Alkynyl-Protected Chiral Bimetallic Ag22Cu7 Superatom with Multiple Chirality Origins

Understanding the origin of chirality in the nanostructured materials is essential for chiroptical and catalytic applications. Here we report a chiral AgCu superatomic cluster, [Ag22Cu7(C equivalent to CR)(16)(PPh3)(5)Cl-6](PPh4), Ag22Cu7, protected by an achiral alkynyl ligand (HC equivalent to CR: 3,5-bis(trifluoromethyl)phenylacetylene). Its crystal structure comprises a rare interpenetrating biicosahedral Ag17Cu2 core, which is stabilized by four different types of motifs: one Cu(C equivalent to CR)(2), four -C equivalent to CR, two chlorides and one helical Ag5Cu4(C equivalent to CR)(10)(PPh3)(5)Cl-4. Structural analysis reveals that Ag22Cu7 exhibits multiple chirality origins, including the metal core, the metal-ligand interface and the ligand layer. Furthermore, the circular dichroism spectra of R/S-Ag22Cu7 are obtained by employing appropriate chiral molecules as optical enrichment agents. DFT calculations show that Ag22Cu7 is an eight-electron superatom, confirm that the cluster is chirally active, and help to analyze the origins of the circular dichroism.

Automated summary

Understanding the origin of chirality in nanostructured materials is crucial for their applications in chiroptical and catalytic fields. In this study, a chiral AgCu superatomic cluster protected by an achiral alkynyl ligand was reported. The crystal structure of this cluster consists of an interpenetrating biicosahedral Ag17Cu2 core stabilized by various motifs. The multiple origins of chirality in Ag22Cu7 were analyzed, and circular dichroism spectra were obtained using appropriate chiral molecules.