First Tungstoantimonate-Based Transition-Metal–Lanthanide Heterometallic Hybrids Functionalized by Amino Acid Ligands

By the routine aqueous solution method, a series of transition-metal–lanthanide heterometallic tungstoantimonates [Ln­(H2O)8]2­[Fe4(H2O)8(thr)2]­[B-β-SbW9O33]2·22H2O [Ln = PrIII (1), NdIII (2), SmIII (3), EuIII (4), GdIII (5), DyIII (6), LuIII (7), thr = threonine] were prepared and structurally characterized by multiple testing techniques. The common structural characteristic of 1–7 is that they are isomorphous and all consist of a [Fe4(H2O)8(thr)2­(B-β-SbW9O33)2]6– subunit with two supporting [Ln­(H2O)8]3+ cations on both sides. It should be pointed out that two thr ligands in the [Fe4(H2O)8(thr)2­(B-β-SbW9O33)2]6– subunit substitute for two water ligands in the classical [Fe4(H2O)10­(B-β-SbW9O33)2]6– polyoxoanion. As far as we know, 1–7 represents the first organic–inorganic tungstoantimonate hybrids consisting of transition metal and lanthanide cations and amino acid components. The fluorescence behavior of 4 has been measured and manifests the remarkable fluorescence feature resulting from the emission signature of EuIII cations. Furthermore, the solid-state electrochemistry and electrocatalytic performances of 1 have been measured in 0.5 mol L–1 Na2SO4+H2SO4 aqueous solution, and the results show that 1 illustrates comparatively apparent catalytic activities toward the BrO3– and H2O2 reduction. The magnetic properties of 3 and 6 have been studied.本研究采用常规水溶液法，合成了一系列过渡金属-稀土异金属钨锑酸盐配合物，其通式为[Ln(H₂O)₈]₂[Fe₄(H₂O)₈(thr)₂][B-β-SbW₉O₃₃]₂·22H₂O [其中Ln=Pr³⁺(1)、Nd³⁺(2)、Sm³⁺(3)、Eu³⁺(4)、Gd³⁺(5)、Dy³⁺(6)、Lu³⁺(7)，thr即苏氨酸(threonine)]，并通过多种测试技术完成了结构表征。 配合物1~7的共同结构特征为：均为同构结构，整体均由一个[Fe₄(H₂O)₈(thr)₂(B-β-SbW₉O₃₃)₂]⁶⁻结构单元构成，该单元的两侧分别负载有两个[Ln(H₂O)₈]³⁺阳离子。 需要指出的是，相较于经典多金属氧阴离子[Fe₄(H₂O)₁₀(B-β-SbW₉O₃₃)₂]⁶⁻，该结构单元中的两个苏氨酸配体取代了其中的两个配位水分子。 据我们所知，配合物1~7是首例由过渡金属阳离子、稀土阳离子与氨基酸组分构建的有机-无机杂化钨锑酸盐材料。 对配合物4的荧光性能开展了测试，结果显示其呈现出由Eu³⁺阳离子发射特征主导的显著荧光特性。 此外，在0.5 mol·L⁻¹ Na₂SO₄+H₂SO₄水溶液中测试了配合物1的固态电化学与电催化性能，结果表明，配合物1对BrO₃⁻与H₂O₂的还原反应均表现出较为明显的催化活性。 同时研究了配合物3和6的磁性能。