Palladium-catalyzed amination of quinaldine-5-triflate

Palladium-catalyzed amination reactions of quinoline triflate and the effect of a Pd catalyst, its ligands, solvents, bases, and temperature were studied. This method facilitated an easier pathway for the preparation of aminoquinoline derivatives as potential precursors of new serotoninerg agents.      

Aminophosphine complex as a catalyst precursor in Suzuki coupling reactions

A palladium complex with an aminophosphine ligand has been prepared and investigated as a catalyst precursor in Suzuki coupling reactions in toluene. Nanoparticles composed of elemental palladium have been isolated from the reaction media and analyzed using transmission electroscopic microscope (TEM), which shows the essential catalysts palladium nanoparticles to have a size of ca. 3.0 nm. dedicate to the 60th birthday of Prof. Dr. Yuan Kou     

Low temperature synthesis and characterization of Mn3O4 nanoparticles

Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn₃O₄ nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn²⁺signal with a highly resolved hyperfine structure.      

Synthesis, characterization and spectroscopic properties of some new phenylazo-6-aminouracil

In this study, a series of new 5-phenylazo-6-aminouracil dyes were prepared by linking m-,p-nitroaniline, m-,p-chloroaniline, m-,p-anisidine, m-,p-toluidine, m-,p-cyanoaniline, p-ethoxyaniline, p-phenoxyaniline, p-ethylaniline, p-acetamidoaniline, p-acetylaniline, p-carboxyaniline and aniline to 6-aminouracil. The prepared dyes were characterized by UV-vis, FT-IR, ¹H NMR spectroscopic techniques and elemental analysis. The effect of acid and base upon the UV-vis spectra of these dyes were investigated. In addition, the solvatochromic behaviors and substituent effects in various solvents were evaluated.      

Alkylation of ambident indole anion in ionic liquids

Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent of the presence of small amounts of protic solvents or water.      

Sub-millivolt amplitude potential oscillations observed in the noise of hydrogen evolution on Ag and Cu microelectrodes

A strange effect was observed while using the method of quasi-simultaneous determination of electrochemical voltage noise and impedance to obtain information on the kinetics of the hydrogen evolution reaction on Ag and Cu microelectrodes. Beyond a certain polarizing current density we found microvolt-amplitude potential oscillations on both electrodes with a frequency in the 5 Hz–5 kHz range. The oscillations were observed in every single experiment with Ag and Cu, while no oscillatory behavior was observed during the control experiments with the Pt microelectrode. The presence of the oscillations indicates that the mechanism of hydrogen evolution is more complex compared to the original assumption.      

Influence of metal and ligand types on stacking interactions of phenyl rings with square-planar transition metal complexes

In order to find out whether metal type influences the stacking interactions of phenyl rings in square-planar complexes, geometrical parameters for Cu, Ni, Pd and Pt complexes, with and without chelate rings, were analyzed and compared. By searching the Cambridge Structural Database, 220 structures with Cu complexes, 211 with Ni complexes, 285 with Pd complexes, and 220 with Pt complexes were found. The results show that the chelate ring has a tendency to make the stacking interaction with the phenyl ring independent of metal type in the chelate ring. However, there are some differences among metals for complexes without a chelate ring. There are a number of structures containing Pd and Pt complexes, without chelate rings, that have short carbon-metal distances and parallel orientations of the phenyl ring with respect to the coordination plane. It was found that some of these complexes have a common fragment, CN, as a part of the ligands. This indicates that the CN supports stacking interactions of square planar complexes with the phenyl ring.      

Separation of Ga(III) from Cu(II), Ni(II) and Zn(II) in aqueous solution using synthetic polymeric resins

Poly (acrylamide-acrylic acid-dimethylaminoethylmethacrylate), p(AM-AA-DMAEM) and Poly(acrylamide-acrylic acid)-ethylenediaminetetracetic acid disodium, p(AM-AA)-EDTANa₂ were prepared by gamma radiation-induced template polymerization technique and used for the separation of Ga (III) from Cu (II), Ni (II), and Zn (II) in aqueous media. The effect of pH and contact time on the separation process was studied. The optimum pH value for the separation process is 3–3.5. The result shows that Ga (III) is first extracted while Cu (II), Ni (II) and Zn(II) are slightly extracted at this pH value. The recovery of metals using HCl, HNO₃ and H₂SO₄ has been studied. The resins may be regenerated using 2M HCl solutions.      

Review of analytical methods for the determination of chlorine dioxide

The present study reviews more than twenty years (1985-present) of published research on the development and application of analytical procedures for the determination of chlorine dioxide, a widely used disinfectant and bleaching agent. The review covers a variety of techniques including batch and automated spectrophotometry and fluorimetry, electroanalysis and chromatography. The analytical figures of merit to the methods are presented, while critical discussion regarding their advantages and disadvantages is addressed.      

Thermal synthesis and characterization of Al χ La1-χ P3O9

New binary lanthanum-aluminum triphosphates were synthesized by thermal-condensation method from H₃PO₄, La₂O₃ and Al(OH)₃. These pigments could be potentially used as special inorganic pigments; their corrosion-inhibition properties were widely studied. Synthesis conditions were determined on the basis of DTA and TG measurements. The products were also characterized by X-ray diffraction analysis. Physical properties — density by pycnometric method, particle size distribution, oil number and critical pigment volume concentration (CPVC), pH and specific conductivity of their aqueous extracts were also determined.      

Indirect determination of lutetium by differential pulse anodic stripping voltammetry at a hanging mercury drop electrode

Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA. Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically, resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL⁻¹ lutetium could be detected after a 2 min deposition.      

Methylcellulose/SiO<Subscript>2</Subscript> hybrids: sol-gel preparation and characterization by XRD,FTIR and AFM

Methylcellulose (MC) / SiO₂ organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO₂. AFM depicts surface roughness which depends on the silica precursor and MC content.      

Preparation and shape control of β-Ni(OH)<Subscript>2</Subscript> nano-particle

A simple and convenient method for the preparation of needle-shape nanoparticles of β-Ni(OH)₂ has been developed. Results show that a needle-shaped β-Ni(OH)₂ can be easily obtained in the presence of ethylenediamine and sodium dodecylbenzene sulfonate within a size from 100 to 200 nm. The shape and structure of the product were characterized by XRD, TEM and FT-IR. It is noteworthy that the formation of needle-shape β-Ni(OH)₂ benefits from the addition of sodium dodecylbenzene sulfonate. The optimum preparation conditions and the possible mechanism are also discussed.      

Microwave-induced combustion synthesis and characterization of NixCo1−xFe2O4 nanocrystals (x = 0.0, 0.4, 0.6, 0.8, 1.0)

A series of Ni-doped cobalt ferrites Ni_xCo1_−xFe₂O₄ (x = 0.0, 0.4, 0.6, 0.8, and 1.0) were prepared using microwave-induced combustion. Nickel, cobalt, and ferric nitrates were used as starting materials and glycine as fuel. The influence of Ni content on the lattice parameter, stretching vibrations, and magnetization was studied. XRD, FTIR, and SEM were used for structure, composition, and morphology investigation. A porous network structure was observed with average particle size 60–67 nm. All samples had a cubic spinel structure. The unit cell parameter “a” decreases linearly with nickel concentration due to the smaller ionic radius of nickel. Magnetization measurements showed that coercivity decreased as Ni content increased; it increased with decreasing temperature.      

Influence of complexation on the composition of equilibrium phases in the system of Ce2(SO4)3-La2(SO4)3

The cocrystallization of Ce₂(SO₄)₃ and La₂(SO₄)₃ is studied in aqueous and H₂SO₄ (150 g/dm³) solutions at 25 °C and 64 °C. The effect of the formation of inner sphere sulfate complexes of the type LnSO ₄ ⁺ in determining the composition of the equilibrium phases is revealed.      

Surface analysis of the size-fractioned urban aerosols by secondary ion mass spectrometry (ToF-SIMS)

The secondary ion mass spectrometry method (ToF-SIMS) has been applied to the analysis of some mineral and organic species on the surface layers of airborne urban particulates. Particulate matter was collected on aluminum sheets of the 8-stage Anderson type cascade impactor from three different sampling sites in the city of Lodz, Poland, which were different in terms of aerosol source apportionment. The obtained results show that vehicle combustion products occur mainly in fine fraction with aerodynamic diameters below 1μm. The main contribution to the mineral components comes from direct and traffic related soil resuspension.      

Synthesis and pharmacological properties of 3-(2-methyl-furan-3-yl)-4-substituted-Δ<Superscript>2</Superscript>-1,2,4-triazoline-5-thiones

By the reaction of 2-methyl-furan-3-carboxylic acid hydrazide with isothiocyanates, 1-[(2-methyl-furan-3-yl)carbonyl]-4-substituted thiosemicarbazides 1 were obtained. Further cyclization with 2% NaOH led to the formation of 3-(2-methyl-furan-3-yl)-4-substituted-Δ²-1,2,4-triazoline-5-thiones 2. The pharmacological effects of 2 on the central nervous system in mice were investigated. Strong antinociceptive properties of the investigated derivatives were observed in a wide range of doses.      

Determination of active components in Chinese medicinal preparations by capillary electrophoresis

The determination of paeoniforin, paeonol, and censenoside Rg₁ in traditional Chinese medicinal preparations, Tze Po San Pien pills and Liuwen Dihuang pills has been investigated by micellar electrokinetic capillary electrophoresis with borate buffer (20 mM), sodium dodecylsulfate (30 mM) and acetonitrile (20%) as background electrolytes (pH 9.30), 20 kV applied voltage and 203 nm UV detection. The effects of SDS concentration, borate, buffer pH, and organic modifier on electrophoretic behavior and separation are discussed. Regression equations revealed linear relationships between the peak-area of each component and the content with the correlation coefficients from 0.9982 to 0.9999. In addition, the levels of the active compounds in two kinds of traditional Chinese medicinal preparations were easily determined with the recoveries from 93.1% to 108.2%.      

Analysis of vibratinal spectra of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives based on density functional theory calculations

The geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP) functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate analysis. The observed and calculated spectra are found to be in good agreement.      

Influence of surfactants on the fading of malachite green

The kinetics of the reaction between malachite green (MG) and sodium hydroxide (MG fading) was studied using a spectrophotometric method in the presence of two cationic surfactants, cetyl-benzyl-dimethyl-ammonium chloride (CBDAC) and hexadecyl-trimethylammonium bromide (HTAB) and one anionic surfactant, sodium dodecyl sulphate (SDS) at concentrations below and above critical micellar concentrations. The cationic surfactants have a catalytic effect, while the anionic surfactant has an inhibitory effect on the reaction. A kinetic model describing the influence of surfactant on reaction rate was developed. The results are discussed on the basis of electrostatic and hydrophobic interactions between the kinetic micelles and malachite green.