论文部分内容阅读
The atomic structure of recently synthesized thiolate-protected Au76 cluster is theoretically predicted via a simple structural rule summarized from the crystal structures of thiolate-protected Au44(SR)28,Au36(SR)24 and Au52(SR)32 clusters.1-3 We find that the Au76(SR)44(N = 7)and recently reported Au52(SR)32(N = 4),Au44(SR)28(N = 3),Au36(SR)24(N = 2)and Au28(SR)20(N = 1)belong to a family of homologous Au20+8N(SR)16+4N cluster whose Au-cores follow one-dimensional polytetrahedral growth pathway.The Au76(SR)44 cluster is predicted to contain an anisotropic face-centered cubic(FCC)Au-core,which can be viewed as combination of two helical tetrahedra-Au4 chains and is remarkably different from the well-known spherical Au-core in ligand protected gold clusters in the size region of 1-2 nm.The intense near infrared(NIR)absorption of Au76(SR)44 is attributed to the synergistic effect of anisotropic Au-core structure and ligand protections.A plausible cluster-to-cluster transformation mechanism is further suggested.