Zhong-Min Gao

New compounds constructed from polyoxometalates and transition metal coordination complexes with lower positive charge

Five new hybrid compounds constructed from polyoxometalates and transition metal coordination complexes with lower positive charge: [PW11CuO39][Cu(bpy)2]5 (1), [BW12O40][Cu(bpy)2]5 (2) [BW12O40][Cu(Phen)2]3[Cu(Phen)(H2O)]2·2H2O (3), [SiW12O40][Cu(bpy)2]4 (4) and [PW12O40][Cu(bpy)2]4 (5) have been prepared and characterized by IR, UV-Vis, XPS, XRD and single crystal X-ray diffraction analyses. The packing motif of the [Cu(bpy)2]+ copper coordination complexes in compound 1 exhibits square supramolecular channels running along the a axis, which are then filled by the [PW11CuO39]5− ions. Compound 2 is isomorphours with compound 1. Compound 3 contains a novel 2-D supramolecular layer structure constructed from [Cu(Phen)2]+ copper coordination complexes through π⋯π interactions. The packing motif of the [Cu(bpy)2]+ copper coordination complexes in compound 4 exhibits a supramolecular channel which is different from compound 1. Compound 5 is isomorphours with compound 4.

The design, syntheses and characterization of a series of hybrids based on polyoxometalates and metal complexes

Six new hybrid compounds based on polyoxometalates and transition metal complexes, [SiW12O40][Ag4(2,2′-bpy)4(4,4′-bpy)3]·2H2O (1), [SiMo12O40][Cu(2,2′-bpy)(H4,4′-bpy)2(H2O)][H4,4-bpy] (2), [PMo12V2O42][Cd2(Phen)2(4,4′-bpy)2(H2O)2(C2O4)]·2H2O (3), [PMo12V2O42][Cu2(4,4′-bpy)2][Cu2(Phen)(4,4′-bpy)2]·3H2O (4), [SiMo12V2O42][Cu2(Phen)2(4,4′-bpy)]2 (5) and [GeMo12V2O42][Cu2(Phen)2(4,4′-bpy)]2 (6) (bpy = bipyridine, Phen = phenanthroline), have been synthesized and characterized. Compound 1 contains a discrete tetranuclear silver-2,2′-bpy-4,4′-bpy complex; compound 2 is the first example where the polyoxometalate supports a metal–aqua–2,2′-bpy-4,4′-bpy complex; it should be noted that the complex contains a 2,2′-bpy and two 4,4′-bpy ligands; compound 3 is the first hybrid compound based on polyoxometalates and metal–aqua–4,4′-bpy–oxalic–phenanthroline complexes; and compound 4 is a novel hybrid compound based on polyoxometalates, extended metal–4,4′-bpy complexes and extended metal–4,4′-bpy–phenanthroline complexes together. Compounds 5 and 6 are isomorphous and isostructural; both exhibit a supramolecular structure constructed from bicapped Keggin POMs and metal–4,4′-bpy–phenanthroline complexes.

New halo(pseudohalo)cadmates templated by protonatated N-heterocyclic/diamine molecules

At ambient temperature, with various mono(di)protonated N-heterocyclic or diamine molecules as the cations, seven new halo(pseudohalo)cadmates [H2(bpee)][Cd(SCN)4] (bpee = 1,2-bis(4-pyridyl)ethene) 1, [H2(bpyp)][CdBr2(SCN)2] (bpyp = 1,2-bis(4-pyridyl)propane) 2, [H2(mbcha)][Cd3Br2(SCN)6] (mbcha = 4,4′-methylenebis(cyclohexylamine)) 3, [(Hdabco)2Cd3(SCN)8] (dabco = 1,4-diazabicyclo[2,2,2]octane) 4, [H2(bp)][Cd(SeCN)4] (bp = 4,4′-bipiperidine) 5 [H2(pdma)][Cd(SeCN)4]·2H2O (pdma = 1,4-phenylenedimethanamine) 6 and [H2(4,4′-dtdpy)][Cd2Br6] (dtdpy = dithioidipyridine) 7 were obtained. X-ray analysis revealed that (i) compound 1 possesses a three-dimensional (3D) supramolecular network structure with the one-dimensional (1D) channels, constructed from the inorganic [Cd(SCN)4]2− chains by weak S⋯S interactions. The H2(bpee)2+ molecules occupy the space of the channels; (ii) with H2(mbcha)2+ as the cation, the anion [Cd3Br2(SCN)6]2− of compound 3 exhibits a 1D ribbon structure, which can be described as a lengthways packing of planar bi-bridged trimers; (iii) compound 4 is the first example of the cation-controlled 3D thiocyanatocadmate with a composition [Cd3(SCN)8]2−; (iv) with H2(4,4′-dtdpy)2+ as the cation, the anion [Cd2Br6]2− of compound 7 also shows a 1D ribbon structure. This ribbon can be described as a transverse stacking of two planar bi-bridged single chains; (v) the ribbons of compounds 3 and 7 can be visualized as a slice of the two dimensional (2D) CdX2 layer; (vi) in compounds 2, 3, 5, 6 and 7, the organic molecules as the linkers extend the inorganic anionic moieties into various 2D supramolecular layer networks.

In situ growth of MnO2 nanosheets on activated carbon fibers: a low-cost electrode for high performance supercapacitors

MnO2 nanosheets were successfully grown in situ on the surface of activated carbon fibers (ACFs) via a facile microwave-assisted hydrothermal method. This environmentally-friendly approach displays the advantages of low temperature, short reaction time and low cost. A series of MnO2/ACFs composites with different MnO2 percentages were prepared and their electrochemical performance as an electrode for supercapacitors was investigated. The 63% MnO2 composite showed the optimal charge storage performance, remarkable rate ability, and excellent cycling capability. The enhanced electrochemical performance is attributed to the combination of good electrical conductivity of ACFs and high capacity of MnO2. This work provides a useful insight into the design and fabrication of hierarchical transition metal oxide and carbon material composite electrodes for potential applications in next generation energy storage systems.

Two new halide-containing polyoxometalate-based compounds

Two new compounds, [CuCl(Phen)(H2O)][PW12O40][4,4′-H2bpy]·1.5H2O (1) and [Cd2(Phen)4Cl2][HPMo12O40](4,4′-bpy) (2) (bpy = bipyridine, Phen = phenanthroline), have been hydrothermally prepared and characterized by IR, UV–vis, XPS, XRD, elemental analysis, cyclic voltammetry analysis, and single-crystal X-ray diffraction analysis. Compound 1 exhibits a 1-D chain structure constructed from polyoxometalates (POMs) and transition metal complexes, whereas 2 presents a supramolecular structure constructed from POMs, metal halide clusters, and organic ligands. Graphical Abstract