A Small Structural Change Makes a Big Difference: Synthesis of a Bowl-Like Polyoxometalate-Encapsulated {Ag₇}⁵⁺ Cluster and Its Structural Derivatives

Ligand-induced structural transformation has been developed as an effective strategy to manipulate the geometric/electronic structures, elemental compositions, and physicochemical properties of atomically precise silver clusters. In this work, we have demonstrated how a small structural change in the configuration of a bowl-like antimonotungstate ({Sb₃W₃₀}-3) ligand can make a big difference in the synthesis of polyoxometalate (POM)-encapsulated Ag clusters (Ag_n@POM). The new bowl-like {Sb₃W₃₀}-3 can successfully induce the formation of a {Ag₇} cluster, {Ag₇(Sb₃W₃₀)}. Interestingly, the {Ag₇(Sb₃W₃₀)} cluster, which can generate exposed Ag sites upon removal of three labile CH₃CN ligands, serves as a common building block for constructing three new types of Ag_n@POM derivatives, namely polymeric {Ag₇(Sb₃W₃₀)}_n, {Ag₁₅(Sb₃W₃₀)₂}, and {Ag₂₃(Sb₃W₃₀)₂}, via either inter-cluster assembly or intra-cluster kernel growth processes. In addition, photocatalytic H₂ evolution studies reveal the importance of accessibility to highly exposed Ag active sites and their synergistic cooperation with the redox-active bowl-like {Sb₃W₃₀}-3 ligand. This study establishes a strategic platform for the rational design and structural evolution of Ag_n@POM clusters, demonstrating how subtle modulation of all-inorganic POM ligands influences their geometric and catalytic properties at the atomic level.