Neoglycopeptide dendrimer libraries as a source of lectin binding ligands

[structure: see text] A 15 625-membered peptide dendrimer combinatorial library was acylated with an alpha-C-fucosyl residue at its four N-termini and screened for binding to fucose-specific lectins. Dendrimer FD2 (Fuc-alpha-CH2CO-Lys-Pro-Leu)4(Lys-Phe-Lys-Ile)2Lys-His-Ile-NH2 was identified as a potent ligand against Ulex europaeus lectin UEA-I (IC50 = 11 microM) and Pseudomonas aeruginosa lectin PA-IIL (IC50 = 0.14 microM).     

General method for ultrathin free-standing films of nanofibrous composite materials

A simple and general method for the preparation of ultrathin, large-area, free-standing films of nanofibrous composite materials was developed. First, positively charged cadmium hydroxide nanostrands of 1.9 nm in diameter and micrometers in length were prepared by mixing dilute aqueous solutions of cadmium chloride and aminoethanol. Negatively charged dye molecules, proteins, nanoparticles, and water-soluble fullerene or carbon nanotubes were mixed with the nanostrands to give a well-dispersed solution of the corresponding nanofibrous composites. After filtration of the dispersions with a polycarbonate membrane filter, uniform films with a thickness of a few tens to hundreds of nanometers and a diameter of a few centimeters were obtained. The films were readily peeled off from the membrane filter by immersion in ethanol. The resultant free-standing films could be further transferred to other substrates, such as quartz plate, gold electrode, and porous alumina membrane, and were characterized by scanning and transmission electron microscopies. We provide herein various nanofibrous free-standing films with optical, biological, metallic, and magnetic properties.     

A method of test for residual isophorone diisocyanate trimer in new polyester-polyurethane coatings on light metal packaging using liquid chromatography with tandem mass spectrometric detection

A method of test for residual isophorone diisocyanate (IPDI) trimer in experimental formulation polyester-polyurethane (PEPU) thermoset coatings on metal food packaging is described. The method involves extraction of coated panels using acetonitrile containing dibutylamine for concurrent derivatisation, and then high performance liquid chromatography with electrospray ionisation tandem mass spectrometric detection (LC-MS/MS). Single laboratory validation was carried out using three different experimental PEPU-based coatings. The calibrations were linear, the analytical recovery was good, no interferences were seen, and substance identification criteria were met. The detection limit of the method is around 0.02 micro g/100 cm(2) of coating, which for a typical sized can and assuming complete migration of any residual IPDI trimer, corresponds to about 0.2 micro g/kg food or beverage. Separate studies indicated that, even if migration occurred at such low levels, the IPDI trimer would not be expected to persist in canned aqueous or fatty foodstuffs as it would hydrolyse to the corresponding aliphatic amine or react with food components to destroy the isocyanate moiety. The method of test developed here for residual IPDI trimer in thermoset polyester-polyurethane coatings should prove to be a valuable tool for investigating the cure kinetics of these novel coatings and help to guide the development of enhanced formulations.     

Asymmetric alpha-alkynylation of piperidine via N-sulfinyliminium salts

Piperidine was stereoselectively alpha-alkynylated in a four-step sequence made up of transformation to a chiral nonracemic N-sulfinylpiperidine, anodic oxidation to N-sulfinyliminium ion equivalent, alkynylation through addition of a mixed organoaluminum derivative, and final acidic deprotection of the sulfoxide. Overall yields are around 50%, and the diastereoselectivity of the nucleophilc addition was between 92 and 99% de, allowing isolation of the final product with 99% enantiomeric purity.     

Vorsprung durch Chemie

The German Chemical Society (GDCh) and the Royal Society of Chemistry (RSC) have worked closely together for many years. David Giachardi, chief executive of the RSC, and Wolfram Koch, GDCh's chief executive, discuss the issues faced by the societies today.     

Synthesis of thermotropic liquid crystalline all-Trans-p-Phenylenevinylene oligomers via two-step metathesis

Liquid crystalline products of oligomeric p-phenylenevinylene derivates were prepared metathetically using a stable molybdenum carbene complex (Mo(NAr^Me₂)(CHCMe₂Ph)[OCMe(CF₃)₂]₂). The synthesis was conducted via two steps: 1. Metathesis polycondensation of 2, 5-dialkyl-1, 4-divinylbenzenes to oligo-(2, 5-dialkyl-1, 4-phenylenevinylene)s, 2. Endcapping of the vinyl groups via cross-metathesis using 3-hexene. The products were characterized by¹H-NMR and UV/Vis spectroscopy, as well as by DSC.     

Surface chemical studies of the influence of In and Al on the decomposition of TEG on GaAs(100)

The interaction of triethylgallium (TEG) with the Ga-stabilized GaAs(100) surface in the presence of In and Al has been investigated using AES (Auger electron spectroscopy), HREELS (high resolution electron energy loss spectroscopy) and TDS (thermal desorption spectroscopy) techniques. Al is shown to greatly increase the saturation surface coverage of TEG on the surface and to suppress the desorption of TEG and diethylgallium (DEG). Etching of the surface Al by TEG is observed, resulting in the formation of gas phase Al organic species. Alkyl migration from GA to Al centres occurs, and the presence of Al substantially enhances the irreversible deposition of C. In is found to enhance DEG desorption and to lower the temperature at which absorbed ethyl groups decompose to gas phase ethene. Computer modelling has been carried out to extract kinetic parameters from measured thermal desorption spectra. These parameters are then used to calculate expected partial growth rates of GaAs during the growth of Ga_xAl_1−xAs and Ga_xIn_1−xAs using TEG. The data provide a molecular level understanding of the GaAs pa rtial growth rate variations arising during the deposition of III–V ternary materials.