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The metal-carbon triple bonds and carbon-carbon triple bonds are both highly unsaturated bonds. As a result, their reactions tend to afford cycloaddition intermediates or products. Herein, we report a reaction of M≡C and C≡C bonds that affords acyclic addition products. These newly discovered reactions are highly efficient, regio- and stereospecific, with good functional group tolerance, and are robust under air at room temperature. The isotope labeling NMR experiments and theoretical calculations reveal the reaction mechanism. Employing these reactions, functionalized dπ-pπ conjugated systems can be easily constructed and modified. The resulting dπ-pπ conjugated systems were found to be good electron transport layer materials in organic solar cells, with power conversion efficiency up to 16.28% based on the PM6: Y6 non-fullerene system. This work provides a facile, efficient methodology for the preparation of dπ-pπ conjugated systems for use in functional materials.

Full-carbon electronics at the scale of several angstroms is an expeimental challenge, which could be overcome by exploiting the versatility of carbon allotropes. Here, we investigate charge transport through graphene/single-fullerene/graphene hybrid junctions using a single-molecule manipulation technique. Such sub-nanoscale electronic junctions can be tuned by band gap engineering as exemplified by various pristine fullerenes such as C60, C70, C76 and C90. In addition, we demonstrate further control of charge transport by breaking the conjugation of their π systems which lowers their conductance, and via heteroatom doping of fullerene, which introduces transport resonances and increase their conductance. Supported by our combined density functional theory (DFT) calculations, a promising future of tunable full-carbon electronics based on numerous sub-nanoscale fullerenes in the large family of carbon allotropes is anticipated., All-carbon electronics holds promise beyond the conventional silicon-based electronics, but it remains challenging to manufacture them with well-defined structures thus tunability. Tan et al. control charge transport in single-molecule junctions using different fullerenes between graphene electrodes.

Bilayer graphene consists of two stacked graphene layers bound together by van der Waals interaction. As the molecular analog of bilayer graphene, molecular bilayer graphene (MBLG) can offer useful insights into the structural and functional properties of bilayer graphene. However, synthesis of MBLG, which requires discrete assembly of two graphene fragments, has proved to be challenging. Here, we show the synthesis and characterization of two structurally well-defined MBLGs, both consisting of two π−π stacked nanographene sheets. We find they have excellent stability against variation of concentration, temperature and solvents. The MBLGs show sharp absorption and emission peaks, and further time-resolved spectroscopic studies reveal drastically different lifetimes for the bright and dark Davydov states in these MBLGs., Molecular bilayer graphene — a discrete assembly of two stacked graphene fragments — is challenging to produce in pure form. Here, the authors are able to synthesize and characterize stable molecular bilayer graphenes by the π−π stacking of two identical, well-defined nanographene sheets.

Chemical functionalization is one of the most powerful and widely used strategies to control the properties of nanomaterials, particularly in the field of graphene. However, the ill-defined structure of the present functionalized graphene inhibits atomically precise structural characterization and structure-correlated property modulation. Here we present a general edge chlorination protocol for atomically precise functionalization of nanographenes at different scales from 1.2 to 3.4 nm and its application in graphene nanoribbons. The well-defined edge chlorination is unambiguously confirmed by X-ray single-crystal analysis, which also discloses the characteristic non-planar molecular shape and detailed bond lengths of chlorinated nanographenes. Chlorinated nanographenes and graphene nanoribbons manifest enhanced solution processability associated with decreases in the optical band gap and frontier molecular orbital energy levels, exemplifying the structure-correlated property modulation by precise edge chlorination., Chemical functionalization of graphene is a useful method for modulating its properties, although this is limited by a lack of control and resulting in poorly defined structures. Here the authors report the atomically precise chlorination of nanographenes and apply the methods to graphene nanoribbons.

A carbon heptagon ring is a key unit responsible for structural defects in sp2-hybrized carbon allotropes including fullerenes, carbon nanotubes and graphenes, with consequential influences on their mechanical, electronic and magnetic properties. Previous evidence concerning the existence of heptagons in fullerenes has been obtained only in off-line halogenation experiments through top-down detachment of a C2 unit from a stable fullerene. Here we report a heptagon-incorporating fullerene C68, tentatively named as heptafullerene[68], which is captured as C68Cl6 from a carbon arc plasma in situ. The occurrence of heptagons in fullerenes is rationalized by heptagon-related strain relief and temperature-dependent stability. 13C-labelled experiments and mass/energy conservation equation simulations show that heptafullerene[68] grows together with other fullerenes in a bottom-up fashion in the arc zone. This work extends fullerene research into numerous topologically possible, heptagon-incorporating isomers and provides clues to an understanding of the heptagon-involved growth mechanism and heptagon-dependent properties of fullerenes., Chemical manipulation of fullerenes has allowed the production of heptagon-containing fullerenes, but they have not been synthesised using bottom-up approaches. Here, a heptagon-containing fullerene[68] is obtained as C68Cl6 from a carbon arc plasma.