A study on the synthesis of calix[4 and 6]arenes using alternately arranged phloroglucinols and p-tert-butylphenols

A method for the synthesis of calix[4 and 6]arenes with two or three alternately arranged phloroglucinols and p-tert-butylphenols was studied using "3+1" and "5+1" approaches, compared to a simple one-pot synthesis based on a "1+1" approach. By using Yb(OTf)3 as a catalyst, each calix[4 and 6]arenes was afforded, in an overall yield of 20.7% and 11.8% in the "3+1" and "5+1" approaches, respectively, and 24.6% and 19.9% using a "1+1" approach with chlorobenzene and toluene as refluxing solvents, respectively.     

Modified Coumarins. 12. Synthesis of 3,4-Cycloannelated Coumarin β-D-Glucopyranosides

O--D-Glucopyranosides were synthesized using 3,4-cycloannelated hydroxycoumarins as aglycons. Phenolic hydroxyls were O-glycosylated via condensation of coumarin potassium salts with acetobromoglucose in homogeneous medium and in a liquid-liquid system using a phase-transfer catalyst.     

Glycosidation with a disarmed glycosyl iodide: promotion and scope

[reaction: see text] Glucuronyl iodide 1 has been studied in detail as a "disarmed" glycosyl donor. In a model reaction, using N-iodosuccinimide (NIS) as a promoter and 2-phenylethanol as acceptor, best results were obtained using NIS with I(2), followed by trimethylsilyltrifluoromethanesulfonate (TMSOTf). When a series of primary and secondary alcohols was glycosylated using these conditions, yields of 60-83% of beta-glucuronides were obtained. Various "nonheavy" metal salts also effectively catalyzed the model reaction but led to significant amounts of alpha-product with less reactive secondary alcohols.     

New gamma rays following the233U α-decay

²³³U -decay was reinvestigated using a radiochemically purified source and high efficiency HPGe coaxial detectors; the lowenergy -spectrum was also measured using a LEPS detector. The energy and intensity values of one hundred sixty three -lines were determined, from which forty eight are newly reported with respect to the last study of Canty et al. A revised²²⁹Th level scheme was built, using the Ritz combination principle, in which nine levels are newly observed, at 371.3, 381.8, 465.5, 569.2, 584.9, 605.1, 620.8, 656.9 and 749.9 keV.     

Evaluation of Digital Image Recognition Methods for Mass Spectrometry Imaging Data Analysis

Analyzing mass spectrometry imaging data can be laborious and time consuming, and as the size and complexity of datasets grow, so does the need for robust automated processing methods. We here present a method for comprehensive, semi-targeted discovery of molecular distributions of interest from mass spectrometry imaging data, using widely available image similarity scoring algorithms to rank images by spatial correlation. A fast and powerful batch search method using a MATLAB implementation of structural similarity (SSIM) index scoring with a pre-selected reference distribution is demonstrated for two sample imaging datasets, a plant metabolite study using Artemisia annua leaf, and a drug distribution study using maraviroc-dosed macaque tissue.

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The Evolution of a Laboratory Syllabus for Quantitative Analysis

In this paper, we describe the evolution of a laboratory syllabus for a course in Quantitative Analysis. Over the past two decades, the syllabus has changed from one having individual students do mostly wet chemical analyses on commercial unknowns to one having groups of students do instrumental analyses on real samples. We describe, in some detail, the current laboratory syllabus, which requires students to calibrate volumetric equipment, to determine the active ingredients in Dristan using UV-visible absorption spectroscopy, to determine calcium levels in over-the-counter tablets using both atomic absorption spectroscopy and an ion-selective electrode, to determine lead in wine bottle caps using differential pulse polarography, to measure pK_a values for sulfonated naphthols using UV-visible absorption spectroscopy and to determine caffeine and aspartame in common beverages using HPLC. Group work is emphasized, and written reports are required. Students have responded quite positively to the current syllabus, especially to the use of real samples.     

Applications of vectorized gold nanoparticles to the diagnosis and therapy of cancer

This critical review focuses on the anti-cancer fight using gold nanoparticles (AuNPs) functionalized with chemotherapeutic drugs in so-called "complexes" (supramolecular assemblies) and "conjugates" (covalent assemblies) as vectors. There is a considerable body of recent literature on various tumor-imaging techniques using the surface plasmon band (SPB) and the "passive" and "active" vectorization of anti-cancer drugs. This article reviews the main concepts and the most recent literature data with emphasis on AuNP preparation, cytotoxicities and use in selective targeting of cancer cells with over-expressed receptors for diagnosis and therapy (108 references).     

The measurement of the isotopic composition of plutonium in an Irish Sea sediment by mass spectrometry

Samples from sediment cores, collected from a site close to the Sellafield outfall and dated using conventional - and -spectrometry, have been analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Thermal Ionisation Mass Spectrometry (TIMS). This has provided information on the isotopic composition of plutonium in the liquid discharges from Sellafield; such information is not available using conventional -spectrometry alone. There was very good agreement between the²⁴⁰Pu/²³⁹Pu ratios obtained by the two MS methods. More recent discharges have been characterised by a progressive decrease in the relative proportion of²³⁹Pu.     

Polyaphrons as Templates for the Sol–Gel Synthesis of Macroporous Silica

Macroporous silica was synthesized using polyaphrons as shape-directing templates in a sol–gel hydrolysis scheme using tetraethyl orthosilicate (TEOS). Polyaphrons are a special class of high internal phase ratio emulsions (HIPRE) that can potentially be used in the continuous processing of long range ordered macroporous solids. The structures so formed were examined using a scanning electron microscope after thermal curing to 400C. The majority of the pores in the silica structures were in the range between 0.1 and 10 m. Key parameters affecting the polyaphrons template characteristics were varied and their effects on the final silica structure were studied.     

Dynamic analysis of on-line high-performance liquid chromatography for multivariate statistical process control

A continuous process was studied over 83.32 h using on-line high-performance liquid chromatography, involving the acquisition of 252 chromatograms. A method for analysis of these data using multivariate statistical process control on peak tables, in real-time, is described. The normal operating condition (NOC) region of the process was identified using evolving principal components analysis to be between 5.77 and 8.13 h. 19 out of the 37 peaks detected throughout the process were found in the NOC region, the remainder representing undesirable contaminants found elsewhere in the process. A major challenge is to develop the peak table as the process evolves, which is dynamically updated as new peaks are detected after the NOC region: this approach involving an "unlocked" peak table is contrasted to an approach using a "locked" peak table where only peaks detected during the NOC region are included in the model. In addition, results are compared to those obtained using baseline corrected and aligned chromatograms, using a NOC region of 5.85-8.33h. D- and Q-charts were obtained. It is shown that the "unlocked" peak table detects out of control samples best and provides good diagnostic insight into problems with the process.     

Metabonomic Studies Comparing Capillary and Conventional HPLC-oa-TOF MS for the Analysis of Urine from Zucker Obese Rats

The application of capillary HPLC and orthogonal acceleration (oa) TOF-MS to a metabonomic investigation of the urinary metabolic profiles of samples obtained from male and female Zucker rats is described. The results obtained using capillary HPLC for performing the chromatographic separation are also compared with the analysis of the same samples by conventional HPLC. Capillary HPLC-MS gave increased sensitivity (ca. 100 fold) despite using a fraction of the sample volume consumed by HPLC (0.5 L vs 10 L). Capillary HPLC-MS also provided a greater peak count (ca. 3000 ions compared to 1500 for HPLC) for the same analysis time compared to conventional HPLC-MS. These data were processed using partial least squares discriminant analysis (PLS-DA)) enabling markers of diurnal variation to be detected for urine samples from both male and female rats.     

Two-carrier liquid-phase synthesis of main-chain liquid crystalline oligomers and characterization of the products

Monodisperse oligomers were synthesized from terephthalic acid and -hydrogen--[oxy-1,4-phenyloxy-1,10-decamethyleneoxy-1,4-phenylene] using a polyethylene glycol support. Isolation of the target oligomers was achieved by use of a second soluble carrier which could be introduced and cleaved selectively, thus allowing to characterize the product chain in solution. The structures of the oligomers were assigned and identified using a combination of analytical methods such as electron impact mass spectrometry, IR- and ¹H-NMR spectroscopy and temperature-resolved pyrolysis-field ionization mass spectrometry (Py-FIMS).     

Analysis of the pungent principles of ginger and grains of paradise by high-performance liquid chromatography using electrochemical detection

Summary The pungent principles of ginger and grains of paradise are examined using a reversed-phase HPLC column. An electrochemical detector is used to selectively detect the phenolic gingerols and shogaols. The retention indices of the compounds are compared using methanowater and acetonitrile-water as eluents.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Development of cysteine-modified screen-printed electrode for the chronopotentiometric stripping analysis of cadmium(II) in wastewater and soil extracts

Screen-printed carbon electrodes were fabricated with amino acid functionality by using in situ co-deposition of mercury and cysteine. The three-electrode configuration (graphite carbon working electrode, carbon counter electrode and silver/silver chloride reference electrode) incorporating a cysteine-modified working electrode exhibited good sensitivity towards cadmium(II). Several experimental variables affecting the sensor stripping response were characterised and optimised. These include cysteine and mercury concentrations, deposition time, deposition potential and stripping current. Surface analysis was also conducted using scanning electron microscopy (SEM) in order to characterize the electrode surface during cadmium analysis. The stripping chronopotentiometric response for cadmium(II) was linear in the concentration range 0.4–800 g L^–1 when a deposition time of 2 min was used. A detection limit of 0.4 g L^–1 was obtained using 0.025 M Tris–HCl buffer containing 0.1 M KCl (pH 7.4) as the supporting electrolyte. The analytical utility of the cysteine-modified sensor was demonstrated by applying it to cadmium analysis in various wastewater and soil samples collected from a contaminated site and extracted using acetic acid. The results obtained using the developed electrodes agreed satisfactorily with the values achieved using atomic absorption spectrometry and inductively coupled plasma mass spectrometry analysis. These results demonstrate the feasibility of using this type of sensor for cadmium analysis.     

Application of directional detection in surveying active ore deposit

Two three-dimensional scans of uranium anomaly obtained by using two directional detectors is presented together with the reconstructed -field. The reasons for using a reconstructed -field in estimation of uranium concentration are briefly discussed.     

Nonempirical SCF-LCAO-MO calculations for (CH)+

Nonempirical molecular orbital calculations, using a minimal basis set of Slater-type atomic orbitals, are reported for the ground state of the (CH)⁺ ion. The C-H bond length calculated using optimized exponents is in excellent agreement with the experimental value, whereas the distances predicted using the conventional free atom exponents are too large by up to 17%.     

Poly(vinyl alcohol) hydrogels: their synthesis and steps towards control of electroendosmosis

Poly(vinyl alcohol) (PVAl) hydrogel networks cross-linked with glutaraldehyde were prepared and their properties as membranes examined using a variety of techniques including preparative electrophoresis. Electroendosmosis (EEO) was observed and shown to be the result of charges on the membrane and of complexation with borate buffer ions. Investigation of "glutaraldehyde" solutions showed acid entities in, or formed in "glutaraldehyde" were responsible for EEO. Techniques for using "glutaraldehyde" which minimize EEO are described.     

Utilizing Distinct Neutron Spectra and a System of Equations to Differentiate Competing Reactions in Activation Analysis

In activation analysis, the continuous neutron spectrum produced in a nuclear reactor can be both beneficial and detrimental. A continuous spectrum allows for activation of particular elements by using any number of neutron energies. However, upper threshold energies exist for most elements where reactions other than an (n, ) absorption will occur. In this situation, two different parent nuclides can be activated to the same product, which creates a problem in performing a quantitative analysis of one or the other nuclide. A methodology is presented where a system of equations is used to solve for the quantities of both nuclides by using different irradiation ports, and using specific neutron filters to "customize" the neutron flux.     

Hypericin and Pseudohypericin. Purity Criteria and Quantitative Determination in Extracts of Saint John’s Wort (Hypericum perforatum)

Summary. Hypericin and pseudohypericin in extracts of St. Johns Wort (Hypericum perforatum) are assayed using UV-Vis, measuring the absorbance at 588nm of a methanolic solution of the compounds. The value of the absorption coefficient is difficult to define insofar as none of the routine purity criteria can be applied to these two compounds. Analysis of the entire UV-Vis spectrum from 220 to 740nm would seem to be a reliable way of comparing different samples. A UV-Vis spectrum was recorded for each of the compounds using a Photodiode array detection system. A more accurate way of determining the levels of hypericin and pseudohypericin in extracts of St. Johns Wort using these reference spectra is described.     

Range corrections using non-analyte spiking

It is shown by using non-analyte spiking to correct for range variations in sample and standard in proton-induced prompt -ray spectrometry, the error introduced by using total ranges instead of effective ranges as a measure of target penetration is negligible, thus making knowledge of the appropriate thresholds irrelevant.