Design and enhanced anticorrosion performance of a Zn5Mo2O11·5H2O/h-BN nanocomposite with labyrinth of nanopores.

Zinc molybdate (ZMO) is a safe and effective grafting material for anticorrosion. Herein, we reported the synthesis of ZMO/h-BN with the labyrinth of capillary pores owing to the in situ growth of ZMO on flake hexagonal boron nitride (h-BN) using the hydrothermal method. The special morphological structure provided a tortuous path for aggressive species to the steel substrate, which extended and blocked the transmission of aggressive species, enhancing the physical corrosion barrier performance. In addition, the capillary pores of ZMO contributed to the competitive adsorption of Cl- in an electrolyte and reduced the diffusion of aggressive species, thus further delaying the corrosion process. Moreover, the capture of oxygen by forming a B-O bond with h-BN and the formation of a molybdate passive film are beneficial for the inhibition of cathodic and anodic reactions. As verified by electrochemical impedance spectroscopy (EIS), the anticorrosion performance of ZMO/h-BN coating increased by 49.58% and 130.72% compared with ZMO and epoxy resin (EP) coatings after immersing in a NaCl aqueous solution (3.50 wt%) for 72 h. This coating matrix provides an avenue for molybdate-based corrosion remediation.

Zinc and cadmium 2-pyrazinephosphonates: syntheses, structures and luminescent properties.

Three new metal(II) 2-pyrazinephosphonates have been synthesized by hydrothermal reactions based on 2-pyrazinephosphonic acid (C(4)H(3)N(2)PO(3)H(2)1) as ligand, namely, Zn(C(4)H(3)N(2)PO(3)) (2), Cd[(C(4)H(3)N(2)PO(3))(H(2)O)] (3) and Cd[(C(4)H(3)N(2)PO(3)H)Cl]·H(2)O (4). In compound 2, the O-P-O bridged inorganic layers are pillared by pyrazinyl groups into a three-dimensional network. In compound 3, the {CdO(5)N} and {CPO(3)} polyhedra are interconnected via edge and corner-sharing into a metal phosphonate layer. In compound 4, the {Cd(2)Cl(2)} dimers are linked by O-P-O bridges into a one-dimensional double chain, and the chains are joined into a layer by pyrazinyl groups. Here we employ pyrazinephosphonic acids as structure directing motifs to form extended structures and materials with interesting luminescent properties. The luminescent properties studied have also been described.

Creating a pseudometallic state of K+ by intercalation into 18-crown-6 grafted on polyfluorene as electron injection layer for high performance PLEDs with oxygen- and moisture-stable Al cathode.

Polymer light-emitting diodes (PLEDs) suffer from inadequate lifetimes because of the use of environmentally sensitive metals as the cathodes. We present the use of water/methanol-soluble polyfluorene grafted with 18-crown-6 chelating to K(+) as the electron-injection layer (EIL) for deep-blue-emission PLEDs, allowing the use of environmentally stable Al as the cathode since electron donation from the 18-crown-6 can reduce K(+) to a stable "pseudometallic state", enabling it to act as an intermediate step for electron injection. Furthermore, when poly(ethylene oxide) was blended into the EIL to provide hole blocking (HB), the device exhibited the highest performance reported to date for a deep-blue-emission PLED based on a conjugated polymer as the emitting layer, with a brightness of 54,800 cd/m(2) and an external quantum efficiency of 5.42%. The use of such an EI-HB layer opens a broad avenue leading toward industrialization of PLEDs.

A novel specific application of pyruvate protects the mouse retina against white light damage: differential stabilization of HIF-1α and HIF-2α.

PURPOSE: To mimic hypoxia preconditioning by a novel specific pyruvate treatment and to study its retinal protection against white light damage. METHODS: Six-to-eight-week-old BALB/c mice were exposed to strong white light calculated to produce photoreceptor degeneration. Some were given injections of pyruvate in a preordained protocol because evidence exists that proves pyruvate can affect the concentration of hypoxia inducible factor (HIF). Western blotting and real-time PCR were used to determine the concentration of proteins and mRNAs in retinas. Morphology was analyzed with toluidine blue staining and was plotted using a spidergraph. A free nucleosome cell death assay was used to examine apoptosis. Retina explant cultures were used to investigate the background mechanism. RESULTS: Pyruvate administration stabilized hypoxia inducible factor (HIF)-1α but not HIF-2α. Expression of the downstream genes hemoxygenase-1 and erythropoietin mirrored the changes of the two HIFs, respectively. Importantly, pyruvate given not only before but also after exposure to light protected photoreceptors against apoptosis. In the retinal explant system, addition or depletion of pyruvate caused only changes of HIF-1α and prolyl hydroxylase (PHD)-2, while HIF-2α and PHD1 were not affected. However, under hypoxic conditions, HIF-2α was stabilized by pyruvate but not HIF-1α. CONCLUSIONS: Pyruvate evoked a hypoxia-like response under normoxic conditions and was retina-protective against strong white light. This response included stabilization of HIF-1α but not HIF-2α. This differential stabilization might be related to the distinct preference of their degrading enzyme of PHD2 and PHD1 in response to pyruvate treatment.

Synthesis and structural and magnetic characterization of a hexadecanuclear cobalt phosphonate compound.

A wheel-like hexadecanuclear cobalt phosphonate [Co(16)(OH)(6)(chp)(22)(O(3)PC(6)H(9))(2)(H(2)O)(4)] has been synthesized by reactions of cobalt perchlorate with cyclohexenephosphonic acid (H(2)O(3)PC(6)H(9)) and 6-chloro-2-hydroxypyridine (Hchp) in the presence of Et(3)N. Magnetic studies on the compound show a general decline of chi(M)T with decreasing T. The appeared maximum of chi(M)T at low temperature suggests the presence of a non-diamagnetic ground state. The alternating current susceptibilities show frequency-dependent signals.

Mixed-valent manganese phosphonate clusters prepared under microwave-assisted and ambient conditions.

Mixed-valent manganese phosphonate clusters [Mn(II)(8)Mn(III)(2)O(2)(O(3)PC(10)H(7))(4)(C(6)H(5)CO(2))(10)(py)(4)(H(2)O)(2)] (1) and [Mn(II)(4)Mn(III)(9)O(4)(OH)(2)(O(3)PC(10)H(7))(10)(C(6)H(5)CO(2))(5)(py)(8)(H(2)O)(6)] (2) are reported. Compound 1 is the first example of manganese phosphonate clusters prepared through a microwave-assisted technique. While compound 2 is obtained under ambient condition, and exhibits slow magnetic relaxation behaviour at low temperature.

o-Phenyl-enediammonium bis-(3-carb-oxy-4-hydroxy-benzene-sulfonate).

In the title salt, C(6)H(10)N(2) (2+)·2C(7)H(5)O(6)S(-), the negative charge of the anion resides on the sulfonate group. In the crystal, the cations and anions are -linked by N-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional network. The complete dication is generated by crystallographic twofold symmetry.

Tetranuclear clusters containing a CrIII-doped MnIII4O2 core: syntheses, structures, and magnetic properties.

The oxidation of MnII carboxylates by (NBu4)Cr2O7 in the presence of different phosphonic acids and chelating ligands results in six CrIII-doped tetranuclear manganese clusters formulated [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(bpy)2] (1), [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(phen)2] (2), [Mn3CrO2(O2CPh)4(O3PC5H4NO)2(phen)2] (3), [Mn3CrO2(O2CPh)4(O3PC6H11)2(bpy)2] (4), [Mn 3CrO2(O2CPh)4(O3PC6H11)2(phen) 2] (5), and [Mn3CrO2(O2CCH3)4(O3PC6H11)2(bpy)2] (6). Single-crystal X-ray analyses reveal that all the compounds contain similar [M4O2]8+ cores with the four metal sites arranged in planar topologies. The metal ions within the core are bridged by both carboxylate and phosphonate ligands. Temperature-dependent magnetic measurements show that in all cases dominant antiferromagnetic interactions are propagated between the metal centers. The ac magnetic measurements on compounds 5 and 6 reveal that both the in-phase and the out-of-phase signals are frequency dependent, characteristic of single-molecule magnet behaviors.

Diaqua-bis(2-pyridylphospho-nato N-oxide-κO,O)cobalt(II).

In the title complex, [Co(C(5)H(5)NO(4)P)(2)(H(2)O)(2)], the Co(II) ion, which lies on a crystallographic inversion center, is coordin-ated by four O atoms from two bidentate 2-phospho-nato-pyridine N-oxide ligands and two O atoms from two water ligands in a slightly distorted octa-hedral environment. Mol-ecules are inter-linked by three O-H⋯O hydrogen bonds and one weak C-H⋯O inter-action, forming a three-dimensional supra-molecular structure.

Tridecanuclear and docosanuclear manganese phosphonate clusters with slow magnetic relaxation.

Two novel mixed-valent manganese phosphonate clusters [MnIIMnIII12O6(OH)6(O3PC6H11)10(py)6] (1) and [MnII4MnIII18O12(O3PC6H11)8(O2CCH3)22(H2O)6(py)2] (2) are reported in this paper. Complex 1 is the first carboxylate-free manganese phosphonate cluster. While compound 2 appears to be the largest manganese cluster thus far that contains phosphonate ligand. Both show slow magnetic relaxation behaviors.

Three-dimensional lanthanide(III)-copper(II) compounds based on an unsymmetrical 2-pyridylphosphonate ligand: an experimental and theoretical study.

Based on an unsymmetrical 2-pyridylphosphonate ligand, two types of Ln(III)-Cu(II) compounds with three-dimensional structures were obtained under hydrothermal conditions, namely, Ln(2)Cu(3)(C(5)H(4)NPO(3))(6).4H(2)O (1.Ln; Ln=La, Ce, Pr, Nd) and Ln(2)Cu(3)(C(5)H(4)NPO(3))(6) (2.Ln; Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). Compounds 1.Ln are isostructural and crystallize in chiral cubic space group I2(1)3. In these structures, each Ln ion is nine-coordinate and has a tricapped triprismatic geometry, while each Cu center is six-coordinate with an octahedral environment. The {LnO(9)} polyhedra and {CuN(2)O(4)} octahedra are connected by edge sharing to form an inorganic open framework structure with a 3-connected 10-gon (10,3) topology in which the Ln and Cu atoms are alternately linked by the phosphonate oxygen atoms. Compounds 2.Ln are isostructural and crystallize in trigonal space group R3. In these structures, the {LnO(6)} octahedra are triply bridged by the {CPO(3)} tetrahedra by corner sharing to form an infinite chain along the c axis. Each chain is connected to its six equivalents through corner sharing of {CPO(3)} tetrahedra and {CuN(2)O(2)} planes to form a three-dimensional framework structure in which the Ln and Cu atoms are linked purely by O-P-O units. The formation of these two types of structures is rationalized by quantum chemical calculations, which showed that both the lanthanide contraction and the electron configuration of Cu(II) play important roles. When Cu(II) was replaced by Zn(II), only the first type of compounds resulted. The magnetic properties of complexes 1.Ln and 2.Ln were investigated. The nature of Ln(III)-Cu(II) (Ln=Ce, Pr, Nd) interactions is illustrated by comparison with their Ln(III)-Zn(II) analogues.

Dinuclear and layered copper 2-pyridylphosphonates with weak ferromagnetism observed in layer compound Cu(C5H4NPO3).

This paper reports the syntheses and structures of three new copper phosphonates based on 2-pyridylphosphonate, namely, Cu(C(5)H(4)NPO(3)H)2 (1), Cu3(OH)2(C(5)H(4)NPO(3))2.2H2O (2) and Cu(C(5)H(4)NPO(3)) (3). Compound 1 has a discrete dimeric structure in which the {CuO(4)N} square pyramids are linked by the {CPO(3)} tetrahedra through corner-sharing. The dimers are further connected into a chain through hydrogen bonds. In compound 2, edge-sharing {Cu(1)O(4)N} square pyramids and {Cu(2)O(4)} planes are found to form an infinite chain with composition {Cu(3)(mu-OH)(2)(mu-O)(4)}. Neighboring chains are linked by the phosphonate groups of the 2-pyridylphosphonate ligands, resulting in inorganic layers containing 4-, 8- and 12-membered rings. The pyridyl groups and the lattice water molecules occupy the inter-layer space. In compound 3, the {Cu(1)O(4)} and {Cu(2)O(2)N(2)} planes are each corner-shared with the {CPO(3)} tetrahedra, forming an inorganic layer containing 8- and 16-membered rings. The pyridyl groups reside between the layers. Crystal data for 1: space group P(-)1, a = 8.4045(19), b = 8.751(2), c = 10.632(2) A, alpha = 66.673(4), beta = 72.566(4), gamma = 70.690(4) degrees , V = 664.7(2) A(3), Z = 2. Crystal data for 2: space group P2(1)/c, a = 7.9544(17), b = 21.579(4), c = 5.0243(10) A, beta = 105.332(3) degrees , V = 831.7(3) A(3), Z = 2. Crystal data for 3: space group P2(1)/c, a = 4.7793(11), b = 15.319(3), c = 8.6022(19) A, beta = 97.156(4) degrees , V = 624.9(2) A(3), Z = 4. Magnetic measurements reveal that dominant antiferromagnetic interactions are propagated between the copper centers in compounds 1-3. For 3, spin canting is observed with a ferromagnetic transition occurring at 9 K.

An iron(III) phosphonate cluster containing a nonanuclear ring.

This communication reports the first example of cyclic ferric clusters with an odd number of iron atoms capped by phosphonate ligands, namely, [Fe9(mu-OH)(7)(mu-O)2(O3PC6H9)8(py)12]. The magnetic studies support a S = 1/2 ground state with an exchange coupling constant of about J approximately equal to -30 K.

Dodecanuclear manganese(III) phosphonates with cage structures.

Treatments of Mn(O(2)CR)(2) (R = Me, Ph) with NBu(4)MnO(4) in CH(3)CN or CH(3)CN/CH(2)Cl(2) in the presence of acetic acid, delta(1)-cyclohexenephosphonic acid (C(6)H(9)PO(3)H(2)), and 2,2'-bipyridine or 1,10-phenanthroline result in three novel dodecamanganese(III) clusters [Mn(12)O(8)(O(2)CMe)(6)(O(3)PC(6)H(9))(7)(bipy)(3)] (1), [Mn(12)O(8)(O(2)CPh)(6)(O(3)PC(6)H(9))(7)(bipy)(3)] (2), and [Mn(12)O(8)(O(2)CPh)(6)(O(3)PC(6)H(9))(7)(phen)(3)] (3). They have a similar Mn(12) core of [Mn(III)(12)(mu(4)-O)(3)(mu(3)-O)(5)(mu-O(3)P)(3)] with a new type of topologic structure. Solid-state dc magnetic susceptibility measurements of complexes 1-3 reveal that dominant antiferromagnetic interactions are propagated between the magnetic centers. The ac magnetic measurements suggest an S = 2 ground state for compounds 1 and 3 and an S = 3 ground state for compound 2.