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.