Synthesis and monolayer film of a series of new twin-tailed gemini cationic surfactants at the air/water interface

A series of new dimeric surfactants, twin-tailed gemini surfactants, 2(12)-s-2(12), were successfully prepared and characterized, and their monolayer films investigated by the measurement of surface pressure-area (π-A) and surface pressure-time (π-t) isotherms at the air/water interface by a Langmuir film balance. Compared to their monomeric counterparts, their collapse pressure (γ_collapse) is smaller, whilst all the molecular area parameters are larger. The limited area (A_limited) and the initial area (A_initial) of these twin-tailed gemini surfactants change with increasing spacer length s, and the surface pressure decreases with increasing time. It was also found that the higher the initial surface pressure, the larger the attenuation.      

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.      

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.      

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.      

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     

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.      

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.      

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.      

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.      

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.      

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.      

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.      

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.      

Polyaniline-polypyrrole coating for solid phase microextraction

A procedure for direct electrochemical deposition of polyaniline-polypyrrole blend coating on the surface of stainless steel wire was suggested. Incorporation of polyaniline and polypyrrole into the blend coating was confirmed by infrared spectroscopy. Key parameters (pyrrole, aniline, dopant and sulphuric acid concentrations and deposition potential) influencing the coating’s mechanical stability and surface homogeneity were optimised and thermostability of the coating was investigated. A possibility to apply the coating as a new fibre for solid phase microextraction was demonstrated. The coating showed better selectivity toward aromatic, hydrophobic compounds.      

Synthesis and proton conductivity of anhydrous dendritic electrolytes

Water soluble PEG cored dendritic hexa-acid which comprises peripheral carboxylic acidic groups were prepared via nucleophilic substitution reactions. Novel anhydrous proton conducting electrolytes were prepared by incorporation of the heterocyclic protogenic solvent imidazole (Im) into PEG cored dendritic hexa acid, (PEG-HA), at several molar ratios of Im to-COOH units of PEG-HA. The complexation of PEG-HA and Im was illustrated by infrared spectroscopy (FT-IR). The materials are thermally stable up to 150 °C as evidenced by thermogravimetry analysis (TGA). Differential scanning calorimetry (DSC) results verified that the organic electrolytes are homogeneous and amorphous. The proton conductivities were characterized by means of AC impedance spectroscopy and a maximum conductivity of 1 × 10⁻³ S/cm was measured at 120 °C in the anhydrous state.      

Ugi products containing boronate esters

The Ugi reaction with formylphenylboronic acid derivatives as the carbonyl component proceeds to give the corresponding boron-containing dipeptide derivatives (Ugi products) in good yields.      

Electrospinning of the hydrophilic poly (2-hydroxyethyl methacrylate) and its copolymers with 2-ethoxyethyl methacrylate

The goal was to electrospin 2-hydroxyethyl methacrylate — based biocompatible polymers and prepare submicron fibres (nanofibers) for biomedicinal applications. Syntheses of poly(2-hydroxyethyl methacrylate) (HEMA) and its copolymer with 2-ethoxyethyl methacrylate (EOEMA), and their characterization by viscometry and molecular weight are described. Their relation to electrospinning is discussed. Electrospinning of HEMA homopolymer from water-ethanol is successful for molecular weights 6.31 × 10⁵ and 1.80 × 10⁶ g/mol. Electrospinning of HEMA/EOEMA copolymers is feasible from ethanol.      

Synthesis and photochromic behavior of some azo-polysiloxanes modified with nucleobases or donor-acceptor groups

This paper presents the syntheses, characterization and photochromic behavior of some new azo-polysiloxanes modified with uracil, cytosine or nitro-phenolic groups. Taking into consideration the possibility of generating H-bonds or donor/acceptor interactions, this class of materials present a potential applicability in the immobilization of biomolecules and their nano-manipulations. Also, such compounds are capable of producing a fluid phase, with directional flowing capacity. For all these polymers, the molecular modeling simulations have shown disordered structures, which would generate amorphous phases, a very important aspect for molecules’ nano-manipulation. The photochromic behavior in the presence of UV irradiation was also evaluated.