Zhanhua Su

Novel antitumor agent, trilacunary Keggin-type tungstobismuthate, inhibits proliferation and induces apoptosis in human gastric cancer SGC-7901 cells.

A new one-dimensional chain-like compound of tungstobismuthate, [(W(OH)2)2 (Mn(H2O)3)2(Na3(H2O)14)(BiW9O33)2](Himi)2·16H2O (1) (imi = iminazole), has been synthesized in aqueous solution. The structure of 1 was identified by elemental analysis, IR, thermogravimetry (TG), X-ray photoelectron spectroscopy (XPS), (183)W-NMR, and single crystal X-ray diffraction. To investigate the inhibitory effect of 1 on human gastric adenocarcinoma SGC-7901 cells, cell proliferation and apoptosis initiation were examined by MTT assay (MTT = 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide), flow cytometry, nuclear staining, transmission electron microscopy, single cell gel electrophoresis, DNA fragmentation, and Western blotting. The results showed that 1 inhibited cell proliferation and induced apoptosis in SGC-7901 cells in dose-dependent manner. In addition, 1 also decreased the expression of bcl-2 protein and nuclear factor-κB p65 protein in SGC-7901 cells. And expression of bcl-2 protein exhibits a decreasing trend with increase of concentration of 1. Thus, 1 possessed a potential antitumor activity in SGC-7901 cells. This suggests that polyoxotungstates will provide a promising and novel antitumor agent in prevention and treatment of gastric adenocarcinoma.

Inorganic–organic hybrids constructed from heteropolymolybdate anions and copper–organic fragments: syntheses, structures and properties

A series of inorganic–organic complexes based on polymolybdate anions and copper–organic subunits, [Cu(H2O)(bim)2]{[Cu(Hbim)2][P2Mo5O23]}·2H2O (1), [Cu(Hbim)2]{[Cu(bim)(H2O)2]2[Cu(bim)2]2[(P2Mo5O23)2]}·20H2O (2), [Cu(phen)(H2O)][Cu(bim)2]2[P2Mo5O23]·H2O (3) and Mg[Cu(bim)(H2O)]2[P2Mo5O23]·4H2O (4) (bim = 2,2′-biimidazole, phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions and their crystal structures have been determined by single-crystal X-ray diffraction analysis. All of these compounds contain the [P2Mo5O23]6− polyoxoanions as building units. The structure determination shows that the polyoxoanion of compound 1 is mono-supported by one copper complex subunit. In compound 2, the [P2Mo5O23]6−cluster is supported by two distinct [Cu(bim)(H2O)2]2+ and [Cu(bim)2]2+ fragments. Compound 3 presents a tri-supported polyoxometalate cluster structure, where each [P2Mo5O23]6− anion is decorated by two [Cu(bim)2]2+ and one [Cu(phen)(H2O)]2+ cations. In compound 4, the [P2Mo5O23]6− anion is supported by four symmetry [Cu(bim)(H2O)]2+ units. The cyclic voltammetry results for 1–4 indicate the known fingerprint of the [P2Mo5O23]6− anion. Although compounds 1–4 contain similar polyoxometalate anions, the mean peak potentials are slightly different, due to their different chemical environments. The magnetic behaviours of 1–4 were also investigated, in the temperature range of 2–300 K.

New extended poly(oxomolybdophosphates) based on strontium(II) linkers

Four new poly(oxomolybdophosphates), Na[FeIII(2,2′-bpy)3]2[FeII2Sr2MoV12O24(OH)6(H2O)8(H2PO4)2(HPO4)2(PO4)4]·[PO4]·9H2O 1, [H2(bpp)]2[MnII2Sr2Mo12O24(OH)6(H2O)8(H2PO4)2(HPO4)2(PO4)4]·8H2O 2, [H2(4,4′-bpy)]2[CdII2Sr2Mo12O24(OH)6(H2O)6(H2PO4)2(HPO4)2(PO4)4]·5H2O 3 and [H2(4,4′-bpy)][MnII2Sr4Mo12O24(OH)6(H2O)12(HPO4)4(PO4)4]·8H2O 4 (2,2′-bpy = 2,2′-bipyridine, bpp = 1,3-bi(4-pyridyl)-propane, 4,4′-bpy = 4,4′-bipyridine), have been hydrothermally synthesized and structurally characterized by elemental analysis, TG, IR, UV-vis and single-crystal X-ray diffraction. All the compounds are based on the [P4Mo6O31]12− (abbreviated as [P4Mo6]) polyoxometalate units, which are further connected into sandwich-type dimeric units by various transition metal (TM) ions. In compounds 1–3, the dimeric {(TM)[P4Mo6]2} units are linked by new {Sr2TM} trinuclear fragments into one-dimensional (1-D) chains. These 1-D chains are further packed into various three-dimensional (3-D) supramolecular assemblies due to the use of different bipyridine-based structure-directing agents. In compound 4, the dimeric {(TM)[P4Mo6]2} units are linkered by an unprecedented {Sr4Mn} pentanuclear unit into new 3-D open framework, exhibiting a 64.82-nbo (niobium-oxide-like) topology. The electrochemical properties of these compounds were investigated.

Three novel coordination polymers constructed from [Cu(CN)] chains

Three new coordination polymers based on [Cu(CN)] chains, [Cu(CN)]3(phen) (1), [Cu(CN)]2(4,4′-bipy) (2) and [Cu(CN)]4(bpp)2 (3) (phen = 1,10′-phenanthroline, bipy = 4,4′-bipyridine and bpp = 1,3-bis(4-pyridyl)propane), have been synthesized by hydrothermal methods and characterized by elemental analysis, IR, X-ray powder diffraction (XRPD) and single crystal X-ray diffraction. Complex 1 features a noncovalence-induced 2D layer and further forms a 3D supramolecular framework by π⋯π interactions. Complex 2 generates an interesting 3D coordination polymer of 2-fold interpenetration with (4.62)(42.610.83) topology. Complex 3 displays 2-fold parallel interpenetration with (4.62)(43.611.72.85)(44.611)(45.615.7) topology. The thermal stability and photoluminescent properties of 1–3 in the solid state at ambient temperature were also investigated.

A new {P2W18} polyoxometalate cluster modified with copper complex based on pz, 2,2–bipy, and in situ amino acid

A new organic–inorganic hybrid compound, [{Cu2(2,2′–bipy)2(pz)(gly)}2P2W18O62]·H2O (bipy = bipyridine, pz = pyrazine, gly = glycine) (1), has been hydrothermally synthesized and characterized by elemental analysis, IR, thermal gravimetric, and single- crystal X-ray diffraction. Compound 1 is an infinite one-dimensional (1-D) chain constructed from [P2W18O62]6− clusters and linker exhibiting an alternating-type structure via equatorial terminal oxygens of the polyanion. The 1-D chains are further extended into 2-D layers and 3-D supramolecular network via weak interactions. The copper complex of 1 consists of three ligands, in which an in situ glycine from pyrazine precursor was observed. Additionally, the electrochemical and electrocatalytic properties of 1 have been studied.

A 3-D inorganic–organic hybrid based on saturated Wells–Dawson polyoxoanion and K+, linked by an Ag–Ag bond

A 3-D complex K2[Ag2(biim)2]2P2W18O62 (biim = biimidazole) (1) has been hydrothermally synthesized and characterized by IR, thermogravimetric, and single-crystal X-ray diffraction. Single-crystal X-ray structural analysis reveals that 1 exhibits a 1-D wavelike chain constructed from µ3-bridging oxygen atoms of [P2W18O62]6− and [Ag2(biim)2]2+. The K+ link to six oxygen atoms of three P2W18 clusters and 12 equatorial terminal oxygen atoms of P2W18 clusters link to six K+, resulting in a 3-D framework with a relatively short Ag–Ag bond [2.836 Å]. The electrochemical behavior of 1 modified carbon paste electrode (1-CPE) has been studied. The results indicate that 1-CPE has remarkable stability.

A 3-D supramolecular compound based on Keggin-type polyoxometalates and potassium-sulfanilamide

A Keggin-type polyoxometalate and potassium-sulfanilamide complex, [{K(C6H10N2O2S)2(H2O)}2(SiW12O40)2] · 2H3O+ · 10H2O (1), has been synthesized and characterized by elemental analyses, IR, TG, and single-crystal X-ray diffraction. Compound 1 exhibits infinite 1-D dimer chains which are constructed from Keggin units [α-SiW12O40]4− bridged by potassium-sulfanilamide fragments. These 1-D chains are linked via π–π interactions between benzene rings of the sulfanilamides to form 2-D layers, which are further packed into 3-D supramolecular assemblies through hydrogen bonds. The electrochemical and electrocatalytic behaviors of 1 have been studied in detail.

Assembly of a new Keggin polyoxometalate-templated complex using flexible 1,2-bis(imidazol-1′-yl)ethane ligand

A new compound, [{CuI(bim)}4{SiW12O40}] (1) (bim = 1,2-bis(imidazol-1′-yl)ethane), was hydrothermally synthesized and characterized by elemental analyses, IR, TG, and single-crystal X-ray diffraction. Compound 1 is an infinite 1-D chain composed of Cu-bim coordination polymers and [α-SiW12O40]4− polyanions. The electrochemical and electrocatalytic behaviors of 1-modified carbon paste electrode (1-CPE) have been studied.

The first 3D host–guest structure based on a three-fold interpenetrated Ag-pz coordination polymer network and Keggin-type aluminum tungstates with photo/electro-catalytic properties

A new 3D POM-based coordination polymer network, [{Ag5(pz)7}{AlW12O40}]·4H2O (1) (pz = pyrazine), has been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, UV-vis, XRD, TG, and single-crystal X-ray diffraction. In compound 1, 3-coordinated Ag3 and 4-coordinated Ag2 are alternately joined together to form a large decagon ring by sharing pz or “V”-like Ag4-pz bridges. Each large ring is connected with six adjacent rings via the edge-sharing modes resulting in an infinite 2-D layer. It is worth noting that the “Y”-shaped Ag1-pz segment is suspended on the ring through sharing pz with the Ag2-pz tetrahedron, which is an important linkage unit extending the 2-D layers to a three-fold interpenetrating Ag-pz network with (103·123) (103)(10)2(122·14) topology. The Keggin {AlW12} as inorganic ‘guest’ units are encapsulated into the channel of the Ag-pz framework to form a complex POMOF 3D network. In addition, compound 1 exhibits better electrocatalytic properties to reduce hydrogen peroxide and good photocatalytic activity for the degradation of rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and azophloxine (AP).

Assembly of six [HxAs2Mo6O26](6−x)− cluster-based hybrid materials from 1D chains to 3D framework with multiple Cu–N complexes

A series of organic–inorganic hybrid compounds, [{Cu(4,4′-bipy)1.5(H2O)2}2{H2As2Mo6O26}] (1), [{Cu (biim)2}2{HAs2Mo6O26}{Cu(biim)Cl}]·H2O (2), (H2bib)[{Cu(H2O)2(bib)}{H2As2Mo6O26}]·2H2O (3), [{(Hbix)Cu(bix)0.5}2{As2Mo6O26}]·2H2O (4), [{Cu(bmb)1.5(H2O)}2{H2As2Mo6O26}]·2H2O (5), 0 and [{Cu2(bth)4}{H2As2Mo6O26}]·H2O (6) (4,4′-bipy = 4,4′-bipyridine; biim = biimidazole; bib = 1,4-bis(1-imidazolyl)benzene; bix = 1,4-bis(imidazol-1-ylmethyl)benzene; bmb = 1,4-bis(benzimidazol-1-yl)benzene; bth = 1,6-bis(1,2,4-triazol-lyl)hexane), were hydro-thermally synthesized and structurally characterized via elemental analysis, TG, IR, XPS, XRD, and single-crystal X-ray diffraction. The crystal structures 1–6 are formed by metal–organic complexes and the [HxAs2Mo6O26](6−x)− cluster. Compounds 1–2 feature infinite 1D-chain structures. Compounds 3–5 form 2D-layer structures in which Cu cations are five-, six-coordinated with polyoxoanions and organic ligands. Notably, compound 6 introduces the POM system into a metal–organic framework (MOF) to form a unique POMOF {42·611·82}{42·64}{44·69·7·8} topological structure. The coordination modes of the [HxAs2Mo6O26](6−x)− cluster in compounds 2, 5 and 6 are reported for the first time. The photocatalytic properties of 1–6 are studied for the decomposition of methylene blue (MB) under UV light. In addition, all the compounds exhibit good electrocatalytic performances for the reduction of nitrite.