All‐Carbon Scaffolds by Rational Design

Abstract

The search for new molecular and regular polymeric allotropes of carbon has greatly stimulated the preparation and investigation of pi-conjugated acetylenic macrocycles, which often represent substructures of proposed 2D carbon networks. Perethynylated dehydroannulenes, expanded radialenes, and radiaannulenes with large, multi-nanometer-sized all-carbon cores are potent electron acceptors, and their optoelectronic as well as stability and solubility properties are greatly enhanced by peripheral donor substitution. Acetylenic scaffolding into three dimensions has generated an expanded cubane with a C(56) core, the first representative of a new class of "platonic" objects. Exceptional chiroptical properties displayed by enantiomerically pure alleno-acetylenic, shape-persistent macrocycles promise fascinating perspectives for the development of molecular and supramolecular chiroptical materials.

Cohesion energetics of carbon allotropes: Quantum Monte Carlo study

“…However, it has some well-known limitations; for example, the DFT calculations based on the exchangecorrelation potential within the Local Density Approximation (LDA) tends to overestimate the cohesive energy of a solid. Even with much experimental effort motivated by the promising DFT-based predictions on graphynes, only flakes or building blocks of finite-size graphynes have been synthesized so far [22][23][24] but there has been no successful report yet for fabrication of extended 2D graphynes. The experimental difficulty in the synthesis of graphynes leads us to speculate that the DFT prediction on graphyne energetics may be too optimistic as a result of an intrinsic limitation of the methodology.…”

Carbon-atom wires: 1-D systems with tunable properties

“…A study reported the synthesis of extended graphdiyne films even though there is no direct evidence for the ordered structure of the system. 169 On the contrary, sp-sp 2 -carbon molecular building blocks for extended graphyne and graphdiynes have been produced by Diederich and co-workers, 170,171 by Haley and coworkers 162,[172][173][174] and by other groups. 175 Very recently conductivity measurements have been performed on model sp-sp 2 -molecules (i.e., carbo-benzene and carbo-n-butadiene) at the single molecule level by means of the scanning tunnelling microscopy break junction method.…”

Competition for Graphene: Graphynes with Direction-Dependent Dirac Cones

“…1 can be assumed to be chemically stable. Indeed, finite building blocks and cutouts have already been synthesized [22,23,[25][26][27][28][29][30], and first steps towards the preparation of extended graphynes and graphdiynes have been proposed and developed [22,24,26,27]. Future synthesis of graphyne materials might involve the use of surfaces as support and templates in approaches related to the recently reported synthesis of graphene on metal surfaces by chemical vapor deposition of organic precursor molecules [12][13][14][15][16][17][18].…”