A double-tartrate-bridged deca-nuclearity europium-tungsten cluster embedded selenotungstate and its selective optical sensing of o-nitrophenol
Yong-Chao Dai, Siyu Zhang, Xinxian Xiao, Mengjuan Li, Jian‐Cai Liu, Lijuan Chen, Junwei Zhao
Abstract
An inorganic–organic hybrid Eu–W-implanted tartrate-connected selenotungstate tetramer {[Eu<sub>4</sub>(H<sub>2</sub>O)<sub>12</sub>W<sub>6</sub>O<sub>12 </sub>(tar)<sub>2</sub>][B-<em>α</em>-SeW<sub>9</sub>O<sub>33</sub>]<sub>4</sub>}<sup>16–</sup> (<strong>1a</strong>, H<sub>4</sub>tar = tartaric acid) was successfully obtained by introducing the flexible multidentate tartrate ligand into the Se-templated lacunary polyoxometalate (POM) and lanthanide (Ln) system. <strong>1a</strong> comprises two equivalent penta-nuclear Eu<sub>2</sub>W<sub>3</sub>-cluster-encapsulated {[Eu<sub>2</sub>(H<sub>2</sub>O)<sub>6</sub>W<sub>3</sub>O<sub>6</sub>][B-<em>α</em>-SeW<sub>9</sub>O<sub>33</sub>]<sub>2</sub>}<sup>4–</sup> dimeric units in an ''open <em>C</em>-shaped'' arrangement that are gathered together by double tetra-dentate tar<sup>4–</sup> linkers. Besides, <strong>1a</strong> exhibits remarkable stability and strong photoluminescence (PL) emission in aqueous medium, which is able to distinguish toxic chemical pollutants, o-nitrophenol (o-NP) from its two isomers m-nitrophenol (m-NP) and p-nitrophenol (p-NP), especially achieving highly selective and sensitive discrimination of o-NP with a low detection limit of 0.73 μM. The practical application of probe <strong>1a</strong> is realized in lake water with good recoveries. The PL sensing mechanism involving static quenching and competitive absorption was elucidated finally. This work paves the way for the designed synthesis of novel organic ligand and Ln-functionalized POM hybrids and the further exploration of POM materials in recognizing environmental pollutants.