A new penta‐Eu^III sandwiched Dawson‐type selenotungstate (ST) [H₂N(CH₃)₂]₁₀H₃{SeO₄Eu₅(H₂O)₈[Se₂W₁₄O₅₂]₂}·40H₂O (1) was constructed by an in‐situ self‐assembly strategy. The unique architectural feature of 1 is that two [Se₂W₁₄O₅₂]^12– segments graft each other by five Eu³⁺ ions via oxygen linkers. Meanwhile, a disordered tetra‐coordinate Se^IV ion locates on the central symmetric site of the structure. What's more, based on its benign fluorescence properties and excellent water solubility, 1 was prepared to be an efficient chemosensor for the selective detection of the Cu²⁺ ion in aqueous solution. The detection was found to be 1.24 × 10^–3 mm. The fluorescence quenching mechanism of the Cu²⁺ ion towards the 1‐based sensor might be caused by the LMCT absorption of the Cu²⁺ ion hindering energy transfer from ST fragments to the Eu³⁺ ion in 1 in aqueous solution. More interestingly, the Cu²⁺‐quenched system could be recovered by addition of cysteine (cys) because the strong chelation between cys and Cu²⁺. The LOD value of detecting cys is 2.17 × 10^–4 mm for the continuous “off‐on” chemosensor, which provides a promising prospect of polyoxometalate‐based materials for environmental monitoring and clinical medical testing.

中文翻译：

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Penta-EuIII夹心Dawson Selenotungstate及其独特的发光特性

新戊铕^III夹道森-型selenotungstate（ST）[H ₂ N（CH ₃）₂ ] ₁₀ ħ ₃ {的SeO ₄铕₅（H ₂ O）₈ [硒₂ w ^ ₁₄ ö ₅₂ ] ₂ } · 40H ₂ O（1）是通过原位自组装策略构建的。的独特的建筑特征1是两个[硒₂ w ^ ₁₄ ö ₅₂ ] ^12-段由5 Eu的接枝彼此通过氧连接子的³⁺离子。同时，无序的四坐标Se ^IV离子位于结构的中心对称位点。此外，基于其良性的荧光特性和出色的水溶性，制备1是一种有效的化学传感器，用于选择性检测水溶液中的Cu ²⁺离子。探测到的是1.24×10 ^–3 m m。Cu ²⁺离子向1基传感器的荧光猝灭机制可能是由于Cu ²⁺离子的LMCT吸收阻碍了1中从ST片段到Eu ³⁺离子的能量转移。在水溶液中。更有趣的是，由于cys与Cu ²⁺之间的强螯合作用，可以通过添加半胱氨酸（cys）来恢复Cu ²⁺猝灭的体系。对于连续的“开-关”化学传感器，cys的LOD值为2.17×10 ^–4 m m，这为基于多金属氧酸盐的材料进行环境监测和临床医学测试提供了有希望的前景。