Zhijie Liang

A New Nb28 Cluster Based on Tungstophosphate, [{Nb4O6(OH)4}{Nb6P2W12O61}4]36–

A structurally intriguing polyanion, [{Nb4O6(OH)4}{Nb6P2W12O61}4](36-) (2), was directly formed by controlling the reaction parameters and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses. Polyanion 2 is the first niobium-substituted Wells-Dawson-based tetramer and contains the largest Nb28 cluster encapsulated by four hexalacunary Wells-Dawson frameworks. The activities of compounds Na12[H24-2]·24H2O (2a), K12[H2P2W12O48]·24H2O, and K7[HNb6O19]·13H2O against three human tumor cell lines were investigated in vitro. The preliminary results revealed that 2a could efficiently inhibit the growth of the human breast cancer MCF-7 cells. Interestingly, the activity of 2a is significantly better than those of the simple reagents.

A {Co4O4} Cubane Incorporated within a Polyoxoniobate Cluster

A novel octacobalt-containing polyoxoniobate, Na6 K12 [H2 Co8 O4 (Nb6 O19 )4 ]⋅39 H2 O, has been prepared by a combination of hydrothermal and diffusion methods. The polyanion [H2 Co8 O4 (Nb6 O19 )4 ](18-) incorporates a tetrameric assembly of Lindqvist-type [Nb6 O19 ](8-) fragments trapping a {Co(II) 4 Co(III) 4 } cluster which comprises a central {Co(III) 4 O4 } cubane core, surrounded by another four Co(II) ions linkers. Furthermore, magnetic measurements show that the compound exhibits antiferromagnetic interactions.

A {Nb6P2W12}-Based Hexameric Manganese Cluster with Single-Molecule Magnet Properties

By deliberately using a metastable polyanion [(NbO2 )6 P2 W12 O56 ](12-) (1), which was formed in situ, we have discovered the unprecedented hexameric cluster {Mn15 (Nb6 P2 W12 O62 )6 } (2), in which the six polyanions [Nb6 P2 W12 O61 ](10-) are alternately connected by four intriguing trinuclear {Mn(III) 3 } moieties and four {Mn(II) } linkers. This discovery is the first in which the phosphoniobotungstate has been made accessible by using transition-metal ions; furthermore, polyanion 2 represents the largest niobotungstate cluster reported to date. Analysis by means of electrospray ionization mass spectrometry (ESI-MS) provides insight into the self-assembly process, and the peaks observed relate to the different charge states of the parent cluster, thus confirming the stability of 2. In addition, magnetic-susceptibility measurements reveal that each {Mn(III) 3 } subunit is a separate single-molecule magnet (SMM). This discovery results from the exploration of the reverse effect of metastable polyanion 1 possessing high reactivity, thereby turning a disadvantage into an advantage. This finding could define a new synthetic strategy for the design and synthesis of magnetic polyoxometalate (POM) clusters.

Grafting transition metal-organophosphonate fragments onto heteropolyoxomolybdate: activity in photocatalysis.

A novel organophosphonate-functionalized heteropolyoxomolybdate incorporated nickel cluster, CsNa9[H2{Ni3O2(H2O)6}(PMo6O21)2{Ni(OOCCH2NHCH2PO3)2}3]·21H2O (1), has been synthesized, which represents the first member of the family of oxomolybdenum organophosphonate containing hexa-nuclear Ni(ii) in a polyanion framework. The polyanion comprises a unique ladder-type {Ni3O10(H2O)6} cluster and three {Ni(OOCCH2NHCH2PO3)2} bridgings, which are capped on either end by a {PMo6O28} group. Photocatalytic experiments indicate that 1 exhibits catalytic activity for the photodegradation of RhB solution. Furthermore, magnetic studies indicate that 1 displays antiferromagnetic interactions.

Lanthanide-containing peroxoisopolytungstate with tetrahedral WO42− template core, [Ln4(WO4)(H2O)16{W7O22(O2)2}4]14−

Two lanthanide-containing peroxoisopolyanions [Ln4(WO4)(H2O)16{W7O22(O2)2}4]14− (Ln = LaIII; PrIII), have been synthesized by reaction of Na2WO4 and lanthanide (Ln) ions in the presence of peroxide. These represent the first two examples of peroxo-containing Ln-stabilized polyanions (LSPs), and have the highest number of W atoms among all known Ln-stabilized isopolytungstates (IPTs) as well.

The {Ni10Nb32} aggregate: a perspective on isopolyniobates as ligands

[H4Ni10(H2O)8Nb32O102]20-, representing the first high-nuclear nickel-cation-bridged polyoxoniobate, has been synthesized. It incorporates two [{Ni2O4}(H2O)2(Nb6O19)]12- and two [Ni3(H2O)2Nb10O34]12- subunits exhibiting a rhombus-like architecture. Furthermore, the solution behaviour was examined by electrospray ionization mass spectrometry and the magnetic properties in the low temperature range indicate the presence of ferromagnetic interactions.

Controlled assembly of hybrid architectures based on carboxylic acid ligands and [(O3PCH2PO3)Mo6O22]12−

The nature of carboxylic acid has a profound effect on constructing POM-based architectures. With different carboxylic acid ligands, three novel diphosphonate-containing compounds have been synthesized and further investigated by elemental analyses, single-crystal X-ray diffraction, IR spectroscopy, UV-vis spectroscopy, X-ray powder diffraction (XRPD), 31P NMR spectroscopy, cyclic voltammetric behavior and thermogravimetric (TG) analyses. [(HO3PCH2PO3)Mo6O18(O2CC6H4OH)2]5− (1a) shows a ring-shaped cluster with a {Mo6} plane framework. [{(HO3PCH2PO3)Mo6O18(CH3CO2)2}2Na2(H2O)2]8− (2a) is a reverse symmetrical “crown-type” structure and the subunits are linked by two Na–O(1W)–Na bridges. The polyanion [{(O3PCH2PO3)(Mo6O18(H2O)2)(O2CCH2CO2)}2(Mo2O5)2(μ3-O)2]12− (3a) appears as an “S-shaped” structure with a centre of inversion.

Insight into the reactivity of in situ formed {(NbO2)3SiW9}: synthesis, structure, and solution properties of a trimeric polytungstosilicate trapping a {MnNb9} core

A new trimeric cluster [(SiW9Nb3O38)3MnO3(H2O)3]13- (1) with three Keggin-type trilacunary SiW9 units connected by a {MnNb9} core were structurally characterized. The polyanion 1 features three corner-shared {Nb3O3} fragments that are linked to each other on two sides via three Nb-O-Nb bridges and by a {MnII} linker. To the best of our knowledge, polyanion 1 represents the first example of a trimeric niobotungstate cluster reported to date, and is revealed for the first time uniting a family of polytungstosilicate clusters. The formation of polyanion 1 exemplifies the reactivity of {(NbO2)3SiW9} with a manganese metal ion, defining a new in situ synthetic strategy for {(NbO2)3SiW9}-based derivatives, featuring POM chemistry between Nb/W mixed-addendum POMs and various transition-metal or lanthanide species.

Assembly of TeO32– Ions Embedded in an Nb/O Cage with Selective Decolorization of Organic Dye

A novel 24-niobic-2-tellurite, [H2Te2Nb24O72]14-, was isolated by incorporating tellurite anions into a polyoxoniobate cage. The synthesized cluster represents the first example of a sandwich-type polyoxoniobate with the largest telluroniobate aggregate. Furthermore, the hybrid material acts as an efficient catalyst for the decolorization of basic fuchsin.

Assembly of niobium-phosphate cluster and in situ transition-metal-containing derivatives

A novel phosphorus incorporated peroxopolyoxoniobate (CN3H6)6H4[P4Nb6(O2)6O24]·4H2O (1) has been successfully synthesized and characterized. Compound 1 possesses a cluster of [P4Nb6(O2)6O24]10− and can be viewed as the fusion of two {P2Nb3(O2)3O14} subunits by corner-sharing of bridging oxygen atoms. Furthermore, by reacting transition metals with the polyanion [P4Nb6(O2)6O24]10− formed in situ, we have discovered a series of transition-metal-containing niobium phosphate cluster derivatives, (CN3H6)4H4[{Cd(H2O)4}{P4Nb6(O2)6O24}]·7H2O (2), Cs3H3{[M(H2O)4.5]2[P4Nb6(O2)6O24]}·5H2O [M = Co (3), Ni (4), Zn (5)] and Cs3H3[{Cd(H2O)4}2{P4Nb6(O2)6O24}]·12H2O (6). Compounds 2–6 are based on the {P4Nb6(O2)6O24}10− cluster and 3, 4 and 5 show zero-dimensional constructions whereas 2 and 6 can form 1D chains attributed to the larger radius of Cd2+.