Synthesis and structure of a stable pentavalent-uranyl coordination polymer

The polymeric complex {[UO2Py5][KI2Py2]}n was isolated by controlled oxidation of uranium tris-iodide in pyridine and structurally characterized using X-ray diffraction. The described synthetic method allows us to isolate a stable derivative of the elusive pentavalent UO2+ species providing a potential starting material for the development of anhydrous UO2+ coordination chemistry.     

Direct crystallographic observation of catalytic reactions inside the pores of a flexible coordination polymer

A new flexible porous coordination polymer (PCP), {[Gd(2)(L)(3)(dmf)(4)]·4DMF·3H(2)O}(n) (1), was synthesized under solvothermal condition by reacting [Gd(NO(3))(3)]·6H(2)O with the ligand 2,6,2',6'-tetranitro-biphenyl-4,4'-dicarboxylic acid (H(2)L). Compound 1 had a 3D coordination polymeric structure with two types of 1D channels (A and B) that were occupied by DMF and water molecules. When crystals of 1 were separately exposed to vapors of various aromatic aldehydes, either the lattice or both the lattice and metal-bound solvent molecules were replaced by aldehyde molecules. The aldehyde molecules inside the pores spontaneously underwent cyanosilylation and Knoevenagel condensation reactions upon exposure to vapors of trimethylsilyl cyanide and malononitrile, respectively. These reactions took place at ambient temperature and pressure. Moreover, both the reactants and the products translocated from one cavity to another. The products that occupied the cavity were expunged upon exposure to the vapors of an aldehyde. Because crystallinity was maintained during these chemical transformations, direct crystallographic observation was possible. Herein, we showed that confinement of the reactants inside the void spaces of the PCP led to the products; we also assessed catalytic activities of this PCP in bulk quantities.     

Porous nanocomposite hydrogel of vinyled montmorillonite-crosslinked maltodextrin-co-dimethylacrylamide as a highly stable polymer carrier for controlled release systems

Nanocomposite hydrogel consisting of dispersed montmorillonite-crosslinked maltodextrin-co-dimethylacrylamide (malt-dex-co-DMAAm) as a highly stable device was developed. Carbon-carbon π-bonds issued from glycidyl methacrylate (GMA) were incorporated onto both the MMT (MMT-π) and the malt-dex (malt-dex-π) structures. The nanocomposite copolymer hydrogel was processed via radical crosslinking reaction of malt-dex-π with MMT-π in the presence of DMAAm. The radical reaction of the carbon-carbon π-bonds at the MMT-π was verified by treating the MMT-π with sodium persulfate. There was an excellent dispersion of the MMT-π at the interior of the matrix even after the nanocomposite hydrogel being swollen, demonstrating that the developed methodology can imprint stability of mineral nanoparticles into a porous polymer network preventing diffusion of water-bonded silicate platelets toward the outside matrix. The water absorption profile became more dependent on the polymer relaxation for mineral-loader nanocomposite hydrogels. Higher water absorption had an impact on reduction of elasticity modulus due to softer polymer network in swollen state.     

Regularities of diene copolymerization by coordination catalytic systems and the mechanism of stereoregulation

A study has been conducted of the relative reactivity of a series of dienes (butadiene, isoprene, 2,3-dimethylbutadiene, cyclohexadiene-1,3), as well as of butadiene and styrene, in copolymerization by various coordination catalyst systems based on transition metals: nickel, cobalt, titanium, chromium, molybdenum, and tungsten. The microstructure of homopolymers and copolymers of dienes has been investigated. Regularities have been established in the mutual influence of the comonomers on the microstructure of a polymer chain. Experimental data on the influence of the concentration of diene monomer, and electron-donating and electron-accepting compounds on the microstructure of polydiene chain have been used in discussing the alternative mechanisms of stereoregulation in diene polymerization by active centers of the π-allyl type.     

The topochemistry of the catalytic systems on the surface of polymer supports

The method of spin labels based on stable iminoxyl radicals has been applied to the investigation of the topochemistry of polymer-supported polyethylene-grafting diallylamine (PE-gr-PDAA)and ofimmobilized catalytic systetms. The effective distances between fixed radicals are comparatively large (r? ～ 25-35Å for the case of functional groups of PE-gr-PDAA and r? ≥ 35Å for the case of fixed components of the catalytic systems). The demonstration of step-by-step penetration of the label into the functional cover (100-300 Å) has been made. Correlation times were calculated in the temperature range 290-440K. The dependence of log τ_c on 1/T shows two linear parts to the curve.The activation energies in the α region for PE-gr-PDAA and for the product of its interaction with TiCl₄. Ti(OC₄H₉)₄, and Al(C₂H₅)₂Cl are equal to 13, 14, 24, and 13 Kcal/mole, respectively. The method has been applied to the investigation of Ziegler-Natta immobilized catalytic systems. It has been noted that the labels are fixed not far from each other (r? ≤ 12Å) after the interaction of the catalytic components.     

Large breathing effect induced by water sorption in a remarkably stable nonporous cyanide-bridged coordination polymer

While metal–organic frameworks (MOFs) are at the forefront of cutting-edge porous materials, extraordinary sorption properties can also be observed in Prussian Blue Analogs (PBAs) and related materials comprising extremely short bridging ligands. Herein, we present a bimetallic nonporous cyanide-bridged coordination polymer (CP) {[Mn(imH)]₂[Mo(CN)₈]}_n (1Mn; imH = imidazole) that can efficiently and reversibly capture and release water molecules over tens of cycles without any fatigue despite being based on one of the shortest bridging ligands known – the cyanide. The sorption performance of {[Mn(imH)]₂[Mo(CN)₈]}_n matches or even outperforms MOFs that are typically selected for water harvesting applications with perfect sorption reversibility and very low desorption temperatures. Water sorption in 1Mn is possible due to the breathing effect (accompanied by a dramatic cyanide-framework transformation) occurring in three well-defined steps between four different crystal phases studied structurally by X-ray diffraction structural analysis. Moreover, the capture of H₂O by 1Mn switches the EPR signal intensity of the Mn^II centres, which has been demonstrated by in situ EPR measurements and enables monitoring of the hydration level of 1Mn by EPR. The sorption of water in 1Mn controls also its photomagnetic behavior at the cryogenic regime, thanks to the presence of the [Mo^IV(CN)₈]⁴⁻ photomagnetic chromophore in the structure. These observations demonstrate the extraordinary sorption potential of cyanide-bridged CPs and the possibility to merge it with the unique physical properties of this class of compounds arising from their bimetallic character (e.g. photomagnetism and long-range magnetic ordering).

A cyanide-bridged coordination polymer {[Mn(imH)]₂[Mo(CN)₈]}_n shows exceptional water sorption properties, very large breathing effect and outstanding stability – properties that are unique for this class of compounds – Prussian blue analogs.     

二茂铁配位高分子吸波材料的合成与性能表征

本文以二茂铁为原料,经独特的分子设计,将导电的共轭基团引入二茂铁高分子化合物中,再使分子中共轭基团和金属原子M配位,合成既含磁性基元的金属原子离域结构,又有导电基元的茂环和共轭取代基组成的大共轭体系的新一类高分子化合物。研究结果表明这种新型的二茂铁高分子材料具有较好的吸波性能。     

Heteropolyacids dispersed within a polymer matrix as a new catalytic systems with controlled oxidative-reductive and acid-base active centers

Polymer support such as polypyrrole was selected as a matrix for heteropolyacid H₅PMo₁₀V₂O₄₀ in an attempt to prepare heterogeneous catalysts containing two different active centers: protons and transition metal ions. Exchanging protons from heteropolyanions dispersed in polymer matrix into ferric or ferrous ions cause the modifications of their catalytic properties. It is manifested by decrease of activity of acid-base centers and increase of activity of oxidative-reductive centers. Oxidation state of iron in all samples before and after catalytic reaction is the same (Fe(III)), but their structure is not similar. For catalysts doped with ferric ions the structural order is much more pronounced than for these doped with ferrous ions.     

Chiral coordination polymer as a luminescence sensor for small organic molecules

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Strong blue-fluorescence-emitted stable monolayers formed in organic solvents by a coordination polymer with long-chained bis-Schiff base

The coordination polymer, P(ZnL) (L=N,N'-bis[2-hydroxy-4-(dodecyloxy)benzaldehyde)]-ethylenedimine), forms a novel uniform lamellar superstructure in organic liquids, which exhibits intense fluorescence in organic dispersions as well as in the corresponding cast films.     

Synthesis and peroxidase-like mimic study in H2O2 detection of a stable polyoxometalate-pillared coordination polymer

Abstract

A stable hamburger-like polyoxometalate (POM)-pillared coordination polymer (CP) [Ag₁₅(trz)₁₀][SiW₁₂O₄₀] (Ag₁₅SiW₁₂) (trz = 1,2,3-triazole) has been synthesized and characterized. Single crystal X-ray diffraction (SCXRD) analysis indicates that SiW₁₂ polyanions are sandwiched between adjacent Ag-trz sheets with two distinct types of pores, giving a three-dimensional POM-pillared sheet framework. Inspired by the reported horseradish peroxidase (HRP) and other enzyme mimics, the peroxidase-like activity of Ag₁₅SiW₁₂ was investigated to catalyze oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H₂O₂. Compared with other POM-involved enzyme mimics, Ag₁₅SiW₁₂ exhibits excellent peroxidase-like activity. Detection of H₂O₂ was also studied in buffer solution, and the result shows broader application range (1–100?μM), faster response time (1?min) and lower detection limit (0.27?μM), which may be ascribed to the distinct structure and maximized synergistic effect of individual components.

     

Vinylation of cellulose in superbase catalytic systems: towards new biodegradable polymer materials

Diverse celluloses including non-mercerized and mercerized ones have been successfully vinylated with acetylene in the superbase catalytic systems MOH/DMSO and MOH/THF (M = Na, K) at 85–140 °C. Depending on the reaction conditions, degree of substitution of the hydroxyl groups by highly reactive polymerazable vinyloxy groups ranges 0.11–1.22, the yields of vinylated celluloses (insoluble in water, but soluble in DMSO) being 41–89 %. Vinylated celluloses are easily decomposed under the action of white rot fungi: Phanerochaete chrysosporium, Trametes versicolor and Trametes hirsutus, and can constitute a basis for the preparation of biodegradable polymer materials (due to polymerization or polyaddition at the vinyloxy group).     

A stable hydroxide-conducting polymer

A stable hydroxide-conducting membrane based on benzimidazolium hydroxide and its analogous anion-exchange polymer is reported for the first time. The molecular and polymeric analogues possess unprecedented hydroxide stability in neutral and KOH solutions as the soluble benzimidazolium salt, made possible by steric crowding around the benzimidazolium C2 position, which is usually susceptible to nucleophilic attack by OH(-). The polymers were cast and insolubilized for the purpose of forming membranes by blending with a poly(benzimidazole) followed by hydroxide-activated electrostatic interactions. The resulting membranes possess ionic (OH(-)) conductivities of up to 13.2 mS cm(-1) and represent a new class of anion-exchange polymers and membranes.     

Design of heterogeneous catalytic systems: New cement-containing catalysts

A procedure for new cement-containing (MO–Al₂O₃, M=Ca, Zn, Ni, Cu) supports, adsorbents and catalysts has been designed.     

Morphology design of porous coordination polymer crystals by coordination modulation

The design of crystal morphology, or exposed crystal facets, has enabled the development (e.g., catalytic activities, material attributes, and oriented film formation) of porous coordination polymers (PCPs) without changing material compositions. However, because crystal growth mechanisms are not fully understood, control of crystal morphology still remains challenging. Herein, we report the morphology design of [Cu(3)(btc)(2)](n) (btc = benzene-1,3,5-tricarboxylate) by the coordination modulation method (modulator = n-dodecanoic acid or lauric acid). A morphological transition (octahedron-cuboctahedron-cube) in the [Cu(3)(btc)(2)](n) crystal was observed with an increase in concentration of the modulator. By suitably defining a coarse-grained standard unit of [Cu(3)(btc)(2)](n) as its cuboctahedron main pore and determining its attachment energy on crystal surfaces, Monte Carlo coarse-grain modeling revealed the population and orientation of carboxylates and elucidated an important role of the modulator in determining the <100>- and <111>-growth throughout the crystal growth process. This comprehension, in fact, successfully led to designed crystal morphologies with oriented growth on bare substrates. Because selective crystal orientations on the bare substrates were governed by crystal morphology, this contribution also casts a new light on the unexplored issue of the significance of morphology design of PCPs.     

Thin films of coordination polymer magnets

Many applications of molecule based magnets, whether they are in information storage, displays, or as components in electronic or spintronic devices, will require putting the active materials on a surface or interfacing them with other components. Although there are many examples of molecule-based magnets, the families of tetracyanoethylene (TCNE) based magnets and Prussian-blue analogs possess materials properties that are close to those required for practical applications, and are the most advanced with respect to studies as thin films. This critical review focuses on fabrication and characterization of thin films of TCNE and Prussian-blue analog coordination polymer magnets. Emphasis is on current developments in thin film heterostructures and potential spintronics applications (135 references).     

Cu(II)-脱乙酰壳聚糖配位聚合物的配位数

IR,ESR和XPS的测试结果表明,脱乙酰壳聚糖(简记CS)膜在铜氨水溶液浸渍过程中Cu(II)既与CS发生配位反应形成Cu(II)-CS配位聚合物,也产生吸附作用。ESR谱示出CuCl~2.2H~2O与Cu(II)-CS膜中的Cu(II)均含有一个单电子,可以利用XPS的Shake-up效应研究Cu(II)-CS配位聚合物的配位数,所得结果为4。又以同样的方法研究Cu(II)-聚乙烯醇(简记PVA)配位聚合物的配位数,发现Cu(II)是以低自旋状态的dsp^2杂化空轨道与PVA的羟基氧配位,其配位数也是4,这与资料所报道的一致,从而间接地验证了此方法研究Cu(II)-CS配位聚合物配位数的可靠性。     

Fluorescence-enhanced nucleic acid detection: using coordination polymer colloids as a sensing platform

Coordination polymer colloids have been used as an effective fluorescent sensing platform for multiplexing nucleic acid detection capable of distinguishing complementary and mismatched target sequences for the first time.     

Organotin-oxometalate coordination polymer catalyzed oxyfunctionalization of monoterpenes

The organotin-oxometalate coordination polymers [(nBu₃Sn)₂MO₄]·nH₂O (where, M = Mo or W) were prepared by the interaction of nBu₃SnCl with sodium salts of molybdate or tungstate and tested in oxyfunctionalization of monoterpenes with urea hydroperoxide (UHP) as an oxidizing agent. The oxyfunctionalization of monoterpenes gave commercially important products such as epoxides, ketones and hydroxyl derivatives. Among the two catalyst, organotin-oxomolybdate [(nBu₃Sn)₂MoO₄] showed higher activities and epoxide selectivities under selected liquid phase oxyfunctionalization conditions with most of the monoterpenes such as limonene, -pinene, β-pinene, carene, camphene, gerniol and linalool. The integrity of the organotin-oxometalates polymers were confirmed by X-ray diffraction BET surface area, FT-IR, FT-Raman, SEM, TG/DTA and MAS NMR (¹³C, ¹¹⁹Sn) analysis. The effects of reaction parameters on limonene conversions and product selectivities have been studied in detail using [(nBu₃Sn)₂MoO₄] catalyst. There was no leaching of the active catalyst into the reaction medium and catalyst was recyclable without loss in its activity in the oxidation reaction.