(CH3)3SiCP,ein silylfunktionelles phospha-alkin

Thermal (CH₃)₃Si-elimination from [(CH₃)₃Si]₂CPCl yields quantitatively the corresponding silylfunctional title compound, which falls in the scale of stability of the up to now known phospha-acetylenes.     

Investigating cyclic peptides inhibiting CD2–CD58 interactions through molecular dynamics and molecular docking methods

The CD2–CD58 protein–protein interaction is known to favor the recognition of antigen presenting cells by T cells. The structural, energetics, and dynamical properties of three known cyclic CD58 ligands, named P6, P7, and RTD-c, are studied through molecular dynamics (MD) simulations and molecular docking calculations. The ligands are built so as to mimic the C and F β-strands of protein CD2, connected via turn inducers. The MD analyses focus on the location of the ligands with respect to the experimental binding site and on the direct and water-mediated hydrogen bonds (H bonds) they form with CD58. Ligand P6, with a sequence close to the experimental β-strands of CD2, presents characteristics that explain its higher experimental affinity, e.g., the lower mobility and flexibility at the CD58 surface, and the larger number and occurrence frequency of ligand-CD58 H bonds. For the two other ligands, the structural modifications lead to changes in the binding pattern with CD58 and its dynamics. In parallel, a large set of molecular docking calculations, carried out with various search spaces and docking algorithms, are compared to provide a consensus view of the preferred ligand binding modes. The analysis of the ligand side chain locations yields results that are consistent with the CD2–CD58 crystal structure and suggests various binding modes of the experimentally identified hot spot of the ligands, i.e., Tyr86. P6 is shown to form a number of contacts that are also present in the experimental CD2–CD58 structure.     

Evaluation of texture parameters in NdFeB magnets by means of X-Ray and magnetic measurements

NdFeB samples of different texture degree were prepared by uniaxial pressing in a magnetic field of different strength. Afterwards, the texture formation was investigated by means of X-ray diffraction. Usually, a fibre texture with the basal plane (001) perpendicular to the applied magnetic field is expected from the used compaction process. However, by introducing a two-parameter Gauss-function describing the texture, deviations from the rotational symmetry of the texture are found. The texture parameters are compared with those obtained by a fit of demagnetization curves. Knowing the intrinsic magnetic properties of the investigated material, demagnetization curves in the first quadrant of the J-H-plane can be calculated on the basis of the texture parameters.Dedicated to Professor Dr. rer.nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Application of adsorptive stripping voltammetry (AdSV) for the analysis of trace metals in brine

Summary Routine analysis of brine for trace metals is important for safe and economical production in the alkali chloride electrolysis. As opposed to many spectroscopic techniques, trace metal determination by adsorptive stripping voltammetry (AdSV) is shown to be performed directly in brine. With minimal sample preparation chromium(VI), iron(III), nickel(II), cobalt(II), titanum(IV), manganese(II), molybdenum(VI) and vanadium(V) can be determined within minutes. The influence of parameters such as pH-value, supporting electrolyte solution, concentration of complexing reagents and possible interferents are investigated for optimal experimental conditions. Minimum detection limits are less than 5 ng/g for all trace metals except 1 ng/g for chromium(VI), cobalt(II) and molybdenium(VI) for 40 s adsorption periods with precisions of better than 7%. AdSV with linear or differential pulse scan is discussed.     

Water‐Soluble Triarylborane Chromophores for One‐ and Two‐Photon Excited Fluorescence Imaging of Mitochondria in Cells

Three water‐soluble tetracationic quadrupolar chromophores comprising two three‐coordinate boron π‐acceptor groups bridged by thiophene‐containing moieties were synthesised for biological imaging applications. Compound 3 containing the bulkier 5‐(3,5‐Me₂C₆H₂)‐2,2′‐(C₄H₂S)₂‐5′‐(3,5‐Me₂C₆H₂) bridge is stable over a long period of time, exhibits a high fluorescence quantum yield and strong one‐ and two‐photon absorption (TPA), and has a TPA cross section of 268 GM at 800 nm in water. Confocal laser scanning fluorescence microscopy studies in live cells indicated localisation of the chromophore at the mitochondria; moreover, cytotoxicity measurements proved biocompatibility. Thus, chromophore 3 has excellent potential for one‐ and two‐photon‐excited fluorescence imaging of mitochondrial function in cells.