Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Nat Commun. 2018 Jun 18;9(1):2379. doi: 10.1038/s41467-018-04837-x.
The synthesis of atomically precise thiolate-stabilized silver (Ag) nanoclusters is the subject of intense research interest, yet the formation mechanism of such nanoclusters remains obscure. Here, electrospray ionization mass spectrometry is successfully applied to monitor the reaction intermediates formed during the sodium-borohydride-reduction of silver 4-tert-butylbenzenethiolate (AgSPh-tBu). We demonstrate a unique evolution route to thiolate-stabilized Ag nanoclusters mediated by Ag-thiolate clusters. The Ag-thiolate clusters form in the initial stage of reduction contain tens of Ag atoms and similar number of ligands, and they are transformed into Ag(SPh-tBu) and Ag(SPh-tBu) nanoclusters in the later reduction process. The number of Ag atoms in the Ag-thiolate clusters determines the reaction path to each final nanocluster product. A similar mechanism is found when silver 2,4-dimethylbenzenethiolate (AgSPhMe) is used as precursor. This mechanism differs markedly from the long-established bottom-up evolution process, providing valuable new insights into the synthesis of metal nanoclusters.
原子精确的硫醇稳定的银（Ag）纳米簇的合成是当前研究的热点，但这种纳米簇的形成机制仍然不清楚。在这里，我们成功地应用电喷雾电离质谱来监测银 4-叔丁基苯硫醇（AgSPh-tBu）在硼氢化钠还原过程中形成的反应中间体。我们展示了一种独特的由硫醇稳定的 Ag 纳米簇介导的 Ag-硫醇簇的演化途径。还原过程中形成的 Ag-硫醇簇在初始阶段含有数十个 Ag 原子和数量相似的配体，它们在后续还原过程中转化为 Ag(SPh-tBu)和 Ag(SPh-tBu)纳米簇。Ag-硫醇簇中的 Ag 原子数量决定了每个最终纳米簇产物的反应途径。当使用银 2,4-二甲基苯硫醇（AgSPhMe）作为前体时，会发现类似的机制。这种机制与传统的自下而上的演化过程明显不同，为金属纳米簇的合成提供了有价值的新见解。
