Controlled synthesis of organic-inorganic hybrid nanofibers by a wet-chemical route

Organic-inorganic hybrid nanofibers are successfully synthesized by incorporating 3,3 ',5,5 '-tetramethylbenzidine (TMB) and H2PtCl6 at room temperature. The morphology and size can be simply controlled by tuning the molar ratio and initial concentration of reactants. A possible formation mechanism was suggested on the basis of the experimental results. The optical properties were investigated and the as-obtained product displays a strong fluorescence emission at room temperature that may be promising for applications in the fabrication of photoelectric materials. (C) 2008 Elsevier B.V. All rights reserved.

Synthesis and assembly of Au-Pt bimetallic nanoparticles

Au-Pt bimetallic nanoparticles (NPs) were synthesized by reducing the mixture of HAuCl4 and K2PtCl6 with ethanol in the presence of cinnamic acid (C6H5CHCHCO2H, CA) through a thermal process. It was found that the isolated NPs could gradually self-assemble into chain-like structures, ultimately to 3-dimensional network nanostructures by adjusting the molar ratio of CA to K2PtCl6. Energy-dispersive Spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction was used to confirm the formation of Au-Pt bimetallic nanostructures.

One-pot green synthesis of biocompatible arginine-stabilized magnetic nanoparticles

A green one-step approach has been developed for the synthesis of amino-functionalized magnetite nanoparticles. The synthesis was accomplished by simply mixing FeCl2 with arginine under ambient conditions. It was found that the Fe2+/arginine molar ratio, reaction duration and temperature greatly influence the size, morphology and composition of magnetic nanoparticles. The arginine-stabilized magnetic nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy techniques.

Phosphine-Free Synthesis of High-Quality CdSe Nanocrystals in Noncoordination Solvents: "Activating Agent" and "Nucleating Agent" Controlled Nucleation and Growth

CdSe nanocrystals (NCs) are prepared in noncoordination solvents (1-octadecene (ODE) and paraffin liquid) with Ion g-chain primary alkylamine as the sole ligand, ODE-Se, and cadmium fatty acid salt as precursors. The obtained NCs meet the four fundamental parameters for high-quality NCs: high crystallinity, narrow size distribution, moderate photoluminescence quantum yield, and broad range size tunableness. Further, by simply regulating the relative molar ratio of alkylamine to cadmium precursor, the regular sized "nuclei" and final obtained NCs can be produced predictably within a certain size range.

Green synthesis of nanowire-like Pt nanostructures and their catalytic properties

We reported a simple and effective green chemistry route for facile synthesis of nanowire-like Pt nanostructures atone step. In the reaction, dextran acted as a reductive agent as well as a protective agent for the synthesis of Pt nanostructures. Simple mixing of precursor aqueous solutions of dextran and K2PtCl4 at 80 degrees C could result in spontaneous formation of the Pt nanostructures. Optimization of the experiment condition could yield nanowire-like Pt nanostructures at 23:1 molar ratio of the dextran repeat unit to K2PtCl4.

Novel hybrid periodic mesoporous organosilica material grafting with Tb complex: Synthesis, characterization and photoluminescence property

A novel periodic mesoporous organosilica (PMO) material was synthesized through one-step co-condensation of 1,2-bis(triethoxysilyl)ethane (BTESE) and benzoic acid-functionalized organosilane (BA-Si) using cetyltrimethylammonium bromide (CTAB) as a structure-directing agent under basic conditions. The materials were fully characterized by FTIR, XRD, N-2 adsorption-desorption isotherms and FESEM. FTIR spectra proved that BA-Si was successfully incorporated into the PMO materials (PMOs) via benzyl group as a linker. XRD and N-2 adsorption-desorption isotherms revealed the characteristic mesoporous structure with highly uniform pore size distributions. FESEM confirmed that the morphology of the PMOs was significantly dependent cri the molar ratio of two organosilica precursors.

Synthesis of mesoporous LaPO4 nanostructures with controllable morphologies

Lanthanum phosphate (LaPO4) nanostructures with different morphologies were prepared by a facile solution-precipitation process. The effect of different reaction conditions on the morphology of nanostructures was studied. When the molar ratio of La3+:H3PO4 was around 1 : 2, 1 : 20, 1 : 100, and 1 : 200, four different morphologies, such as near-spherical, snowflake-like, star-shaped, lens-like nanostructures and short nanorods, were obtained, respectively. Meanwhile, similar shapes developed when the molar ratio of H3PO4 to ionic surfactants, such as SDS and CTAB, was varied. In addition, Eu3+ doped and Ce3+/Tb3+ co-doped LaPO4 nanostructures showed morphology evolution similar to undoped LaPO4 nanostructures. The optical properties of these doped LaPO4 were also characterized.

beta-NaYF4 and beta-NaYF4:Eu3+ Microstructures: Morphology Control and Tunable Luminescence Properties

beta-NaYF4 hexagonal microprisms and microrods with different aspect ratios have been prepared via a simple hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. The influences of reaction temperature and the molar ratio of NaF to y(3+) on the crystal phases and shapes of final products have been studied in detail. The aspect ratios of products increase gradually with the increase of reaction temperature and NaF/Y3+ molar ratio. The growth mechanisms of crystals prepared under the different conditions are presented systematically. More importantly, the systematical investigation on the luminescence properties of beta-NaYF4:xEu(3+) (x = 0.5, 1, 2, 3, 5, and 10 mol %) with hexagonally microprismatic morphology shows the characteristic emissions of Eu3+ (D-5(J)-F-7(J'), J, J' = 0, 1, 2, 3). Under the excitation of single wavelength light of 397 nm, the luminescence colors of the corresponding products can be tuned feasibly from bluish white to yellow to red by changing the doping concentration of Eu3+.

Reactive compatibilization of LLDPE/PS blends with a new type of Lewis acid as catalyst

The reactive compatibilization of LLDPE/PS (50/50 wt%) was achieved by Friedel-Crafts alkylation reaction with a combined Lewis acids (Me3SiCl and InCl3 center dot 4H(2)O) as catalyst. The graft copolymer at the interface was characterized by Fourier transform infrared spectroscopy and the morphology of the blends was analysized by scanning electron microscopy. It was found that the combined Lewis acids had catalytic effect on Friedel-Crafts alkylation reaction between LLDPE and PS, and the catalytic effect was maximal when the molar ratio of InCl3 center dot 4H(2)O to Me3SiCl was 1:5. The graft copolymer LLDPE-g-PS was formed via the F-C reaction and worked as a tailor-made compatibilizer to reduce the interfacial tension. The mechanical properties of reactive blend with combined Lewis acids as catalyst was notably improved compared to that of physical LLDPE/PS blend and serious degradation had been decreased compared to the reactive blend system with AlCl3 as catalyst; we interpreted the above results in term of acidity of combined Lewis acids.

Enhanced luminescence of BPO4 by mixing with SiO2 and Al2O3

In this paper, BPO4-xSiO(2) (X: SiO2/BPO4 molar ratio, 0-70%) and BPO4-xAl(2)O(3) (X: Al2O3/BPO4 molar ratio, 0-20%) powder samples were prepared by the Pechini-type sol-gel (PSG) process using glycerol and poly(ethylene glycol) as additives. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), diffuse reflection spectra, photoluminescence (PL) excitation and emission spectra, kinetic decay, and X-ray photoelectron spectra (XPS), respectively. It was found that the Pechini-type sol-gel-derived BPO4-xSiO(2) annealed at 1000 degrees C and BPO4-xAl(2)O(3) annealed at 960 degrees C exhibited bright bluish-white emissions centered at 428 and 413 nm, respectively. The luminescence decay curve analysis indicates that each sample has two kinds of lifetimes (more than 0.4 ms and less than 10 ns) and two types of kinetic decay behaviors, which can be fitted into a double-exponential function and a single-exponential function, respectively.

Synthesis and Stabilization of Novel Aliphatic Polycarbonate from Renewable Resource

A novel aliphatic polycarbonate from renewable resource was prepared by copolymerization of furfuryl glycidyl ether and CO2 using rare earth ternary catalyst; its number-average molecular weight (M-n) reached 13.3 x 10(4) g/mol. The furfuryl glycidyl ether and CO2 copolymer (PFGEC) was easy to become yellowish at ambient atmosphere due to post polymerization cross-linking reaction oil the furan ring; the gel content was 17.2 wt % after 24 h exposure to air at room temperature. PFGEC could be stabilized by addition of antioxidant 1010 (tetrakis[methylene (3.5-di(tert-butyl)-4-hydroxhydrocinnamate)]methane) in 0.5-3 wt % after copolymerization. The Diels-Alder (DA) reaction between N-phenylmaleimide and the pendant furan ring was also effective for the stabilization of PFGEC by reducing the amount of furan ring and introducing bulky groups into PFGEC. The cyclization degree could reach 72.1% when the molar ratio of N-phenylmaleimide to furan ring was 3: 1, and no gel was observed after 24 h exposure to air. The glass transition temperature (T-g) of PFGEC was 6.8 degrees C, and it increased to 40.3 degrees C after DA reaction (molar ratio of N-phenylmaleimide to furan ring was 3: 1).

A Novel Strategy to Branched Polyacrylonitrile Via One-Pot RAFT Copolymerization of Acrylonitrile and an Asymmetrical Divinyl Monomer

Branched polyacrylonitriles were prepared via the one-pot radical copolymerization of acrylonitirle and an asymmetric divinyl monomer (allyl methacrylate) that possesses both a higher reactive methacrylate and a lower reactive allyl. RAFT technique was used to keep a low-propagation chain concentration via a fast reversible chain transfer euilibration and thus the cross-linking was prevented until a high level of monomer conversions. This novel strategy was demonstrated to engenerate a branched architecture with abundant pendant functional vinyl and nitrile groups, and controlled molecular weight as a behavior of controlled/living radical polymerization characteristics. The effect of the various experimental parameters, including temperature, brancher to monomer molar ratio, and chain transfer agent to initiator molar ratio, on the control Of moleculer dimension (molecular weight and polydispersity indices) and the degree of branching were investigated in detail. Moreover, H-1 NMR and gel permeation chromatography confirm the branched architecture of the resultant polymer. The intrinsic viscosity of the copolymer is also lower than the linear counterpart.

Facile Hydrothermal Synthesis and Luminescent Properties of Large-Scale GdVO4:Eu3+ Nanowires

Large-scale GdVO4:Eu3+ nanowires with diameters of about 15 nm and lengths of several micrometers were achieved by a facile hydrothermal method in the presence of disodium ethylenediamine tetraacetate (Na2H2L). The influences of several parameters, such as pH value, reaction temperature, and molar ratio of Na2H2L to Gd3+ on the final products were investigated. The formation mechanism of the as-obtained GdVO4:Eu3+ nanowires is proposed on the basis of time-dependent experiments. It is found that the organic additive Na2H2L, which acts as a shape modifier, has a dynamic effect by adjusting the growth rates of different facets, resulting in the formation of the GdVO4:Eu3+ nanowires. The luminescent spectrum of GdVO4:Eu3+ nanowires shows the strong characteristic dominant emission of the Eu3+ ions at 614 nm.

Facile shape-controlled synthesis of luminescent europium benzene-1,3,5-tricarboxylate architectures at room temperature

The large-scale synthesis of the metal-organic framework Eu(1,3,5-BTC)center dot 6H(2)O nanocrystallites with delicate morphologies such as sheaflike, butterflylike, and flowerlike superstructures composed of nanowires have been realized via a simple solution phase method at room temperature. Time-dependent experiments indicate that these superstructures were constructed by the splitting crystal growth mechanism, as has been noted in some minerals in nature. The synthetic parameters such as reaction time, concentration and molar ratio of reactants, surfactant, and reaction temperature all affected the morphology of the Eu(1,3,5-BTC)center dot 6H(2)O architectures. These well-arranged architectures exhibit red emission corresponding to the D-5(0) -> F-7(2) transition of the Eu3+ ions under UV light excitation, and the lifetime is determined to be about 0.22 ms.

Formation of [Ru(bpy)(3)](2+)-containing microstructures induced by electrostatic assembly and their application in solid-state detection of electrochemiluminescence

Tris(2,2'-bipyridine)ruthenium(II) ((Ru(bpy)(3)](2+)) is one of the most extensively studied and used electrochemiluminescent (ECL) compounds owing to its superior properties, which include high sensitivity and stability under moderate conditions in aqueous solution. In this paper we present a simple method for the preparation of [Ru(bpy)(3)](2+)-containing microstructures based on electrostatic assembly The formation of such micro-structures occurs in a single process by direct mixing of aqueous solutions of [Ru(bpy)(3)]Cl-2 and K-3[Fe(CN)(6)] at room temperature. The electrostatic interactions between [Ru(bpy)(3)]Cl-2 cations and [Fe(CN)(6)](3-) anions cause them to assemble into the resulting microstructures. Both the molar ratio and concentration of reactants were found to have strong influences on the formation of these microstructures. Most importantly, the resulting [Ru(bpy)(3)](2+)- containing microstructures exhibit excellent ECL behavior and, therefore, hold great promise for solid-state ECL detection in capillary electrophoresis (CE) or CE microchips.