Separation strategy for acidic chiral pharmaceuticals with capillary electrochromatography on polysaccharide stationary phases

The effect of five factors on the capillary electrochromatographic enantioseparation of acidic compounds was studied using an experimental design. The studied factors were pH, acetonitrile content in the mobile phase, temperature, buffer concentration, and applied voltage. These experiments allowed defining a generic separation strategy applicable on acidic compounds with chemical and structural diversity. The starting screening conditions consist of a 45 mM ammonium formate electrolyte at pH 2.9 mixed with 65% acetonitrile, an applied voltage of 15 kV, and a temperature of 25 degrees C. The screening phase occasionally can be followed by an optimization procedure. Evaluation of the proposed strategy pointed out that it allows achieving baseline resolution within a relatively short time when a beginning of separation is obtained at the starting conditions. This strategy revealed enantioselectivity for 11 compounds out of 15, of which 10 could be baseline-separated after the proposed optimization steps.     

Synthesis of para-substituted styrenes

Using double Stille cross-coupling reaction bromo (or chloro)benzylbromide is easily transformed into substituted styrene monomers bearing a wide range of substituents in para position     

Synthesis, characterization and potential biomedical applications of N-succinimidyl ester functionalized, polypyrrole-coated polystyrene latex particles

N-Succinimidyl ester functionalized polypyrrole-coated polystyrene latex particles (PS_E-PPyNSE) were prepared by the in situ copolymerization of pyrrole and the active ester-functionalized pyrrole (pyrrole-NSE) in the presence of polystyrene latex particles. Polystyrene microspheres were prepared by emulsion polymerization (PS_E) leading to particles having a diameter of 450 nm. These PS_E particles were precoated with poly(N-vinylpyrrolidone) prior to the in situ copolymerization of pyrrole and pyrrole-NSE. The initial comonomer concentration fractions were 25/75, 50/50 and 75/25 for pyrrole and pyrrole-NSE, respectively. The PPy-coated PS_E particles were characterized in terms of morphology, particle size, electrophoretic mobility and chemical composition. The study of morphology by means of scanning electron microscopy showed roughening of the underlying PS_E particles owing to the addition of PPyNSE, the overlayer thickness of which was estimated to be around 7 nm. Moreover, loading PPyNSE overlayers resulted in a shift of the electrophoretic mobility from –5.31 m cm/V s to a very small but positive value (0.082–0.112 m cm/V s). X-ray photoelectron spectroscopy and IR spectroscopy permitted the detection of pyrrole-NSE repeat units at the surface indicating that pyrrole and pyrrole-NSE did indeed copolymerize. The PS_E-PPyNSE particles were further evaluated as bioadsorbents of human serum albumin used as a test protein. For this study, PS_E-PPyNSE₅₀ particles, synthesized from a comonomer feed ratio of 50/50 in pyrrole/pyrrole-NSE, were used and were shown to attach efficiently human serum albumin macromolecules with a maximum amount of 0.2 mg m^–2.

Sinulochmodins A-C, three novel terpenoids from the soft coral Sinularia lochmodes

An unprecedented C,C-linked dimeric norcembranoid (sinulochmodin A, 1), a novel isocembranoid (sinulochmodin B, 2), and a novel yonarane norditerpenoid (sinulochmodin C, 3) were isolated from the soft coral Sinularia lochmodes. The structures of these metabolites were elucidated by extensive spectroscopic analysis and on the basis of the absolute structures of two related norditerpenoids (4 and 5), which were determined for the first time by a modified Mosher method. A plausible pathway for the biosynthesis of 1 and 3-5 from 2 was postulated. [structure: see text]     

Facile reduction of aromatic nitro/azido functionality on solid support employing Al/NiCl2·6H2O and Al/NH4Cl: synthesis of pyrrolo[2,1-c][1,4]benzodiazepines

An efficient and mild method for the reduction of aromatic nitro and azido groups on solid support using Al/NiCl₂·6H₂O and Al/NH₄Cl is described. This solid phase reduction technique has been applied towards the synthesis of DNA binding pyrrolo[2,1-c][1,4]benzodiazepine antitumour antibiotics.     

Structure and Magnetic Properties of Nickel–Zinc Ferrite Nanoparticles Prepared by Glass Crystallization Method

Summary. The magnetic and microstructure properties of Fe₂O₃–0.4NiO–0.6ZnO–B₂O₃ glass system, which was subjected to heat treatment in order to induce a magnetic crystalline phase (Ni_0.4Zn_0.6-Fe₂O₄ crystals) within the glass matrix, were investigated. DSC measurement was performed to reveal the crystallization temperature of the prepared glass sample. The obtained samples, produced by heat treatment at 765°C for various times (1, 1.5, 2, and 3 h), were characterized by X-ray diffraction, IR spectra, transmission electron microscopy, and vibrating sample magnetometer. The results indicated the formation of spinel Ni–Zn ferrite in the glass matrix. Particles of the ferrite with sizes ranging from 28 to 120 nm depending on the sintering time were observed. The coercivity values for different heat-treatment samples were found to be in the range from 15.2 to 100 Oe. The combination of zinc content and sintering times leads to samples with saturation magnetization ranging from 12.25 to 17.82 emu/g.     

Potentiodynamic and cyclic voltammetric behaviour of a lead electrode in NaOH solution

Summary The electrochemical behaviour of lead in NaOH solution was studied by potentiodynamic and cyclic voltammetric techniques in combination with X-ray diffraction analysis. The active dissolution of lead involves a small shoulderA1 followed by a peakA1 prior to a passive region. The shoulderA1 is assigned to the electroformation of a Pb(OH)₂ film, whereas peakA1 is due to the formation of PbO. Beyond the passive region, the current density increases again, forming a small shoulderA2 and a peakA2 prior to the oxygen evolution potential. The shoulderA2 and the peakA2 are correlated to the electrooxidation of PbO to Pb₃O₄ and PbO₂, respectively. The intensity of the anodic peaks increases with increasing alkali concentration, temperature and scan rate. In cyclic voltammetry, the reverse scan shows two cathodic peaksC1 andC2 which are correlated to the electroreduction of PbO and PbO₂ respectively, to Pb.

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Potentiodynamisches und cyclovoltammetrisches Verhalten einer Bleielektrode in NaOH-Lösung

Zusammenfassung Das elektrochemische Verhalten von Blei in NaOH wurde mittels potentiodynamischer und cyclovoltammetrischer Techniken unter Zuhilfenahme der Röntgenbeugungsanalyse untersucht. Die aktive Auflösung von Blei verläuft über eine SchulterA1, die von einem einer passiven Region vorgelagerten PeakA1 gefolgt wird. Die SchulterA1 wird der elektrochemischen Bildung eines Pb(OH)₂-Films, der PeakA1 der Bildung von PbO zugeschrieben. Jenseits der passiven Region steigt die Stromdichte wieder an, und vor Erreichen des Sauerstoffpotentials treten eine kleine SchulterA2 und ein PeakA2 auf, die mit der Elektrooxidation von PbO zu Pb₃O₄ und PbO₂ korrelieren. Analog dazu beobachtet man in der cyclischen Voltammetrie zwei kathodische PeaksC1 undC2, die der Elektroreduktion von PbO und PbO₂ zu Pb entsprechen. Die Intensität der anodischen Peaks steigt mit steigender Alkalikonzentration, Temperatur und Scangeschwindigkeit.

     

Photoreaction of 2′-chloro-4-R-benzanilide: synthesis of 2-(4-R-phenyl)-1,3-benzoxazole and 9-R-phenanthridin-6(5H)-one (R=H, CH3, CH3O)

The UV photolysis of 2′-chloro-4-R-benzanilides in acetonitrile solution under nitrogen atmosphere leads to the formation of intramolecular photocyclization products (9-R-phenanthridin-6(5)-one, 20–30%), along with the minor photoreduction, photo-Fries, and intramolecular photosubstitution products. The photoreaction of 2′-chloro-4-R-benzanilide in acetonitrile solution containing 10% of water or aqueous sodium hydroxide however gives 2-(4-R-phenyl)-1,3-benzoxazole as a major product (30%) along with the photoreduction, photo-Fries and intramolecular photocyclization products.     

Activity concentrations of 210Po in the soft parts of cockle (Anadara granosa)at Kuala Selangor, Malaysia

Polonium-210 has been measured in the soft parts of Anadara granosa purchased at Kuala Selangor, West Coast of Malaysia in August 2001, April 2002 and September 2002. It is shown that ²¹⁰Po is non-uniformly distributed within cockles of various sizes (i.e., 2.5, 3.0, 3.5 and 4.0 cm of shell length) and the concentration of ²¹⁰Po in the soft parts of cockle was significantly different (p<0.05) due to sampling date. The highest value was observed in the smallest cockle with a shell length of 2.5 cm (411.6±26.16 Bq/g dry wt.). It is clear that there is an allometric relationship between ²¹⁰Po activity concentration and individual cockle weight. This may reflect on the differences of metabolic rate and growth age of cockles. The mean activity concentration of ²¹⁰Po measured in Kuala Selangor filtered water were 1.75±0.17, 0.79±0.08 and 1.13±0.20 Bq/kg for August 2001, April 2002 and September 2002, respectively. The yield concentration factors for ²¹⁰Po in the soft parts of cockles varies from 27.3^. 10³ to 106.9^. 10³. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of spectroscopy of gamma-radiation from the inelastic scattering of reactor fast neutrons for elemental analysis

Gamma-spectra of stainless-steel and soil samples have been measured to study the potentialities of using spectroscopy of γ-radiation from the inelastic scattering of reactor fast neutrons for element analysis of various materials. Contents of iron, chromium, nickel, manganese, silicon and titanium in stainless steel, and those of silicon, iron, aluminium, magnesium, calcium, sodium, titanium, carbon and oxygen in soil have been determined by comparing the spectra of the samples with those of specially prepared mixtures of elements. The distinguishing features, advantages, and limitations of this method are discussed.