A Double Helical 4h Assembly Pattern With Secondary Hierarchical Complexity In An Ag-70 Nanocluster Crystal

The hierarchical assemblies of well-defined structural nanoclusters can help to better understand those of biologically important molecules such as DNA and proteins. Herein, we disclose the synthesis and characterization of a new silver nanocluster, that is Ag-70(SR)(42)(PPh3)(5) (Ag-70-TPP). Directed by the ligands, Ag-70-TPP nanoclusters undergo self-hierarchical assembly into a highly space-efficient complex secondary structure of a double helical 4H (DH4H) close packing pattern. The chirality of Ag-70-TPP, and the van der Waals forces interactions between the ligands are believed to drive its DH4H arrangement, and the observed interlocking of the phosphine ligands of adjacent Ag-70-TPP nanoclusters also contributed. Overall, this work has yielded important and unprecedented insights into the internal structure and crystallographic arrangement of nanoclusters.