Topology-dependent conjugation effects in graphdiyne molecular fragments

Designing All Graphdiyne Materials as Graphene Derivatives: Topologically Driven Modulation of Electronic Properties

“…As a general rule, in structures formed by different units, L is found to have a larger effect than h, while H and R dominate over L, and finally, T seems to dominate all over the other units, even if these relative effects have been shown to have a non-negligible dependence on the DFT functional choice, in particular for some peculiar structures. Therefore, we demonstrated that the local topology is strongly responsible for the metallic/semiconductive behavior, while the formation of long conjugation pathways, along which a larger/lower conjugation can occur, seems to play only a minor role, in agreement with the behavior of γ-GDY fragments …”

“…Therefore, we demonstrated that the local topology is strongly responsible for the metallic/semiconductive behavior, while the formation of long conjugation pathways, along which a larger/lower conjugation can occur, seems to play only a minor role, in agreement with the behavior of γ-GDY fragments. 32 These findings give a relevant indication to properly develop new semiconductive sp−sp 2 carbon materials, since they are able to give general and simple topological rules to design new systems built as a proper combination of simple building blocks (h, H, R, L, and T units), where the electronic properties are properly tailored by precisely controlling their topology. This will offer many outcomes in view of applications and some insights into engineering new carbon nanostructured materials with tailored properties.…”

“…Several papers report on the prediction of properties of γ-GDY mainly through density functional theory (DFT) calculations. ,,− From the experimental side, synthetic bottom-up approaches have been successfully employed to produce sub-fragments of GDY of different topologies and dimensions, in particular, by Haley and co-workers. − Later, different papers reported the preparation and characterization of extended 2D GDY sheets prepared through organometallic synthesis techniques, showing promising routes to the production of these systems, even though significant efforts should still be put to further investigate and understand their properties. − Recent advances in on-surface synthesis allow the preparation of hybrid sp–sp 2 carbon nanostructures and their atomic-scale investigation with surface science techniques. ,,− The recent possibilities to realize new systems have opened new opportunities well beyond the sole investigation of their fundamental properties. Hence, the identification of possible guidelines to support the synthetic efforts is mandatory in a knowledge-based research approach.…”

Acetylene-Mediated Electron Transport in Nanostructured Graphene and Hexagonal Boron Nitride

“…The p x p y bands appear very close to E F , which suggests these electronic channels should be readily accessible via moderate electrode bias, doping, or electrostatic gates. The existence of such p x p y bands in AcGrs is, in fact, the main difference between this family of materials and the well-known sp–sp 2 hybridized graphynes − and graphdiynes, − which also display a π-conjugated Dirac cone in their electronic band structure. Bond current analysis of the quantum transport simulations demonstrates that our reported transport mechanism uniquely arises from the interaction between closely packed adjacent acetylene units, which is possible only when acetylenes are connected via zigzag edged, either graphene or BN, nanoribbons.…”

“…This feature arises from its π-conjugated electronic structure and has launched a global search for other π-conjugated 2D carbon allotropes which may host this unique characteristic. In this line, different types of the so-called postgraphene organic Dirac materials (or PGODs) have been theoretically predicted, with the most notable examples being graphynes, − graphdiynes, − and 2D π-conjugated organic polymers. − Importantly, different members of PGODs have been recently synthesized. ,− …”