Morais Alysson F, Silva Ivan G N, Lima Bonifácio C, Garcia Fernando A, Mustafa Danilo
Departamento de Física dos Materiais e Mecânica, Instituto de Física da Universidade de São Paulo, São Paulo, SP 05508-090, Brazil.
Departamento de Física Aplicada, Instituto de Física da Universidade de São Paulo, São Paulo, SP 05508-090, Brazil.
ACS Omega. 2020 Sep 8;5(37):23778-23785. doi: 10.1021/acsomega.0c02848. eCollection 2020 Sep 22.
Luminescent layered double hydroxides (LDH) intercalated by isophthalate (ISO) and nitrilotriacetate (NTA) have been synthesized and characterized by powder X-ray diffraction (PXRD), extended X-ray absorption fine structure (EXAFS), elemental analysis (ICP-OES and CHN), and photoluminescence spectroscopy. While PXRD shows the successful formation of ZnAlEu LDHs, EXAFS reveals that the Eu activators are hosted in the hydroxide layers with an eightfold, oxygen-rich coordination, distinct from the sixfold coordination expected for the octahedral sites of metal cations in LDHs. This kind of coordination should locally distort the brucite-like layers. Additionally, the intercalation of ISO and NTA in the LDHs is shown to change the coordination environment around Eu compared to nitrate-intercalated ZnAlEu LDHs, which suggests that these anions directly interact with the Eu centers and/or strongly affect their coordination geometry. Finally, from the photoluminescence results, analyzed based on the Judd-Ofelt theory, it is determined that Eu is most likely in an environment with no inversion symmetry.
已合成了由间苯二甲酸酯（ISO）和次氮基三乙酸（NTA）插层的发光层状双氢氧化物（LDH），并通过粉末X射线衍射（PXRD）、扩展X射线吸收精细结构（EXAFS）、元素分析（ICP-OES和CHN）以及光致发光光谱对其进行了表征。虽然PXRD表明成功形成了ZnAlEu LDHs，但EXAFS显示Eu激活剂以八重富氧配位的形式存在于氢氧化物层中，这与LDHs中金属阳离子八面体位置预期的六重配位不同。这种配位会使类水镁石层局部变形。此外，与硝酸根插层的ZnAlEu LDHs相比，LDHs中ISO和NTA的插层显示出改变了Eu周围的配位环境，这表明这些阴离子直接与Eu中心相互作用和/或强烈影响其配位几何结构。最后，根据基于Judd-Ofelt理论分析的光致发光结果，确定Eu最有可能处于没有反演对称性的环境中。
