On the phenomena occurring at the interface between iron and iron–platinum thin films

FePt films were rf sputtered at room temperature and 550?C on MgO monocrystalline substrates. Room temperature films were post-annealed at 550?C. The high temperature growth induces a tetragonal distortion of the structure with the formation of L1₀-FePt phase. Soft iron layers, with different thickness, were e-beam deposited on these hard films. The phenomena occurring at the interface have been analysed and connected with the final magnetic behaviour of the system. It has been found that a strong exchange coupling between soft and hard layers has been established through the formation of an interfacial layer constituted by FePt small particles.     

Hypercoordinated diorganoantimony(III) compounds of types [2-(Me2NCH2)C6H4]2SbL and [PhCH2N(CH2C6H4)2]SbL (L = Cl,ONO2, OSO2CF3). Synthesis,structure and catalytic behaviour in the Henry reaction

The compounds [2-(Me₂NCH₂)C₆H₄]₂SbL (L = ONO₂ ( 2 ), OSO₂CF₃ ( 3 )) and [PhCH₂N(CH₂C₆H₄)₂]SbL (L = ONO₂ ( 5 ), OSO₂CF₃ ( 6 )) were prepared by reacting [2-(Me₂NCH₂)C₆H₄]₂SbCl ( 1 ) and [PhCH₂N(CH₂C₆H₄)₂]SbCl ( 4 ), respectively, with the appropriate silver(I) salt in a 1:1 molar ratio. The new species 2 – 6 were structurally characterized in solution using multinuclear NMR and in the solid state using infrared spectroscopy. The solid-state structures for compounds 2 , 4 and 6, as well as for the hydrolysis ionic product [{2-(Me₂N⁺HCH₂)C₆H₄}{2-(Me₂NCH₂)C₆H₄}SbOH][CF₃SO₃]⁻ ( 3h ) were determined using single-crystal X-ray diffraction. Medium to strong intramolecular N→ Sb interactions were observed in all these four compounds, thus resulting in hypercoordinated organoantimony(III) species 14-Sb-6 in 2 and 10-Sb-4 in the cation of 3h and in 4 and 6 . Compounds 1 – 6 and the starting amines PhCH₂NMe₂ and PhCH₂N(CH₂C₆H₄Br-2)₂ were investigated as catalysts in the Henry (nitroaldol) addition of nitromethane to benzaldehyde. The activity of compounds 1 – 6 resulted as an effect of the cooperation of the positively charged antimony with the negatively charged nitrogen.     

On interactive buckling in a sandwich structure

This work revisits an interactive buckling model for sandwich beams proposed relatively recently by Hunt and Wadee (Proc R Soc Lond A 454:1197–1216, 1998). Our asymptotic investigations reveal an interesting resonant behaviour which is shown to lie at the origin of the corresponding localised deformations reported in the literature. The very good agreement between the asymptotic results and various direct numerical simulations reinforces the validity of our theoretical arguments and provides an incentive for further research.     

Photopolymerized silver-containing conducting polymer films. Part II. Physico-chemical characterization and mechanism of photopolymerization process

Physico-chemical and mechanical characterizations of nanophase silver-containing polypyrrole films prepared using a new photopolymerization process were performed. In general, the recorded physical, chemical, and mechanical data characteristic of these films was similar to corresponding literature data obtained from electropolymerized or chemically polymerized polypyrrole. However, photopolymerized polypyrrole films possessed an unusually high anion-to-monomer ratio of 0.8:1. Also, the photopolymerized material contained silver nanoparticles, having diameters of 2 μm or less, uniformally distributed throughout the polymer matrix. While the photopolymerization mechanism is complex, it is suggested that a pyrrole–silver cation complex is most likely the key component involved in the photopolymerization initiation step. Paper submitted for inclusion in the special issue of the Journal of Solid State Electrochemistry honoring the 85th birthday of Professor John O’M. Bockris.     

Modification of the surface adsorption properties of alumina-supported Pd catalysts for the electrocatalytic hydrogenation of phenol

The electrocatalytic hydrogenation (ECH) of phenol has been studied using palladium supported on gamma-alumina (10% Pd-Al2O3) catalysts. The catalyst powders were suspended in aqueous supporting electrolyte solutions containing methanol and short-chain aliphatic acids (acetic acid, propionic acid, or butyric acid) and were dynamically circulated through a reticulated vitreous carbon cathode. The efficiency of the hydrogenation process was measured as a function of the total electrolytic charge and was compared for different types of supporting electrolyte and for various solvent compositions. Our results show that these experimental parameters strongly affect the overall ECH efficiency of phenol. The ECH efficiency and yields vary inversely with the quantity of methanol present in the electrolytic solutions, whereas the presence of aliphatic carboxylic acids increased the ECH efficiency in proportion to the chain length of the specific acids employed. In all cases, ECH efficiency was directly correlated with the adsorption properties of phenol onto the Pd-alumina catalyst in the studied electrolyte solution, as measured independently using dynamic adsorption isotherms. It is shown that the alumina surface binds the aliphatic acids via the carboxylate terminations and transforms the catalyst into an organically functionalized material. Temperature-programmed mass spectrometry analysis and diffuse-reflectance infrared spectroscopy measurements confirm that the organic acids are stably bound to the alumina surface below 200 degrees C, with coverages that are independent of the acid chain length. These reproducibly functionalized alumina surfaces control the adsorption/desorption equilibrium of the target phenol molecules and allow us to prepare new electrocatalytic materials to enhance the efficiency of the ECH process. The in situ grafting of specific aliphatic acids on general purpose Pd-alumina catalysts offers a new and flexible mechanism to control the ECH process to enhance the selectivity, efficiency, and yields according to the properties of the specific target molecule.     

Synthesis of luminescent heterometallic bis-lanthanide complexes via selective, sequential metallation

A modular synthetic method for the differential incorporation of two lanthanide ions into a single molecular scaffold is reported; the mixed bimetallic Tb/Eu complex displays an interesting solvent polarity-dependent ratiometric luminescence.     

Simple determination of betamethasone and chloramphenicol in a pharmaceutical preparation using a short monolithic column coupled to a sequential injection system

This contribution describes the use of a new separation method based on a reversed-phase sequential injection chromatography (SIC) technique for simultaneous determination of chloramphenicol and betamethasone in pharmaceutical eye drops. A short monolithic column coupled with a sequential injection analysis (SIA) system enabled separation of two compounds in one step. A Chromolith Flash RP-18e, 25 x 4.6 mm column with a 5 mm precolumn (Merck, Germany) and a FIA1ab 3000 system (USA) with a 6-port selection valve and 5 mL syringe were used for sequential injection chromatographic separations in this study. The mobile phase used was acetonitrile-water (30:80, v/v), flow rate 0.48 mL/min; UV detection was at two wavelengths, i.e., 241 and 278 nm (absorption maxima of betamethasone and chloramphenicol, respectively). The basic validation parameters showed good results: linearity of determination for both compounds including internal standard (propylparaben) >0.999; repeatability of determination (RSD) in the range 0.8-1.7% at two different concentration levels, and detection limits in the range 0.5-1.0 mg/mL. The chromatographic resolution between compound peaks was greater than 2.1 and the analysis time was less than 8 min under optimal conditions. The developed sequential injection chromatography method was compared with the HPLC method and was found to be applicable for routine analysis of active compounds in pharmaceutical preparations.