The Synthesis of New Triazole Ligands and Determination of Complex Stability Constants with Transition Metal Cations in Aqueous Media

Six new triazole compounds were synthesized. These compounds containing the substituted benzylidenamino group were obtained by reaction of 3-(pyridine-4-yl)-5-p-tolyl-4-amino-4H-l,2,4-triazole 1 with the corresponding aldehyde. The reduced forms were prepared with NaBH₄ in methanol. The structures of the compounds were determined by IR, ¹H NMR, and ¹³C NMR spectral data, and their interaction with cations such as Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ba²⁺, Sr²⁺, Ca²⁺, Cu²⁺, Cr³⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺ and Ag⁺ were investigated by using UV-visible spectrophotometry. Of the tested metal cations, Cu²⁺, Cr³⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺ and Ag⁺ complexed with the ligands. The complex stability constants (log ₁₀ K) were measured in slightly acidic aqueous media at 25.0±0.1 °C. These stability constants were determined by measuring the increase in solubility of the nearly insoluble ligand molecule due to complex formation with a soluble cation, and this method is discussed. It was found that the position of chlorine atoms on the benzene ring strongly affects the complexation of Cu²⁺ ion with these ligands.     

Synthesis and micellar properties of 1-decyl-2,3-dimethylimidazolium bromide surfactant in water and water-ethanolamine mixtures at 298.15 K

1-Decyl-2,3-dimethylimidazolium bromide (ddmimBr) has been synthesized by the reaction of 1,2-dimethylimidazole and 1-bromodecane. Micellization of ddmimBr surfactant in water (W) and water-ethanolamine (W-EA) with the weight percent of EA changing within the range 0-39.79%, has been investigated at 298.15 K. Information about the influence of the added EA on the critical micelle concentration (CMC) was obtained through density and surface tension measurements. This last provides information about the dependence of the surface excess concentration, the minimum area per surfactant molecule and the surface pressure at the CMC on the added weight percentage of organic solvent. The effect of binary aqueous mixtures of W-EA on the apparent molar volume (phi V) of the ddmimBr has been investigated. The apparent molar volume upon aggregation (Delta phi V) shows a maximum at about 15 wt% of EA, this behavior is discussed in terms of the changes of the solvent structure. Partial specific volume data, obtained by density measurements, indicate that the fraction of solvent molecules interact with the surfactant remained roughly constant.     

Application of Multicriteria Methodology in the Development of Improved RP-LC-DAD for Determination of Rizatriptan and Its Degradation Products

A simple, rapid, and stability-indicating reversed-phase high-performance liquid chromatographic (LC) method for analysis for dutasteride has been successfully developed. Chromatography was performed on a 150 mm × 4.6 mm C₁₈ column with acetonitrile–water 60:40 (v/v) as isocratic mobile phase at 1.0 mL min⁻¹. Ultraviolet detection of dutasteride was at 210 nm. Its retention time was approximately 10 min and its peak was symmetrical. Response was a linear function of concentration over the range 0.2–1 μg mL⁻¹ (R ² = 0.997) and the limits of detection and quantitation were was 0.05 and 0.10 μg mL⁻¹, respectively. The method was validated for linearity, precision, repeatability, sensitivity, and selectivity. Selectivity was validated by subjecting dutasteride stock solution to photolytic, acidic, basic, oxidative, and thermal degradation. The peaks from the degradation products did not interfere with that from dutasteride. The method was used to quantify dutasteride in pharmaceutical preparations.

     

Isoperimetric domains of large volume in homogeneous three-manifolds

Given a non-compact, simply connected homogeneous three-manifold X   and a sequence _{Ωn}n${\{{\Omega }_n\}}_n$ of isoperimetric domains in X   with volumes tending to infinity, we prove that, as n→∞$n\to \infty$:

(1)

The radii of the _Ωn${\Omega }_n$ tend to infinity.     

The commutant of L(H) in its ultrapower may or may not be trivial

Kirchberg asked in 2004 whether the commutant of L(H) in its (norm) ultrapower is trivial. Assuming the Continuum Hypothesis, we prove that the answer depends on the choice of the ultrafilter.