Chemical Solution Synthesis Research Articles

Influence of Surfactant Micelles on Morphology and Photoluminescence of Zinc Oxide Nanorods Prepared by One-Step Chemical Synthesis in Aqueous Solution

Single-crystalline ZnO nanorods with different morphologies of radial-shaped needles and single needle were prepared by one-step chemical synthesis in aqueous solutions with and without the surfactant sodium dodecyl sulfate (SDS). The ZnO nanorods prepared in the SDS solution have narrower average width, smaller aspect ratio, and wider optical band gap of about 3.36 eV compared with those prepared in water. In both cases, ZnO nanorods exhibit visible photoluminescence by various lattice defects. These results indicate that a confinement of growing ZnO crystals by spherical micelles leads to more uniform growth, and thus the ZnO nanorods in the SDS solution have narrower average width and more uniform morphology than those in water. It is suggested that a band gap narrowing does not occur for ZnO nanorods in SDS solution because dodecyl sulfate ions effectively passivate lattice defects of neutral oxygen vacancies which produce shallow donor levels.

Enhanced Dielectric and Crystalline Properties in Ferroelectric Barium Titanate Thin Films

AbstractA chemical solution synthesis technique incorporating barium titanate and a high‐temperature liquid phase is developed. In a temperature range conventional to thin‐film growth, the presence of the liquid phase dramatically enhances grain growth, densification, and overall crystalline quality. By controlling the liquid‐phase stoichiometry and molar fraction, thin films with grain sizes greater than 10 μm that pronounce X‐ray peak splitting, low loss, and permittivity values in excess of 3000 at room temperature can be produced. These properties are comparable, and in some cases superior, to those observed in well‐prepared bulk barium titanate. As such, the historical difficulty in reproducing bulklike properties in polycrystalline barium titanate is overcome. These results have broad implications for the expanded use of ferroelectric thin films by demonstrating bulk properties in thin layers and by providing a means of achieving these properties with low thermal budgets.

Assessment of Chemical Solution Synthesis and Properties of Gd2Zr2O7 Thin Films as Buffer Layers for Second-Generation High-Temperature Superconductor Wires

Chemical solution processing of Gd2Zr2O7 (GZO) thin films via sol-gel and metalorganic decomposition (MOD) precursor routes have been studied on textured Ni-based tape substrates. Even though films processed by both techniques showed similar property characteristics, the MOD-derived samples developed a high degree of texture alignment at significantly lower temperatures. Both precursor chemistries resulted in exceptionally dense, pore-free, and smooth microstructures, reflected in the cross-sectional and plan-view high-resolution scanning and transmission electron microscopy studies. On the MOD GZO buffered Ni–3at.% W (Ni–W) substrates with additional CeO2/YSZ sputtered over layers, a 0.8-μm-thick YBa2Cu3O7−δ (YBCO) film, grown by an ex situ metalorganic trifluoroacetate precursor method, yielded critical current, Ic (77 K, self-field), of 100 A/cm width. Furthermore, using pulsed-laser deposited YBCO films, a zero-field superconducting critical current density, Jc (77 K), of 1 × 106 A/cm2 was demonstrated on an all-solution, simplified CeO2(MOD)/GZO(MOD)/Ni–W architecture. The present study establishes GZO buffers as a candidate material for low-cost, all-solution coated conductor fabrication.

Synthesis and properties of nickel–cobalt–boron nanoparticles

Amorphous cobalt nickel boride nanoparticles were synthesised by chemical reduction synthesis in aqueous solution. Careful control of synthesis conditions and post reaction oxidation enabled the nanoparticles to be converted into a core-shell structure comprising of an amorphous Co–Ni–B core and an outer metal oxide sheet. These particles had interesting magnetic properties including saturation magnetisations and coercivities of the order of 80 emu/g and 170 Oe respectively, making them suitable for a potential use as an exchange-pinned magnetic material.

The chemical synthesis in solution and characterization of transition metal dichalcogenideMX2 (M = Mo,W; X = S, Se) nanoparticles

MX2 nanoparticles,with M = Mo,W and X = S or Se, were synthesized via a chemical reaction between molybdenum carbonyl (ortungsten carbonyl) and chalcogen dissolved in para-xylene solution. X-ray diffractionand high-resolution transmission electron microscopy analysis showed that theMoS2,WS2,MoSe2 and WSe2 powders were constituted of rounded amorphous nanoparticles. Upon annealing at550 °C the nanoparticles crystallized, losing their round shape. The four materialssynthesized under similar conditions showed that the annealed selenide nanoparticles(MoSe2 and WSe2) are well crystallized, with aligned stacks of 5–10 layers (002 vander Waals (vdW) planes), while the annealed sulfide nanoparticles(MoS2 and WS2) exhibit curved and tangled 002 planes, randomly distributed in the particle.

Modern Methods for the Synthesis of Peptide—Oligonucleotide Conjugates

AbstractFor Abstract see ChemInform Abstract in Full Text.

Pharmacological Activity of Complexes of Nonsteroidal Antiinflammatory Drugs with Glycyrrhizic Acid Obtained by Liquid- and Solid-State Synthesis

The use of solid-state technologies in the pharmaceutical industry significantly increases the possibilities of creating both original drugs and new forms of the preparations. At the Institute of Solid State Chemistry and Mechanochemistry, a new technology for obtaining dispersed solid systems of pharmacologically active compounds based on impact-wear processing of a powder mixture of the initial substances in special mills [1] was developed. Recently, this technology was used to develop a new rapidly soluble form of aspirin [2]. We have studied the possibility of using the new method for obtaining dispersed solid preparations of nonsteroidal antiinflammatory drugs (NSAIDs) with -glycyrrhizic acid (GA). GA is a biologically active triterpene glycoside extracted from roots of licorice (Glycyrrhiza sp.), known to exhibit high antiinflammatory activity without the complications typical of NSAIDs [3 – 5]. Previously, it was established that molecular complexes of GA with acetylsalicylic acid (ASA), orthophen (ORT), and butadione exhibit a lower toxicity and a less pronounced ulcerogenic effect than the same drugs without GA [6, 7]. The purpose of this study was to determine the average lethal doses (LD50), evaluate the ulcerogenic action, and assess the antiinflammatory effect of GA – ASA and GA – ORT complexes obtained by solid-state synthesis and compare these properties to those of the analogous compounds synthesized by conventional chemical synthesis in solution. EXPERIMENTAL CHEMICAL PART

A novel chemical solution technique for the preparation of nano size titanium powders from titanium dioxide

Abstract Nano size titanium powder was prepared by a novel chemical solution synthesis route from titanium dioxide (TiO 2). TiO 2 was allowed to form a complex, titanium catecholate precursor, in the presence of ammonium sulfate and concentrated sulfuric acid. The complex was filtered, washed with cold isopropyl alcohol and dried. Titanium hydride was prepared by heating the titanium catecholate precursor at 800°C in a hydrogen atmosphere. The product was then dehydrogenated in 8 × 10 −6 torr vacuum to get nano size titanium powders. The powder characteristics have been studied by X-ray diffraction, ICP, laser particle size analysis, and scanning and transmission electron microscopy. The latter indicated that the powders were 21.6 nm in size and selected area diffraction showed the powders to be crystalline.

Magnetic properties of metal–quinone high-spin complexes prepared by solid-state mechano-activation and by chemical synthesis in solution. Comparative study with very high-field and low-temperature EPR and ENDOR

EPR spectroscopy at high frequencies and low temperatures and ENDOR spectroscopy at X- and W-bands have been applied to investigate two- and three-spin complexes of the type MQ2˙ and MQ3˙ generated by mechanochemical treatment (by grinding or by the action of elastic waves) of solid mixtures of quinones and metals (M = Al, Ga, In, Cd, Sn, Zn). In addition, complexes obtained in liquid-phase reactions of metal amalgams with quinones were investigated. The magnetic-resonance parameters and the observed thermal spin polarization provide evidence for the identity of the magnetic complexes produced in solutions and by solid-state mechanochemical treatment. In particular, the presence of ground-state triplet and quartet species has been demonstrated in both cases. In addition, the exchange and the dipole–dipole interaction parameters were evaluated, their comparison providing information about the electronic intramolecular interaction.

The Photochemical Activation of Carbon Dioxide Using a Nickel Complex

The radical anion CO is formed by photochemical reduction of CO2 mediated by the redox-active Ni3 cluster 1, as shown recently by Kubiak et al. The CO radical ion can be trapped with cyclohexene to yield cyclohexanedicarboxylic acid with the formation of two new CC bonds. This reaction is an important step towards the use of CO2 as a building block for chemical synthesis in solution.

ChemInform Abstract: SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL PROPERTIES OF FIVE ENKEPHALIN‐LIKE PENTAPEPTIDES CONTAINING P‐NITROPHENYLALANINE

AbstractDie Synthese der Titelverbindungen (V) wird nach konventionellen Methoden in Lösung durchgeführt.

Synthesis, Characterization, and Biological Properties of Five Enkephalin‐like Pentapeptides Containingp‐Nitrophenylalanine

AbstractFive pentapeptides with the amino acid sequenceL‐tyrosyl‐D‐alanyl‐glycyl‐L‐p‐nitrophenylalanyl‐X, wherein X =L‐leucine,L‐leucine amide,L‐methionine amide,L‐1‐adamantylalanine amide, andL‐neopentylglycine amide were prepared by chemical synthesis in solution and characterized chemically and physically. The effect of the incorporation of the unnatural amino acids adamantylalanine and neopentylglycine, ‘fat’‐analogues of leucine and methionine, on the inhibition of electrically evoked contractions of the myenteric plexus‐longitudinal muscle preparation from guinea pig ileum was studied. Their activities relative to the peptides with X = Leu · OH, Leu‐NH2, and Met‐NH2(X = Neo‐NH2is particularly potent) are discussed in terms of hydrophobic and steric factors, and resistance towards enzymic degradation.