Synthesis of one-dimensional sp3 carbon nanothread single crystals

Figure Caption: Illustration of the synthesis of one-dimensional sp<sup>3</sup>  carbon nanothread single crystals under slow uniaxial compression.
Figure Caption: Illustration of the synthesis of one-dimensional sp3 carbon nanothread single crystals under slow uniaxial compression.

In general, few single-crystal organic monomers react under topochemical control to produce single-crystal extended solids. Using a slow compression under uniaxial stress, a team using HPCAT facilities has successfully converted polycrystalline or single-crystal benzene monomer into single-crystalline packings of carbon nanothreads, a one-dimensional sp3 carbon nanomaterial. The long-range order over hundreds of microns of these crystals allows them to readily exfoliate into fibers. The mechanochemical synthesis produces macroscopic single crystals despite large dimensional changes caused by the formation of multiple strong, covalent C−C bonds to each monomer. Therefore, it appears not to follow a topochemical pathway, but one guided by uniaxial stress to which the nanothreads consistently align. The robust, reproducible formation of nanothread crystals from benzene suggests that other unsaturated molecular crystals that are unsuitable for topochemical reaction may form single-crystalline packings of polymers or nanothreads upon slow uniaxial compression, providing a general route to synthesizing single crystalline packings of low-dimensional fully or partially saturated carbon-based nanomaterials with extended bonding. More in X. Li et al, J. Am. Chem. Soc., 139, 16343-16349, 2017.