Graphdiyne is a new sp- and sp2-hybridized 2D π-conjugated carbon material with unique electronic properties and well-dispersed pores. It has been extensively studied and used in various fields, including catalysis, electronics, optics, and energy storage and conversion. By examining 2D graphdiyne fragments with conjugation, a deeper understanding of its intrinsic structure-property relationships can be gained.
Yongjun Li and colleagues, Chinese Academy of Sciences, Beijing, P. R. China, have synthesized an atomic precise wheel-shaped nanographdiyne composed of six dehydrobenzo  annulenes (DBAs) It is the smallest macrocyclic unit of graphdiyne.
It was created using sixfold intramolecular Eglinton coupling in the hexabutadiyne precursors obtained through sixfold Cadiot–Chodkiewicz cross-coupling of hexaethynylbenzene. To introduce six large hindrance diyne arms into the central benzene ring in one step, the researchers designed 2-methyl-but-3-yn-2-ol groups, rather than steric bulky −Sii-Pr3 groups, into the nanographdiyne precursors. External substituents inhibit the intermolecular alkyne coupling through the protection of large peripheral groups, which has an important impact on the synthesis yield.
The planar structure of the nanographdiyne was determined through X-ray crystallographic analysis. The full cross-conjugation of the six 18π electron circuits yields to π-electron conjugation along the giant π core, allowing for unique electronic properties to emerge. The nanographdiyne has defined energy gaps and can be considered the well-defined molecular cutout of graphdiyne.
The researchers believe that this work offers a feasible method for synthesizing future graphdiyne fragments with different functional groups and/or heteroatom doping, as well as for studying the unique electronic and photophysical properties and aggregation behavior of graphdiyne.
- Synthesis of a Wheel-Shaped Nanographdiyne,
Guilin Hu, Jingyi He, Jing Chen, Yongjun Li,
J. Am. Chem. Soc. 2023.