Molecular Gold Nanocluster Au156 Showing Metallic Electron Dynamics

• Published in: Journal of the American Chemical Society 2021-10, Vol.143 (41), p.17059-17067
• Main Authors: Hu, Feng, Guan, Zong-Jie, Yang, Gaoyuan, Wang, Jia-Qi, Li, Jiao-Jiao, Yuan, Shang-Fu, Liang, Gui-Jie, Wang, Quan-Ming
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.1c06716

The boundary between molecular and metallic gold nanoclusters is of special interest. The difficulty in obtaining atomically precise nanoclusters larger than 2 nm limits the determination of such a boundary. The synthesis and total structural determination of the largest all-alkynyl-protected gold nanocluster (Ph4P)6[Au156(CCR)60] (R = 4-CF3C6H4-) (Au 156 ) are reported. It presents an ideal platform for studying the relationship between the structure and the metallic nature. Au 156 has a rod shape with the length and width of the kernel being 2.38 and 2.04 nm, respectively. The cluster contains a concentric Au126 core structure (Au46@Au50@Au30) protected by 30 linear RCC–Au–CCR staple motifs. It is interesting that Au 156 displays multiple excitonic peaks in the steady-state absorption spectrum (molecular) and pump-power-dependent excited-state dynamics as revealed in the transient absorption spectrum (metallic), which indicates that Au 156 is a critical crossover cluster for the transition from molecular to metallic state. Au 156 is the smallest-sized gold nanocluster showing metal-like electron dynamics, and it is recognized that the cluster shape is one of the important factors determining the molecular or metallic nature of a gold nanocluster.