Synthesis and Applications of Graphdiyne Derivatives

Graphdiyne (GDY) bearing sp-and sp²-hybridized carbon networks, which is usually artificially synthesized via the in situ homocoupling reaction of hexaethylbenzene on copper foil, is an emerging two-dimensional (2D) carbon allotrope. During preparation, well-defined GDY structures including nanowires, nanowalls, and nanotubes are obtained. Such materials with varying morphologies have been shown to possess promising electronic, chemical, magnetic, and mechanical properties, rendering them applicable in various domains including energy storage, catalysis, and field emission. In addition, replacing hexaethylbenzene with other aryne derivatives under similar synthesis conditions has resulted in the generation of various GDY derivatives. Thus, a series of GDY derivatives with specific structures and controllable sizes have been readily prepared in recent years. Aryne precursors typically contain polycyclic aromatic carbocycles, heteroarenes (e.g., N, B, S, P, Si, Ge, and Ga). The intrinsic GDY has also been doped with metal elements (e.g., Hg, Ag, and Au). Chemical synthetic strategies such as Glaser coupling, Glaser-Hay coupling, and Eglinton coupling are also described. The structural design of various precursors has been effectively tailored to the constitution of the local carbon framework of GDY-based materials, which has enabled the realization of the targeted performance in terms of the electronic conductivity, band gap, mobility, cavity size, and charge separation. For example, three-dimensional (3D) carbyne riched nanospheres formed by the extended coupling of spatially rigid-structured spirobifluorene have provided abundant storage spaces and convenient multi-directional transmission paths for metal ions. The use of hetero-doped GDY has enabled the effective optimization of the thermal stability and mechanical, electronic, and optical properties. Metal element-based GDY, referred to as “metalated” GDY, could serve as efficient bifunctional catalysts possessing favorable transport properties to facilitate the diffusion of small molecules. By extension, such materials can be used more broadly in electrochemical energy storage, electrocatalysis, optoelectronics, nonlinear optics, oil-water separation, and numerous other fields. In this review, we have summarized the design, synthesis, and structural characterization of various GDY derivatives through the recently demonstrated substitution of various aryne precursors for hexaethylbenzene, while examining the functional relationships between the desired optoelectronic properties of GDY derivatives and their defined nanostructures and morphologies. In addition, important prospective applications of GDY derivatives have been described. These observations may motivate the construction of novel polar and electron-rich GDY derivatives with unique properties that can address practical challenges encountered in various devices.