of γ-graphyne using dynamic covalent chemistry

Most attempts to synthesize graphynes are limited to using irreversible coupling reactions, which often result in the formation of nanometre-scale materials that lack long-range order. Here the periodically sp–sp2-hybridized carbon allotrope, γ-graphyne, was synthesized in bulk via a reversible dynamic alkyne metathesis of alkynyl-substituted benzene monomers. The balance between kinetic and thermodynamic control was managed through the simultaneous use of two different hexa-alkynyl-substituted benzenes as the comonomers to yield crystalline γ-graphyne. Additionally, the ABC staggered interlayer stacking of the graphyne was revealed using powder X-ray and electron diffraction. Finally, the folding behaviour of the few-layer graphyne was also observed on exfoliation, and showed step edges within a single graphyne flake with a height of 9 nm.