Au₃₆(SR)₂₂ Nanocluster and a Periodic Pattern from Six to Fourteen Free Electrons in Core Size Evolution

An Au-36(S-tBu)(22) nanocluster (NC) is synthesized using the bulky tert-butyl thiol as the ligand. Single-crystal X-ray crystallography reveals that it has an Au-25 core which evolves from the Au-22 core in the previously reported Au-30(S-tBu)(18), and the Au-25 core is protected by longer staple-like surface motifs. The new Au-36 NC extends the members of the face-centered cubic structural evolution by adding an Au-3 triangle and an Au-4 tetrahedron unit. Additionally, it is found that Au-36 emits near-infrared photoluminescence at 863 nm with a quantum yield (QY) of 4.3%, which is five times larger than that of Au-30(S-tBu)(18)& horbar;the closest neighbor in the structural evolution pattern. The higher QY of Au-36 is attributed to a larger radiative relaxation (k(r)), resulting from the structural effect. Finally, we find that the longer staple motifs lead to enhanced stability of Au-36(S-tBu)(22) relative to Au-30(S-tBu)(18).