The ring-shaped polyoxometalate (POM) [P₈W₄₈O₁₈₄]^40– contains a large cavity and is an attractive inorganic multidentate ligand for accumulating metal cations. Until now, several multinuclear metal cores are constructed within the {P₈W₄₈} framework in aqueous solvents. However, it is still challenging to control the number and arrangement of introduced metal cations because of the numerous coordination sites inside the {P₈W₄₈} framework. In this study, we developed a novel approach for the selective synthesis of several multinuclear copper-containing ring-shaped POMs in organic solvents using methoxy groups as organic protecting ligands for the reactive coordination sites. Reacting a tetra-n-butylammonium (TBA) salt of [P₈W₄₈O₁₈₄]^40– (P8W48) with 4 and 8 equiv of copper(II) acetate in the presence of methanol (MeOH), tetra- and octacopper cores were incorporated into the cavity to form TBA₁₁H₁₃[Cu₄(H₂O)₄P₈W₄₈O₁₇₆(OCH₃)₈]·28H₂O·3CH₃NO₂ (Cu4) and TBA₁₄H₂[Cu₈(H₂O)₁₂P₈W₄₈O₁₇₆(OCH₃)₈]·24H₂O·CH₃CN (Cu8), respectively. For both structures, methoxy groups served as protecting ligands and temporarily inactivated vacant coordination sites. Without MeOH, dodeca- and hexadecacopper cores were constructed inside the cavity to form TBA₁₄H₂[Cu₁₂(H₂O)₁₆P₈W₄₈O₁₈₄]·4H₂O (Cu12) and TBA₁₆H₈[Cu₁₆(OH)₁₆(H₂O)₄P₈W₄₈O₁₈₄]·12H₂O·C₃H₆O (Cu16), respectively. The arrangement of copper ions on the same {P₂W₁₂} units could be controlled by the input number of copper ions. Moreover, all four POMs could be synthesized from P8W48 by the stepwise addition of 4 equiv of copper(II) acetate, clarifying the introduction process.

中文翻译：

---

环状多金属氧酸盐内多核铜芯受控构建的配体保护策略

环状多金属氧酸盐 (POM) [P ₈ W ₄₈ O ₁₈₄ ] ^40–含有一个大空腔，是一种有吸引力的无机多齿配体，用于积累金属阳离子。到目前为止，在水性溶剂中的 {P ₈ W ₄₈ } 框架内构建了几个多核金属核。_{然而，由于{P 8} W ₄₈内部有许多配位点，控制引入金属阳离子的数量和排列仍然具有挑战性。} 框架。在这项研究中，我们开发了一种在有机溶剂中选择性合成几种多核含铜环状 POM 的新方法，该方法使用甲氧基作为反应性配位点的有机保护配体。[P ₈ W ₄₈ O ₁₈₄ ] ^40- ( P8W48 )的四正丁基铵 (TBA) 盐与 4 和 8 equiv 的乙酸铜 (II) 在甲醇 (MeOH)、四铜和八铜核的存在下反应并入空腔形成 TBA ₁₁ H ₁₃ [Cu ₄ (H ₂ O) ₄ P ₈ W ₄₈ O₁₇₆ (OCH ₃ ) ₈ ]·28H ₂ O·3CH ₃ NO ₂ ( Cu4 )和TBA ₁₄ H ₂ [Cu ₈ (H ₂ O) ₁₂ P ₈ W ₄₈ O ₁₇₆ (OCH ₃ ) ₈ ]·24H ₂ O· CH ₃ CN ( Cu8 )。对于这两种结构，甲氧基用作保护配体和暂时失活的空位配位点。在没有 MeOH 的情况下，在空腔内构建十二铜和十六铜芯以形成 TBA ₁₄H ₂ [Cu ₁₂ (H ₂ O) ₁₆ P ₈ W ₄₈ O ₁₈₄ ]·4H ₂ O ( Cu12 )和TBA ₁₆ H ₈ [Cu ₁₆ (OH) ₁₆ (H ₂ O) ₄ P ₈ W ₄₈ O ₁₈₄ ] ·12H ₂ O·C ₃ H ₆ O( Cu16 )。_{铜离子在同一{P 2} W ₁₂上的排列} 单位可以通过输入的铜离子数量来控制。此外，所有四种 POM 都可以通过逐步添加 4 equiv 的乙酸铜 (II)从P8W48合成，从而阐明了引入过程。