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A transition-metal-templated 3-D supramolecular framework based on molybdenum–vanadium polyoxoanions
Abstract
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 new 2D hybrid compounds derived from Keggin-type [BW12O40]5− anion, proline and 4,4’-bipy were synthesized, namely, [CoII2(proline)(4,4’-bipy)(H4,4’-bipy)2(OH)(H2O)2][BW12O40]•3H2O (1) and [CoII3(proline)2(4,4’- bipy)2(H4,4’-bipy)4(OH)2(H2O)4][BW12O40]2•6H2O (2). They are characterized by single-crystal X-ray diffraction, FT-IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analyses (TGA) and XPS spectra. All compounds represent 2D framework, but the structures possess some distinctions to a certain degree. In compound 1, 1D wave-like chains are formed. The chains and polyanions are stacked each other in an ABAB fashion to yield a 2D network. However, compared with compound 1, compound 2 exhibits the same construction except for the opposite arrangement mode. Moreover, their electrochemical behaviors and fluorescence properties have been investigated. The electrochemical properties show that compounds 1, 2 display good electrocatalytic activities for the reduction of nitrite.
Two supramolecular compounds [Cu(imz)2][Cu(phen)(imz)]2{[Cu(phen)]2[PMo6
VIMo6
VV2
IVO42]}(1) and [Co2(2,2′-bpy)4(C2O4)][Co(2,2′-bpy)3][PMo7
VIMo5
VV2
IVO42](2,2′-bpy)0.5·H2O(2)(phen=1,10′-phenanthroline, imz= imidazole, 2,2′-bpy=2.2′-bipyridine) have been synthesized hydrothermally and characterized by elemental analyses, infrared spectrum, UV-Vis, X-ray photoelectron spectroscopy(XPS), electron spin resonance(ESR) spectra, thermogravimetry analyses and single crystal X-ray diffraction analyses. Single-crystal X-ray diffraction analyses revealed that both the compounds represent the examples of compounds based on the bi-capped Keggin polyoxoanion {PMo12V2O42} and transition metal mixed-organic-ligand coordination complexes. Compound 1 consists of bi-capped Keggin polyoxoanion [PMo12V2O42]5− supported copper coordination groups, which are further inter-connected with two types of copper complex fragments forming a 3D supramolecular framework via π⋯π stacking, C-H⋯O and N-H⋯O hydrothermal bonding interactions. Compound 2 is a new hybrid consisted of polyoxoanion [PMo12V2O42]4−, [Co2(2,2′-bpy)4(C2O4)]2+ and [Co(2,2′-bpy)3]2+. There are no direct interactions in compound 2, but the polyoxoanions together with two different cobalt complex groups construct a 3D supramolecular network through C-H⋯O hydrogen bonding interactions.
The title compound, [Co(C2H8N2)3]2[SiMo8V4O40(VO)2]·6H2O, was prepared under hydrothermal conditions. The asymmetric unit consists of a transition metal complex [Co(en)3]3+ cation (en is ethylenediamine), one half of an [SiMo8V4O40(VO)2]6− heteropolyanion, two solvent water molecules in general positions and two half-molecules of water located on a mirror plane. In the complex cation, the Co3+ ion is in a distorted octahedral coordination environment formed by six N atoms of the three chelating en ligands. One of the en ligands exhibits disorder of its aliphatic chain over two sets of sites of equal occupancy. The [SiMo8V4O40(VO)2]6− heteropolyanion is a four-electron reduced bivanadyl-capped α-Keggin-type molybdenum–vanadium–oxide cluster. In the crystal, it is located on a mirror plane, which results in disorder of the central tetrahedral SiO4 group: the O atoms of this group occupy two sets of sites related by a mirror plane. Furthermore, all of the eight μ2-oxide groups are also disordered over two sets of sites with equal occupancy. There are extensive intermolecular N—H⋯O hydrogen bonds between the complex cations and inorganic polyoxidoanions, leading to a three-dimensional supramolecular network.
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 ππ 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.
Two new polytungstate-based compounds, [Co(mbpy)3][W6O19] (1) and [Ni(mbpy)3]2[VW12O40] (2) (mbpy = 4,4′-dimethyl-2,2′-bipyridyl), have been hydrothermally synthesized and characterized by IR spectroscopy, TG analysis, and single-crystal X-ray diffraction. Single crystal X-ray structural analyses demonstrate that the compounds consist of [M(mbpy)3] (M = Co or Ni) as cations anchored to W-containing polyoxoanions through non-covalent intermolecular interactions. The inorganic polyanions exhibit different cluster structures: Lindqvist-type [W6O19] isopolyoxoanion in 1; V-centered Keggin-type [VW12O40] heteropolyoxoanion in 2.
Two new compounds, [Zn(phen)3]2[γ-As8V14O42(H2O)] · 4H2O (1) and [Cd(phen)3]2[γ-As8V14O42(H2O)] · 2H2O (2) (phen = 1,10′-phenanthroline), have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, infrared spectrum, and thermogravimetric analysis. Compound 1 crystallizes in the triclinic space group P1 with a = 11.429(4) Å, b = 15.760(5) Å, c = 15.952(5) Å, α = 108.825(5)°, β = 92.194(5)°, γ = 104.155(5)°, V = 2615.6(15) Å, Z = 1; 2 crystallizes in the triclinic space group P1 with a = 11.450(4) Å, b = 15.629(6) Å, c = 16.302(6) Å, α = 109.177(5)°, β = 92.628(5)°, γ = 104.251(4)°, V = 2644.8(17) Å, Z = 1. Single-crystal structural analysis shows that both 1 and 2 consist of a new type of [γ-As8V14O42(H2O)] cluster anion.
In this study, a series of compounds based on Dawson-type phosphomolybdates, H3(C6NO2H6)2[K(H2O)3(C6NO2H5)3][P2Mo18O62] 5.5H2O (1), (C6NO2H6)6[Ln(H2O)7(C6NO2H5)2]2[P2Mo18O62]2·13.5H2O (Ln = Ce (2), La (3)) have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy methods, TG analysis, and single-crystal X-ray diffraction. Compound 1 consists of [P2Mo18O62]6− building units joined by potassium-pyridine-3-carboxylic acid complexes, resulting in a wavelike polyoxometalate (POM) chain, which further interacts with each other via intermolecular interactions to form a 3-D supramolecular channel framework containing guest water molecules. Compounds 2 and 3 possess a 3-D supramolecular framework with 1-D tunnel constructed from [P2Mo18O62]6− and mononuclear lanthanide coordination complex fragments. To the best of our knowledge, 1 not only represents the first example of 1-D hybrid assembly based on Dawson-type phosphomolybdate, but also the first hybrid compound constructed from Dawson-type POMs and alkali–metal coordination complex fragments.
A heterometallic polyoxometalate [Co(en)2][Co(bpy)2]2[PMoVI5MoV3VIV8O44]·4.5H2O (en = ethylenediamine, bpy = 2,2′-bipyridine) 1, has been hydrothermally synthesized, which is the first example of a two-dimensional framework where polyoxometalate anions are linked by two types of complex fragments.
The synthesis and structural characterization of three new polyoxomolybdenum(V) phosphate frameworks have been achieved by using dimeric {Mo<sub>6</sub>}<sub>2</sub> moieties as inorganic building blocks and protonated organic amines as counter ions. The structure-directing role of the organic cations was investigated and it was shown, that the geometry and the rigidity of the amines as well as their hydrogen bonding capabilities influence the formation of layered or chain-like superstructures.
A polyoxomolybdenum/vanadium-sulfite {M(18)} cluster-based compound, [Mo(VI)(11)V(V)(5)V(IV)(2)O(52)(mu(9)-SO(3))](7-), is reported that exhibits a unique structural motif, arising from the incorporation of five V(V) and two V(IV) ions into a {M(18)} cluster framework templated by SO(3)(2-); this cluster compostion was first identified using cryospray mass spectrometry.
This chapter describes a simple but powerful approach to predicting the structure and properties of complex solids and liquids. It is based on studies of large numbers of crystal structures and the empirical concepts of chemical bond and atomic valence. The valence of an atom is assumed to be distributed between the bonds it forms. The resulting bond valences correlate well with bond lengths and other bond properties. Bond valences determined from experimentally measured bond lengths are used to calculate atomic valences, which can be used in a number of ways to help in the determination and evaluation of crystal structures. The properties of bond valences lead to a structure-based scale of Lewis acid and base strength that can be used to predict which structures are likely to be stable and what bonding topologies these might have. In many of these cases, a detailed prediction of bond lengths and bond angles is possible.
A new compound [Zn(phen)2]2[
][Zn(phen)2(H2O)]2[
] · 7H2O (phen = phenanthroline) has been synthesized under hydrothermal conditions and characterized by IR, TG analysis and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P21/C, a = 21.609(4) Å, b = 16.537(3) Å, c = 21.279(4) Å, α = 90°, β = 100.25(3)°, γ = 90°, V = 7483(3) ų, Z = 2. The basic building unit in 1 is the [PMo8V6O42] cluster. The most remarkable structural feature of 1 is that there exist two distinct [PMo8V6O42] clusters. One is covalently linked by [Zn(phen)2] complexes to form a 2D covalent layer, the other supports two [Zn(phen)2(H2O)] complexes forming a discrete bisupporting structure. It is interesting that discrete bisupporting clusters locate in the space of two adjacent covalently layers to form a 3D supramolecular framework.
The synthesis and single-crystal X-ray structure analysis of the unusual Mo/V polyoxometalate compound Na0.5K6.5[MoVI8VIV4O36(VVO4)(VIVO) 2]·12.5H2O which contains capped α-Keggin fragments linked to a chain is reported; this chain is an interesting object for magnetochemists and can be considered to consist of an assembly of electron storage units.
The reaction of α-[SiMo12O40] with trivalent cations Ln and N-methyl-2-pyrrolidone leads to a series of complexes of formula [Ln(NMP)4(H2O)n]H[SiMo12O40] · 2NMP · mH2O [where Ln = La (1), Pr (2), Nd (3), Sm (4), Gd (5), n = 4, Ln = Dy (6), Er (7), n = 3. NMP = N-methyl-2-pyrrolidone]. The syntheses, X-ray crystal structures, IR, and ESR spectra and thermal properties of the complexes 1, 2, 4, 6, 7 have been reported previously. Here, we report X-ray crystal structures, IR, UV, ESR spectra and thermal properties of the complexes [Nd(NMP)4(H2O)4]H[SiMo12O40] · 2NMP · 1.5H2O (3), and [Gd(NMP)4(H2O)4]H[SiMo12O40] · 2NMP · H2O (5). In addition, the electrochemical behaviour of this series of complexes in aqueous solution and aqueous-organic solution has been investigated and systematic comparisons have been made. All these complexes exhibit successive reduction process of the Mo atoms.
Three neutral polyoxometalates [PVW11O40{M(phen)2H2O}2] · 3H2O (phen = 1,10′-phenanthroline, M=Co 1, Zn 2, Ni 3) are composed of water and the neutral Keggin-type polyoxometallate covalently linking a pair of transition metal complex fragments on opposite sides. The transition metal lies in the center of a distorted octahedron. Multi hydrogen-bonding interactions between coordinated waters of neutral polyoxometalate molecules and terminal oxygen atoms of Keggin units and between bridging oxygens of Keggin units and lattice water create a two dimensional layer and between the layers there exist van der Waals forces. The framework of the neutral molecule begins to decompose at ca 500°C. Compound 1 exhibits a weak antiferromagnetic interaction in the 2–300 K range.
The new mixed Mo/V heteropoly compound [Ni(C2N2-H8)3]2Na[MoV2MoVI6VIV8O40(PO4)]·H2O with a tetra-capping Keggin structure has been synthesized hydrothermally and its structure determined by X-ray diffraction
Two new heteropoly tungstovanadate derivatives, [Fe(phen)3]2[W10.5V4.5O42]·3H2O (1) and [Fe(phen)3]2[W10V5O42].6H2O (2) (phen=1,10′-phenanthroline), have been synthesized under hydrothermal conditions by using different starting materials, and characterized by elemental analysis, IR, ESR, XPS, TGA and single-crystal X-ray diffraction analysis. Crystal data for compound 1: C72H54Fe2N12O45V4.5W10.5, monoclinic, space group C2/c, a=30.244(9)Å, b=13.586(3)Å, c=24.707Å, β=99.882(8)°, V=10002(5) Å3, Z=4; for compound 2, C72H60Fe2N12O48V5W10, monoclinic, space group C2/c, a=30.246(6) Å, b=13.909(3)Å, c=25.329(5) Å, β=100.34(3)°, V=10483(4) Å3, Z=4. The crystal structure analysis reveals that both polyoxoanions are decorated with the [Fe(phen)3]2+ cations, and that they have analogous structure to each other with slightly different packing modes of the polyoxoanions, [Fe(phen)3]2+ cations and water molecules. They are further linked to form two-dimensional (2D) supramolecular networks through extensive hydrogen bonding.
More often than previously thought, the solid-state structures of carboxylic acids display hydrogen bonding motifs that differ from those of the classic carboxylic acid dimers. In studies aimed at engineering crystals with predictable structures, a specially designed tetracarboxylic acid was found to crystallize with THF to form a solid-state host–guest complex (clathrate); the host lattice is shown on the right.
Inorganic metal–oxygen cluster anions form a class of compounds that is unique in its topological and electronic versatility and is important in several disciplines. Names such as Berzelius, Werner, and Pauling appear in the early literature of the field. These clusters (so-called isopoly- and heteropolyanions) contain highly symmetrical core assemblies of MOx units (M = V, Mo, W) and often adopt quasi-spherical structures based on Archimedean and Platonic solids of considerable topological interest. Understanding the driving force for the formation of high-nuclearity clusters is still a formidable challenge. Polyoxoanions are important models for elucidating the biological and catalytic action of metal–chalcogenide clusters, since metal–metal interactions in the oxo clusters range from very weak (virtually none) to strong (metal–metal bonding) and can be controlled by choice of metal (3d, 4d, 5d), electron population (degree of reduction), and extent of protonation. Mixed-valence vanadates, in particular, show novel capacities for unpaired electrons, and the magnetic properties of these complexes may be tuned in a stepwise manner. Many vanadates also act as cryptands and clathrate hosts not only for neutral molecules and cations but also for anions, whereby a remarkable “induced self-assembly process” often occurs. Polyoxometalates have found applications in analytical and clinical chemistry, catalysis (including photocatalysis), biochemistry (electron transport inhibition), medicine (antitumoral, antiviral, and even anti-HIV activity), and solid-state devices. These fields are the focus of much current research. Metal–oxygen clusters are also present in the geosphere and possibly in the biosphere. The mixed–valence vanadates contribute to an understanding of the extremely versatile geochemistry of the metal. The significant differences between the chemistry of the polyoxoanions and that of the thioanions of the same elements is of relevance to heterogeneous catalysis, bioinorganic chemistry, and veterinary medicine.
The novel title compound {NiII4MoV12} demonstrates the concept of generating targeted spin topologies using reduced polyoxometalates: The four electrophilic nickel centersforming a tetrahedronare fixed by a nucleophilic highly reduced diamagnetic ε-Keggin cluster of Td symmetry generated in solution. This cluster not only has a structural role but actually participates in the transmission of the exchange interaction.
Two new compounds [Hbpy]2[Ce(Hbpy)(DMF)5(H2O)2][H2W12O40] · 0.5H2O (1) and [La(DMF)7(H2O)][PMo12O40] · DMF · (CH3)2NH (2) (DMF = N,N-dimethylformamide, bpy=4,4′-bipyridine) have been synthesized and characterized by single-crystal X-ray diffraction, IR spectra, TG analysis and electrochemical analysis. In 1, the [Ce(Hbpy)(DMF)5(H2O)2] unit is supported on the α-Keggin polyoxoanion [H2W12O40] via bridging oxygen atoms, and further extended into 2-D supramolecular networks by hydrogen-bonding and π–π interactions. There exist one-dimensional channels surrounded by supramolecular interactions, in which 4,4′-bipy ligands reside. Compounds constructed from Ln(III) and [H2W12O40] polyoxoanions are rare. For 2, the [La(DMF)7(H2O)] is supported by [PMo12O40] units via the surface bridging oxygens, and further extended into 2-D supramolecular networks through hydrogen bonds. As for 1, a one-dimensional channel exists in 2, in which DMF resides. To our surprise, (CH3)2NH molecules exist in the structure of 2, from hydrolysis of DMF under catalysis of 12-molybophosphate. The electrochemistry of 1 is investigated.
A novel isopolyoxomolybdate complex (C10H18N)4Mo8O26·6(CH3)2SO 1 was synthesized, purified and characterized by means of elemental analysis, IR and H NMR spectra and single-crystal X-ray diffraction. It crystallizes in a triclinic system with a = 11.5090(6), b = 12.8399(3), c = 14.774(13) Å, α = 105.390(16), β = 93.09(4), γ = 106.100(10)°, V = 2003.1(2) Å, Z = 2, R1 = 0.0789, wR2 = 0.2190. Complex 1 is constructed from [Mo8O26], (C10H18N) and (CH3)2SO and extends to form a two-dimensional network via hydrogen bonds and weak interactions in the ab plane. Chicken embryo experiments show that Compound 1 has high antiviral activity in vitro.
Two new organic-inorganic hybrid compounds based on polyoxometalate building blocks, [CuI(bpy)2]2{[CuII(bpy)]2 O40} (1), H[Cu(bpy)(H2O)]{[Cu(bpy)]4(PO4)2}{PW11 CuO39} · H2O (2) (bpy = 2,2′-bipyridine), have been solvothermally synthesized and characterized by elemental analyses, IR, and TG analysis. Single crystal X-ray diffraction reveals that 1 is built from the reduced α-Keggin polyoxoanion [ O40]6− bicapped by two [CuII(bpy)]2+ through four bridging oxo groups on two opposite [Mo4O4] faces. 1 shows mild photoluminescence in the solid state at room temperature. 2 is based on monovacant Keggin anion {PW11CuO39}5− linked through Cu(bpy)2+ and , generating a one-dimensional chain. Magnetism indicates predominantly antiferromagnetic interaction in 2.
Three porous coordination polymers, {[Co(dpdo)4(H2O)2][H(H2O)6](PMo12O40)} n (1), {[Co(dpdo)4(H2O)2][H3O(CH3OH)4](PMo12O40)} n (2) and {[Co(dpdo)4(H2O)2][K(CH3OH)4](PMo12O40)} n (3) (where dpdo is 4,4′-bipyridine-N,N′-dioxide), with special channels for the chain-like assembly of polymeric Keggin-type anions have been synthesized through self-assembly of Co2+ and dpdo ligands in acetonitrile/water or methanol/water solutions and characterized by single crystal X-ray diffraction. Based on layers constructed by [Co(dpdo)4(H2O)2]2 + and different bridging units for charge compensation between layers, the three compounds exhibit similar noninterwoven networks with large channels occupied by the poly-Keggin-anion chains. Thermogravimetric analyses suggest that the three supramolecular networks have different thermal stabilities based on different cationic bridging units.
A new 3-D organic–inorganic hybrid phosphomolybdate, [Ag(bipy)]4(H2P2Mo5O23) · 3H2O (1) (bipy = 4,4′-bipyridine) has been hydrothermally synthesized and characterized by elemental analyses, IR, TG, and fluorescent properties. Compound 1 crystallizes in the monoclinic space group C2/c with a = 23.830(5), b = 21.030(4), c = 24.501(5) Å, β = 110.38(3)°, V = 11510(4) Å3, Z = 8, and R 1 (wR 2) = 0.0507 (0.1210). It contains unique 3-D metal organic frameworks based on silver-complex fragments and hexa-connected P2Mo5 clusters via covalent bonds and represents the highest connection numbers of P2Mo5 clusters to date.
A new organic–inorganic polyoxometalate compound [Co(2,2′-bipy)3]H[Al(OH)6 (Mo6O18)] · 17H2O has been synthesized and characterized by elemental analysis, IR, UV spectra, thermogravimetry and differential thermal analysis (TG-DTA) and single-crystal X-ray diffraction analysis. The title compound crystallizes in a monoclinic, C2/c space group, with a = 37.292(8), b = 14.214(3), c = 25.050(5) Å, β = 120.62(3), V = 11426(4) Å3, Z = 8, F(000) = 7200, D c = 2.116 Mg m−3, R = 0.0748, wR 2 = 0.1853. Crystal structural analysis indicates that the asymmetric unit in the crystal structure of the title compound consists of one B-Anderson–Evans type heteropolyoxoanion, one octahedral [Co(2,2′-bipy)3]2+ coordination cation, seventeen water molecules of crystallization and a proton based on charge balance. The curves of TG-DTA indicate that weight loss of the title compound is divided into three stages. The third weight loss reveals that the backbone of heteropolyoxoanion decomposes at 744°C.
The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal–oxygen–carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.
A bicapped, highly reduced vanadylpolymolybdophosphate Keggin complex [(C2H5)3NH]5[PMoV6MoVI6O40(VIVO)2], (TEA) 1, has been prepared hydrothermally and characterized by single-crystal X-ray diffraction, IR, UV/visible, cyclic voltammetry, elemental analysis, redox titration, and 51V and 31P NMR on its degradation products. The kinetics of decomposition of 1 in aqueous solution under both aerobic and anaerobic conditions is complex.
Very large polycyclic compounds, with one or more nitrogen atoms in their structures, were separated from fossil fuel samples and characterized spectroscopically. High chromatography were essential to separate such complex mixtures: within structures of 3-10-rings, almost 170 peaks were resolved and over 600 nitrogen polycyclics were spectrally characterized. Most of the structural data were obtained from mass spectroscopy; however, fluorescence emission spectra yielded additional information concerning the shape of molecules.
The novel two- and three-dimensional solid materials [Cu(en)2(H2O)]{PMoVI8VIV6O42[Cu(en)2][Cu0.5(en)]3}·5.5H2O and H3{VVMoVI8VIV6O42[Cu(en)2]4}[MoO4]2·14H2O (en = ethylenediamine) have been hydrothermally assembled and structurally characterized. Both networks are based on mixed Mo/V bicapped Keggin clusters interconnected through the transition metal complex moieties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A new three-dimensional coordination polymer, {Cu3(4,4′-bpy)3(H2O)[PMo12O40(VO)2]·5H2O}n (1) (4,4′-bpy = 4,4′-bipyridine), which represents the first example of 3D polycatenation generated by unprecedented parallel catenation of the 1D double ladders, has been hydrothermally synthesized. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Three compounds based on polyoxometalate building blocks, [Cu(en)2]{[Cu(en)2]2[MoVI5MoV3VIV8O40(PO4)]} · 4H2O (1), [Co(en)2]{[Co(en)2]2[HMoVI4MoV4VIV8O40(PO4)]} · 5H2O (2) and [Ni(en)2]{[Ni(en)2]2[MoVI5MoV3VIV8O40(VO4)]} · 2H2O (3) (en = ethylenediamine), have been synthesized and characterized by elemental analysis, IR, XPS, XRD, TGA and single-crystal X-ray diffraction analysis. The result of structure determination shows that isomorphic compounds 1, 2 and 3 feature a one-dimensional chain built from the reduced tetra-capped pseudo-Keggin polyoxoanion, which is further interconnected by [M(en)2]2+ (M = Cu, Co and Ni) groups via the terminal oxygen atoms of polyoxoanions. The crystal data for these compounds are the following: 1, monoclinic, space group C2/c, a = 26.702(3) Å, b = 13.4539(14) Å, c = 19.5987(19) Å, β = 108.650(2)°, V = 6671.0(12) Å3, Z = 4; 2, monoclinic, space group C2/c, a = 26.244(3) Å, b = 13.5070(17) Å, c = 19.581(3) Å, β = 106.881(2)°, V = 6641.8(15) Å3, Z = 4; 3, monoclinic, space group C2/c, a = 26.2789(15) Å, b = 13.5408(6) Å, c = 19.6312(9) Å, β = 106.2590(10)°, V = 6706.1(6) Å3, Z = 4. Variable-temperature magnetic susceptibility measurements of compounds 1 and 3 reveal the feature of antiferromagnetic exchange in these compounds.
Three new cobalt borate compounds. [Co(DlEN)(2)][B5O6(OH)(4)] (DIEN = diethylenetriamine) (1). [B5O7(OH)(3)Co(TREN)] (TREN tris(2-aminoethyl)amine) (2). and [Co-2(TETA)(3)][B5O6(OH)(4)](4) (TETA = triethylenetetramine) (3) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, elemental analysis and thermogravimetry. The structures exhibit interesting 3D supramolecular hydrogen-bonded architectures, involving the similar borate polyanion [B5O6+n(OH)(4-n)](,(n+1)=) (n = 0 for 1 and 3. and n = 1 for 2) and the templating transition metal complexes which are generated in situ under mild solvothermal conditions. Crystal data: 1, monoclinic, space group C2/m (No. 12) a = 15.2372(3) angstrom, h = 11.5987(2) angstrom. c = 8.4163(3) angstrom. beta = 93.601(4)degrees, V = 1484.49(7) angstrom(3), Z = 2: 2, monoclinic, P2(1)/c (No. 14), a 8.9881(3) angstrom, b = 20.7648(5) angstrom, c = 9.368 1(2) angstrom, beta = 99.926(4)degrees. V = 1722.25(8) angstrom(3), Z = 4: 3, triclinic, space group P-1 (No. 2), a = 12.3717(4) angstrom, b= 20.7648(5) angstrom, c = 19.0925(3) angstrom, alpha = 77.009(5)degrees. beta = 80.095(2)degrees. gamma = 82.334(3)degrees. V = 2925.3(2) angstrom(3), Z = 2.
The design of new materials by directing the self-assembly of organic-inorganic hybrid molecular assemblies of polyoxometalate crown-ether complexes with supramolecular cations is reviewed with a particular focus on mixed-valence [PMo12O40](4-) building blocks. Structurally configurable supramolecular cations of organic ammonium and crown ethers, i.e. protonated aromatic amines complexed by crown ethers are also outlined. The design principles for the one-electron reduced mixed-valence polyoxomolybdate cluster of [PMo12O40](4-) are also deduced. The construction principles behind these assemblies and also the concept of using cluster-based "crowns" to complex the cations to extend the design concept further is discussed, especially in the development of inorganic crowns that could combine the properties of the electronically interesting building block along with the receptor building blocks. .
A new optical supramolecular compound constructed from a polyoxometalate cluster and an organic substrate [(H3O)(C12H10N3)2(PW12O40)] (1) has been synthesized via a hydrothermal reaction and has been structurally characterized by X-ray diffraction. The solid-state diffuse reflectance, IR, and photoluminescence spectra of the title compound indicate that there is an interaction between the alpha-PW12O40 and the organic substrate. The light-yellow title compound shows a certain second-order nonlinear optical response of I(2omega) = 2I(KDP)(2omega).
Organic-inorganic hybrid materials based on polyoxometalate building blocks with capping La3+ ions and bidentate oxygenated ligands have been obtained by reaction at room temperature of the [epsilon-PMo12O36(OH)4[La(H2O)4]]5+ polyoxocation with glutarate (C5H6O(2)(2-)) and squarate (C4O(4)(2-)) organic ligands. [epsilon-PMo12O37(OH)3[La(H2O)4(C5H6O4)0.5]4].21 H2O (1) and [epsilon-PMo12O39(OH)[La(H2O)6]2-[La(H2O)5(C4O4)0.5]2].17 H2O (2) form unprecedented 1D chains built from alternating polyoxocations and organic ligands connected through LaO links. The structures of these materials are compared to the 2D hybrid organic-inorganic framework [NC4H12]2-[Mo22O52(OH)18[La(H2O)4]2[La(CH3CO2)2]4].8H2O (3) isolated from the hydrothermal reaction of elemental precursors (MoO(4)(2-), Mo, La3+) in acetate buffer. Compound 3 is built from previously undescribed polyoxometalate units with twenty-two MoV centers capped by six La3+ ions, four of which are bridged by acetate ligands.
A twist in the tale: A racemic mixture of the chiral [Co(dien)2]Cl3 complex has been used as a template in preparing an open-framework zinc phosphate with multidirectional helical channels, consisting of alternate ZnO4 and PO4 tetrahedra. The framework contains 12-membered ring channels along the [100] direction, within which [Co(dien)2]3+ ions are located. Each channel is enclosed by chiral interpenetrating double helices (see picture; dien=diethylenetriamine).
Five different cobalt succinate materials synthesized from an identical starting mixture using temperature as the only independent variable show increasing condensation and density at higher synthesis temperatures.
Three Keggin-based supramolecular architectures were synthesized on the basis of same molecular building units, showing that the pH value of the reaction plays a crucial role in controlling the topological structures of the supramolecular architectures.
A large protonated water cluster, H+(H2O)27, has been trapped and stabilized within the well-modulated cavity of a 3D metal-organic framework formed by cobalt(II) and 4,4'-bipyridine-N,N'-dioxide with a globular Keggin structure [PW12O4]3- anion as template. The structurally characterized protonated water cluster might comprise a (H2O)26 shell with Oh symmetry and a monowater core within the center which is suggested to be a hydronium ion with the Eigen model.
(Figure Presented) Bridging two traditional but distinct research areas - polyoxometalate chemistry and cuprous halide clusters - the (4,12)-connected 3D framework (NH4)[Cu24I10L12][PMo V2MoVI10O40]3 has been built by covalent linkage of nanoscale Keggin anions and [Cu 24I10L12]14+ clusters (see picture; L is a multidentate N-heterocyclic ligand); it exhibits remarkable photoluminescent and electrochemical properties.
Rational self-assembly of hexaniobate Lindqvist-type precursor [HNb6O19]7- with soluble Cu2+ salts utilizing different strategies produces a series of giant polyniobate clusters, namely, (H2en)1.25[Cu(en)2(H2O)]2Cl4[Nb24O72H21.5]7 H2O (1; en: ethylenediamine), [Cu(en)2]3[Cu(en)2(H2O)]9[{H2Nb6O19} subset{[({KNb24O72H10.25}{Cu(en)2})2{Cu3(en)3(H2O)3}{Na1.5Cu1.5(H2O)8}{Cu(en)2}4]6}]144 H2O (2), K12Na4[H23NaO8Cu24(Nb7O22)8]106 H2O (3), and K16Na12[H9Cu25.5O8(Nb7O22)8] 73.5 H2O (4). Their structures were determined and further characterized by single-crystal X-ray diffraction analysis, IR and Raman spectroscopy, thermogravimetric analysis (TGA), and elemental analysis. Structural analyses reveal that compound 2 comprises a giant capsule anion based on a wheel-shaped cluster encapsulating a Lindqvist diprotonated cluster [H2Nb6O19]6- unit, and forms a honeycomb-like structure with the inclusion of Lindqvist-type anions [H2Nb6O19]6- in the holes, whereas 3 and 4 represent an unprecedented giant cube-shaped framework. All the compounds are built from [Nb7O22]9- fundamental building blocks. Solution Raman spectroscopy studies of 2 and 3 reveal that the solid-state structures of these polyniobate cluster anions disassemble and exist in the form of the [Nb6O19]8- unit in solution. Magnetic susceptibility measurement of 3 shows antiferromagnetic coupling interactions between CuII ions with the spin-canting phenomenon.
Very complicated inorganic solids can be self-assembled from structurally simple precursors as illustrated by the hydrothermal synthesis of the vanadium phosphate, [(CH(3))(2)NH(2)]K(4)[V(10)O(10)(H(2)O)(2)(OH)(4)(PO(4))(7)].4H(2)O, 1, which contains chiral double helices formed from interpenetrating spirals of vanadium oxo pentamers bonded together by P(5+). These double helices are in turn intertwined with each other in a manner that generates unusual tunnels and cavities that are filled with (CH(3))(2)NH(2)(+) and K(+) cations, respectively. The unit cell contents of dark blue phosphate 1, which crystallizes in the enantiomorphic space group P4(3) with lattice constants a = 12.130 and c = 30.555 angstroms, are chiral; only one enantiomorph is present in a given crystal. Magnetization measurements show that 1 is paramagnetic with ten unpaired electrons per formula unit at higher temperatures and that antiferromagnetic interactions develop at lower temperatures.
Directed combination of {Ni6PW9} building blocks with various rigid carboxylate linkers under hydrothermal conditions yields a series of unprecedented polyoxometalate-organic frameworks (POMOFs) with remarkable structural diversity including 1D, 2D, and 3D structures based on monomers, dimers, or infinite helical chains (see picture for 3D structure: WO 6: red; NiO6: green; PO4: yellow; 1,2,4-benzenetricarboxylate: gold). (Figure Presented).
The field of inorganic open-framework materials is dominated by aluminosilicates and phosphates. The metal carboxylates have emerged as an important family in the last few years. This family includes not only mono- and dicarboxylates of transition, rare-earth, and main-group metals, but also a variety of hybrid structures. Some of the carboxylates possess novel adsorption and magnetic properties. Dicarboxylates and related species provide an effective means of designing novel hybrid structures with porous and other properties. In some of these structures, the dicarboxylate acts as a linker between two inorganic units. Hybrid nanocomposites are also of particular note, for example, cadmium oxalate host lattices that can accommodate extended alkali-metal halide structures. This Review discusses the synthesis, structure, and properties of various types of open-framework metal carboxylates.
The Dawson anion P 2W 18O 62 (6-) has been used as a noncoordinating polyoxoanion template for the construction of two metal-organic frameworks, namely, [M 2(bpy) 3(H 2O) 2(ox)][P 2W 18O 62]2(H 2-bpy). nH 2O (M = Co(II), n = 3 ( 1); M = Ni(II), n = 2 ( 2)) (bpy = 4,4'-bipyridine; ox = C 2O 4 (2-)). Single-crystal X-ray analysis reveals that both of the structures exhibit 3D host frameworks constructed from the oxalate-bridged binuclear superoctahedron secondary building units (SBUs) and bpy linkers and the voids of which are occupied by Dawson anions, guest bpy, and water molecules. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the transition-metal centers in compounds 1 and 2. Furthermore, a compound 1-modified carbon paste electrode ( 1-CPE) displays good electrocatalytic activity toward the reduction of nitrite.