了解金属纳米团簇的形成机制对于进一步发展其化学制备方法是必要的。我们利用盐酸(HCl)和十二硫醇(RSH)共同刻蚀L3 (L3: 1, 3-双二苯基膦丙烷)包覆的多分散性的Aun (15 ≤ n ≤ 60)团簇成功制备出单分散性的Au13(L3)2(SR)4Cl4纳米团簇，并结合原位同步辐射X射线吸收谱、原位真空紫外-可见吸收光谱和质谱技术，研究了Au13(L3)2(SR)4Cl4纳米团簇的动力学形成过程。结果表明，Au团簇从多分散到单分散的转变经历了3个明显不同的动力学步骤。首先，尺寸较大的多分散金属团簇Aun主要在HCl刻蚀作用下，形成尺寸较小的亚稳的中间产物Au8–Au11团簇。然后，这些中间产物与反应溶液中已有的Au(Ⅰ)-Cl物种反应，并与SR发生部分配体交换，逐渐长大为由SR和L3保护的Au13团簇。最后，形成的Au13团簇经过一个较缓慢的结构重组过程，最终形成稳定的Au13(L3)2(SR)4Cl4的纳米团簇。
Gold nanoclusters are promising materials for a variety of applications because of their unique "superatom" structure, extraordinary stability, and discrete electronic energy levels. Controlled synthesis of well-defined Au nanoclusters strongly depends on rational design and implementation of their synthetic chemistry. Among the numerous approaches for the synthesis of monodisperse Au nanoclusters, etching of pre-formed polydisperse clusters has been widely employed as a top-down method. Understanding the formation mechanism of metal nanoclusters during the etching process is important. Herein, we synthesized monodisperse Au13(L3)2(SR)4Cl4 nanoclusters via an etching reaction between polydisperse 1, 3-bis(diphenyl-phosphino)propane (L3)-protected polydisperse Aun (15 ≤ n ≤ 60) clusters and a mixed solution of HCl/dodecanethiol (SR). The Au13 product, with a mean size of (1.1 ± 0.2) nm, shows pronounced step-like multiband absorption peaks centered at 327, 410, 433, and 700 nm. The synthetic protocol has a suitable reaction rate that allowss for real-time spectroscopic studies. We used a combination of in situ X-ray absorption fine structure (XAFS) spectroscopy, UV-Vis absorption spectroscopy, and matrix-assisted laser desorption ionization mass-spectrometry (MALDI-MS) to study the kinetic formation process of monodisperse Au13 nanoclusters. Emphasis was given to the detection of reaction intermediates. The study revealed that the size-conversion of the Au13 nanoclusters can be divided into three stages. In the first stage, the polydisperse Au15–Au60 clusters, covering a wide m/z range of 3000-13000, are prominently decomposed into smaller Au8-Au11 (within a m/z range of 3000–4000) species owing to the etching effect of HCl. They are immediately stabilized by the absorbed SR, L3, and Cl- ligands to form metastable intermediates, as indicated by the high intensity of the Au-ligand coordination peak at 0.190 nm as well as the low intensity of the Au–Au peaks (0.236 and 0.288 nm) in the Fourier-transform (FT) EXAFS spectra. In the second stage, these Au8–Au11 intermediates are grown into Au13 cores. The experimental X-ray absorption near-edge