Metal Exchange Method Using Au₂₅ Nanoclusters as Templates for Alloy Nanoclusters with Atomic Precision

A metal exchange method based upon atomically precise gold nanoclusters (NCs) as templates is devised to obtain alloy NCs including CuxAu25‑x­(SR)18, AgxAu25‑x­(SR)18, Cd1Au24­(SR)18, and Hg1Au24­(SR)18 via reaction of the template with metal thiolate complexes of CuII, AgI, CdII, and HgII (as opposed to common salt precursors such as CuCl2, AgNO3, etc.). Experimental results imply that the exchange between gold atoms in NCs and those of the second metal in the thiolated complex does not necessarily follow the order of metal activity (i.e., galvanic sequence). In addition, the crystal structure of the exchange product (Cd1Au24­(SR)18) is successfully determined, indicating that the Cd is in the center of the 13-atom icosahedral core. This metal exchange method is expected to become a versatile new approach for synthesizing alloy NCs that contain both high- and low-activity metal atoms.本研究设计了一种以原子级精确金纳米团簇（nanoclusters, NCs）为模板的金属交换方法，通过将该模板与Cu(II)、Ag(I)、Cd(II)和Hg(II)的金属硫醇盐配合物（而非CuCl₂、AgNO₃等常见盐类前驱体）反应，成功制备得到CuxAu₂₅₋ₓ(SR)₁₈、AgxAu₂₅₋ₓ(SR)₁₈、Cd₁Au₂₄(SR)₁₈及Hg₁Au₂₄(SR)₁₈等合金纳米团簇。实验结果表明，纳米团簇中的金原子与硫醇盐配合物中的第二种金属原子之间的交换反应，未必遵循金属活性顺序（即电化序列）。此外，本研究成功解析了交换产物Cd₁Au₂₄(SR)₁₈的晶体结构，证实镉原子位于13原子二十面体核的中心位置。该金属交换法有望成为一种通用的新型合成策略，用于制备同时包含高活性与低活性金属原子的合金纳米团簇。