Synthesis and characterization of 3d-transition metals doped ZnO thin films and nanostructures for possible spintronic applications

The objective of the present study is the formation of single phase Zn1−xTMxO thin films by PLD and increase the solubility limit of TM dopants. The TM doped ZnO nanostructures were also grown by hydrothermal method. The structural and morphological variation of ZnO:TM thin films and nanostructures with TM doping concentration is also investigated. The origin and enhancement of ferromagnetism in single phase Zn1−xTMxO thin films and nanostructures using spectroscopic techniques were also studied. The dependence of ablation parameters on the structural and optical properties of ZnO thin films were studied

Synthesis and Characterization of Novel Spiro-Starburst-Structures as Blue Light Emitters and Zeolites

Spiro-starburst-structures with symmetric globular structures in forms of first and second generations that readily form stable amorphous glasses have been synthesized and then characterised in this work. During the synthesis of these materials, possibilities of the extension of the chains of the phenyl rings in 2,2’,7 and 7’-positions of the central core of the spirobifluorene as well as the 2’,7 and 7’-positions of the terminal spirobifluorene units of the spiro-starburst-structures have been investigated so that solubilities and morphologies of the compounds are not negatively influenced. Their morphological properties have been explored by recording their decomposition temperature and glass transition temperature. These compounds possessing two perpendicular arrangement of the two molecular halves show high glass transition temperature (Tg), which is one of the most important parameter indicating the stability of the amorphous state of the material for optoelectronic devices like organic light emitting diodes. Within the species of second generation compounds, for example, 4-spiro3 shows the highest Tg (330 °C) and the highest branching degree. When one [4B(SBF)SBF-SBF 84] or two [4SBFSBF-SBF 79] terminal spirobifluorene units are removed, the Tg decreases to 318 °C and 307 °C respectively. Photo absorption and fluorescence spectra and cyclic voltammetry measurements are taken in account to characterize the optoelectronic properties of the compounds. Spiro-starburst-structures emit radiation in the blue region of the visible spectrum. The peak maxima of absorption and emission spectra are observed to be at higher wavelength in the molecules with longer chromophore chains than in the molecules with shorter chromophore chains. Excitation spectra are monitored with their emission peak maxima. The increasing absorbing species in molecule leads to increasing molar extinction coefficient. In the case of 4B(TP)SBF-SBF 53 and 4B(SBF)SBF-SBF 84, the greater values of the molar extinction coefficients (43*104 and 44*104 L mol-1 cm-1 respectively) are the evidences of the presence of four times octiphenyl conjugation rings and eight times terminal fluorene units respectively. The optical properties of solid states of these compounds in the form of thin film indicate that the intermolecular interaction and aggregation of individual molecules in neat amorphous films are effectively hindered by their sterically demanding structures. Accordingly, in solid state, they behave like isolated molecules in highly dilute solution. Cyclic voltammetry measurements of these compounds show electrochemically reversibility and stability. Furthermore, the zeolitic nature (host-guest) of the molecular sieve of the synthesized spiro-starburst-structures has been analysed by thermogravimetric analysis method.

Synthesis and Characterization of Magnetic Nanoparticles with High Magnetization and Good Oxidation Resistibility

Magnetic nanoparticles attract increasing attention because of their current and potential biomedical applications, such as, magnetically targeted and controlled drug delivery, magnetic hyperthermia and magnetic extraction. Increased magnetization can lead to improved performance in targeting and retention in drug delivery and a higher efficiency in biomaterials extraction. We reported an approach to synthesize iron contained magnetic nanoparticles with high magnetization and good oxidation resistibility by pyrolysis of iron pentacarbonyl (Fe(CO)[subscript 5]) in methane (CH[subscript 4]). Using the high reactivity of Fe nanoparticles, decomposition of CH[subscript 4] on the Fe nanoparticles leads to the formation of nanocrystalline iron carbides at a temperature below 260°C. Structural investigation indicated that the as-synthesized nanoparticles contained crystalline bcc Fe, iron carbides and spinel iron oxide. The Mössbauer and DSC results testified that the as-synthesized nanoparticle contained three crystalline iron carbide phases, which converted to Fe[subscript 3]C after a heat treatment. Surface analysis suggested that the as-synthesized and subsequently heated iron-iron carbide particles were coated by iron oxide, which originated from oxidization of surface Fe atoms. The heat-treated nanoparticles exhibited a magnetization of 160 emu/g, which is two times of that of currently used spinel iron oxide nanoparticles. After heating in an acidic solution with a pH value of 5 at 60°C for 20 h, the nanoparticles retained 90 percentage of the magnetization.

Synthesis and characterization of thermally stable second-order nonlinear optical side-chain polyimides containing thiazole and benzothiazole push-pull chromophores

Push-pull nonlinear optical (NLO) chromophores containing thiazole and benzothiazole acceptors were synthesized and characterized. Using these chromophores a series of second-order NLO polyimides were Successfully prepared from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA) and 3,3'4,4'-benzophenone tetracarboxylic dianhydride (BTDA) by a standard condensation polymerization technique. These polyimides exhibit high glass transition temperatures ranging from 160 to 188 degrees C. UV-vis spectrum of polyimide exhibited a slight blue shift and decreases in absorption due to birefringence. From the order parameters, it was found that chromophores were aligned effectively. Using in situ poling and temperature ramping technique, the optical temperatures for corona poling were obtained. It was found that the optimal temperatures of polyimides approach their glass transition temperatures. These polyimides demonstrate relatively large d(33) values range between 35.15 and 45.20 pm/V at 532 nm. (C) 2008 Elsevier B.V. All rights reserved.

Synthesis and characterization of fluorescent poly(aromatic amide) dendrimers

The synthesis of a series of poly(aromatic amide) dendrimers up to the second generation is described herein. The AB, building block used throughout the synthesis of the dendrimers was the allyl ester of 3,5-diaminocinnamic acid, which has been synthesized from 3,5-dinitrobenzoic acid in good yield with use of a four-step procedure. Dendron synthesis was achieved via a convergent approach with use of a sequence of deprotection/coupling steps. Two commercially available alcohols, L-menthol and citronellol, were coupled to the AB(2) monomer by using an alkyl diacid spacer and two core units; 1,7-diaminoheptane and tris(2-aminoethyl)amine have been used to produce the final dendrimers. Characterization was carried out by NMR and IR spectroscopies, MALDI-TOF mass spectrometry, GPC, and DSC. The novel monomer and dendritic derivatives exhibited a strong fluorescence emission in the visible region (lambda approximate to 500 nm) of the spectrum and a weak emission in the near-infrared (lambda approximate to 850 nm) upon excitation in the near-UV region. The fluorescence emission characteristics were found to be solvent and dendrimer generation dependent.

Synthesis and characterization of biocompatible, thermoresponsive ABC and ABA triblock copolymer gelators

The synthesis of doubly thermoresponsive PPO-PMPC-PNIPAM triblock copolymer gelators by atom transfer radical polymerization using a PPO-based macroinitiator is described. Provided that the PPO block is sufficiently long, dynamic light scattering and differential scanning calorimetry studies confirm the presence of two separate thermal transitions corresponding to micellization and gelation, as expected. However, these ABC-type triblock copolymers proved to be rather inefficient gelators: free-standing gels at 37 degrees C required a triblock copolymer concentration of around 20 wt%. This gelator performance should be compared with copolymer concentrations of 6-7 wt% required for the PNIPAM-PMPC-PNIPAM triblock copolymers reported previously. Clearly, the separation of micellar self-assembly from gel network formation does not lead to enhanced gelator efficiencies, at least for this particular system. Nevertheless, there are some features of interest in the present study. In particular, close inspection of the viscosity vs temperature plot obtained for a PPO43-PMPC160-PNIPAM(81) triblock copolymer revealed a local minimum in viscosity. This is consistent with intramicelle collapse of the outer PNIPAM blocks prior to the development of the intermicelle hydrophobic interactions that are a prerequisite for macroscopic gelation.

One-pot synthesis and characterization of soluble poly(aryl ether-ketone)s having pendant carboxyl groups

Aromatic poly(ether-ketone)s having pendant carboxyl groups have been obtained by direct, one-pot, Friedel-Crafts copolycondensation of 4,4'-diphenoxybenzophenone with a mixture of terephthaloyl chloride (TC) and trimellitic anhydride acid chloride (TAAC), over a wide range of TAAC/TC molar ratios, in the presence of anhydrous aluminum chloride. The syntheses were performed as precipitation-polycondensations, and the polymers were obtained in particulate form. Besides globular particles of polymer, small quantities of elongated, needlelike particles were observed when the mole ratio TAAC/TC was less than 1. Use of X-ray microdiffraction with synchrotron radiation has revealed that the needlelike material consists of a cyclic compound containing 10 phenylene units, i.e., the crystals are of a [2 + 2] macrocyclic dimer. The polymers obtained are soluble in strong acids and in mixtures of methanesulfonic acid or trifluoroacetic acid with chlorinated hydrocarbons. The molecular structures of the polymers were confirmed by H-1 and C-13 NMR spectroscopy. Reaction of TAAC with 4,4'-diphenoxybenzophenone produced mainly meta-orientation of the resulting ketone linkages. The size of the polymer particles, their molecular weights, and the melting behavior of the products obtained depend on the TAAC/TC ratio used. Ortho-keto acid residues, formed during reaction of anhydride groups of TAAC with 4,4'-diphenoxybenzophenone, exhibit ring-chain tautomerism. A carboxyl-containing aromatic polyketone derived from p-terphenyl, and thus having with no ether linkages in the main chain, was prepared by analogous chemistry, and functional derivatives of carboxy-substituted polyketones were also obtained and characterized.

Synthesis and characterization of Cu(II) complexes of tetradentate and tridentate symmetrical Schiff base ligands involving o-phenelenediamine, salicylaldehyde and diacetylmonoxime

A mononuclear complex [CuL] (1), a binuclear complex [Cu2LCl2(H2O)] (2), a trinuclear complex [Cu3L2](ClO4)(2) (3) involving o-phenylenediamine and salicylaldehyde and another binuclear complex of a tridentate ligand (H2L1) [Cu2L (2) (1) ](CH3COO)(2) (4) involving o-phenylenediamine and diacetylmonoxime have been synthesized, where H2L = N,N'-o-phenylenebis(salicylideneimine) and H2L1 = 3-(2-aminophenylimino)butan-2-one oxime. All the complexes have been characterized by elemental analyses, spectral and magnetic studies. The binuclear complex (2) was characterized structurally where the two Cu(II) centers are connected via an oxygen-bridged arrangement.

Synthesis and characterization of nickel(II) and copper(II) complexes with tetradentate Schiff base ligands

The 1:1 condensation of 1,2-diaminopropane and 1-phenylbutane-1,3-dione at high dilution gives a mixture of two positional isomers of terdentate mono-condensed Schiff bases 6-amino-3-methyl-1-phenyl-4-aza-2-hepten-1-one (HAMPAH) and 6-amino-3,5-dimethyl-1-phenyl-4-aza-2-hexen-1-one (HADPAH). The mixture of the terdentate ligands has been used for further condensation with pyridine-2-carboxaldehyde or 2-acetylpyridine to obtain the unsymmetrical tetradentate Schiff base ligands. The tetradentate Schiff bases are then allowed to react with the methanol solution of copper(II) and nickel(II) perchlorate separately. The X-ray diffraction confirms the structures of two of the complexes and shows that the condensation site of the diamine with 1-phenylbutane-1,3-dione is the same.

Synthesis and characterization of inorganic-organic hybrid gallium selenides

Two semiconducting hybrid gallium selenides, [Ga6Se9(C6H14N2)4][H2O] (1) and [C6H14N2][Ga4Se6(C6H14N2)2] (2), were prepared using a solvothermal method in the pres-ence of 1,2-diaminocyclohexane (1,2-DACH). Both materials consist of neutral inorganic layers, in which 1,2-DACH is co-valently bonded to gallium. In (1), the organic amine acts as a monodentate and a bidentate ligand, while in (2) bidentate and uncoordinated 1,2-DACH molecules coexist.

Synthesis and characterization of NiMn(2)O(4) nanoparticles using gelatin as organic precursor

Nanoparticles of NiMn(2)O(4) were successfully obtained by mixing gelatin and inorganic salts NiCl(2) center dot 6H(2)O and MnCl(2) center dot 4H(2)O in aqueous solution. The mixture has been synthesized at different temperatures and resulted in NiMn(2)O(4) nanoparticles with crystallites size in the range of 14-44 nm, as inferred from X-ray powder diffraction (XRPD) data. We have also observed that both the average crystallite size and the unit cell parameters increase with increasing synthesis temperature. Magnetic measurements confirmed the presence of a magnetic transition near 110K. (C) 2008 Published by Elsevier B.V.

Synthesis and characterization of glass-ceramic microspheres for thermotherapy

Glass microspheres containing radionuclides are used to treat liver cancer. A promising alternative therapy is being developed based on the magnetic hyperthermia which is related to the heat supplied by a magnetic material under an alternating current magnetic field. The advantage of this option is that most of killed cells are cancer cells which are more susceptible to the temperature raise. In the present work aluminum iron silicate glasses containing minor glass modifiers and nucleating agents were synthesized as irregular shape particles which were further transformed in microspheres by using a petrol liquefied gas-oxygen torch. The optimized processing parameters which lead to microspheres that give a response to the magnetic field were determined. The dissolution rate in water at 90 degrees C was determined to be 3 x 10(-8) g cm(-2) min(-1). The microsphere size distribution was determined by laser scattering. The crystalline phase responsible for the ferromagnetic response was identified as magnetite. Since this phase has a high saturation magnetization and high Curie temperature, it is potentially useful for biomedical applications. The hysteresis magnetic loop was measured for materials produced in different conditions, and some of them showed to be appropriated for thermotherapy. The ratio Fe(3+)/Fe(total) was determined by Mossbauer spectroscopy. (C) 2010 Elsevier B.V. All rights reserved.

Synthesis and characterization of phosphate glass microspheres for radiotherapy applications

Class microspheres containing the radioisotope (32)P, a beta(-) particle emitter, and half-life of 14.3 days, can be easily introduced in specific human organs such as liver, pancreas. and uterus to kill cancer cells. In the present work phosphate glass microspheres were produced with different compositions and particle size distribution in the range of 20- 30 mu m. Two different thermal processes were used to spherodize glass particles originally with irregular shapes. Samples were characterized by X-rays diffraction to check the amorphous structure, energy dispersive X-rays fluorescence spectroscopy to determine the final glass composition, and Fourier transformed infrared spectroscopy to determine the structural groups in the glass structure. The dissolution rate of glass samples in water was determined at 90 degrees C, and in simulated body fluid (SBF) at 37 degrees C. Classes with dissolution rates close to 10(-5) g/(cm(2) day) were obtained, which make them suitable for the present application. Scanning electron microscopy was used to evaluate the shape of the microspheres before and after the dissolution tests. The cytotoxicity tests showed that these microspheres can be used for biological applications. (C) 2008 Elsevier B.V. All rights reserved.

Oxide surface modification: Synthesis and characterization of zirconia-coated alumina

Four aluminas were used as Supports for impregnation with a zirconium oxide with the aim to achieve a coating, without phase separation, between Support and modifier. The Supports were impregnated with different concentrations Of zirconium aqueous resin, obtained through the polymeric precursor method. After impregnation the samples were calcined and then characterized by XRD, which led to identification of crystalline zirconia in different concentrations from each support used. Using a simple geometric model the maximum amount Of Surface modifier Oxide required for the complete coating of a support with a layer of unit cells was estimated. According to this estimate, only the support should be identified below the limit proposed and crystalline zirconium oxide Should be identified above this limit when a complete coating is reached. The results obtained From XRD agree with the estimated values and to confirm the coating, the samples were also characterized by EDS/STEM, HRTEM, XPS, and XAS. The results showed that the zirconium oxide oil the Surface of alumina Support reached the coating in the limit of 15 Zr nm(-2), without the formation of the ZrO(2) phase. (c) 2009 Elsevier Inc. All rights reserved.

Synthesis and characterization of a new copper(II) complex with nadolol, an aminoalcoholic beta-blocker. Crystal structure of Na[Cu(nadololate)(CO(3))] center dot H(2)O

This work reports the synthesis and characterization of a new copper complex with nadolol, a beta-blocker aminoalcohol. The stoichiometry found was Na[Cu(nadololate)(CO(3))] center dot H(2)O. Electronic and vibrational spectroscopy analysis was performed, and the crystal structure of Na[Cu(nadololate)-(CO(3))] center dot H(2)O was determined by X-ray diffraction.