Showing papers in "Journal of Inorganic and Organometallic Polymers and Materials in 2014"

Ultra-Fine Characteristics of Starch Nanoparticles Prepared Using Native Starch With and Without Surfactant

Abstract: Starch nanoparticles (St-NPs) were synthesized using native maize starch (NS). The synthesis was carried out as per the Solvent displacement method after being modified. Modification involved the use of aqueous alkaline medium as the solvent and ethanol as the organic non-solvent. This was done with a view to assure easier and more reproducible St-NPs preparation without consuming more solvent. The modified method for preparation of St-NPs was evaluated; investigation into factors affecting it were made in order to discover the optimum conditions for such preparation. Factors studied included concentration of starch as well as concentration of surface-active agent, namely, Tween® 80, which was added before precipitation. World-class facilities was used for evaluation of the obtained St-NPs such as transmission electron microscopy, particle size analyzer, polydispersity index (PdI), Fourier transform infrared (FT-IR) spectroscopy and, X-ray diffraction. The results indicate that there are no changes of the chemical structure of St-NPs as indicated by FT-IR and the crystallinity pattern is converted from A-type to amorphous (V-type). The data obtained indicate also that the smallest, highly distributed particles size with good PdI of St-NPs are obtained in the presence of 20 % Tween® 80 (based on weight of NS).

Facile Chemical Synthesis and Characterization of Copper Tungstate Nanoparticles

Abstract: Copper tungstate nanoparticles were synthesized by a chemical precipitation reaction in aqueous ambient involving direct addition of copper ion solution to the solution of tungstate reagent. Optimization of the synthesis procedure was carried out using Taguchi robust design as a statistical method. In order to controllable, simple and fast synthesis of copper tungstate nanoparticles, effects of some synthesis conditions such as reagents concentrations (i.e., copper and tungstate ions), flow rate of copper feeding and temperature of the reactor on the particle size of synthesized copper tungstate were investigated by the aid of an orthogonal array. The results of optimization process showed that copper tungstate nanoparticles could be prepared by controlling the effective parameters and at optimum conditions of synthesis procedure, the size of prepared copper tungstate particles was about 56 nm. Chemical composition and microstructure of the prepared copper tungstate nanoparticles were characterized by means of X-ray diffraction, scanning electron microscopy, UV–Vis spectrophotometry, FT-IR spectroscopy and Photoluminescence.

Titanate Anodes for Sodium Ion Batteries

Abstract: For reasons of cost and supply security issues, there is growing interest in the development of rechargeable sodium ion batteries, particularly for large-scale grid storage applications. Like the much better known and technologically important lithium ion analogs, the devices operate by shuttling alkali metal cations between two host materials, which undergo insertion processes at different electrochemical potentials. A particular challenge for the sodium systems is identification of a suitable anode material due to the fact that sodium does not intercalate into graphite. Although several alternatives, including disordered carbons and alloys are being investigated, the most promising options at present lie with titanates, not in the least because of attractive characteristics such as low toxicity, ease of synthesis, wide availability, and low cost. A large variety of sodium titanate compounds can be prepared, many of which have tunnel or layered structures that can readily undergo reversible reductive intercalation reactions. A brief overview of the physical, structural, and electrochemical characteristics of several of the most promising materials for sodium-ion battery applications is given in this paper, and a comparison is made between the sodium and the lithium insertion behaviors. For some of these compounds, insertion of sodium occurs at unusually low potentials, a feature that has important implications for the design of high-energy sodium-ion systems.

Magnetic and Optical Properties of Mn1−xZnxFe2O4 Nanoparticles

Abstract: Mn1−xZnxFe2O4 (x = 0.0−1.0) NPs (MZF NPs) were synthesized by a citric acid assisted sol–gel process. MZF NPs show superparamagnetic characteristics at room temperature. Saturation magnetization (Ms) of MnFe2O4 NPs is 70.52 emu/g is very close to the bulk saturation magnetization value of 80 emu/g. The observed Ms = 35.90 emu/g value for ZnFe2O4 particles is much greater than the bulk Ms value of 5 emu/g. This case is attributed to cation distribution change from normal spinel to mixed structure. The small Mr/Ms ratios (the maximum 0.147) specify uniaxial anisotropy in the Mn1-xZnxFe2O4 NPs. The average crystallite diameter (D mag) was evaluated from magnetic analyses. The obtained D mag values are between 27.67 and 33.60 nm and this range is in great accordance with the results calculated from XRD measurements. Among the NPs, the samples with more zinc content show higher diffuse reflectance. The optical direct band gap of MZF NPs is found to decrease from 2.1 to 1.90 eV as the zinc content rises.

Synthesis, Characterization and Conducting Properties of Nanocomposites of Intercalated 2-Aminophenol with Aniline in Sodium-Montmorillonite

Abstract: A simple method was used to synthesize poly(2-aminophenol), poly(2-aminophenol-co-Aniline) and polyaniline nanocomposites with sodium-montmorillonite (Na-M) using in situ intercalative oxidative polymerization. Morphology and thermal properties of the synthesized nanocomposites were examined by transmission electron microscopy (TEM) and thermogravimetric analysis. The thermal analysis shows an improved thermal stability of the nanocomposites in comparison with the pure poly(2-aminophenol). The intercalation of polymers into the clay layers was confirmed by X-ray diffraction studies, TEM images and FTIR spectroscopy. In addition, the room temperature conductivity values of these nanocomposites varied between 8.21 × 10−5 and 6.76 × 10−4 S cm−1. The electrochemical behavior of the polymers extracted from the nanocomposites, has been analyzed by cyclic voltammetry. Good electrochemical response has been observed for polymer films; the observed redox processes indicate that the polymerization into Na-M produces electroactive polymers.

Green Chemical Synthesis of Silver Nanoparticles and its Catalytic Activity

Abstract: Silver nanoparticles (Ag(0) NPs) were synthesized by the chemical reduction method, in which ceftriaxone (antibiotic) used as reducing (to convert Ag+ to Ag(0)) and capping agent. UV–Visible spectroscopy revealed the first indication of formation of Ag(0) NPs. FT-IR spectroscopy showed the interaction of formation of bonding between antibiotic standard and silver. X-ray powder diffraction powder pattern confirmed the crystalline nature of prepared Ag(0) NPs. These Ag(0) NPs were used as catalyst for three organic hazardous chemicals i.e., 4-nitro-1,3-Phenylene diamine, 6-methyl-2-nitroanilline, 4-methyle-2-nitroanilline. The prepared Ag(0) NPs showed good catalytic activity against these compounds.

New Facile Process for Synthesis of Borosiloxane Resins

Abstract: The first example of a new, one pot synthesis of polyborosiloxane resins by dehydrocarbon condensation of trimethyl borate with diphenylsilane in the presence of tris(pentafluorophenyl)borane is reported. The new condensation process, which leads to the formation of Si–O–B linkages with a release of methane, was performed in hydrocarbon solvent under mild conditions. The obtained polyborosiloxane glassy product is halogen-free and has a low content of hydroxyl groups. High temperature decomposition of polyborosiloxane resin yields a silicon-boron-oxycarbide ceramic with a high yield above 54 %, when the process is carried out under a nitrogen atmosphere. The char yield is about 10 % lower for thermal decomposition in the presence of air than in nitrogen. The polyborosiloxane resins obtained by the new process could find applications as high temperature adhesives, precursors to ceramic materials and novel halogen-free flame retardants.

Synthesis of Ferrocene-Based Hyperbranched Polyether and Its Catalytic Performance for Thermal Decomposition of Ammonium Perchlorate

Abstract: A series of ferrocene-based hyperbranched polyethers (HBPE-Fc) with different ferrocene content were synthesized by esterification of ferrocenecarbonyl chloride and hyperbranched polyether (HBPE). 1H NMR and FT-IR were used to confirm the structure of HBPE and HBPE-Fc. GPC was used to calculate the molecular weights. The catalytic performance of the synthesized HBPE-Fc for thermal decomposition of ammonium perchlorate (AP) was investigated by TG and DTG techniques. The results showed that HBPE-Fc exhibited good catalytic activity on the thermal decomposition of AP. The influence factors on catalytic performances, such as substitution degree of ferrocene and mass ratio of AP/HBPE-Fc were discussed as well.

Uranyl Coordination Polymers Incorporating η5-Cyclopentadienyliron-Functionalized η6-Phthalate Metalloligands: Syntheses, Structures and Photophysical Properties

Abstract: The reaction of two η5-cyclopentadienyliron(II)-functionalized terephthalate and phthalate metalloligands, namely [(η5-C5H5)FeII(η6-1,4-HO2CC6H4CO2H)][(η5-C5H5)FeII(η6-1,4-HO2CC6H4CO2)][PF6] and [(η5-C5H5)FeII(η6-1,2-HO2CC6H4CO2H)][(η5-C5H5)FeII(η6-1,2-HO2CC6H4CO2)][PF6]—hereafter [H2 CpFeTP][HCpFeTP][PF6] and [H2 CpFeP][HCpFeP][PF6], respectively—with [UO2(NO3)2]·6H2O under hydrothermal conditions yielded four new coordination polymers; (1) [(UO2)F(HCpFeTP)(PO4H2)]·2H2O, (2) [(UO2)2(CpFeTP)4]·5H2O, (3) [(UO2)2F3(H2O)(CpFeP)], and (4) [H2 CpFeP][UO2F3]. The use of metalloligands has proven to be a viable route towards the incorporation of a secondary metal center into uranyl bearing materials. Depending upon the protonation state, the iron sandwich metalloligands may vary from zwitterionic neutral or monoanionic coordinating species as observed in compounds 1–3, or a positively charged species that hydrogen bonds with anionic [UO2F3]− chains as observed in 4. Further, the hydrolysis of the charge balancing PF6 − anion increases the diversity of UO2 2+ coordinating species by contributing both F− and PO4 3− anions (1, 3, 4). The luminescent properties of 1–4 were also studied and revealed the absence of uranyl emission, suggestive of a possible energy transfer from the uranyl cation to the iron(II) metal center.

Synthesis and Characterization of Lanthanum Oxide Nanoparticles from Thermolysis of Nano-sized Lanthanum(III) Supramolecule as a Novel Precursor

Abstract: A new nano-sized La(III) supramolecular compound, [pyda.H]2[La2(pydc)4(H2O)4]·2H2O (1), where [pyda.H]+ = 2,6-diaminopyridinium, and [pydc]2− = 2,6-pyridinedicarboxylate, was synthesized by the sonochemical method and characterized by field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD) and elemental analyses. Lanthanum oxide nanoparticles were prepared by direct thermal decomposition of 1 nanostructures in a programmable furnace up to 800 °C in ambient atmosphere. The structural characterization was performed by powder XRD; and, morphological observations by FESEM revealed that the quasi-spherical La2O3 nanoparticles obtained are well crystallized and uniform in both morphology and particle size. The study demonstrates that supramolecular compounds may be suitable precursors for the simple one-pot preparation of nanoscale metal oxide materials with different morphologies.

Rapid Synthesis of Cobalt Metal Organic Framework

Abstract: Metal-organic framework (MOF) has been shown to potential applications due to the high porous hybrid structure Cobalt MOF was synthesized rapidly by ultrasound energy with about 3,000 m2/g surface area by BET method Furthermore, this component is crystalline with significant thermal stability, on account of X-ray diffraction and thermal analysis, respectively Based on high roughness, crystallinity, and unreported type of FTIR spectrum, a new structure of Co-MOF structure was proposed

Synthesis and Characterization of Chitosan/Polyvinylpyrrolidone/Zeolite Composite by Solution Blending Method

Abstract: Polymer/clay composites have been studied for several decades; in the study, polymer/zeolite composite beads have been prepared by a simple solution blending method using chitosan, polyvinylpyrrolidone and zeolite particles as organic and inorganic components, respectively. Different techniques, such as SEM, FTIR spectroscopy, and thermogravimetry have been used to characterize the composite beads. Chitosan/polyvinylpyrrolidone/zeolite (CH/PVP/Z) beads are expected to have a potential as an adsorbent for wastewater treatment. To investigate its applicability, copper (II) was selected as a model compound. The results showed that the composite beads had effective loading capacity and it is a promising adsorbent for heavy metal removal.

Structural and Dielectrical Properties of Ag- and Ba-Substituted Hydroxyapatites

Abstract: Ag- and Ba-doped hydroxyapatite (HAp) samples were synthesized by sol–gel method. The crystallite sizes for all the samples were found to vary from 26 to 39 nm. Neither Ag nor Ba did result in dramatic changes in the morphology of all the samples, and the Ca/P molar ratio was varied. The dielectric parameters of the samples were changed with the dopant content. The maximum and minimum values of the dielectric constant were observed for 2.0 %Ba-HAp and 0.5 %Ba-HAp samples. The alternating current conductivity indicates that all the samples exhibit the insulator behavior. The results of the biological tests revealed that Ag-containing samples have an antimicrobial activity, while no antimicrobial activity was detected for both HAp and Ba-doped HAp samples.

Synthesis, Thermal and Morphological Properties of Polyurethanes Containing Azomethine Linkage

Abstract: This paper presents synthesis, photophysical, electrochemical, thermal and morphological properties of Schiff bases containing various side-group substitutions and polyurethanes (PUs) containing azomethine linkage Morphological properties of PUs containing azomethine bonding were investigated by scanning electron microscopy (SEM) SEM images showed that PU containing azomethine consist of semi-crystalline particles Thermal transitions in PUs containing azomethine units were studied using DSC The obtained DSC curves showed that PUs containing azomethine are semi-crystalline materials due to they contain both crystallization and melting peaks Electrochemical properties also investigated by using cyclic voltammetry (CV) According to the cyclic voltommagrams and CV data, PUs containing azomethine have below 20 eV electrochemical band gap

DFT Investigation of Formaldehyde Adsorption Characteristics on MgO Nanotube

Abstract: The adsorption characteristics of formaldehyde on to MgO nanotube along inner surface, outer surface and terminating end are studied using DFT method with B3LYP/LanL2DZ basis set. The favorable adsorption site is discussed in terms of adsorbed energy which is found to be adsorption of C atom in HCHO with O atom in MgO along inner surface, outer surface and terminating end. The average energy gap variations for all the possible adsorption sites in MgO nanotube are reported. Mulliken population analysis confirms the transfers of electrons from MgO nanotube to HCHO. The conductivity of MgO base material is influenced by the energy gap variation when HCHO is adsorbed on to MgO nanotube. The result of the present study reveals that synthesizing MgO in nanotube form will enhance HCHO sensing characteristics.

Fabrication of 3D Polypyrrole/Graphene Oxide Composite Hydrogels with High Performance Swelling Properties

Abstract: The polypyrrole (PPy)/graphene oxide (GO) composite hydrogels with hierarchical porous structures were fabricated by one-step self-assembly method. The static oxidation polymerization of pyrrole monomer in GO aqueous solution resulted in the formation of three-dimensional (3D) PPy/GO composite hydrogels, which consisted of one-dimensional PPy nanofibers and two-dimensional GO nanosheets. The as-prepared composite hydrogels exhibited shrinking–swelling behavior with cycles of suction and water-supplying. The effects of GO nanosheets content on the swelling properties were investigated. Results showed that the well-dispersed GO nanosheets in the hydrogel networks resulted in a significant improvement in water absorbencies of the hydrogels. PPy/GO composite hydrogels exhibited unobvious variation in the water absorbency even in saline solutions. Such excellent properties in water absorbencies endow the conducting 3D PPy/GO composite hydrogels with great potential applications in electrochemical sensors or controlled release.

Ancillary Ligand-Mediated Syntheses, Structures and Fluorescence of Three Zn/Cd(II) Coordination Polymers Based on Nitrobenzene Dicarboxylate

Abstract: The Zn/Cd(II)-nbdc carboxylate motifs mediated by various dipyridyl-typed ligands afforded three new coordination compounds, namely, [Zn(nbdc)(bpa)0.5(H2O)]·H2O (1), [Zn2(nbdc)2(bpp)2]·H2O (2), and [Cd(nbdc)(bpe)0.5(H2O)2] (3) (H2nbdc = 4-nitrobenzene-1,2-dicarboxylic acid, bpa = 1,2-bi(4-pyridyl)ethane, bpe = 1,2-di(4-pyridyl)ethylene, and bpp = 1,3-bis(4-pyridyl)propane), which were synthesized by hydrothermal reaction and characterized by elemental analysis, IR, thermal analysis (TGA), and fluorescent analysis. The single-crystal X-ray diffractions reveal that three complexes display a diverse range of connectivity topology from 1D to 3D, which is dependent on the type of dipyridyl-typed ligands and metal centers. Complex 1 is the 1D chain featuring Zn-carboxylate binuclears extended further by bpa coligands. Complex 2 is the 2D thick-layer containing double-stranded chains cross-linked further by bpp coligands. Complex 3 is the 3D framework with (63)(65.8) ins topology featuring Cd-carboxylate chiral layers pillared by bpe coligands. The thermal stabilities and fluorescence properties for complexes 1–3 are investigated.

Effect of l-Histidine Substitution on Sol–Gel of Transition Metal Coordinated Poly Ethyleneimine: Synthesis and Biochemical Characterization

Abstract: The study was aimed to investigate the effect of chemical modification of branched poly ethyleneimine (PEI) on chelation of transition metal ions (Me2+) including Zn2+, Cu2+ or Ni2+ and sol–gel conversion thereof. To modulate chelation property of PEI, imidazole moieties were introduced into the polymer backbone by carbodiimide chemistry at different molar ratios of fmoc-protected l-histidine. The synthesis was characterized by 1H-NMR spectroscopy and size exclusion chromatography. Potentiometric titration of PEI/Me2+ aqueous dispersions showed formation of stable complexes at pH above 5 depending on the degree of l-histidine substitution. FT-IR spectroscopy showed the imidazole ring of l-histidine was involved in the coordination interactions between PEI and Me2+. Addition of Zn2+ to PEI solution induced sol–gel conversion at a critical molar ratio decreasing by a higher degree of l-histidine modification. The gelation process led to formation of stable globular nanostructures as confirmed by atomic force microscopy with projected mean diameters less than 200 nm. Cellular experiment showed that l-histidine substitution enhanced cyto-compatibility of PEI, moreover cytotoxicity decreased significantly upon coordination of Zn2+ with the polymers. Conclusively, the coordination complexes of Zn2+ and l-histidine substituted PEI could serve as a nano system for biomedical applications.

Recent Progresses of Iridium Complex-Containing Macromolecules for Solution-Processed Organic Light-Emitting Diodes

Abstract: Recent progresses of iridium complexes-containing macromolecules, including the linear polymers, dendrimers as well as supramolecular polymers, for solution-processable phosphorescent organic light-emitting devices, have been reviewed. The synthesis, structural characterization and optoelectronic properties of iridium-based electrophosphorescent materials are summarized.

Cluster-Containing Coordination Polymers Built Upon (Cu2I2S2)m Units (m = 2, 3) and ArSCH2C≡CCH2SAr Ligands: Is the Cluster Size Dependent Upon Steric Hindrance or Ligand Rigidity?

Abstract: Two equivalents of CuI react with p-MeC6H4SCH2C≡CCH2SC6H4-p-Me (L2) to form the 2D network [(Cu4I4)(p-MeC6H4SCH2C≡CCH2SC6H4-p-Me)2] n (polymer 2) contrasting with the previously reported reaction with C6H5SCH2C≡CCH2SC6H5 (L1) which makes a 3D network [(Cu6I6)(C6H5SCH2C≡CCH2SC6H5)3] n (polymer 1) (2009, Dalton Trans. 948). The crystal structure of the latter polymer has been re-determined at 115, 155, 195, 235 and 275 K to study the impact of the recording temperature on the metric parameters, notably the Cu···Cu distances within the hexagonal prism Cu6I6 cluster. Steric hindrance between a 2D/(Cu4I4) versus 3D/(Cu6I6) appears to drive the selectivity. Upon using the ligand o-MeC6H4SCH2C≡CCH2SC6H4-o-Me (L3) with CuI, a new material (polymer 3) is formed but no X-ray structure determination was possible. From obvious steric considerations and the presence of a high energy emission characteristic of the well-known Cu4I4 cluster (absent in the Cu6I6 one), and the similarity in emission lifetime for both high and low energy emission of polymers 2 and 3, the nature of this polymer was proposed to be [(Cu4I4)(o-MeC6H4SCH2C≡CCH2SC6H4-o-Me)2] n .

Colloidal Synthesis of ZnS, CdS and Zn x Cd 1−x S Nanoparticles from Zinc and Cadmium Thiobiuret Complexes

Abstract: ZnS, CdS and Zn x Cd1−x S nanoparticles were synthesised from the thermolysis of 1,1,5,5-tetra-iso-propyl-4-thiobiuret complexes of Zn and/or Cd in oleylamine. The influence of the different reaction parameters (precursor concentration, growth temperature, reaction time and injection solvent/capping agent combination) on the size, morphology and optical properties of the produced nanoparticles were studied. ZnS nanoparticles with size smaller than 4.3 nm had the cubic phase whereas the particles with size larger than 4.3 nm had a hexagonal crystal structure as suggested by the selected area electron diffraction. Transmission electron microscopy showed the formation of spherical ZnS nanoparticles in addition to few ZnS nanorods only at growth temperature of 280 °C. Powder X-Ray diffraction (p-XRD) showed that the obtained CdS nanoparticles were cubic under all reaction conditions except when dodecanethiol was used as an injection solvent which produced hexagonal CdS. The change in the crystal structure of the CdS nanoparticles was accompanied with a change in morphology from spherical to triangular. Cubic Zn x Cd1−x S nanoparticles were obtained under all reaction conditions. Lattice spacing of the Zn x Cd1−x S nanoparticles showed a very good agreement with Vegard’s law. The optical properties of the Zn x Cd1−x S nanoparticles were highly dependent on the ZnS to CdS precursor ratio and the solvents/capping agent combinations. This in detail study on the relationship of solvent systems (capping agents), thermolysis temperatures, time of reactions and precursors will help in understanding to control the morphology, size of the crystallites and phase of the materials.

Discrete and Polymeric Lead(II) Complexes Containing 4-Methyl-1,2,4-triazole-3-thiol Ligand: X-ray Studies, Spectroscopic Characterization, and Thermal Analyses

Abstract: [Pb(Hmptrz)4(NO3)2] complex (1) and [Pb(μ-mptrz)2(H2O)]n complex (2) (Hmptrz is 4-methyl-1,2,4-triazole-3-thiol) were prepared from the reaction of 4-methyl-1,2,4-triazole-3-thiol with Pb(NO3)2 and Pb(OAc)2·3H2O in CH3OH/H2O, respectively. Both complexes were characterized by elemental analysis, IR, UV–Vis, 1H NMR, 13C{1H}NMR, and luminescence spectroscopy and their structures were studied by single-crystal X-ray crystallography. The thermal stabilities of the title complexes were studied by thermogravimetric and differential thermal analyses. Complex 1 is a discrete and complex 2 is a polymer; both structures are without precedent in the literature.

A Theoretical Study on the Influence of Carbon and Silicon Doping on the Structural and Electronic Properties of (BeO)12 Nanocluster

Abstract: The influence of carbon and silicon atoms doping on the structural and electronic properties of the (BeO)12 nanocluster is investigated through density functional theory calculations. It has been found that doping process induces local deformation at bond lengths and angles near the doping site. The results indicate that C or Si doping decreases the energy gap of the (BeO)12 nanocluster. It seems that the electronic character of the (BeO)12 nanocluster could be adjusted by particular impurity. The electronic charge distributions are also analyzed using Atoms in Molecules theory. Natural bond orbital analyses are also performed for scrutinizing the structural properties of the considered nanoclusters.

Synthesis, Crystal Structure of Tetra-Nuclear Macrocyclic Cu(II) Complex Material and Its Application as Catalysts for A 3 Coupling Reaction

Abstract: A novel tetra-nuclear macrocyclic Cu(II) complex has been synthesized by the reaction of cupric acetate monohydrate with N-acetyl-l-phenylalanine and 4,4-bipyridine in water/ethanol (v:v = 1:1) solution, and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The results show that the Cu(II) complex belongs to monoclinic, space group P 21 with a = 14.993(3) A, b = 14.831(3) A, c = 22.262(4) A, β = 99.37(3)°, V = 4884.2(16) A3, Z = 2, D c = 1.420 μg m−3, μ = 0.942 mm−1, F(000) = 2,160, and final R 1 = 0.0701, ωR 2 = 0.1905. The molecules form three dimensional tubular structures by the interaction of hydrogen bonds and π–π interaction. The A3 coupling reaction of phenylacetylene, aldehyde and amine (piperidine) in the presence of Cu(II) complex as an efficient heterogeneous catalyst has been studied. The catalyst displayed high activity and afforded the corresponding propargylamines with excellent yields. The Cu(II) complex catalyst was reused three times without significant loss of its catalytic activity.

One Dimensional Structure of Zn(II) Metal Organic Framework (MOF) Assembled Rapidly at Room Temperature: Structural, Thermal Study, and Luminescent Properties

Abstract: One-dimensional structure of Zinc(II) metal organic framework ([Zn2(C10H8N2)3(NO3)4]∞) has been synthesized at room temperature and structurally characterized by elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. The five-coordinated Zn(II) complex exhibits trigonal bipyramidal coordination geometry. The Zn(II) ion is stabilized by three-connected nodes to form 1D ladder structure. The 1D chain is further connected to each other via hydrogen bonding to form 2D structure. Disordered CH2Cl2 solvent molecules were trapped in the pores. The luminescent and thermal properties have been also investigated. In addition, the activation thermodynamic parameters, ΔE*, ΔH*, ΔS* and ΔG* are calculated from the DTA curves using Coats–Redfern method.

Comparison of the Synthesis and Bioerodible Properties of N-Linked Versus O-Linked Amino Acid Substituted Polyphosphazenes

Abstract: Phosphazene polymers with N-linked and O-linked amino acid side groups are of biomedical interest, especially for their ability to bioerode under physiological conditions. Polyphosphazenes containing serine and threonine substituents, which contain two different functional sites for attachment to a polyphosphazene backbone (N- and O-terminus), were synthesized using an improved technique, and their hydrolysis behavior was investigated. In aqueous media the solid polymers yield hydrolysis products phosphate, ammonia, the amino acid, and ethanol and have the potential to be used in several different biomedical applications ultimately determined by their hydrolysis behavior. A hydrolysis study in deionized water revealed that all the polymers are hydrolytically sensitive, regardless of the type of linkage to the polyphosphazene backbone, although the hydrolysis rates may be different. Polymers with amino acid ester side groups linked through the N-terminus underwent solid phase hydrolysis between 16 and 60 % within a 6-week period. This is the fastest reported solid state hydrolysis of any amino acid ester substituted polyphosphazene. The mechanism of hydrolysis is by bulk erosion as monitored by environmental scanning electron microscopy. Polymers with the amino acid units linked through the O-terminus are soluble in water; thus their solid state erosion profile in aqueous media could not be determined. However, 31P NMR spectroscopy confirmed their hydrolytic sensitivity in aqueous solution and the formation of phosphorus-containing oligomeric species, the concentrations of which increased during the 6-week hydrolysis period. Complete hydrolysis did not occur within 6 weeks. The O-linked species are possible starting points for bioerodible hydrogel formation.

High Performance Photocatalysts Based on N-doped Graphene-P25 for Photocatalytic Reduction of Carbon Tetrachloride

Abstract: Carbon tetrachloride (CCl4) is a kind of toxic and persistent groundwater contaminant. Considering keeping drinking water safe, a novel kind of N-doped graphene (NGS)-P25 TiO2 photocatalyst was prepared by a facile one-step hydrothermal method for the removal of CCl4 from contaminated water. Simultaneously, nitrogen-doping and the reduction of graphene oxide, and loading of P25 were finished during the same process. The photocatalytic efficiency of resulted NGS-P25 nanoparticles was studied for the degradation of CCl4. The results indicated that NGS-P25 exhibited the highest photocatalytic activity under UV light irradiation, outperforming graphene-P25, bare P25 or NGS. The effects of NGS-P25 dosage, irradiation time, CCl4 concentration and pH on CCl4 photocatalytic degradation efficiency were discussed in detail. Accordingly, the optimum experimental conditions were obtained. Moreover, the high performance photocatalyst of NGS-P25 can be extended to environmental pollution control and remediation towards various pollutants.

“Key-vs.-Lock”-Like Polymer Reactor Made of Molecularly Imprinted Polymer Containing Metal Nanoparticles

Abstract: This study aimed at the present dilemma in selective catalysis, about how to furnish metal-nanoparticle catalysts with predictable selectivity. This issue was addressed by developing a “key-vs.-lock”-like polymer reactor made of an elaborate molecularly imprinted polymer containing metal nanoparticles, which was capable of predictably and selectively catalyzing its specified substrate. Unlike reported polymer reactors and enzyme-like imprinted polymer catalysts, which lack either predictable selectivity or reactive metal nanoparticles, this polymer reactor has incorporated both of the molecular recognition ability of the polymer carrier and the catalytic sites of metal nanoparticles into one entire entity and thereby dictated selective catalysis. This study highlighted how this polymer reactor works in a selective way in contrast to reported catalytic polymers or polymer reactors, which thus opens opportunities of tailoring selective catalysts for controlled chemical processes.

Synthesis, Crystal Structure, Vibrational Spectra, Optical Properties and Thermal Analysis of a New Chlorocadmate Templated by 1-(2-Ammoniumethyl) Piperazinium

Abstract: Chemical preparation, X-ray single crystal diffraction, thermal analysis, electrochemical measurements, IR, Raman and UV spectroscopic investigations of a novel organic–inorganic hybrid material, (C6H18N3)Cd2Cl7(H2O)·2H2O, are described. The 1-(2-ammoniumethyl) piperazinium aquapentachlorocadmate(II) hexacholorocadmate(II) dihydrate crystallizes in the triclinic system with P−1 space group. Its unit cell dimensions are a = 9.174(3) A, b = 9.709(3) A, c = 12.956(4) A, α = 96.77(3)°, β = 72,10(2)°, γ = 113.99(4)° with V = 1003,2(5) A3, and Z = 2. The structure provides a new interesting example of infinite inorganic layers of [Cd2Cl7(H2O)] n 3n− following the b crystallographic direction. The CdCl6 2− and CdCl5(H2O)− anions are interconnected by O–H···Cl, N–H···O and N–H···Cl hydrogen bonds. Thermal analysis reveals the hydrous character of the compound. IR and Raman spectra are reported and discussed on the basis of group theoretical analysis. The optical study was also investigated by UV–Vis absorption spectra. Cyclic voltammetry was studied to evaluate the spectral and structural changes accompanying electron transfer.

Platinum Phosphinito Catalysts for Nitrile Hydration

Abstract: The reaction of PEt2OH with K2PtCl4 yields [PtCl{(PEt2O)2H}]2 (2). The X-ray crystal structure of 2 shows that the two chloride ligands bridge the two Pt atoms. The structure is unusual in that the PtCl2Pt unit is bent, which is the first example of a platinum phosphinito chloride-bridged dimer that is bent. Dimer 2 is a poor catalyst for the hydration of acetonitrile (and presumably other nitriles). Likewise, the monomeric catalyst that results from the reaction of 2 with sodium hydroxide is not a good hydration catalyst. In an attempt to form a more reactive monomeric catalyst, PtCl(PMe2OH){(PMe2O)2H} (1) was reacted with sodium hydroxide. This reaction resulted in the formation of two species, tentatively characterized as Na[PtCl(PMe2O){(PMe2O)2H}] (5) and Na[PtCl(OH){(PMe2O)2H}] (6). Complexes 5 and 6 could not be separated. However, the mixture of the two complexes quickly hydrated acetonitrile. The catalyst mixture of 5 and 6 was efficiently poisoned by cyanide, which prevented its use as a catalyst for the hydration of cyanohydrins.