The surfaces of metal nanoclusters, including their interface with metal oxides, exhibit a high reactivity that is attractive for practical purposes. This high reactivity, however, has also hindered the synthesis of structurally well-defined hybrids of metal nanoclusters and metal oxides with exposed surfaces and/or interfaces. Here we report the sequential synthesis of structurally well-defined {Ag₃₀} nanoclusters in the cavity of ring-shaped molecular metal oxides known as polyoxometalates. The {Ag₃₀} nanoclusters possess exposed silver surfaces yet are stabilized both in solution and the solid state by the surrounding ring-shaped polyoxometalate species. The clusters underwent a redox-induced structural transformation without undesirable agglomeration or decomposition. Furthermore, {Ag₃₀} nanoclusters showed high catalytic activity for the selective reduction of several organic functional groups using H₂ under mild reaction conditions. We believe that these findings will serve for the discrete synthesis of surface-exposed metal nanoclusters stabilized by molecular metal oxides, which may in turn find applications in, for example, the fields of catalysis and energy conversion.

金属纳米团簇的表面，包括它们与金属氧化物的界面，表现出高反应性，这对于实际用途很有吸引力。然而，这种高反应性也阻碍了具有暴露表面和/或界面的金属纳米簇和金属氧化物的结构明确的杂化物的合成。在这里，我们报道了在被称为多金属氧酸盐的环形分子金属氧化物的空腔中顺序合成结构明确的{Ag _{30 }纳米团簇。}{Ag ₃₀纳米团簇具有暴露的银表面，但在溶液和固态中都通过周围的环形多金属氧酸盐物质稳定。这些团簇经历了氧化还原诱导的结构转变，没有发生不需要的团聚或分解。此外，{Ag _{30 }纳米团簇在温和的反应条件下使用H 2}选择性还原多个有机官能团表现出高催化活性。我们相信，这些发现将有助于由分子金属氧化物稳定的表面暴露的金属纳米团簇的离散合成，这反过来又可能在催化和能量转换等领域找到应用。