Arylidene imidazothiazoles. Synthesis,structure and benzodiazepine receptor binding

A series of arylidene imidazo[2,1-b]thiazoles was synthesized, in order to investigate the influence of different spatial arrangements of the arylidene substituent towards the bicyclic structure of imidazo[2,1-b]-thiazole on benzodiazepine receptor affinity. 1,2- And 2,3-cyclized derivatives of mono- and di-substituted Z-5-arylidene-2-thiohydantoins were investigated. As an example of E isomers E-5-benzylidene-2,3-dihydroimidazo[2,1-b]thiazol-6(5H)-one was obtained. The spatial arrangement of the arylidene sub stituent toward the bicyclic structure as well as the character of isomers had little influence on the benzo diazepine receptor affinity of the compounds. It seems that the greatest influence on biological activity has the nature and the number of substituents on the phenyl ring. All investigated imidazo[2,1-b]thiazoles were less active than previously described arylidene imidazo[2,1-b]thiazepinones.     

X-ray and high resolution selenium-77 solid state NMR spectroscopy as complementary probes to structural studies of organophosphorus diselenides

high resolution solid state NMR spectroscopy was employed to study structural properties of bis(diisopropoxyphosphorothioyl) diselenide 1 and bis(dineopentoxyphosphorothioyl) diselenide 2. The principal elements T_ii of effective dipolar/chemical shift tensor were calculated from spinning sideband intensities employing the WIN-MAS program. The values of anisotropy and asymmetry parameters reflect the distortion of the selenium environment. It was found that the T₃₃ component mostly contributes to changes in the isotropic chemical shifts. CP/MAS experiments were used to decide the assignment of space group by counting the number of crystallographically unique selenium centers in the unit cell. Crystals of diselenide 1 are triclinic, space group P with a=8.485(3) Å, b=8.508(1) Å, c=8.511(2) Å, =98.835(15)°, β=111.653(24)°, γ=93.524(21)°, V=559.5(3) ų, D_c=1.544(2) g/cm³ and Z=1. Refinement using 2222 reflections for 157 variables gives R=0.037. Crystals of diselenide 2 are triclinic, space group P1 with a=9.1418(8) Å, b=9.1465(8) Å, c=9.9200(9) Å, =74.751(8)°, β=74.629(7)°, γ=82.216(7)°, V=769.7(1) ų, D_c=1.365(2) g/cm³ and Z=1. Refinement using 3316 reflections for 297 variables gives R=0.0272.     

High-energy phonon branches of an individual metallic carbon nanotube

We present excitation-energy dependent Raman measurements between 2.05 and 2.41 eV on the same individual carbon nanotube. We find a change in the Raman frequencies of both the D mode (63 cm(-1)/eV) and the high-energy modes. The observed frequencies of the modes at approximately 1600 cm(-1) as a function of laser-energy map the phonon dispersion relation of a metallic tube near the Gamma point of the Brillouin zone. Our results prove the entire first-order Raman spectrum in single-wall carbon nanotubes to originate from double-resonant scattering. Moreover, we confirm experimentally the phonon softening in metallic tubes by a Peierls-like mechanism.     

Electrophilic properties of nitroheterocyclic compounds. Potential hypoxic cells radiosensitizers

Investigation of the reduction potential and calculation of the partition coefficient n-octanol/water allow the assessment of the potential suitability of nitropirydine N-oxide compounds in radiotherapy of cancer. Experiments were carried out using cyclic voltammetry with HMDE as working electrode. The electrode reduction of the investigated compounds is quite irreversible and strongly dependent on pH.     

固体氧化物燃料电池——材料与前瞻(英文)

本文依据固体氧化物燃料电池(SOFC)于运作条件下的基本性能,诸如化学稳定性、电迁移、催化和热机械性能等评述SOFC组成部分(电极材料和电解质)的基本性质.示明由氧偏离化学计量比引起的电极材料结构缺陷与其电子性质及催化活性之间的相互关系,提出单室燃料电池概念.     

Validation of the Method of Selected Polychlorinated Biphenyls Determination in Human Milk Samples

A method for determination of trace concentrations of individual PCB congeners in human milk was validated. The analytical procedure included the following steps: acetone : hexane extraction, clean-up of extracts with concentrated sulfuric acid and solid phase extraction (SPE) on Florisil. The identification and quantification of analytes in purified extracts were carried out by high-resolution gas chromatography (HRGC) with electron capture detection (ECD) and/or with low-resolution mass spectrometry (LRMS). Recoveries of 14 PCB congeners from spiked cow milk samples, based on HRGC-ECD were between 87.3 and 93.6%. The precision of analyte determination was established as close to or less than 10%. The detection limits ranged between 0.14 and 0.26 ng/g fat and the quantification limits between 0.57 and 0.86 ng/g fat. The method was linear and characterized by good correlation coefficients (>0.99) for most of the compounds studied. The quality of the method under validation was verified by the analysis of Standard Reference Material (CRM-450) and interlaboratory exercise.     

CO Extrusion in Homogeneous Gold Catalysis: Reactivity of Gold Acyl Species Generated through Water Addition to Gold Vinylidenes

Herein, we describe a new gold‐catalyzed decarbonylative indene synthesis. Synergistic σ,π‐activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.     

Copper- or manganese-doped ZnS quantum dots as fluorescent probes for detecting folic acid in aqueous media

3-Mercaptopropionic acid-capped core/shell ZnS:Cu/ZnS and ZnS:Mn/ZnS doped quantum dots (QDs) prepared through hydrothermal methods exhibit high photoluminescence intensity as well as good photostability. These water-dispersible nanoparticles exhibit high fluorescence sensitivity to folic acid due to the high affinity of the carboxylate groups and nitrogen atoms of folic acid towards the Zn surface atoms of the doped dots. Quenching of the fluorescence intensity of the QDs allows the detection of folic acid concentrations as low as 11 μM, thus affording a very sensitive system for the sensing of this biologically active molecule in aqueous solution. The possible quenching mechanism is discussed.