铕（III）磷钨酸盐的水相形态研究。

Aqueous speciation studies of europium(III) phosphotungstate.

作者信息

Zhang Cheng, Howell Robertha C, Scotland Kymora B, Perez Frances G, Todaro Louis, Francesconi Lynn C

机构信息

Department of Chemistry, Hunter College and Graduate School of the City University of New York, New York 10021, USA.

出版信息

Inorg Chem. 2004 Nov 29;43(24):7691-701. doi: 10.1021/ic049655h.

DOI:10.1021/ic049655h

PMID:15554634

Abstract

The incorporation of lanthanide ions into polyoxometalates may be a unique approach to generate new luminescent, magnetic, and catalytic functional materials. To realize these new applications of lanthanide polyoxometalates, it is imperative to understand the solution speciation chemistry and its impact on solid-state materials. In this study we find that the aqueous speciation of europium(III) and the trivacant polyoxometalate, PW9O34 9-, is a function of pH, countercation, and stoichiometry. For example, at low pH, the lacunary (PW11O39)7- predominates and the 1:1 Eu(PW11O39)4-, 2, forms. As the pH is increased, the 1:2 complex, Eu(PW11O39)2 11- species, 3, and (NH4)22[(Eu2PW10O38)4(W3O8(H2O)2(OH)4].44H2O, a Eu8 hydroxo/oxo cluster, 1, form. Countercations modulate this effect; large countercations, such as K+ and Cs+, promote the formation of species 3 and 1. Addition of Al(III) as a counterion results in low pH and formation of [Eu(H2O)3(alpha-2-P2W17O61)]2, 4, with Al(III) counterions bound to terminal W-O bonds. The four species observed in these speciation studies have been isolated, crystallized, and characterized by X-ray crystallography, solution multinuclear NMR spectroscopy, and other appropriate tech-niques. These species are 1, (NH4)22[(Eu2PW10O38)4(W3O8(H2O)2(OH)4].44H2O (P; a=20.2000(0), b=22.6951(6), c=25.3200(7) A; alpha=65.6760(10), beta=88.5240(10), gamma=86.0369(10) degrees; V=10550.0(5) A3; Z=2), 2, Al(H3O)[Eu(H2O)2PW11O34].20H2O (P, a=11.4280(23), b=11.5930(23), c=19.754(4) A; alpha=103.66(3), beta=95.29(3), gamma=102.31(3) degrees; V =2456.4(9) A3; Z=2), 3, Cs11Eu(PW11O34)2.28H2O (P; a=12.8663(14), b=19.8235(22), c=21.7060(23) A; alpha=114.57(0), beta=91.86(0), gamma=102.91(0) degrees ; V=4858.3(9) A3; Z=2), 4, Al2(H3O)8[Eu(H2O)3(alpha-2-P2W17O61)]2.29H2O (P; a=12.649(6), b=16.230(8), c=21.518(9) A; alpha=111.223(16), beta=94.182(18), gamma=107.581(17) degrees ; V=3842(3) A3; Z=1).

摘要

将镧系离子引入多金属氧酸盐中可能是一种制备新型发光、磁性和催化功能材料的独特方法。为了实现镧系多金属氧酸盐的这些新应用，必须了解溶液物种形成化学及其对固态材料的影响。在本研究中，我们发现铕(III)和三缺位多金属氧酸盐PW9O34 9-的水相物种形成是pH值、抗衡阳离子和化学计量比的函数。例如，在低pH值下，缺位的(PW11O39)7-占主导，形成1:1的Eu(PW11O39)4-，即2。随着pH值升高，形成1:2的配合物Eu(PW11O39)2 11-物种，即3，以及(Eu2PW10O38)4(W3O8(H2O)2(OH)4].44H2O，一种Eu8羟基/氧簇，即1。抗衡阳离子调节这种效应；大的抗衡阳离子，如K+和Cs+，促进物种3和1的形成。添加Al(III)作为抗衡离子会导致低pH值，并形成[Eu(H2O)3(α-2-P2W17O61)]2，即4，其中Al(III)抗衡离子与末端W-O键结合。在这些物种形成研究中观察到的四种物种已被分离、结晶，并通过X射线晶体学、溶液多核NMR光谱和其他适当技术进行了表征。这些物种分别是1，(NH4)22[(Eu2PW10O38)4(W3O8(H2O)2(OH)4].44H2O (P；a = 20.2000(0)，b = 22.6951(6)，c = 25.3200(7) Å；α = 65.6760(10)，β = 88.5240(10)，γ = 86.0369(10)°；V = 10550.0(5) Å3；Z = 2)，2，Al(H3O)[Eu(H2O)2PW11O34].20H2O (P，a = 11.4280(23)，b = 11.5930(23)，c = 19.754(4) Å；α = 103.66(3)，β = 95.29(3)，γ = 102.31(3)°；V = 2456.4(9) Å3；Z = 2)，3，Cs11Eu(PW11O34)2.28H2O (P；a = 12.8663(14)，b = 19.8235(22)，c = 21.7060(23) Å；α = 114.57(0)，β = 91.86(0)，γ = 102.91(0)°；V = 4858.3(9) Å3；Z = 2)，4，Al2(H3O)8[Eu(H2O)3(α-2-P2W17O61)]2.29H2O (P；a = 12.649(6)，b = 16.230(8)，c = 21.518(9) Å；α = 111.223(16)，β = 94.182(18)，γ = 107.581(17)°；V = 3842(3) Å3；Z = 1)。