Carbon dioxide (CO 2 ) and sulfides in gasoline are the main causes of air pollution. Considerable attention has been devoted to solving the problems, and the catalytic reaction seems to be a good choice. Owing to the high density of Lewis acid (LA) active sites and large numbers of open methoxide groups, polyoxovanadates (POVs) are an undisputed option as a heterogeneous catalyst for the CO 2 cycloaddition reaction and catalytic oxidation of sulfides. On the basis of the above, a series of, have been legitimately designed and triumphantly isolated. In the synthesis process, three different kinds of Lewis bases (LBs), ethanediamine, 1,2-diaminopropane, and 1,2-cyclohexanediamine, were used to modify LA {V 8 } clusters to form four diverting windmill-shaped configuration. Among them, the vanadium atoms in V 8 -1a are +4 valence of V IV , while the vanadium atoms in V 8 -1−3 are mixed valence states of V IV and V V . Magnetic property investigation indicates that the antiferromagnetic coupling interactions between V IV ions all exist in the four compounds. The compound V 8 -1 also demonstrated high catalytic activity in the cycloaddition of CO 2 to several epoxides under relatively mild conditions (70 °C, 0.5 MPa). More importantly, the reaction pressure 0.5 MPa is the lowest among the high nuclear polyoxometallates (POMs). Furthermore, V 8 -1 also has an excellent catalytic conversion for the oxidation of sulfides. The catalytic tests manifested that V 8 -1 was a very efficient difunctional heterogeneous catalyst for CO 2 cycloaddition reaction and catalytic oxidation of sulfides.

The maximum exposure of polyoxometalates (POMs) is of great significance to enhance the catalytic performance of HKUST-1 with incorporated Keggin-type POMs. Herein, two phosphovanadomolybdates were encapsulated into the HKUST-1 via a hydrothermal method to obtain two polyoxometalate-based metal–organic frameworks, formulated as [Cu12(BTC)8(H2O)12]­[H4PMo11VO40]@(H2O)30 (1) and [Cu12(BTC)8(H2O)12]­[H5PMo10V2O40]@(H2O)49 (2). Single-crystal X-ray diffraction analysis indicates that two compounds contain unique high-nuclearity water clusters without organic counter cations. The octahedral-shaped water cluster (H2O)30 was constructed from square-pyramid-shaped (H2O)5 for compound 1, while the huge cage-shaped water cluster (H2O)49 of compound 2 consisted of crown-like (H2O)8 and one water molecule, which substitute the organic counter cations involved in the structural construction. More importantly, after removing the water clusters via simple heat treatment, the active sites of the two compounds were fully exposed, leading to good catalytic activities for both benzene hydroxylation reaction and oxidative desulfurization. Furthermore, the catalytic test confirmed that compound 2 may be a bifunctional heterogeneous catalyst with great promise for both benzene hydroxylation and oxidative desulfurization.

The unpredictability of the polyoxometalate (POM) coordination model and the diversity of organic ligands provide more possibilities for the exploration and fabrication of various novel POM-based materials. In this work, a series of POM-based l a n t h a n i d e ( L n )Sm, 1; Eu, 2; Tb, 3), have been successfully isolated by the reaction of classical Keggin POMs, a Ln 3+ ion, and a Schiff-base ligand [2,6-diacetylpyridine bis(semicarbazone), abbreviated as DAPSC]. Both the hindrance effect of the organic ligand and charge balance endow the cluster with fascinating structural features of discrete and linear arrangement. The title compounds with dimensions of ca. 4 × 1 × 1 nm 3 are first trimeric polyoxometalatebased nanosized compounds, constructed by saturated POM anions (SiW 12 O 40 4− , denoted as SiW 12 ). Moreover, the properties (stability, electrochemistry, third-order nonlinear optics, and magnetism) of the compounds have also been studied.

Two novel and fascinating high-nuclearity lanthanide-transition (4f–3d) heterometallic clusters were obtained based on an anion-template (Cl–) and ligand-controlled approach, formulated as [Gd40­Ni44­(CO3)12­(CH3COO)4­(IDA)44­(C2O4)­(μ2-O)4­(μ3-OH)60­(μ3-O)6­(H2O)12]·Cl10·20H2O (abbreviated as Gd40Ni44, 1) and [Eu40­Ni44­(CO3)12­(CH3COO)6­(IDA)44­(C2O4)­(μ2-O)4­(μ3-OH)62­(μ3-O)4­(H2O)12]·Cl10·23H2O (abbreviated as Eu40Ni44, 2), where H2IDA = iminodiacetic acid and H2C2O4 = oxalic acid. Structural analysis exhibits that the compounds 1 and 2 were both constructed by two enticing bowl-like anion units Ln20Ni22, featuring peanut-like structures. Besides, the assembly of Ln20Ni22 was templated by five Cl– ions. Magnetically, compound 1 shows a significant magnetocaloric effect, with −ΔS m = 36.05 J kg–1 K–1 at 3 K for ΔH = 7 T.

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The self-assembly of the high-nuclearity Ln-exclusive nanoclusters is challenging but of significance due to its aesthetically pleasing architectures and far-reaching latent applications in magnetic cooling technologies. Herein, two novel high-nuclearity lanthanide nanoclusters were successfully synthesized under solvothermal conditions, formulated as {[Gd18(IN)20(HCOO)8(μ6-O)(μ3-OH)24(H2O)4]·4H2O} n and {[Eu18(IN)16(HCOO)8(CH3COO)4(μ6-O)(μ3-OH)24(H2O)4]·5H2O} n (abbreviated as Gd18 and Eu18 , HIN = isonicotinic acid). Both of them possess novel and exquisite windmill-shaped cationic cores in the family of high-nuclearity Ln-exclusive nanoclusters. Remarkably, the adjacent second building units are interconnected into a three-dimensional (3D) metal–organic framework by IN– ligands. As expected, the abundant existence of GdIII ions endows Gd18 with a favorable magnetic entropy change at 2.0 K for ΔH = 7.0 T (−ΔS m max = 40.0 J kg–1 K–1), and Eu18 displays the typical luminescence of EuIII ions.

Designing and synthesizing lanthanide clusters have always been a research hotspot. Herein, three lanthanide clusters with the formulas [Ln8(IN)14(μ3-OH)8(μ2-OH)2(H2O)8]·xH2O (Ln = 1-Gd and x= 11; Ln = 2-Dy and x=...

Two Ni-substituted polyoxometalates (NiSPs), [Ni 6 (Py) 2) (Py = pyridine, Im = imidazole), were successfully hydrothermally synthesized. Compounds 1 and 2 have significantly different configurations by introducing different amounts of imidazole ligands. For compound 1, two malposed {Ni 6 (Py) 6 PW 9 } units that are face to face are bridged by two Ni−O−W bonds to constitute an isolated dimeric structure. Differently, the {Ni 7 (Py) 6 (Im)PW 9 } 2 dimer in compound 2 connects with four adjacent dimers by four {WO 4 } groups in an interesting two-dimensional (2-D) arrangement. The magnetism of compounds 1 and 2 was studied, and magnetic test results demonstrated that both compounds have ferromagnetic interactions between the nickel centers. Meanwhile, the third-order nonlinear optical (NLO) measurements indicated that compound 1 can serve as potential nonlinear optical materials.