Synthesis,characterization, spectroscopy,X-ray structure and gaussian hybrid computational investigation of (−)-(S)-1-[2-(benzenesulfonamido)-3-phenylpropanoyl]-4-[(4-methyl)phenyl]thiosemicarbazide

Abstract

The molecule (?)-(S)-1-[2-(benzenesulfonamido)-3-phenylpropanoyl]-4-[(4-methyl)phenyl] thiosemicarbazide was synthesized and its structure analyzed by X-ray diffraction to understand its geometry, and inter/intra-molecular interactions. Theoretical calculations were carried out using DFT and TD-DFT methods with B3LYP/6-31G(d, p) and B3LYP/6-31G?+?(d, p) basis sets. Theoretical bond parameters, harmonic vibration frequencies, and chemical shifts are in good agreement with the experimental results. Electronic properties of the molecule derived from frontier orbitals, molecular electrostatic potential, and theoretical UV-Visible spectrum are validated experimentally.     

Synthesis of Novel Thioethers and Sulfoxide Compounds

Abstract

Thiosubstituted butadiene and butenyne compounds were synthesized from the reactions of 1,1,3,3,4,4-hexachloro-1-butene or 1,1,2,4,4-pentachlorobuta-1,3-diene with different thiols in EtOH/H₂O solution of NaOH. Tris(thio)substituted butadiene compound was treated with potassium tert-butoxide to obtain tris(thio)substituted butatrienyl halide compound. The novel sulfoxide compounds were synthesized from the reactions of polyhalobutadiene compounds with aliphatic thiols in CHCl₃ with m-CPBA at 0°C. The structures of the novel compounds were characterized by micro analysis, FT-IR, ¹H-NMR, ¹³C-NMR, and MS.     

Synthesis and characterization of sulfonated homo‐ and co‐polyimides based on 2,4 and 2,5‐diaminobenzenesulfonic acid for proton exchange membranes

A series of sulfonated homo‐ and random co‐polyimides (co‐SPI) based on 2,4‐diaminobenzenesulfonic acid (2,4‐DABS) and 2,5‐diaminobenzenesulfonic acid (2,5‐DABS) has been synthesized via conventional two‐step polyimidization method. 2,4‐DABS and 2,5‐DABS were used as sulfonated diamine compounds, 4,4′‐oxydianiline (ODA) and 4,4′‐diaminodiphenyl sulfone (DDS) were used as non‐sulfonated diamine compounds. Mixtures of sulfonated and non‐sulfonated diamine compounds were reacted with benzophenonetetracarboxylic dianhydride (BTDA) to obtain co‐SPI membranes. Molar ratios of sulfonated to non‐sulfonated diamine were systematically varied to produce copolymers of controlled compositions. The co‐SPIs were evaluated for thermal oxidative stability, ion exchange capacity (IEC), water uptake, proton conductivity, solubility, and hydrolytic stability. Proton conductivity and hydrolytic stability of the co‐SPIs were compared with the fully aromatic polyimide, homo‐SPIs (BTDA/2,4‐DABS and BTDA/2,5‐DABS). Regarding thermogravimetric analysis (TGA) analysis, it is concluded that desulfonation temperature in the range of 200–350°C suggests high stability of sulfonic acid groups. co‐SPIs with 40 mol% of 2,4‐DABS showed similar or higher proton conductivity than Nafion® 117 in water. Proton conductivity values of the co‐SPIs were mainly a function of IEC and water uptake. Consequently, the optimum concentration of 2,4‐DABS was found to be in the range of 30–40 mol% from the viewpoint of proton conductivity, IEC, and hydrolytic stability. Copyright © 2008 John Wiley & Sons, Ltd.     

Undertaking data analysis of student outcomes as professional development for teachers

The study reports on collaborations with practitioners to examine the results of students’ performances on high stakes tests as a means to strengthen practitioners’ knowledge of probability and statistics and to empower their conduct of investigations on student performance. Four issues are summarized: the development of their statistical reasoning, their understanding of the meaning of and relationships among the concepts of validity, reliability and fairness as applied to testing, their introduction to the history of testing and its relationship to science, society and cultural inequality, and their reports of independent inquiries. Data on performance on pre- and post-tests demonstrate growth in teacher reasoning and in their professionalism in raising important issues about testing     

Speciation of antimony using chromosorb 102 resin as a retention medium.

The selective retention of the Sb(III) chelate with ammonium pyrrolidine dithiocarbamate (APDC) on a column of Chromosorb 102 resin from a buffered sample solution including Sb(V) was used for the determination of Sb(III). The retained antimony was eluted with acetone. The retention of the Sb(III)-iodide compounds with sodium iodide on the Chromosorb 102 resin column from the same solution after reducing Sb(V) to Sb(III) by iodide in acidic solution was used to preconcentrate the total antimony. The retained antimony was eluted with 0.25 mol l(-1) HNO3. The antimony in the effluent was determined by flame atomic-absorption spectrometry. Also, the total antimony was determined directly by graphite-furnace atomic absorption spectrometry. The Sb(V) concentration could be calculated by the difference. The recoveries were > or = 95%. The detection limits of a combination of the column procedure and flame AAS for antimony were 6 - 61 microg l(-1) and comparable to 4 microg l(-1) for a direct GFAAS measurement. The relative standard deviations were <6%. The procedure was applied to the determination of Sb(III) and Sb(V) in spiked tap water, waste-water samples and a certified copper metal with the satisfactory results.     

Fiber optic pH sensing with long wavelength excitable Schiff bases in the pH range of 7.0-12.0

Most of the fluorescent pH probes work near neutral or acidic regions of the pH scale. In this work, two different fluorescent Schiff bases, chloro phenyl imino propenyl aniline (CPIPA) and nitro phenyl imino propenyl aniline (NPIPA), have been investigated for pH sensing in the alkaline region. Absorption and emission based spectral data, quantum yield, fluorescence lifetime, photostability and acidity constant (pK(a)) of the Schiff bases were determined in conventional solvents and in PVC. The long wavelength excitable immobilized Schiff bases CPIPA (lambda(ex)=556 nm) and NPIPA (lambda(ex)=570 nm) exhibited absorption and emission based optical response to proton in the pH range of 8.0-12.0 and 7.0-12.0, respectively. Response of the CPIPA was fully reversible within the dynamic working range. The response times were between 3-13 min. A relative signal change of 95% and 96% have been achieved for sensor dyes of CPIPA and NPIPA, respectively. The CPIPA displayed better fluorescence quantum yield (varphi(F)=3.7 x 10(-1)) and higher matrix compatibility compared to NPIPA (varphi(F)=1.6 x 10(-1)) in immobilized PVC. The CPIPA and NPIPA exhibited a slight cross sensitivity to the ions of Hg(+) and Fe(3+), respectively.     

Simultaneous determination and validation of some binary mixtures of antihypertensive drugs using ratio derivative spectrophotometric method

Ratio derivative spectrophotometric technique is presented for the rapid, accurate and precise simultaneous determination of olmesartan medoxomil (OLM), hydrochlorothiazide (HCT), and zofenopril (ZOF) as well as HCT binary mixtures in their dosage forms. First derivative of the ratio spectra (DD1) by measurements using different amplitudes was used and calibration graphs were established for 0.5–12 mg/mL HCT and 0.5–20 mg/mL OLM and ZOF. This method depends on first derivative of the ratio spectra by division of the absorption spectrum of the binary mixture by a standard spectrum of one of the components and then calculating the first derivative of the ratio spectrum. The first derivative of the ratio amplitudes at 250.4 and 291.5 nm for OLM, 250.4 and 298.1 nm for ZOF and 231.8, 332.2, 232.3 and 280.4 nm for HCT were selected for the determination. The proposed methods were successfully applied for determining of both drug combinations (ZOF-HCT and OLM-HCT) in their synthetic mixtures and in pharmaceutical dosage forms. The described procedures are extensively validated, non-destructive and do not require any separation steps.     

LC–MS Method for the Sensitive Determination of Metoclopramide: Application to Rabbit Plasma, Gel Formulations and Pharmaceuticals

To support real biological sample application, a simple, selective and rapid LC–MS method has been developed and validated for the sensitive determination of metoclopramide in rabbit blood, ex vivo permeation studies and pharmaceutical dosage form. LC–MS analysis was performed isocratically on a Zorbax SB-C₁₈ column with a mobile phase consisting of methanol:ammonium acetate buffer (pH 3.0) 75:25 (v/v) at a flow rate of 0.70 mL min^?1. The outlet of the column was connected to a single quadrupole mass spectrometer with positive mass spectrometric detection. Ions were detected in the positive multiple reaction monitoring mode. The assay was linear over the concentration range of 1.25–200 pg μL^?1 with a limit of detection of 0.077 pg μL^?1 for standard solutions and 2.5–200 pg μL^?1 with a limit of detection of 0.42 pg μL^?1 for serum samples. The method is applicable, covering a variety of pharmaceutical and biological studies. Metoclopramide was extracted from rabbit blood by liquid–liquid extraction using ether as the extraction solvent. The reproducibility of the method was found to be between 0.96 and 1.98 % (RSD) values. The proposed method has been extensively validated for the determination of metoclopramide in all working media. The sample preparations, flow rate and run time of the analytical systems are not time consuming. Moreover, for the stability of metoclopramide, the effect of temperature, UV light, H₂O₂, HCl and NaOH were also investigated.     

Stability-Indicating UPLC Method for the Determination of Bisoprolol Fumarate and Hydrochlorothiazide: Application to Dosage Forms and Biological Sample

A sensitive, selective and accurate ultra performance liquid chromatographic method has been developed and validated for the simultaneous determination of bisoprolol fumarate and hydrochlorothiazide in their combined dosage forms and as well as in spiked human urine samples. The separation was achieved on an Acquity UPLC BEH C18 1.7 μm (2.1 × 50 mm) column, at 40 °C with mobile phase consisting of acetonitrile:phosphate buffer (20 mM) at pH 3.0 with a gradient elution at 225 nm. Bisoprolol fumarate and hydrochlorothiazide were well separated in <1.5 min with good resolution and without any tailing and interference of excipients. The method was fully validated according to ICH guidelines in terms of accuracy, precision, linearity and specificity. A linear response was observed over the concentration range 0.5–150 μg mL^?1 for hydrochlorothiazide and 0.5–250 μg mL^?1 for bisoprolol fumarate. Limit of detection and limit of quantitation for hydrochlorothiazide were calculated as 0.01 and 0.03 μg mL^?1, respectively, and for bisoprolol fumarate were 0.07 and 0.21 μg mL^?1, respectively. Moreover, bisoprolol fumarate and hydrochlorothiazide were subjected to degradation conditions such as hydrolytic, oxidative and thermal stress conditions to evaluate the ability of the proposed method for the separation of bisoprolol fumarate and hydrochlorothiazide from their degradation compounds.