Über Chalkogenolate. 161. Umsetzung von 1,2-Ethandithiolaten mit Kohlenstoffdisulfid 3. Kristall- und MolekülStruktur von 1,2-Ethan-bis(methyltrithiocarbonat)

On Chalcogenolates. 161. Reaction of 1,2-Ethanedithiolates with Carbon Disulfides. 3. Crystal and Molecular Structure of 1,2-Ethane-bis(methyltrithiocarbonate) The title compound H₃CS? CS? SCH₂CH₂S? CS? SCH₃ crystallizes with Z = 2 in the triclinic space group P1 with cell dimensions a = 6.769(1) Å, b = 8,334(2) Å, c = 11.222(1) Å, α = 80.93(1)°, β = 72.01(1)°, γ = 78.58(2)°. The crystal structure has been determined from single crystal X-ray data measured at ?40°C and refined to a conventional R of 0.035 for 2004 independent reflections (R_w = 0.042). The structure consists of isolated molecules, which are linked together by weak interaction forces. The S? CS? S groups are plane.     

Fluorescence Assay Based on Aptamer-Quantum Dot Binding to <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> Spores

A novel assay was developed for the detection of Bacillus thuringiensis (BT) spores. The assay is based on the fluorescence observed after binding an aptamer-quantum dot conjugate to BT spores. The in vitro selection and amplification technique called SELEX (Systematic Evolution of Ligands by EXponential enrichment) was used in order to identify the DNA aptamer sequence specific for BT. The 60 base aptamer was then coupled to fluorescent zinc sulfide-capped, cadmium selenide quantum dots (QD). The assay is semi-quantitative, specific and can detect BT at concentrations of about 1,000 colony forming units/ml.     

An Alternative to the Sandmeyer Approach to Aryl Iodides

Iodoarenes are important synthons for a wide range of organic transformations. Here we report a general strategy to prepare singly iodinated electron‐rich aromatic compounds through the intermediacy of diaryliodonium salts. This process, which incorporates a phase separation that greatly simplifies product purification, is an attractive replacement for the Sandmeyer approach to iodoarenes that are otherwise difficult to access.     

Synthesis and surface characterization of heparin-immobilized polyetherurethanes

Novel poly(ether urethanes) containing diester groups in the side chains (PU) were synthesized from 4,4′-diphenylmethyl diisocyanate, polytetramethylene glycol, and diethyl bis(hydroxymethyl)malonate as a chain extender. The surface modification of the PU film was carried out by a hydrolysis reaction, poly(ethylene oxide) (PEO) grafting, and heparin immobilization, and the surface-modified PUs were then characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), and a contact angle goniometer. The concentration of carboxylic acid groups introduced on the PU surfaces as determined by the rhodamine interaction method was 61 nmol/cm² when treated with 4N NaOH/methanol (1 : 2 v/v) for 30 min and subsequently with a citric acid–methanolic aqueous solution. The amounts of heparin coupled to the carboxyl groups on the PU surfaces and to the terminus amino groups on the PU-PEO were 0.92 and 0.84 μ g/cm², respectively. There was almost no heparin released from the immobilized surface of a physiological solution for 100 h, thereby indicating the strong stability of immobilized heparin. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2331–2338, 1998     

SYNTHESIS AND CHARACTERIZATION OF HYDROPHOBIC-HYDROPHILIC MULTIBLOCK COPOLYMERS FOR BIOMEDICAL APPLICATIONS*

The synthesis and characterization of amphiphilic copolymers of poly(dimethyl siloxane)(PDMS),poly(ethylene oxide)(PEO), and heparin(Hep) were investigated. These multiblock copolymers wereidentified using ~1H-NMR, FTIR, end group analysis, and sulfur elemental analysis. The multiblockcopolymers were characterized by using DSC and X-ray diffractometry. The glass transition temperature,crystalline melting characteristics, annealing effect, and cold crystallization of the block copolymers weredetermined by DSC. The crystallinity of the block copolymers was also determined by X-ray diffractionmethod.     

A new paramagnetic center in ZnGeP2

An unusual E.P.R. signal is observed in as grown samples of ZnGeP₂. The defect concentration is $\text{?0.5 × 10}{}^{\mathrm{?5}}\text{(}\text{2 × 10}{}^{17}\text{cm}{}^3\text{)}$. The g-values are g_ζζ = 2.04, g_νν = 2.08 and g_ξξ = 2.00. The observed splittings are attributed to hyperfine interaction with two phosphorus ions. The hyperfine tensor, A, is extraordinarily anisotropic.