Pengtao Ma

Rare sandwich-type polyoxomolybdates constructed from Di-/tetra-nuclear transition-metal clusters and trivacant keggin germanomolybdate fragments.

Two types of rare sandwich-type germanomolybdates [Na(12)(H(2)O)(36)][Cu(2)(beta-Y-GeMo(9)O(33))(2)].3H(2)O (1), [N(CH(3))(4)](4) [Na(6)(H(2)O)(24)][Cr(2)(beta-Y-GeMo(9)O(33))(2)].7H(2)O (2), and [Na(11)(H(2)O)(25)]H[M(4)(H(2)O)(2)(alpha-B-GeMo(9)O(34))(2)].6H(2)O (M = Ni(II) for 3, M = Mn(II) for 4 and M = Co(II) for 5) have been synthesized and characterized by elemental analyses, ICP spectra, IR spectroscopy, UV spectroscopy, thermogravimetry (TG) analyses (for 1-3), X-ray photoelectron spectroscopy (XPS) (for 1 and 3), X-ray powder diffraction (XRPD) (for 1 and 3) and single-crystal X-ray diffraction. To our knowledge, 1-5 represent the first sandwich-type germanomolybdates containing both {beta-Y-GeMo(9)O(33)}/{alpha-B-GeMo(9)O(34)} fragments and transition-metal clusters. Interestingly, 1 and 2 display the rare dinuclear transition-metal substituted sandwich-type structures with unusual trivacant {beta-Y-GeMo(9)O(33)} germanomolybdate units whereas 3-5 exhibit the first tetranuclear transition-metal substituted sandwich-type structures with familiar trivacant {alpha-B-GeMo(9)O(34)} germanomolybdate units. Surface photovoltage spectroscopy (SPS) and electric field induced surface photovoltage spectroscopy (EFISPS) measurements reveal that 1 and 3 bear the behavior of the n-type semiconductor. Magnetic measurements indicate 1 and 3 demonstrate antiferromagnetic exchange interactions and ferromagnetic exchange interactions, respectively.

Nona-copper(II)-containing 18-tungsto-8-arsenate(III) exhibits antitumor activity

The nona-Cu(II)-containing tungstoarsenate(III) [H4{Cu(II)9As(III)6O15(H2O)6}(α-As(III)W9O33)2](8-) (1a) has been synthesized and characterized. Polyanion 1a comprises a unique, cylindrical {Cu(II)9As(III)6O15(H2O)6}(6+) cluster, which forms a large central cavity and is capped on either end by an [α-As(III)W9O33](9-) capping group. It exhibits remarkable activity against K562 leukaemia cells, as well as induces HepG2 cell apoptosis and autophagy.

Self‐Assembly of [B‐SbW9O33]9− Subunit with Transition Metal Ions (Mn2+, Cu2+, Co2+) in Aqueous Solution: Syntheses, Structures and Magnetic Properties of Sandwich Type Polyoxometalates with Subvalent SbIII Heteroatom

Rational self-assembly of Sb(2)O(3) and Na(2)WO(4), or (NH(4))(18)[NaSb(9)W(21)O(86)] with transition-metal ions (Mn(2+), Cu(2+), Co(2+)), in aqueous solution under controlled conditions yield a series of sandwich type complexes, namely, Na(2)H(2)[Mn(2.5)W(1.5)(H(2)O)(8)(B-beta-SbW(9)O(33))(2)]32 H(2)O (1), Na(4)H(7)[Na(3)(H(2)O)(6)Mn(3)(mu-OAc)(2)(B-alpha-SbW(9)O(33))(2)]20 H(2)O (OAc=acetate anion) (2), NaH(8)[Na(2)Cu(4)Cl(B-alpha-SbW(9)O(33))(2)]21 H(2)O (3), Na(8)K[Na(2)K(H(2)O)(2){Co(H(2)O)}(3)(B-alpha-SbW(9)O(33))(2)] 10 H(2)O (4), and Na(5)H[{Co(H(2)O)(2)}(3)W(H(2)O)(2)(B-beta-SbW(9)O(33))(2)]11.5 H(2)O (5). These structures are determined by using the X-ray diffraction technique and further characterized by obtaining IR spectra and performing elemental analysis. Structure analysis reveals that polyoxoanions in 1 and 5 comprise of two [B-beta-SbW(9)O(33)](9-) building units, whereas 2, 3, and 4 consist of two isomerous [B-alpha-SbW(9)O(33)](9-) building blocks, which are all linked by different transition-metal ions (Mn(2+), Cu(2+), or Co(2+)) with different quantitative nuclearity. It should be noted that compound 2 represents the first one-dimensional sinusoidal chain based on sandwich like tungstoantimonate building blocks through the carboxylate-bridging ligands. Additionally, 3 is constructed from sandwiched anions [Na(2)Cu(4)Cl(B-alpha-SbW(9)O(33))(2)](9-) linked to each other to form an infinitely extended 2D network, whereas 5 shows an interesting 3D framework built up from offset sandwich type polyoxoanion [{Co(H(2)O)(2)}(3)W(H(2)O)(2)(B-beta-SbW(9)O(33))(2)](6-) linked by Co(2+) and Na(+) ions. EPR studies performed at 110 K and room temperature reveal that the metal cations (Mn(2+), Cu(2+), Co(2+)) reside in a square-pyramidal geometry in 2, 3, and 4. The magnetic behavior of 1-4 suggests the presence of weak antiferromagnetic coupling interactions between magnetic metal centers with the exchange integral J=-0.552 cm(-1) in 2.

Rare‐Earth–Transition‐Metal Organic–Inorganic Hybrids Based on Keggin‐type Polyoxometalates and Pyrazine‐2,3‐dicarboxylate

Five rare-earth-transition-metal (RE-TM) heterometal organic-inorganic hybrids based on Keggin-type silicotungstates and mixed ligands H2pzda (pzda=pyrazine-2,3-dicarboxylate) and en (en=ethylenediamine) (enH2)[Cu(en)2(H2O)]2{[Cu(en)2][Cu(en)2(H2O)][(α-SiW11 O39)RE(H2O)(pzda)]}2·n H2O (n≈4; RE=YIII (1), DyIII (2), YbIII (3), and LuIII (4)) and [Cu(en)2(H2O)]2{[Cu(en)2]2[Cu(pzda)2][(α-H2SiW11O39)Ce(H2O)]2}·n H2O (5; n≈8) have been hydrothermally synthesized and structurally characterized. Compounds 1-5 all contain the dimeric mono-RE substituted Keggin [RE(α-SiW11O39)]210- subunits linked by H2pzda ligands. Interestingly, 1-4 exhibit discrete structures, in which the H2pzda ligand acts as a tetradentate ligand to bind the RE and Cu cations, whereas 5 displays a 1D double-chain architecture, in which the H2pzda ligand adopts a new pentadentate mode to connect the Ce and Cu cations. To our knowledge, 1-5 represent the first monovacant Keggin-type silicotungstates containing both RE-TM heterometals and mixed ligands. The luminescence of 2 is derived from the combination of the DyIII cations and H2pzda ligands, whereas the luminescence properties of 1 and 3-5 are attributable to the H2pzda ligands.

Assembly of polyoxometalate-based inorganic–organic compounds from silver–Schiff base building blocks: synthesis, crystal structures and luminescent properties

Three polyoxometalate-based inorganic–organic hybrid compounds constructed from silver(I)-L (L = N,N′-bis-pyridin-2-ylmethylene-hydrazine) species and saturated Keggin type polyoxoanions, {[Ag3L3](PW12O40)(CH3CN)(DMF)2.5}n (1), [Ag4L3(CH3CN)4][Ag2L(CH3CN)3](PMo12O40)2·CH3CN (2) and [(SiMo12O40){Ag2L(CH3CN)3}2]·(CH3CN)2 (3), have been synthesized and structurally characterized by IR spectroscopy, UV spectroscopy, thermogravimetric (TG) analyses and complete single crystal structure analyses. The structure of 1 containing [PW12O40]3− anions as templates exhibits a one-dimensional chain structure constructed by the coordination of a silver center and bis-bidentate bridging ligands with the pyridyl rings adopting a transoid configuration. Compound 2 displays an AB-type arrangement supramolecular structure, in which A is a two-dimensional sheet formed by linking the adjacent [Ag4L3(CH3CN)4]4+ units through the cooperativity of intermolecular π–π interactions and C–H⋯π interactions, while B is composed of [PMo12O40]3− anions and binuclear [Ag2L(CH3CN)4]2+ cations. Compound 3 exhibits a new bisupporting Keggin-polyoxometalate structure in which the [SiMo12O40]4− core supports two [Ag2L(CH3CN)3]2+ fragments in two opposite positions. The luminescent properties of L and 1–3 in the solid state were investigated.

Four types of 1D or 2D organic–inorganic hybrids assembled by arsenotungstates and CuII–LnIII/IV heterometals

Four types of organic–inorganic hybrids Na[Cu(en)2(H2O)]4[Cu(en)2]2[Cu(H2O)4]0.5{Cu(en)2[H2CeIV(α-AsW11O39)2]2}·10H2O (1), Na3[Cu(en)2(H2O)][Cu(en)2]1.5[H3Ln(α-AsW11O39)2]·xH2O [Ln = PrIII, x = 5 (2); Ln = NdIII, x = 4.5 (3); Ln = SmIII, x = 5.5 (4); Ln = EuIII, x = 4 (5); Ln = TbIII, x = 4 (6)], [Cu(dap)(H2O)2]0.5[Cu(dap)2(H2O)]2[Cu(dap)2]3[Ln(α-AsW11O39)2]·xH2O [Ln = PrIII, x = 3 (7); Ln = EuIII, x = 3 (8)] and [Cu(dap)2]5.5[Ln(α-AsW11O39)2]·xH2O [Ln = TbIII, x = 6 (9); Ln = DyIII, x = 5 (10)] (en = ethylenediamine, dap = 1,2-diaminopropane) have been hydrothermally synthesized and fully characterized by elemental analyses, IR spectra, solid-state UV spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1 exhibits the first 2D TM–Ln heterometallic sheet architecture with a 4-connected topology established by tetrameric [Cu(H2O)4{Cu(en)2[H2Ce(α-AsW11O39)2]2}2]26− units via [Cu(en)2]2+ bridges. 2–6 are isomorphic and display the unique 2D (6,3)-network topology constructed from 1 : 2-type [H3Ln(α-AsW11O39)2]8− units through [Cu(en)2]2+ linkers. 7–8 represent the first 1D “dendritic” chain-like TM–Ln heterometallic POMs based on the 1 : 2-type [Ln(α-AsW11O39)2]11− units. 9–10 are the unique 2D sheets built by 1 : 2-type [Ln(α-AsW11O39)2]11− units and [Cu(dap)2]2+ connectors, in which the [Ln(α-AsW11O39)2]11− subunits act as 5-connected nodes and adjacent 2D sheets are packed in the mode of –AAA–. The photocatalytic measurements show that 1–10 can to some extent inhibit the photodegradation of rhodamine-B (RhB). Moreover, the luminescence properties of 5–6 and 8–9 have been investigated.

Three-dimensional lanthanide polyoxometalate organic complexes: correlation of structure with properties

A family of three-dimensional (3D) architectures based on lanthanide-substituted polyoxotungstate building blocks [Ln(HL)(L)(H2O)6{Ln(H2L)0.5(α-PW11O39H)Ln(H2O)4}]2·nH2O (Ln = La, n = 8 (1); Ln = Ce, n = 12 (2); Ln = Pr, n = 8 (3); H2L = 2,5-pyridinedicarboxylic acid) have been successfully synthesized under hydrothermal conditions and further characterized by elemental analyses, X-ray powder diffraction (XRPD), IR spectra, UV spectra, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. The common features of 1–3 are that they all consist of 1D zigzag chain [{Ln(α-PW11O39H)}2]6− moieties and the chains further form into 3D structure via metal–organic cations. Furthermore, the photocatalysis properties of 1–3 for degradation of the rhodamine-B (RhB) upon 500 W Hg lamp irradiation have been examined. The magnetic properties of compounds 2 and 3 have been studied by measuring their magnetic susceptibility in the temperature range of 2–300 K.

Two 1-D multi-nickel substituted arsenotungstate aggregates

Two multi-nickel substituted arsenotungstate aggregates [enH2]2[Ni(H2O)4]2[Ni(en)2]2[Ni(en)]2{[(α-AsW6O26)Ni6(OH)2(H2O)3(en)(B-α-AsW9O34)]2[W4O16][Ni3(H2O)2(en)]2}·16H2O (1) and [Ni(H2O)(en)2]2[Ni(H2O)3(en)][Ni(H2O)(en)]{[(α-AsW6O26)Ni6(OH)2(en)2.5(B-α-AsW9O34)]2H4[W4O16][Ni4(H2O)2(en)2]2}·13H2O (2) (en = ethylenediamine) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. 1 is a 1D chain architecture built by eighteen NiII substituted {[(α-AsW6O26)Ni6(OH)2(H2O)3(en)(B-α-AsW9O34)]2[W4O16][Ni3(H2O)2(en)]2}16− units via two [Ni(H2O)4]2+ and two [Ni(en)2]2+ bridges. 2 also displays a 1D chain motif constructed from twenty NiII substituted {[(α-AsW6O26)Ni6(OH)2(en)2.5(B-α-AsW9O34)]2H4[W4O16][Ni4(H2O)2(en)2]2}8− units via single en bridges. Notably, 1 and 2 not only represent rare eighteen/twenty NiII substituted arsenotungstates, but also display an unusual construction motif simultaneously containing the trivacant Keggin [B-α-AsW9O34]9−, hexavacant Keggin [α-AsW6O26]11− and tetrameric [W4O16]8− fragments. Magnetic measurements demonstrate that 1 and 2 indicate the ferromagnetic couplings within NiII centers.

A novel type of heteropolyoxoanion precursors {[Ca(H2O)]6[P4M6O34]2}12-(M = WVI, MoVI) constructed by two [P4M6O34]12-subunits via a rare hexa-calcium cluster

A novel type of heteropolyoxoanion (HPOA) precursors [[Ca (H(2)O)](6)[P(4)M(6)O(34)](2)](12-) [M = W(VI) (1), Mo(VI) (2)] has been synthesized and structurally characterized, which represents the rare membership of the HPOA family constituted by two early-transition-metal clusters ([P(4)M(6)O(34)](12-)) and a main-group metal cluster of high nuclearity ([Ca(6)](12+)).

Construction of polyoxometalate-based inorganic-organic compounds using silver(I) double helicates as secondary building blocks.

Two polyoxometalate-based silver(I) compounds including a three-dimensional porous crystalline array and a double-helicate bisupporting cluster were achieved using metal-organic helicates and Keggin [PMo(12)O(40)](3-) as secondary building blocks.