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Two new organic–inorganic hybrid compounds, [Cu(phen)(prz)]2[PMoV1MoVI7VIV2VV4O42]·4H2O (1) and [Ag2(phen)4]2[PMoV1MoVI7VIV2VV4O42] (2) (phen = 1,10-phenanthroline, prz = pyrazine), have been synthesized and characterized by IR, XPS, XRD, UV–vis, fluorescent spectra analyses, elemental analyses, X-ray diffraction analyses, TG analyses, and cyclic voltammetric measurements. Both compounds are formed by Keggin POM cores and transition metal fragments. Compound 1 exhibits an unprecedented 1-D chain structure constructed from [PMoV1MoVI7VIV2VV4O42]4− and [Cu(phen)(prz)]2+ in the –A–B↑–C–B↓– linking mode. Compound 2 shows a supramolecular structure formed by [PMoV1MoVI7VIV2VV4O42]4− and [Ag2(phen)4]2+.

A polyoxometalate [Co(phen)3][Co(en)3][Co(en)2(H2O)2][Co(en)2]0.5[ O40(VIVO)2] · 6H2O (1) (en = ethylenediamine, phen = 1,10-phenanthroline) has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, electron paramagnetic resonance, X-ray photoelectron spectroscopy, elemental analyses, and thermogravimetry. The structure is an interesting 3-D supramolecular network containing bi-capped Keggin-type molybdenum–vanadium clusters with transition metal complexes generated in situ under mild hydrothermal conditions. Compound 1 contains four different counteractions being coordinated complexes of cobalt. The magnetic properties of 1 have also been studied in the temperature range of 4–300 K, and its magnetic susceptibility obeys the Curie–Weiss law, showing ferromagnetic coupling.

Two compounds based on polyoxometalates, (4,4′-H2bpy)7(4,4′-Hbpy)[ ]2[ ] ·10H2O (1) and (4,4′-H2bpy)6(4,4′-bpy)[ ]2 · 18H2O (2), have been prepared under hydrothermal conditions and characterized by IR, XPS spectra, TG analyses, and single crystal X-ray diffraction. Both compounds consist of 4,4′-bipyridine units and polyoxometalates: [ ]5− for 1 and [ ]6− for 2. In addition, 1 contains both Keggin-type and disordered Keggin-type anions, while 2 contains a (H2O)10 water cluster.

Two new polyoxometalates [HN(C2H5)3]3[PMo12O40] (1) and [NH2(C2H4NH3)2]2[Mo5P2O23] (2) have been hydrothermally synthesized and characterized by IR, UV-Vis, XPS spectra, TG analyses, and single crystal X-ray diffraction. Crystal data for 1: monoclinic, space group C2/c, a = 24.651(5) A, b = 10.822(2) A, c = 22.413(5) A, β = 120.37(3)°, and V = 5158.7(18) A3; for 2: triclinic, space group P-1, a = 9.821(2) A, b = 9.948(2) A, c = 14.687(3) A, α = 95.490(3)°, β = 98.870(3)°, γ = 95.710(3)°, and V = 1401.7(5) A3. The crystal structure analyses reveal complex hydrogen bonds in both 1 and 2 in 3-D supramolecular arrays constructed from different polyoxoanions and organic ligands.

Two supramolecular compounds [Fe(2,2′-bipy)3]2[ (Cl)] · 4.67H2O (1) and [Ni(enMe)3]2[ (Cl)] · 2H2O (2) have been prepared under hydrothermal conditions and characterized by elemental analyses, IR, TGA, ESR, magnetic properties, and single crystal X-ray diffraction analyses. Crystal data for 1: tetragonal, I-42d, a = 13.6043(19), b = 13.6043(19), c = 50.544(10) A, V = 9354(3) A3; for 2: hexagonal, P6(3)/m, a = 12.6046(12), b = 12.6046(12), c = 22.563(5) A, V = 3104.4(7) A3. Compound 1 is constructed from cations [Fe(2,2′-bipy)3]3+, polyoxovanadates [ (Cl)]6−, and water molecules. Compound 2 is composed of cations [Ni(enMe)3]2+, clusters [ (Cl)]8−, and water molecules. There are hydrogen-bonding interactions between polyoxovanadates, organic moieties, and/or water molecules in 1 and 2, forming different 2-D layered networks.