Construction Engineering of Symmetrical and Unsymmetrical Diynes for the Growth of Graphdiyne and Its Derivatives.

Graphdiyne (GDY) and its derivatives are new stable network carbon materials consisting of sp and sp hybridized carbon atoms. Although those new materials have various applications, synthesizing abundant 1,3-diynes in GDY and its derivatives is still a great challenge until now. Here we utilized the copper trichloro complex (CuTC) generated in the presence of N,N,N,N'-tetramethylethylenediamine, O and trichloromethane to couple terminal alkynes efficiently. Large two-dimensional (2D) network graphdiyne (GDY), hydrogen substituted graphdiyne (H-GDY) and hydrogen substituted graphdiyne with bipyridine (H-GDY(BPY)) film were successfully synthesized on Cu foil surface. The formation of abundant symmetrical (-C≡C-C≡C-) and unsymmetrical diynes (-C≡C-C≡C-) in GDY, (H-GDY) and H-GDY(BPY) was confirmed by Raman spectra. SEM and TEM images showed two-dimensional (2D) morphology of the three carbon materials. Furthermore, Element mapping images, FTIR, Solid-state C NMR and XPS demonstrated that bipyridine units were successfully integrated on H-GDY backbone via heterocoupling of terminal alkynes of 1,3,5-triethynylbenzene and 5,5'-bis-ethynyl-2,2'-bipyridine. In photocatalytic reaction, H-GDY(BPY) sheets exhibited a remarkable enhancement of the photocatalytic H generation compared with H-GDY and GDY. The result suggested that the CuTC catalyzed 1,3-diynes construction system is an efficient way to introduce the active centers into the structure of graphdiyne analogues by rationally designing the introduced active groups at molecular level.