Bouquet-like uranium-containing selenotungstate consisting of two different Keggin-/Anderson-type units with excellent photoluminescence quantum yield

摘要

We present the synthesis,characterization and photoluminescence properties of uranium-containing selenotungstate,[(UO_(2))_(3)(SeO_(3))_(3)Na_(5)(H_(2)O)_(6)(SeW_(6)O_(21))(SeW_(9)O_(33))_(3)]^(21–),which was isolated by a one-pot reaction of uranium nitrate with sodium tungstate and sodium selenite in a pH 5.2 aqueous solution at 90°C.In this study,the effect of the introduction of lone-electron pair containing heteroatoms on the structure is demonstrated,a three-layered heterometallic{Se_(3)U_(3)Na_(5)}cluster is encapsulated by two different anionic building block units:three trivacant Keggin{B-α-Se W_(9)O_(33)}and one Anderson{SeW_(6)O_(21)}.To our knowledge,the{Se_(3)U_(3)Na_(5)}cluster has never been observed in the polyoxometalate chemistry.The solidstate photoluminescence properties and lifetime decay behaviours of the title compound(1)have been measured at room temperature,and the photoluminescence spectrum displays the characteristic emission bands of corresponding uranyl cations.In addition,the photoluminescence quantum yield of 1 is 72%,which is almost three times that of starting material UO_(2)(NO_(3))_(2)·6H_(2)O(27%).By using this strategy,we envision that an increasing number of assemblies with‘open’clusters may be designed and obtained,in which the exposed oxygen atoms show strong affinity towards metal ions,providing new opportunities to generate bigger clusters or to tune existing properties.