Structure of Chiral Au44(2,4-DMBT)26 Nanocluster with an 18-Electron Shell Closure

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• 作者：Lingwen Liao ; Shengli Zhuang ; Chuanhao Yao ; Nan Yan ; Jishi Chen ; Chengming Wang ; Nan Xia ; Xu Liu ; Man-Bo Li ; Lingling Li ; Xiaoli Bao ; Zhikun Wu
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：August 24, 2016
• 年：2016
• 卷：138
• 期：33
• 页码：10425-10428
• 全文大小：283K
• 年卷期：0
• ISSN：1520-5126

文摘

The 18-electron shell closure structure of Au nanoclusters protected by thiol ligands has not been reported until now. Herein, we synthesize a novel nanocluster bearing the same gold atom number but a different thiolate number as another structurally resolved nanocluster Au₄₄(TBBT)₂₈ (TBBTH = 4-tert-butylbenzenelthiol). The new cluster was determined to be Au₄₄(2,4-DMBT)₂₆ (2,4-DMBTH = 2,4-dimethylbenzenethiol) using multiple techniques, including mass spectrometry and single crystal X-ray crystallography (SCXC). Au₄₄(2,4-DMBT)₂₆ represents the first 18-electron closed-shell gold nanocluster. SCXC reveals that the atomic structure of Au₄₄(2,4-DMBT)₂₆ is completely different from that of Au₄₄(TBBT)₂₈ but is similar to the structure of Au_38Q. The arrangement of staples (bridging thiolates) and part of the Au₂₉ kernel atom induces the chirality of Au₄₄(2,4-DMBT)₂₆. The finding that a small portion of the gold kernel exhibits chirality is interesting because it has not been previously reported to the best of our knowledge. Although Au₄₄(2,4-DMBT)₂₆ bears an 18-electron shell closure structure, it is less thermostable than Au₄₄(TBBT)₂₈, indicating that multiple factors contribute to the thermostability of gold nanoclusters. Surprisingly, the small difference in Au/thiolate molar ratio between Au₄₄(2,4-DMBT)₂₆ and Au₄₄(TBBT)₂₈ leads to a dramatic distinction in Au 4f X-ray photoelectron spectroscopy, where it is found that the charge state of Au in Au₄₄(2,4-DMBT)₂₆ is remarkably more positive than that in Au₄₄(TBBT)₂₈ and even slightly more positive than the charge states of gold in Au-(2,4-DMBT) or Au-TBBT complexes.