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Metal Salts (metal + salt)
Kinds of Metal Salts Selected AbstractsChemInform Abstract: Electrophilic Aromatic Nitration Using Perfluorinated Rare Earth Metal Salts in Fluorous Phase.CHEMINFORM, Issue 33 2002Min Shi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Micellar Approach to Magnetic Ultrahigh-Density Data-Storage Media: Extending the Limits of Current Colloidal Methods,ADVANCED MATERIALS, Issue 3 2007A. Ethirajan An alternative route for producing L10FePt nanoparticles based on the self-organization of diblock copolymers into spherical micelles is presented. It overcomes all of the drawbacks of current colloidal strategies towards densely packed arrays of ferromagnetic FePt nanoparticles while still guaranteeing areal densities exceeding 1,Tbits,inch,2. The figure shows a sketch of the metal-salt-loaded micelles deposited on a substrate: a polystyrene shell (red) covers the poly(2-vinylpyridine) core (blue) forming a nanoreactor loaded with metal salt (yellow). [source] Synthesis, characterization, and electrical properties of diazophenylene bridged Co, Ni, Cu, Ce, and Er phthalocyanine polymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Cemil Alkan Abstract In this research, diazophenylene bridged metal-phthalocyanine (Pc) polymers were produced from diazonium salt of 1,4-diaminophenylene and presynthesized 1,8,15,22-tetraamino metal-Pcs. 1,8,15,22-Tetraamino metal-Pc complexes of Co, Ni, Cu, Ce, and Er were obtained by reducing 1,8,15,22-tetranitro metal-Pc complexes synthesized from 3-nitrophthalic anhydride, urea, metal salt, and ammonium molybdate catalyst. Complexes and polymers were characterized by Fourier transform infrared (FTIR), ultraviolet,visible (UV,vis), and X-ray powder diffraction spectroscopes. X-ray analysis of the polymers showed that there were short-range orientations in the polymers. Thermal analysis of the complexes and the polymers were done by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA) at a heating rate of 10°C min,1 under nitrogen atmosphere. Ash analysis was performed to determine the metal content of the polymers. Viscosimetry and ebullioscopy measurements of the soluble part of the polymers were done for molecular weight analysis of the soluble part in tetrahydrofuran (THF) at 25°C. Four-probe conductivity measurements on isothermal conditions revealed that the polymer samples showed 104 fold increases in their electrical conductivities when doped with iodine. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Substitution-reduction: an alternative process for the [18F]N -(2-fluoroethylation) of anilinesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2004Emmanuelle Briard Abstract Substitution of a halo atom (chloro or bromo) in easily prepared N -haloacetyl-anilines with no-carrier added (NCA) cyclotron-produced [18F]fluoride ion (18F, t1/2= 109.8 min; ,+=96.9%), followed by reduction with borane,tetrahydrofuran (BH3,THF), provides an alternative route to NCA [18F]N -(2-fluoroethyl)-anilines. This two-step and one-pot process is rapid (,50 min) and moderately high yielding (,40% decay-corrected radiochemical yield (RCY) overall). In the nucleophilic substitution reaction, 18-crown-6 is preferred to Kryptofix® 222 as complexing agent for the solubilization of the counter-ion (K+), derived from an added metal salt, in acetonitrile. Weakly basic potassium bicarbonate is preferred as the added metal salt. Inclusion of a small amount of water, equating to 4,5 molar equivalents relative to 18-crown-6, base or precursor (held in equimolar ratio), is beneficial in preventing the adsorption of radioactivity onto the wall of the glass reaction vessel and for achieving high RCY in the nucleophilic substitution reaction. BH3,THF is effective for the rapid reduction of the generated [18F]N -fluoroacetyl-aniline to the [18F]N -(2-fluoroethyl)-aniline. Copyright © 2004 John Wiley & Sons, Ltd. [source] The antioxidant activity and stability of the phenolic fraction of green olives and extra virgin olive oilJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2001Turkan Keceli Abstract The antioxidant activity of phenolic extracts from olives and olive oil has been assessed by scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and by studying the effects on the stability of stripped olive oil in the absence and presence of ferric chloride. The olive extracts contained a much higher concentration (1940,5800,mg,kg,1) of phenolic components than the olive oil extract (180,mg,kg,1). Some olive extracts were more effective than the olive oil extract in scavenging DPPH radicals, but the three varieties of olives examined showed relatively large differences in both polyphenol concentration and antioxidant activity of extracts. ,-Tocopherol and extracts from both olives and olive oil were effective antioxidants in stripped olive oil at 60,°C. Ferric chloride reduced the stability of stripped olive oil, but the olive extract studied was significantly more effective as an antioxidant in the presence of the metal salt than the olive oil extract or ,-tocopherol. Ferric ions catalysed the oxidation of caffeic acid, oleuropein and phenolic components of the olive and olive oil extracts in aqueous solution (pH 5.4). The olive extract oxidised more rapidly than the olive oil extract in aqueous solution. © 2001 Society of Chemical Industry [source] Can radical cations of the constituents of nucleic acids be formed in the gas phase using ternary transition metal complexes?,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2005Sheena Wee Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) of ternary transition metal complexes of [M(L3)(N)]2+ (where M,=,copper(II) or platinum(II); L3,=,diethylenetriamine (dien) or 2,2,:6,,2,-terpyridine (tpy); N,=,the nucleobases: adenine, guanine, thymine and cytosine; the nucleosides: 2,deoxyadenosine, 2,deoxyguanosine, 2,deoxythymine, 2,deoxycytidine; the nucleotides: 2,deoxyadenosine 5,-monophosphate, 2,deoxyguanosine 5,-monophosphate, 2,deoxythymine 5,-monophosphate, 2,deoxycytidine 5,-monophosphate) was examined as a means of forming radical cations of the constituents of nucleic acids in the gas phase. In general, sufficient quantities of the ternary complexes [M(L3)(N)]2+ could be formed for MS/MS studies by subjecting methanolic solutions of mixtures of a metal salt [M(L3)X2] (where M,=,Cu(II) or Pt(II); L3,=,dien or tpy; X,=,Cl or NO3) and N to ESI. The only exceptions were thymine and its derivatives, which failed to form sufficient abundances of [M(L3)(N)]2+ ions when: (a) M,=,Pt(II) and L3,=,dien or tpy; (b) M,=,Cu(II) and L3,=,dien. In some instances higher oligomeric complexes were formed; e.g., [Pt(tpy)(dG)n]2+ (n,=,1,13). Each of the ternary complexes [M(L3)(N)]2+ was mass-selected and then subjected to collision-induced dissociation (CID) in a quadrupole ion trap. The types of fragmentation reactions observed for these complexes depend on the nature of all three components (metal, auxiliary ligand and nucleic acid constituent) and can be classified into: (i) a redox reaction which results in the formation of the radical cation of the nucleic acid constituent, N+.; (ii) loss of the nucleic acid constituent in its protonated form; and (iii) fragmentation of the nucleic acid constituent. Only the copper complexes yielded radical cations of the nucleic acid constituent, with [Cu(tpy)(N)]2+ being the preferred complex due to suppression, in this case, of the loss of the nucleobase in its protonated form. The yields of the radical cations of the nucleobases from the copper complexes follow the order of their ionization potentials (IPs): G (lowest IP),>,A,>,C,>,T (highest IP). Sufficient yields of the radical cations of each of the nucleobases allowed their CID reactions (in MS3 experiments) to be compared to their even-electron counterparts. Copyright © 2005 John Wiley & Sons, Ltd. [source] Disulfides, Imines, and Metal Coordination within a Single System: Interplay between Three Dynamic EquilibriaCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2007Rupam Abstract We report a system in which three distinct dynamic linkages, disulfide (SS), imine (CN), and coordinative (N,metal) bonds were shown to be capable of simultaneous reversible exchange. The "disulfide layer" of the system under study consists of two homo-disulfides, bis(4-aminophenyl) disulfide 1 and bis(4-methoxyphenyl) disulfide 2 that equilibrate in the presence of catalytic amount of triethylamine to favor the formation of a hetero-disulfide product, 4-aminophenyl-4,-methoxyphenyl disulfide 3. The addition of 2-formylpyridine and a metal salt strongly perturbed this 1+2,3 equilibrium through the formation of metal complexes incorporating disulfide 1 as a subcomponent. CuI perturbed the equilibrium by a factor of 3.3, and FeII by a factor of 179, in both cases in favor of the homo-disulfides. The disulfide equilibrium could be further modified, following metal-complex formation, by coordinative (transmetallation: substitution of FeII for CuI) or covalent (imine exchange: the substitution of one amine residue for another) exchange. Thus, although the three kinds of dynamic linkages were demonstrated to be mutually compatible, changes at one kind of linkage could be used to predictably perturb an equilibrium involving another. [source] Rapid synthesis of lead oxide nanorods by one-step solid-state chemical reaction at room temperatureCHINESE JOURNAL OF CHEMISTRY, Issue 11 2004Ya-Li Cao Abstract A simple and facile method was reported to synthesize lead oxide nanorods. Nanorods of lead oxide were obtained directly from grinding solid metal salt and sodium hydroxide in agate mortar with the assistance of a suitable nonionic surfactant in only one step, which is different from the result of hydroxide in solution. The product has been characterized by XRD, TEM and SEM. The formation mechanism of rod-like morphology is discussed and the surfactant plays an important soft-template role in modifying the interface of solid-state reaction and according process of rod-formation. [source] Pentadentate Ligands for the 1:1 Coordination of Lanthanide(III) Salts,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2007Markus Albrecht Abstract Three hydrazone type ligands, namely 2 -H, 3, and 4, which were designed to form 1:1 complexes with lanthanoid(III) ions, are presented. Although the tetradentate ligand 2, leads to an interesting complex [(2)(2 -H)YCl2] with yttrium(III), a more general principle for the coordination of the metal ions by hydrazone-type ligands can be found with ligand 3, where 1:1 complexes are obtained with an effective coordination of the metal salts by the ligand. The stabledimer [{(3)Nd(CF3SO3)}2(,-CF3SO3)3]CF3SO3 was characterized by X-ray structure determination. Depending on the size of the metal ion, additional co-ligands can also be bound to the metal centers. This is observed in the molecular structures of [(3)Pr(NO3)2(MeOH)2](NO3), [(3)NdCl2(MeOH)(EtOH)]Cl, [(3)ErCl2(MeOH)]Cl, and [(3)LuCl2]Cl. The solid-state molecular structures of 4 and 4·HCl show the helicating ability of this ligand upon metal coordination. The corresponding lanthanide complexes of 4 are characterized by standard techniques such as NMR and CD spectroscopy and mass spectrometry.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Metal-Free Air Oxidation of Thiols in Recyclable Ionic Liquid: A Simple and Efficient Method for the Synthesis of DisulfidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2010Devender Singh Abstract An efficient procedure for the oxidative coupling of alkyl, aryl and heteroaryl thiols with atmospheric oxygen is reported. The methodology utilizes BMIM-BF4 as a recyclable solvent and does not require support materials or metal salts. Symmetric disulfides are obtained in excellent yields. [source] N,N -Dimethylformamide as a Reaction Medium for Metal Nanoparticle SynthesisADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Isabel Pastoriza-Santos Abstract The versatility of wet chemical methods has rendered them extremely popular for the preparation of metal nanoparticles with tailored size and shape. This Feature Article reviews the use of N,N -dimethylformamide (DMF) for the reduction of metal salts, mainly Au and Ag, while also acting as a solvent. Apart from describing the ability of DMF to reduce metal salts, the effect of different parameters, such as the concentration of capping agent and metal precursors, the presence of preformed seeds acting as catalysts or their crystalline structure, on particle morphology are analyzed. Published reports on the use of different capping agents are summarized, with particular emphasis on the role of poly(vinylpyrrolidone) to determine the morphology of the particles. Finally, a brief overview is provided on the modulation of the optical response in DMF-based metal nanoparticle colloids with tunable size and shape. [source] Preparation of Inorganic Materials Using Ionic LiquidsADVANCED MATERIALS, Issue 2 2010Zhen Ma Abstract Conventional synthesis of inorganic materials relies heavily on water and organic solvents. Alternatively, the synthesis of inorganic materials using, or in the presence of, ionic liquids represents a burgeoning direction in materials chemistry. Use of ionic liquids in solvent extraction and organic catalysis has been extensively studied, but their use in inorganic synthesis has just begun. Ionic liquids are a family of non-conventional molten salts that can act as templates and precursors to inorganic materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility for both organic and inorganic molecules, and much synthetic flexibility. In this Review, the use of ionic liquids in the preparation of several categories of inorganic and hybrid materials (i.e., metal structures, non-metal elements, silicas, organosilicas, metal oxides, metal chalcogenides, metal salts, open-framework structures, ionic liquid-functionalized materials, and supported ionic liquids) is summarized. The status quo of the research field is assessed, and some future perspectives are furnished. [source] Combinatorial Fabrication of Fluorescent Patterns with Metal Ions Using Soft Lithography,ADVANCED MATERIALS, Issue 8 2006L. Basabe-Desmonts A new combinatorial methodology for the fabrication and direct visualization of fluorescent and metal-ion micrometer patterns is presented. Microcontact printing is used to transfer different metal salts onto a variety of fluorescent monolayers on glass (see figure). [source] From Starch to Metal/Carbon Hybrid Nanostructures: Hydrothermal Metal-Catalyzed Carbonization,ADVANCED MATERIALS, Issue 18 2004H. Yu An efficient method has been successfully realized for the controlled synthesis of various metal/carbon nanoarchitectures. The formation of metal/carbon nanocables and nanochains via a facile and mild hydrothermal carbonization co-reduction process (HCCR) is reported. The method involves the use of starch and noble metal salts as starting materials under mild conditions (, 200,°C). [source] Copper(II) Triflate as a Source of Triflic Acid: Effective, Green Catalysis of Hydroalkoxylation ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Mathieu J.-L. Abstract The hydroalkoxylation of dicyclopentadiene (DCPD) and norbornene (NB) with 2-hydroxyethyl methacrylate (HEMA) for the synthesis of industrially relevant monomers has been investigated with various metal-based Lewis acids and strong Brønsted acids. In the absence of other additives, copper(II) triflate is the most efficient catalyst system. Kinetics, electron spin resonance (ESR), catalyst poisoning and cross experiments indicate that triflic acid (TfOH) is the true active catalyst in these reactions. This in situ generation of TfOH occurs via reduction of Cu(OTf)2 by the olefin reagent (DCPD, NB). The copper ions present in the reaction mixture act as radical polymerization retardants, preventing polymerization of HEMA (which is observed with most other metal salts and strong Brønsted acids investigated), thus improving the selectivity and yield (up to 95%) for the desired products. These observations have led to the development of a highly effective green process, using bulk reagents (no solvent) and a cheap, metal-free catalyst system, based on TfOH and a phenolic radical inhibitor (2,5-di- tert -butylhydroxytoluene, BHT). [source] Density functional theory studies on the dissociation energies of metallic salts: relationship between lattice and dissociation energiesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2001Chang Kon Kim Abstract The formation and physicochemical properties of polymer electrolytes strongly depend on the lattice energy of metal salts. An indirect but efficient way to estimate the lattice energy through the relationship between the heterolytic bond dissociation and lattice energies is proposed in this work. The heterolytic bond dissociation energies for alkali metal compounds were calculated theoretically using the Density Functional Theory (DFT) of B3LYP level with 6-311+G(d,p) and 6-311+G(2df,p) basis sets. For transition metal compounds, the same method was employed except for using the effective core potential (ECP) of LANL2DZ and SDD on transition metals for 6-311+G(d,p) and 6-311+G(2df,p) calculations, respectively. The dissociation energies calculated by 6-311+G(2df,p) basis set combined with SDD basis set were better correlated with the experimental values with average error of ca. ±1.0% than those by 6-311+G* combined with the LANL2DZ basis set. The relationship between dissociation and lattice energies was found to be fairly linear (r>0.98). Thus, this method can be used to estimate the lattice energy of an unknown ionic compound with reasonably high accuracy. We also found that the dissociation energies of transition metal salts were relatively larger than those of alkaline metal salts for comparable ionic radii. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 827,834, 2001 [source] Synthesis and structure of new 5-(arylidene)-3-(4-methylbenzoyl)thiazolidine-2,4-dionesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2010Katarina M. Popov-Pergal The derivatives of 5-substituted-2,4-thiazolidinedione have a broad spectrum of biological activities. In this article, new 5-(arylidene)-3-(4-methylbenzoyl)thiayolidine-2,4-diones 3a,k, with arylidene groups such as 4-phenylbenzylidene 3a, 3,4-dimethoxybenzylidene 3b, 2-hydroxybenzylidene 3c, 4-ethoxybenzylidene 3d, 5-methyl-2-furfurylidene 3e, 4-dimethylaminobenzylidene 3f, 1-naphthylidene 3g, 3,4-methylenedioxybenzylidene 3h, 4-benzyloxybenzylidene 3i, benzylidene 3j, and 4-methoxybenzylidene 3k, were synthesized by direct acylation of alkali metal salts of 5-arylidene-2,4-thiazolidinediones with 4-methylbenzoylchloride. Their structures were confirmed by elemental analysis, IR, 1H NMR and MS spectroscopy. In addition, crystal structure of the compound 3d was determined using single-crystal X-ray diffraction data. J. Heterocyclic Chem., 2010. [source] Proton and metal-ion activation of C,H exchange in five-membered azolesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2002Erwin Buncel Abstract Factors influencing C,H isotopic exchange rates in five-membered azoles, that is imidazoles and thiazoles, under catalysis by H+ and Mn+, especially transition metals, Pt(II) and Co(III) are discussed. Hydrogen ion catalysis through N(3) protonation of azoles 1,3 is generally the most efficient, with rate enhancements in the range 102,109 over the neutral process being attained. Metal-ion coordination also results in effective catalysis, though less so than catalysis by protons. Catalysis of C,H exchange by Mn+ can be studied through addition of the metal salts to a buffered solution of the heterocycle in which labile complexes exist, or on synthesized complexes such as 4,13 which are substitution-inert thus precluding complications from unknown dissociation equilibria. A delicate balance of factors influence the ease of C,H exchange, including: (1) the magnitude of the fractional charge located at N(3) of the heterocycle through Mn+,N(3) , bond polarization; (2) metal-to-ligand , back-bonding; (3) the electronic structure of the metal ions. These considerations have obvious consequences for deuterium- and tritium-labelling of a number of biomolecules, e.g. proteins, enzymes, nucleic acids, some vitamins, as well as drugs which incorporate five-membered azoles in their structures. Copyright © 2002 John Wiley & Sons, Ltd. [source] Characterization of natural wax esters by MALDI-TOF mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2009Vladimír Vrkoslav Abstract The applicability of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) to the analysis of wax esters (WEs) was investigated. A series of metal salts of 2,5-dihydroxybenzoic acid (DHB) was synthesized and tested as possible matrices. Alkali metal (Li, Na, K, Rb, Cs) and transition metal (Cu, Ag) salts were studied. The matrix properties were evaluated, including solubility in organic solvents, threshold laser power that should be applied for successful desorption/ionization of WEs, the nature of the matrix ions and the mass range occupied by them, and the complexity of the isotope clusters for individual metals. Lithium salt of dihydroxybenzoic acid (LiDHB) performed the best and matrices with purified lithium isotopes (6LiDHB or 7LiDHB) were recommended for WEs. Three sample preparation procedures were compared: (1) mixing the sample and matrix in a glass vial and deposition of the mixture on a MALDI plate (Mix), (2) deposition of sample followed by deposition of matrix (Sa/Ma), and (3) deposition of matrix followed by deposition of sample (Ma/Sa). Morphology of the samples was studied by scanning electron microscopy. The best sample preparation technique was Ma/Sa with the optimum sample to matrix molar ratio 1 : 100. Detection limit was in the low picomolar range. The relative response of WEs decreased with their molecular weight, and minor differences between signals of saturated and monounsaturated WEs were observed. MALDI spectra of WEs showed molecular adducts with lithium [M + Li]+. Fragments observed in postsource decay (PSD) spectra were related to the acidic part of WEs [RCOOH + Li]+ and they were used for structure assignment. MALDI with LiDHB was used for several samples of natural origin, including insect and plant WEs. A good agreement with GC/MS data was achieved. Moreover, MALDI allowed higher WEs to be analyzed, up to 64 carbon atoms in Ginkgo biloba leaves extract. Copyright © 2008 John Wiley & Sons, Ltd. [source] Improved Aging Characteristics of NTC Thermistor Thin Films Fabricated by a Hybrid Sol,Gel,MOD ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2006Dmitry A. Kukuruznyak Negative temperature coefficient thermistor oxide thin films with improved aging characteristics are described. Better thermal stability has been achieved by incorporating sol,gel techniques with metallo-organic decomposition methods. A compositional range was identified whereby borosilicate may incorporate into the thermistor oxides, forming nanocomposites showing thermistor electrical characteristics. Thermistor thin films, with composition Ni0.48Co0.24Cu0.6Mn1.68O4·0.22SiO2·0.15B2O3 were deposited onto glass substrates from a solution containing organic transition metal salts, tetraethyl orthosilicate and triethyl borate. Electrical resistance measurements verified characteristic thermistor behavior. Nanocomposite thin films exhibited a factor of four improvement as compared with pure oxides after aging at 150°C for 500 h. [source] Low-Temperature Fabrication of Oxide Composites for Solid-Oxide Fuel CellsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2004Hongpeng He Composites of yttria-stabilized zirconia (YSZ) with Sr-doped LaCrO3 (LSC) and Sr-doped LaMnO3 (LSM) were prepared by impregnation of a porous YSZ matrix with aqueous solutions of the appropriate metal salts, followed by sintering to various temperatures. XRD measurements showed that perovskite phases formed after sintering at 1073 K, a temperature well below that at which solid-state reactions with YSZ occur. The conductivities of the LSC,YSZ and LSM,YSZ composites prepared in this way were maximized at a sintering temperature of 1373 K for LSC,YSZ and 1523 K for LSM,YSZ, although reasonable conductivities were achieved at much lower temperatures. The conductivities of the two composites increased much more rapidly with the content of the conductive oxide than has been found with conventional composites formed by mixing and sintering the oxide powders. The implications for using this approach to develop novel electrodes for SOFC applications are discussed. [source] Microwave-Assisted Synthesis of Fine Particle Oxides Employing Wet Redox MixturesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2002Solomon Sundar Manoharan Interaction of electromagnetic radiation with a physical mixture of metal nitrates and amides/hydrazides is observed to initiate high-temperature reactions, useful for realizing several high-temperature ceramic materials. A judicious choice of such redox mixtures undergoes exothermic reactions when they couple with microwave radiation. The coupling of electromagnetic radiation with metal salts and amides/hydrazides depends on the dielectric properties of the individual components in the reaction mixture. The approach has been used to prepare ,-Fe2O3, Fe3O4, MgCr2O4, ,-CaCr2O4, and La0.7Ba0.3MnO3. [source] Noble Metal Decoration and Alignment of Carbon Nanotubes in Carboxymethyl CelluloseMACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2008Mallikarjuna N. Nadagouda Abstract A facile microwave method (MW) is described that accomplishes alignment and decoration of noble metals on carbon nanotubes (CNT) wrapped with carboxymethyl cellulose (CMC). Carbon nanotubes such as single- and multi-walled, and Buckminsterfullerene (C-60) are well dispersed using the sodium salt of CMC under sonication. Addition of respective noble metal salts then generates noble metal-decorated CNT composites at room temperature. However, aligned nanocomposites of CNTs could only be generated by exposing the above nanocomposites to MW irradiation. The CNT composites are characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray mapping, transmission electron microscopy, and UV-visible spectroscopy. The general preparative procedure is versatile and provides a simple route to manufacturing useful metal-coated CNT nanocomposites. [source] Metal Nanoparticle/Polymer Hybrid Particles: The Catalytic Activity of Metal Nanoparticles Formed on the Surface of Polymer Particles by UV-IrradiationMACROMOLECULAR SYMPOSIA, Issue 1 2009Toshiyuki Tamai Abstract Summary: Polymer particles decorated with metal nanoparticles were prepared by UV-irradiation of polystyrene particles incorporating polymethylphenylsilane (PS/PMPS) and P[S- co -NIPAM]/PMPS particles (NIPAM: N-isopropyl acrylamide) in the presence of metal salts. The metal nanoparticle/polymer hybrid particles were used as a catalyst for the reduction of 4-nitrophenol with NaBH4. The Pd- and Ag-P(S- co -NIPAM)/PMPS hybrid particles had larger metal nanoparticles and the lower catalytic activity than those of Pd- and Ag-PS/PMPS, respectively. The surface functional group of the polymer particles affected the formation of the metal nanoparticles and their catalytic activity. [source] Hybrid metal/silicon nanocomposite systems and their catalytic activityPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2009Sergej Polisski Abstract In this work we studied the reduction of metal salts and their mixtures on extended hydrogen-terminated porous silicon surfaces. For these experiments we employed salts of Au, Ag, Pt and their mixtures. We show that the size and shape of resulting metal and metal alloy nanoparticles depends on the pore morphology. This has been confirmed by transmission electron microscopy measurements and plasmon resonance experiments. Finally we demonstrate catalytic activity of formed Pt nanoparticles in PSi matrix via monitoring the conversion of carbon monoxide. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Flame retardancy mechanisms of metal phosphinates and metal phosphinates in combination with melamine cyanurate in glass-fiber reinforced poly(1,4-butylene terephthalate): the influence of metal cationPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008Ulrike Braun Abstract The pyrolysis and fire behavior of glass-fiber reinforced poly(butylene terephthalate) (PBT/GF) with two different metal phosphinates as flame retardants in combination with and without melamine cyanurate (MC) were analyzed by means of thermogravimetry, thermogravimetry coupled with infrared spectroscopy, flammability, and cone calorimeter tests as well as scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence spectroscopy. In PBT/GF, dosages of 13,20% of the halogen-free flame retardant aluminum phosphinate or aluminum phosphinate in combination with MC fulfill the requirements for electrical engineering and electronics applications (UL 94,=,V-0; LOI,>,42%), whereas the use of the same amount of zinc phosphinate or zinc phosphinate in combination with MC does not improve the fire behavior satisfactorily (UL 94,=,HB; LOI,=,27,28%). The performance under forced flaming conditions (cone calorimeter) is quite similar for both of the metal phosphinates. The use of aluminum and zinc salts results in similar flame inhibition predominantly due to the release of the phosphinate compounds in the gas phase. Both metal phosphinates and MC interact with the polymer changing the decomposition characteristics. However, part of the zinc phosphinate vaporizes as a complete molecule. Because of the different decomposition behavior of the metal salts, only the aluminum phosphinate results in a small amount of thermally stable carbonaceous char. In particular, the aluminum phosphinate-terephthalate formed is more stable than the zinc phosphinate-terephthalate. The small amount of char has a crucial effect on the thermal properties and mechanical stability of the residue and thus the flammability. Copyright © 2008 John Wiley & Sons, Ltd. [source] Advanced nucleating agents for polypropylene,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2007Dima Libster Abstract The present short review aims to summarize advanced nucleating agents for polypropylene (PP). Reviewing the relevant literature, we focused on powerful nucleators that are capable of significantly increasing the crystallization temperature of the polymer at very low working concentrations and also serving as clarifying agents. The nucleation mechanism and efficiency of these compounds are discussed in detail. The nucleating agents were divided into groups according to their tendency to induce monoclinic (,), hexagonal (,), or orthorhombic (,) PP cell geometries. The major , -nucleators and clarifiers are sorbitol-based compounds that speed-up the polymer crystallization due to gelation phenomena and induction of epitaxial crystallization by the metal salts of substituted aromatic heterocyclic phosphate. Among , -nucleators, N,N,-dicyclohexyl-2,6-naphthalene dicarboxamide was found to be very efficient and its nucleation ability was highly concentration dependent. In addition, it was shown that nucleation efficiency of a nucleator can be significantly increased by a new dispersion method comprising its solubilization in a microemulsion. Moreover, the nucleator (HPN-68) increased the , -modification present in the polymer. Copyright © 2007 John Wiley & Sons, Ltd. [source] Degradation of polyamide-6 by using metal salts as catalyst,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002a Klun Abstract Polyamide-6 (PA-6) is a widely used polycondensation polymer that can be recycled by hydrolysis to its monomer ,-caprolactam. The reaction is normally catalyzed by mineral acids. Using microwaves as the source of heating, zinc chloride, acetate and triflate were evaluated as non-acid catalysts for the reaction. Gravimetric and electron spray ionization mass spectrometry analysis of reaction products showed ZnCl2 as the most effective salt catalyst. A 50wt% (versus PA-6) addition gave 75% water-soluble, low-molecular-weight oligomers, which is approximately 25% lower than when using phosphoric acid. The triflate salt was effective only when used as an addition to a mineral acid, whereas the acetate was ineffective. FTIR and NMR spectroscopy of degradation products showed that dissociated ions from ZnCl2 bind to the amide group of the polymer. Using the triflate salt no such interaction could be observed, indicating that the degradation and catalysis mechanisms differ with the chloride and triflate salt. Five water-stable lanthanide triflates showed no catalytic effect on the reaction. Copyright © 2003 John Wiley & Sons, Ltd. [source] Amorphous blends of poly(zwitterions) and zwitterionomers of the ammonioalkoxydicyanoethenolate type with some alkali metal saltsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2001Monique Galin Abstract Poly(zwitterions) and zwitterionomers of the ammonioethoxydicyanoethenolate type (functional dipolar unit R3N+,(CH2)2,O,CO,C,,(CN)2, µ,=,25.9 D) show the very specific property of solvation of some alkali metal salts to yield amorphous blends. For homopolymers in the (meth)acrylic series, solvation is observed up to a ratio r,=,[salt]/[zwitterion] of 1 for LiClO4 and NaSCN and of 0.5 for NaCF3SO3: it results in a significant plasticization (increasing order LiClO4,<,NaSCN,<,NaCF3SO3) and in the development in some cases of a poorly defined (lamellar?) local order, as evidenced by the presence of a single broad peak in the small-angle x-ray scattering (SAXS) patterns (Bragg distances of about 15,20 Å). For the amorphous blend of a biphasic poly(tetramethyleneoxide) segmented zwitterionomer and NaCF3SO3 (r,=,0.5), selective solvation of the salt in the hard zwitterionic domains induces a transition from a lamellar structure (zwitterionic sublayer of about 9,Å thickness) to an hexagonal packing of ionic-zwitterionic cylinders (radius of about 15 Å). Ionic conductivity, measured in a narrow range of temperature just above the glass transition temperature, is characterized for most systems by an activation energy of about 1,1.8,eV; the drastic decrease of the conductivity by a factor of 103, when going from the homopolymer to the zwitterionomer blends, is typical of the inhibition of the ionic percolation process by the lack of connectivity of the ionic-zwitterionic domains. Copyright © 2001 John Wiley & Sons, Ltd. [source] Selective imaging of positively charged polar and nonpolar lipids by optimizing matrix solution compositionRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2009Yuki Sugiura Previous studies have shown that matrix-assisted laser desorption/ionization,imaging mass spectrometry (MALDI-IMS) is useful for studying the distribution of various small metabolites, particularly lipids. However, in this technique, selective ionization of the target molecules is imperative, particularly when analyzing small molecules. Since the sample clean-up procedures available for the MALDI-IMS of small metabolites are limited, the tissue sample will contain numerous molecular species other than the target molecules. These molecules will compete for ionization resulting in severe ion suppression. Hence, it is necessary to develop and optimize a sample preparation protocol for the target molecules. In this study, through model experiments using reference compounds, we optimized the composition of the matrix solution used for positively charged lipids in terms of the concentration of the organic solvent and presence/absence of alkali metal salts. We demonstrated that a high concentration of organic solvent in the matrix solution favors the preferential detection of lipids over peptides. The presence of alkali metal salts in the matrix solution was favorable for the detection of polar lipids, while a salt-free matrix solution was suitable for the detection of nonpolar lipids. Furthermore, potassium salts added to the matrix solution caused merging of various lipid adducts (adducts with proton, sodium, and potassium) into one single potassiated species. Using the optimized protocols, we selectively analyzed phosphatidylcholine (PC) and triacylglycerol (TG) with different fatty acid compositions in a rat kidney section. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||