Systematic Enumeration of sp³ Nanothreads

Abstract

Slow decompression of crystalline benzene in large-volume high-pressure cells has recently achieved synthesis of a novel one-dimensional allotrope of sp(3) carbon in which stacked columns of benzene molecules rehybridize into an ordered crystal of nanothreads. The progenitor benzene molecules function as six-valent one-dimensional superatoms with multiple binding sites. Here we enumerate their hexavalent bonding geometries, recognizing that the repeat unit of interatomic connectivity ("topological unit cell") need not coincide with the crystallographic unit cell, and identify the most energetically favorable cases. A topological unit cell of one or two benzene rings with at least two bonds interconnecting each adjacent pair of rings, accommodates 50 topologically distinct nanothreads, 15 of which are within 80 meV/carbon atom of the most stable member. Optimization of aperiodic helicity reveals the most stable structures to be chiral. We generalize Euler's rules for ring counting to cover this new form of very thin one-dimensional carbon, calculated their physical properties, and propose a naming convention that can be generalized to handle nanothreads formed from other progenitor molecules.

Diamond Nanothread as a New Reinforcement for Nanocomposites

“…Also, the structure of the DNT can be further altered by changing the connectivity of the constituent carbon rings. [ 12,13 ] Together with the hydrogen exposure surface of the DNT that is easy for the chemical modifi cations, such imperfections are expected to enhance the interfacial load transfer, and make the DNT an ideal reinforcement candidate for nanocomposites. Here, load transfer is defi ned as the load bearing ability of the interface, which is related to the energy required to "break" the interface and pull out the DNT.…”

Monochromated Low-Dose Aberration-Corrected Transmission Electron Microscopy of Diamondoid Carbon Nanothreads

“…Their diamond-like structure is predicted to have interesting mechanical properties that are on par with or greater than carbon nanotubes [2]. In addition, the solid-state synthesis is entirely driven by kinetic control and devoid of waste, which may open up new routes to fabricate efficient carbon nanomaterials [3,4]. Therefore, it is important to probe the atomic and chemical structure of nanothreads to elucidate the reaction mechanisms that result in their synthesis and determine their macroscale physical and chemical properties.…”

Coexistence of Normal and Auxetic Behavior in a Thermally and Chemically Stable sp3 Nanothread: Poly[5]asterane

“…[3] Ap olymerp hase of compressedb enzene wasa lso predicted by first-principles calculations. It is thereforel ikely that an efficient synthetic technique to produce sp 3 -hybridized one-dimensional nanostructures is not far away.Computational studies on one-dimensional nanostructures consisting of sp 3hybridized carbona toms, such as polytwistane, [5] polytriangulane, [6] and sp 3 -hybridizedn anothreads, [7] have gained momentum, as they are also promising candidates to compete with sp 2 -hybridized carbon nanotubes and graphene when hard-ness of the materials is of interest. It is thereforel ikely that an efficient synthetic technique to produce sp 3 -hybridized one-dimensional nanostructures is not far away.Computational studies on one-dimensional nanostructures consisting of sp 3hybridized carbona toms, such as polytwistane, [5] polytriangulane, [6] and sp 3 -hybridizedn anothreads, [7] have gained momentum, as they are also promising candidates to compete with sp 2 -hybridized carbon nanotubes and graphene when hard-ness of the materials is of interest.…”

“…It is thereforel ikely that an efficient synthetic technique to produce sp 3 -hybridized one-dimensional nanostructures is not far away.Computational studies on one-dimensional nanostructures consisting of sp 3hybridized carbona toms, such as polytwistane, [5] polytriangulane, [6] and sp 3 -hybridizedn anothreads, [7] have gained momentum, as they are also promising candidates to compete with sp 2 -hybridized carbon nanotubes and graphene when hard-ness of the materials is of interest. [7,8] Carbon-based polyprismanes,aclass of one-dimensional nanostructures, are stacked layerso fd ehydrogenated cycloalkane molecules, namely prismanes (Scheme 1a). [5,6] Furtherc omputational studies have predictedt hat polytwistane also has substantial mechanical stability.…”

“…[5,6] Furtherc omputational studies have predictedt hat polytwistane also has substantial mechanical stability. Threem embers of this family, namely, [ 3]prismane, [11] [4]prismane (cubane), [12] and [5]prismane [13] were synthesized.Experimental and computationala ttempts to find intramolecular [2+ +2] photocycloaddition pathways toward [7]prismane and it analogues were also made in the past. [9] The prismanesa nd polyprismanesa re highly strained materials [9,10] in whichthe bond angles differ considerably from the usual tetrahedral angle (109.58)o fs p 3 -hybridized carbon.…”