Hydrothermal Synthesis of Metal Silicates

Organically templated metal phosphates have been extensively studied because of interesting structural chemistry and potential applications in catalysis. However, in most cases the organic templates cannot be removed without collapse of the frameworks. This is in contrast to the high thermal stability and extensive applications of zeolites in refinery and petrochemical processes. Therefore, studies have been directed to the synthesis of transition metal silicates to produce more stable framewo…     

Electrochemistry of Hydroquinone Derivatives at Metal and Iodine-modified Metal Electrodes

IntroductionPlatinumand gold surfaces can adsorb a wide vari-ety of ions, atoms and molecular functional groups,which is often accompanied by oxidation-reduction ordissociation of them. Numerous previous works havemade great progress in studying the surfa…     

Time Positron Diagnostics of Metal β-Diketonates

The effects of the nature of the metal atom and -substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the -system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium -diketonates is accompanied by the formation of a protonated complex; for -organylthioacetylacetonates, annihilation follows the inhibition mechanism.     

Preparation of Metal Particle Catalysts Wrapped in Organosilicon Compound via Metal Vapor Synthesis

Three kinds of metal catalysts Ni/D_4, Ni-Mn/D_4, Ni-Mn-La/D_4, wrapped in organosilicon compound were prepared by metal vapor synthesis. Their feature was characterized with XRD, TEM, XPS, FMR and static magnetic measurement. The metal particle size in catalysts was less than 3.5 am. The results of XPS showed that the metals in the catalysts existed in zero and other valent state. Inner metal, as an organosilicon compound folded around the metal particle, was protected from oxidation. FMR and static magnetic measuremeat revealed that metal particles were spheroidal and of superparamagnetism. Of all the caralysts the catalytic activity of Ni-Mn-La/D_4 was the highest in hydrogenating furfuraldehyde into furfuralcohol.     

Cleavage of Nucleotides by Lanthanide Metal Complexes

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Synthesis of β-Cyclodextrin Bonded Metal Porphyrins

InrecentyearsstUdyondevelopingnovelmimicenZymemodelsthathavebothoNOO-decomPositionandO,'(or.OH)dismutaseabilityisaveryactiveresearchfield1'2.Thesemodelsshowverytwrtanteffectinprovidingprotectionfromtissuedamageassociatedwithvariousmpesofinfiammatorydiseases.MetallopoIPhyrinsassuPeroxidedismutase(SOD)mimicshaveshowedtheabilitytocatalysttheseharmfulradicals.Groveandco-workersrePorted[Mn(III)TMPyP]and[Fe(III)TMPyP]whichhaveshowedveryefficientbehaviorasperoxynitritereductaseandcandep…     

Photorechargeable Properties of Metal Hydride-SrTiO3 Electrode

A photosensitive metal hydride electrode was prepared by modification with perovskite-type SrTiO3 photocatalyst. The photorechargeable properties of the prepared electrodes were investigated by using electrochemical cyclic voltammetry and EIS measurements. The results showed that the modified electrode exhibited the obvious photorechargeable properties. The reduction current increased remarkably under the xeon light irradiation compared with the unmodified electrode. During the photocharging process, the potential of the modified electrode shifted quickly to negative direction and a potential plateau of about -0.90V (vs. Hg/HgO) occurred at the end of light irradiation. The corresponding discharge capacity of the electrode was about 5.4 mAh/g.     

Simulations of Metal Cu in Heating Process

Introduction In order to study the short-range order as well as thermodynamic properties, two distinct techniques of computer simulation, namely, the molecular dynamics and Monte Carlo methods, are most frequently em-ployed. In both techniques, the interaction potential is the primary input for computation. Mitra and co-workers1 have used a two-body model with Coulombic interac-tions and a power-law repulsion, fitted to the short- range structure and melting temperature of cristobalite. Thre…     

Modification of Metal Complex on the StereoselectiveHydrogenation of 2,3-Butanedione

Nanoscopic metal clusters, because of their substantial difference from metal atoms and bulk metals in size and structure, have attracted great interest especially in the field of catalysis1. It is well known that additives can markedly affect the properties of metal catalysts. The effect of metal ions has been well studied in the field of heterogeneous catalysis2. However, the study of metal complex effect is scarce. We have reported that the metal complex can considerably modulate both the a…     

Catalytic Oxidation of Cyclohexene by Dendrimer-bond Metal Catalysts

Since Tomalia and Dovornic discussed the promising outlook of surface-functionalized dendrimer catalysts in 1994, [1] dendritic catalysts have been proposed to many kinds of catalysis. These well-defined macromolecular structures enable the construction of precisely controlled catalyst structures. The large number of the peripheral functionalities enhanced their activity in many processes. [2,3]We report herein a new method of using the dendritic catalysts in the oxidation of cyclohexene. The…     

A Convenient Synthetic Method of Metal Dendritic Porphyrins

Metal porphyrins are natural antioxidant reagent1-3. However, due to the characteristics of structures, they are only soluble in inorganic acids and part of polar organic solvents. Thus, it is limited to be used as effective pharmaceutical preparations. T…     

Photobleaching of γ-Glycidoxypropyltrimethoxysilane-Chelated Metal Alkoxide Gel Films

Thick photosensitive inorganic-organic hybrid gel films are fabricated using a silica–PEO(poly(ethylene oxide)) polymeric network and several chelated metal alkoxides: Ti(OEt)₄, Al(OBu^sec)₃, Zr(OPr ⁿ )₄. The -glycidoxypropyltrimethoxysilane (GPTS) and the metal alkoxides stabilized by -ketoester or -diketone are used as precursors. The chelated metal complex in the gel films are photodecomposed and forms the oxide network by UV exposure. The photodecomposition of the chelate ring and the photobleaching of the UV absorption bands are investigated as a function of UV exposure time. The photobleaching rates with respect to chelating agents, metal alkoxides and photon energy are compared.     

Synthesis of Polymer-Bonded Quaternary Ammonium Type Metal Porphyrins

Synthetic metalloporphyrin are efficient models of the cytochrome P-450 family ofmono-oxygen enzymes and have been largely used as catalysts in oxidation of alkanesand epoxidation of alkenesl. Polymer-bonded metalloporphyrin reveal many advantageson the catalytic reaction, where the catalysts can be easily separated from the products,recovered, and reused2. Quaternary ammonium salts as phase transfer catalysts werewide used in aqueous-organic two-phase conditions. Unfortunately, most porphyrin…     

Polymerization of α-Hydroxyacetylenes by Transition Metal Catalysts

Abstract

α-Hydroxyacetylenes (2-propyn-1-ol, DL-3-butyn-2-ol, 1-octyn-3-ol, 2-phenyl-3-butyn-2-ol) with a hydroxy functional group were polymerized by various Mo- and W-based catalysts. In general, the catalytic activities of Mo-based catalysts were greater than those of W-based catalysts for these polymerizations. In the polymerization of 2-propyn-l-ol, MoCl₅ alone and the MoCl₅-EtAlCl₂ catalyst system gave a quantitative yield of polymer. In the polymerization of 2-propyn-l-ol and its homologues by Mo-based catalysts, the polymer yield decreased as the bulkiness of the substituent increased. On the other hand, the polymer yield increased as the bulkiness of the substituent increased in WCl₆-EtAlCl₂-catalyzed polymerization. Polymers with a bulkier substituent showed better solubility in organic solvents than those without a substituent [e.g., poly (2-propyn-l-ol)]. The structures of the resulting polymers were characterized by various instrumental methods such as ¹H- and ¹³C-NMR, IR, and UV-visible spectroscopies. Thermogravimetric analyses and thermal transitions of the resulting polymers were also studied.     

Sulfone–Metal Exchange and Alkylation of Sulfonylnitriles

The first general sulfone–metal exchange is described. Treating substituted 2-pyridylsulfonylacetonitriles with either BuLi or Bu₃MgLi generates metalated nitriles that efficiently intercept a variety of electrophiles to afford quaternary nitriles. The 2-pyridylsulfone is critical for the sulfone–metal exchange because chelation anchors the organometallic proximal to the electrophilic, tetrasubstituted sulfone to override complex-induced deprotonation. Alkylating commercial 2-pyridinesulfonylacetonitrile with mild bases, either K₂CO₃ or DBU, and subsequent sulfone–metal exchange and alkylation rapidly assembles quaternary nitriles by three alkylations, only one of which requires an organometallic reagent.     

Synthesis and Structural Characterization of Alkali Metal Guanidinates

Reactions of 1,3-diisopropylcarbodiimide with alkali metal amides, MN（SiMe3）2 （M=Li or Na） in hexane or THF produced the alkali metal guanidinates { （i-PrN）2C [N（SiMe3）2]Li }2 （1） and { （i-PrN）2C[N（SiMe3）2]Na（THF） } 2 （2） in nearly quantitative yields. Both complexes 1 and 2 were well characterized by elemental analysis, IR spectra, ^1H and ^13C NMR spectra, and X-ray diffraction. It was found that the guanidinates adopt different coordination modes in these complexes.     

Effect of Larger Pore Size on the Sorption Properties of Isoreticular Metal–Organic Frameworks with High Number of Open Metal Sites

Four isostructural CPO-54-M metal-organic frameworks based on the larger organic linker 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid and divalent cations (M=Mn, Mg, Ni, Co) are shown to be isoreticular to the CPO-27 (MOF-74) materials. Desolvated CPO-54-Mn contains a very high concentration of open metal sites, which has a pronounced effect on the gas adsorption of N₂, H₂, CO₂ and CO. Initial isosteric heats of adsorption are significantly higher than for MOFs without open metal sites and are slightly higher than for CPO-27. The plateau of high heat of adsorption decreases earlier in CPO-54-Mn as a function of loading per mole than in CPO-27-Mn. Cluster and periodic density functional theory based calculations of the adsorbate structures and energetics show that the larger adsorption energy at low loadings, when only open metal sites are occupied, is mainly due to larger contribution of dispersive interactions for the materials with the larger, more electron rich bridging ligand.     

Theoretical Investigations of Nonlinear Optical Properties of Transition Metal Cluster Anions

In the framework of density functional theory （DFT）, the electronic excitations and nonlinear optical （NLO） properties of six binuclear transition metal cluster anions with the formula of [Ch2M-（μ-Ch）2-M＇CN]^2- （M = Mo, W; Ch = S, Se; M＇ = Cu, Ag） have been systemically investigated at both cases of gas phase and DMF solution. The obtained electronic absorption spectra reveal that the element replacements of metals M and ligands Ch have significant influence on the absorptions, especially on the low-lying ones. In addition, the transitions of μ-Ch→M are dominant for the low-lying excitations, whereas the transitions of M＇→M as well as Ch→M are mainly responsible for the higher excitations. The calculated molecular first and second hyperpolarizabilities present the remarkable element substitution and solvent effects. The analyses show that the transitions involving μ-Ch→M charge transfer make the critical contributions to the first hyperpolarizability t, and that the charge transfers from the moieties of MCh4 to M＇CN as well as those of μ-Ch→M and M＇→M are responsible for the second hyperpolarizability y. Moreover, the introduction of solvent leads to the results that the transitions within the moieties of MCh4 and M＇CN make larger contributions to the hyperpolarizability, especially to γ.     

Study of Anticancer Properties of Graphene Oxide–Metal Oxide Composite

Graphene and graphene oxide (GO) have garnered significant attention due to their exceptional properties. GO, enriched with various functional groups such as epoxy, hydroxyl, and carboxylic groups, has exhibited remarkable potential in biomedical applications. The combination of GO with metals has proven to be a promising platform for cellular imaging, with this study focusing on the preparation of diverse hybrids of GO with metal oxides (GO/MO) and their potential as anticancer agents. In this research, GO is functionalized with MOs like TiO₂, Fe₃O₄, and Cu₂O using specific chemical methods and investigated for the anticancer activity for the application as cancer therapeutic agent. The resulting GO/MO hybrids exhibits favorable thermal and mechanical properties. Moreover, their cytotoxicity against human lung cancer cells is assessed in vitro, revealing the promising anticancer activity of GO/MO hybrids. Notably, the GO/Cu₂O hybrid demonstrates particularly high cytotoxicity in human lung cancer cells.     

A Study of Metal Ions Packing Hydrated Layer of Inclusion Crystals

The inclusion crystal formed by the hexamethylenamine with p-nitrophenol has a layer type structure,and is divided or-ganic layer and inorganic layer,the latter has a width of 1.0136nm.Metal ions can enter hydrated layer of the crystal,the con-tents of the cations and water in the crystal are determined.The XRD analysis of the layer type structure of the crystal is also giv-en.