Synthesis and ligand properties of thianthrenophane

Thianthrenophane 1 has a cavity which offers enough room to potentially enable endohedral coordination to small ions or molecules. For the complexation of silver(I) perchlorate the complex stability constants of 1 logK1=5.45 +/- 0.13 and of thianthrene logK2=9.16 +/- 0.10 were determined by UV/Vis titration. Single competition transport experiments with ten metal salts demonstrate a very high selectivity of 1 as a carrier for silver(I) and a distinctly higher transport rate compared to carriers such as thianthrene and 1,4,8,11-tetrathiacyclotetradecane (14-ane-S4). Although the X-ray crystal structure analysis of the polymeric [Ag(1)]ClO4.(dioxane)7 complex shows an exohedral coordination to silver(I) we suggest that the formation of an endohedral [Ag(1)]+ complex is the explanation for the unusual carrier selectivity of silver(I) by 1 in bulk liquid membrane.     

Application of dried blood spots combined with high-performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometry for simultaneous quantification of vincristine and actinomycin-D

A sensitive, specific and efficient high-performance liquid chromatography-tandem mass spectrometry assay for the simultaneous determination of vincristine and actinomycin-D in human dried blood spots is presented. Dried blood spots were punched out of a collection paper with a 0.25-in.-diameter punch. The analytes were extracted from the punched-out disc using sonication during 15 min in a mixture of acetonitrile–methanol–water (1:1:1, v/v/v) containing the internal standard vinorelbine. Twenty-microlitre volumes were injected onto the HPLC system. Separation was achieved on a 50 × 2.1 mm ID Xbridge C₁₈ column using elution with 1 mM ammonium acetate–acetonitrile (70:30, v/v) adjusted to pH 10.5 with ammonia and run in a gradient with methanol at a flow rate of 0.4 mL/min. HPLC run time was 6 min. The assay quantifies vincristine from 1 to 100 ng/mL and actinomycine-D from 2 to 250 ng/mL using a blood sample obtained by a simple finger prick. Validation results demonstrate that vincristine and actinomycin-D can be accurately and precisely quantified in human dried blood spots with the presented method. The assay can now be used to support clinical pharmacologic studies with vincristine and actinomycin-D.     

Novel Xylan Gels Prepared from Oat Spelts

Gels and pastes are used in many areas including application in the cosmetic, pharmaceutical and medical industries. A xylan derivative with pasty consistency was prepared in addition to the synthesis of xylan ethers and esters. The water content of the gel can be widely varied. The gel is formed although the xylan contains no cross-linking group. The hydrophobic and hydrophilic nature of the xylan gel can be adjusted by modifying the xylan. All of the gels can be dried using different methods (air drying, solvent exchange as well as freeze drying) and the dried gels can again disperse in water. The gels were characterised by porosity measurements (mercury intrusion), dynamic vapour sorption (DVS), scanning electron microscopy (SEM) and dispersion stability investigation respectively.     

The resurgence of Coulter counting for analyzing nanoscale objects

This review discusses recent advances in the science and technology of Coulter counting. The Coulter counting principle has been used to determine the size, concentration, and in favorable cases the surface charge, of nanometer-scale colloidal particles, viruses, DNA and other polymers, and metal ions. A resurgence of interest in the field of COulter counting is occurring because of the advent of new technologies that permit fabrication of membranes containing single, robust, and chemically well-defined channels having smaller and more uniform sizes than could be prepared in the past. These channels are prepared from biological materials, such as self-assembling membrane proteins, and from synthetic materials such as polymers, carbon nanotubes, and silicon-based inorganic materials. In addition to particle characterization, there have been a few recent examples of using Coulter counters to study chemical processes, such as the dehybridization of DNA.     

Synthesis of alpha-D-Galp-(1-->3)-beta-D-Galf-(1-->3)-D-man,a terminal trisaccharide of Leishmania type-2 glycoinositolphospholipids

The synthesis of alpha-D-Galp-(1-->3)-beta-D-Galf-(1-->3)-D-Man, present in the type-2 glycoinositolphospholipids and in the core of the lipophosphoglycan of Leishmania, is described. The glycosyl aldonolactone approach, followed by reduction of the lactone with diisoamylborane, was utilized for the introduction of the internal galactofuranosyl unit and the trichloroacetimidate method for the O-glycosidation reaction. A high-yield synthesis of the beta-D-Galf-(1-3)-D-Man unit, also present in the lipopeptidophosphoglycan of Trypanosoma cruzi, is reported.     

Characterization and electrochemical studies of molybdenum(VI) dioxodialkylbipyridyl complexes. X-ray crystal structure of MoO2(o-MeC6H4CH2)2(bipy)

Summary New Mo^VI-dioxodialkyl complexes, MoO₂R₂(bipy), R = CH₂CH₂Ph and p-MeC₆H₄CH₂; bipy = 2,2-bipyridine, have been synthesized. The i.r. and the ¹H-n.m.r. spectra of these complexes are noted. The structure of MoO₂(o-MeC₆H₄CH₂)₂(bipy) was determined by X-ray analysis. Significant differences in the redox characteristics of these dioxodialkylcompounds are reflected in the contrasting patterns: whereas reduction of MoO₂-(CH₂CH₂Ph) ₂(bipy) is a reversible one-electron process, under similar conditions MoO₂(p-MeC₆H₄CH₂)₂(bipy) and MoO₂(o-MeC₆H₄CH₂)₂(bipy) are reduced irreversibly. Similarly, solutions of MoO₂(CH₂CH₂Ph)₂(bipy) remain unchanged but oxygenated organic products are formed from MoO₂(p-MeC₆H₄CH₂)₂(bipy) and MoO₂ (o-MeC₆H₄CH₂)₂(bipy).