Total Structure Determination of the Largest Alkynyl-Protected FCC Gold Nanocluster Au110 and the Study on its Ultrafast Excited-State Dynamics.

Great attention has been paid to nanoclusters having face-centered-cubic (FCC) metal kernels, because of the similarity of metal packing to bulk gold. So far, there is no precedent example of an all-alkynyl-protected fcc gold nanocluster with gold atom number more than 100. We report the synthesis and total structure determination of an alkynyl-gold nanocluster [NEt3H]2[Au110(p-CF3C6H4C≡C)48] (Au110). It has a fcc Au86 kernel with 24 peripheral Au(C≡CR)2 staples. The Au86 kernel consists of six close packing layers in the pattern of Au6: Au16: Au21: Au21: Au16: Au6. Electronic absorption spectroscopy shows Au110 has a molecular-like discrete electronic structure, and transient absorption experiments reveal its nonmetallic nature.