Organic-inorganic one-dimensional hybrid aggregates constructed from aromatic-bisphosphonate-functionalized polyoxomolybdates

Five novel lanthanide-substituted polyoxomolybdates (NH₄)₅Na₃H₂[{Ln(H₂O)₇}₂{Mo₅O₁₅(1,4-O₃PCH₂C₆H₄CH₂PO₃)}₄]·nH₂O [Ln = Tb³⁺ (1), Ho³⁺ (2), Er³⁺ (3), Tm³⁺ (4), Yb³⁺ (5); n = 33, 32, 41, 30, 47] have been prepared in a conventional aqueous solution reaction of ammonium molybdate with Ln³⁺ ions and p-xylyenediphosphonic acid. Crystal structure analyses reveal that 1-5 are isomorphic. The prominent architecture characteristic is that their structural units consist of a tetrameric cyclic-shaped [{Mo₅O₁₅(1,4-O₃PCH₂C₆H₄CH₂PO₃)}₄]^16- segment stabilized by two [Ln(H₂O)₇]³⁺ cations, which are connected to propagate one-dimensional chain by Ln³⁺ ions. As is known, compounds 1-5 stand for the first Ln-substituted aromatic-bisphosphonate-functionalized polyoxomolybdates. The solid-state photoluminescence measurement of 1 has been performed at ambient temperature, and it displayed the characteristic emissions of Tb ions based on its 4f-4f transitions. In addition, the magnetic properties of 1-5 compounds show that they all exhibit anti-ferromagnetic interactions.

Assembly of a Hexameric Cluster of Polyoxomolybdotriphosphonate Builts from [Zn(H2O){TeMo6O21}{N(CH2PO3)3}]6- Subunits and Its Optical and Catalytic Properties

The crown-shaped organotriphosphonate-modified 36-molybdenum cluster (NH₄)₁₈Na₇H₁₁[Zn(H₂O)TeMo₆O₂₁{N(CH₂PO₃)₃}]₆·23H₂O (1) has been synthesized, which is the largest zinc-containing organophosphonate-based polyoxometalate to date. Compound 1 was prepared in buffer solution (pH 5.5) with heptamolybdate and amino trimethylene phosphonic acid (ATMP) as the organic ligand. The polyanion constructed from a hexmeric assembly of [Zn(H₂O){TeMo₆O₂₁}{N(CH₂PO₃)₃}]^6- subunits has been fully investigated by a few characterization methods. In this work, we discovered that 1 exhibited reversible photochromism and it changed from white to reddish brown upon UV irradiation. In addition, compound 1, as a catalyst, can oxidize sulfides to sulfoxides, showing a high yield/conversion and a good selectivity.

Coordination-Assembled Molecular Cages with Metal Cluster Nodes

Molecular cages have attracted great attention because of their fascinating topological structures and well-defined functional cavities. These discrete cages were usually fabricated by coordination assembly approach, a process employing directional metal-ligand coordination bonds due to the nature of the divinable coordination geometry and the required lability to encode dynamic equilibrium/error-correction. Compared to these coordination molecular cages with mononulcear metal-nodes, an increasing number of molecular cages featuring dinuclear and then polynuclear metal-cluster nodes have been synthesized. These metal-cluster-based coordination cages (MCCCs) combine the merits of both metal clusters and the cage structure, and exhibit excellent performances in catalysis, separation, host-guest chemistry and so on. In this review, we highlight the syntheses of MCCCs and their potential functions that is donated by the metal-cluster nodes.

Control over the synthesis of homovalent and mixed-valence cubic cobalt-imidazolate cages

A series of cubic cobalt-imidazolate cages have been successfully synthesized via subcomponent self-assembly in different solvents under solvothermal conditions.

Shining a light on the photo-sensitisation of organic-inorganic hybrid polyoxometalates

Finding new ways of using visible light (or, more specifically, solar irradiation) to drive commercially significant and/or challenging chemical processes is an ongoing research goal. Polyoxometalates (POMs) are discrete, metal-oxide clusters which are cheap, robust and easily synthesised but can also act as versatile molecular building blocks, allowing for astonishing variety in their structures and properties. In particular, the rich redox chemistry and inherent photo-activity of POMs makes them attractive for use in a variety of photochemical applications, however POMs characteristically only absorb strongly in the UV region. In this perspective, we discuss the various strategies which have been employed in order to sensitise POMs to visible light, with a particular focus on hybrid inorganic-organic POM species. We will discuss the two clear photo-activation mechanisms which have been developed to date and provide an outlook on some of the possible future directions of the field.

Halide encapsulation by dicarboxylate oxido-vanadium cage complexes

Compounds [Bu₄N]₂[V₈O₁₆(oda)₄⊂2Cl], 1, [Bu₄N]₂[V₈O₁₆(glut)₄⊂2Cl], 2, and [Bu₄N][V₄O₈(glut)₂⊂F], 3, (oda = oxydiacetate, O(CH₂COO)₂^2-; glut = glutarate, CH₂(CH₂COO)₂^2-) were obtained by a stepwise reaction of in situ prepared [Bu₄N]VO₃ with HCl (or HF for 3) and then with the dicarboxylic acid X(CH₂COOH)₂ (X = O and CH₂), under appropriate reaction conditions. Multinuclear magnetic resonance (¹H, ¹³C{¹H}, ³⁵Cl, ¹⁹F and ⁵¹V), electrochemical studies, X-ray structural determinations (single crystal and powder), thermogravimetric analyses (TGA) and Density Functional Theory (DFT) calculations were employed to characterise these polyoxovanadate complexes 1-3. They included encapsulated halide anions, two chloride ions in 1 and 2 and one fluoride ion in 3, where the shape and dimensions of the cage were governed by the halide size. The stabilizing template effect of the chloride ion towards the bowl-shaped [V₄O₈(OOCR)₄] fragment (i.e. the half part of 1 and 2), containing a crown-shaped {V₄O₈} subunit, or that of the fluoride ion towards the planar {V₄O₈} moiety in 3, was definitively demonstrated by DFT calculations. The HOMO composition of 1 prompted us to study the possible oxidation of the two encapsulated chloride ions toward a chlorine molecule. The electrochemical behaviors of 1-3 were thus investigated. However, the chlorine molecule in the model [V₈O₁₆(oda)₄⊂(Cl₂)], 6c, was not capable to stabilise the polyoxovanadate cage [V₈O₁₆(oda)₄], 4c, according to DFT calculations.

Mimicking cellular phospholipid bilayer packing creates predictable crystalline molecular metal–organophosphonate macrocycles and cages

Evolution of metal–organophosphonates from macrocycles into cages.

Ligand-Directed Assembly of Polyoxovanadate-Based Metal-Organic Polyhedra

Three new polyoxovanadate-based metal-organic polyhedra (VMOPs) have been successfully synthesized and structurally characterized. Single crystals of three VMOPs were obtained by reaction of VCl3 and different carboxylate ligands (2,5-H2TDA = thiophene-2,5-dicarboxylic acid for VMOP-4, m-H2BDC = 1,3-benzenedicarboxylic acid for VMOP-5, 2,6-H2NDC = 2,6-naphthalenedicarboxylic aid for VMOP-6) under solvothermal conditions. Though all of the three hybrids feature the same {V(V)V4(IV)} units, their structures exhibit differences changing from truncated triangular prism to truncated quadrangular prism to octahedron, mainly depending on the nature of carboxylate ligands. Furthermore, the magnetic investigations reveal that VMOP-4-6 show similar ferromagnetic behaviors.

Polyoxovanadate-based organic-inorganic hybrids: from {V5O9Cl} clusters to nanosized octahedral cages

Three polyoxovanadate-based metal-organic polyhedra (denoted as VMOP-1, -2, and -3), adopting isostructural discrete octahedral cage geometries, were successfully synthesized under solvothermal conditions. These structures are all built up from the same pentavanadate {V5O9Cl} cluster connected by linear bidentate ligands (H2L1 = H2BDC, H2L2 = H2BDC-NH2, H2L3 = H2BDC-Br), respectively.

Photoluminescent lead(II) coordination polymers stabilised by bifunctional organoarsonate ligands

Four lead(II) coordination polymers were isolated under hydro(solvo)thermal conditions. The applied synthetic methodology takes advantage of the coordination behaviour of a new bifunctional organoarsonate ligand, 4-(1, 2, 4-triazol-4-yl)phenylarsonic acid (H2TPAA) and involves the variation of lead(II) reactants, metal/ligand mole ratios, and solvents. The constitutional composition of the four lead(II) coordination polymers can be formulated as [Pb2(TPAA)(HTPAA)(NO3)]·6H2O (1), [Pb2(TPAA)(HTPAA)2]·DMF·0.5H2O (DMF = N, N-Dimethylformamide) (2), [Pb2Cl2(TPAA)H2O] (3), and [Pb3Cl(TPAA)(HTPAA)2H2O]Cl (4). The compounds were characterized by single-crystal and powder x-ray diffraction techniques, thermogravimetric analyses, infra-red spectroscopy, and elemental analyses. Single-crystal x-ray diffraction reveals that 1 and 2 represent two-dimensional (2D) layered structures whilst 3 and 4 form three-dimensional (3D) frameworks. The structures of 1, 2, and 4 contain one-dimensional (1D) {PbII/AsO3} substructures, while 3 is composed of 2D {PbII/AsO3} arrays. Besides their interesting topologies, 1-4 all exhibit photoluminescence properties in the solid state at room temperature.

A new vanadium sulfate with ferrimagnetic and NLO properties constructed from novel discrete umbrella-like [VV(μ3-O)4VIV4O5(SO4)4(en)]5− anions

A new umbrella-like vanadium sulfate shows significant zero field splitting and strong two photon absorption.

Homologous size-extension of hybrid vanadate capsules - solid state structures, solution stability and surface deposition

The dimensions and cavity sizes of the molecular capsules with the general formula [V10O18L4](10-) can be controlled modularly through the nature of the bifunctional, rigid organophosphonate ligands L(1) and L(2) (L(1) = bis(4-phosphonatophenyl)ethyne and L(2) = bis(4-phosphonatophenyl)butadiyne); the solution stability of the molecular entities as demonstrated by ESI-MS studies permits their assembly on the Au(111) surface on a sub-monolayer scale giving rise to a 2D supramolecular structure that is comparable to the packing arrangements of the capsules in the crystal structures.

Organic–inorganic hybrid polyhedra that can serve as supermolecular building blocks

Small cubicuboctahedral hybrid nanoballs can serve as octahedral supermolecular building blocks for the generation of primitive cubic nets.

Exploring the coordination chemistry of bifunctional organoarsonate ligands: syntheses and characterisation of coordination polymers that contain 4-(1,2,4-triazol-4-yl)phenylarsonic acid

The syntheses, crystal structures, luminescent and magnetic properties of five triazol-phenylarsonic acid-based M(ii) coordination polymers are reported (M = Co, Cu, Mn, Cd).

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.

catena-Poly[[[dichlorido(pyridin-1-ium-3-yl)arsenic(III)]-μ-chlorido] mono-hydrate]

The crystal structure of the title compound, {[AsCl3(C5H5N)]·H2O} n , is characterized by polymeric chains consisting of alternating arsenic and chlorine atoms running parallel to the a axis. O-H⋯Cl and N-H⋯O hydrogen bonds mediated by non-coordinating water mol-ecules assemble these chains into a three-dimensional framework. The As(III) atom, the atoms of the pyridinium ring and the water O atom have m site symmetry and the bridging Cl atom has site symmetry 2. This is the first reported organotrichloro-arsenate(III) in which arsenic adopts a ψ-octa-hedral fivefold coordination.

Tetrabutylammonium hydrogen phenylarsonate–phenylarsonic acid (1/1)

The structure of the title salt adduct, (C₄H₉)₄N⁺·C₆H₅AsO₃H⁻·C₆H₅AsO₃H₂, features chains along the a axis comprising alternating hydrogen phenyl­arsonate anions and phenyl­arsonic acid mol­ecules linked by O—H⋯O hydrogen bonds.

Polyoxometalates functionalized by bisphosphonate ligands: synthesis, structural, magnetic, and spectroscopic characterizations and activity on tumor cell lines

We report the synthesis and characterization of eight new Mo, W, or V-containing polyoxometalate (POM) bisphosphonate complexes with metal nuclearities ranging from 1 to 6. The compounds were synthesized in water by treating Mo(VI), W(VI), V(IV), or V(V) precursors with biologically active bisphosphonates H(2)O(3)PC(R)(OH)PO(3)H(2) (R = C(3)H(6)NH(2), Ale; R = CH(2)S(CH(3))(2), Sul and R = C(4)H(5)N(2), Zol, where Ale = alendronate, Sul = (2-Hydroxy-2,2-bis-phosphono-ethyl)-dimethyl-sulfonium and Zol = zoledronate). Mo(6)(Sul)(2) and Mo(6)(Zol)(2) contain two trinuclear Mo(VI) cores which can rotate around a central oxo group while Mo(Ale)(2) and W(Ale)(2) are mononuclear species. In V(5)(Ale)(2) and V(5)(Zol)(2) a central V(IV) ion is surrounded by two V(V) dimers bound to bisphosphonate ligands. V(6)(Ale)(4) can be viewed as the condensation of one V(5)(Ale)(2) with one additional V(IV) ion and two Ale ligands, while V(3)(Zol)(3) is a triangular V(IV) POM. These new POM bisphosphonates complexes were all characterized by single-crystal X-ray diffraction. The stability of the Mo and W POMs was studied by (31)P NMR spectroscopy and showed that all compounds except the mononuclear Mo(Ale)(2) and W(Ale)(2) were stable in solution. EPR measurements performed on the vanadium derivatives confirmed the oxidation state of the V ions and evidenced their stability in aqueous solution. Electrochemical studies on V(5)(Ale)(2) and V(5)(Zol)(2) showed reduction of V(V) to V(IV), and magnetic susceptibility investigations on V(3)(Zol)(3) enabled a detailed analysis of the magnetic interactions. The presence of zoledronate or vanadium correlated with the most potent activity (IC(50)~1-5 μM) against three human tumor cell lines.