Cu(I) catalyst in DMF: an efficient catalytic system for the synthesis of furans from 2-(1-alkynyl)-2-alken-1-ones

The cyclization of 2-(1-alkynyl)-2-alken-1-ones 1 proceeded very smoothly in the presence of alcohols 2 with a catalytic amount of Cu(I)Br in DMF at 80 degrees C, leading to the formation of highly substituted furans 3. The catalytic system reported herein is easy to handle, compared to the previously known system wherein the reaction between 1 and 2 needed to use moisture sensitive gold(III) chloride.     

Effect of Pyrophosphate Ions on the Mechanism of Discharge–Ionization of Copper in Acid Sulfate Solutions

The acceleration of the electrodeposition and anodic dissolution of copper in acid sulfate solutions, caused by sodium pyrophosphate, is found to be due to a chemical heterogeneous stage, which involves an adsorbed pyrophosphate ion (probably, H₂P₂O₇ ^2–). The assumption about the presence of a surface complex on the surface of copper is substantiated. As follows from adsorption isotherms, obtained for strongly acid (to 2 M H₂SO₄) solutions from anodic Tafel plots, the effect of the acid concentration on the rate of the discharge–ionization of copper is caused by its effect on the surface coverage by the adsorbate. Measurements of the quasi-equilibrium potential of the freshly renewed surface of copper confirm the assumption about the inhibiting of the surface diffusion of adsorbed atoms by adsorbed pyrophosphate.     

EPR spectroscopy and polarography of nitroazoles. 3. Nitropyrazoles

The results of an EPR investigation are presented with polarographs of electrochemical excitation of nitropyrazoles in acetonitrile. It is shown that 3- and 4-nitropyrazoles are excited in two single-electron stages with formation of dianion radicals. Upon excitation, N-alkylnitropyrazoles form stable anion radicals. 1-Nitro- and 1,4-dinitropyrazoles are excited upon splitting off of the NO₂ anion. Excitation potentials of the nitropyrazoles and hyperfine interaction constants for the corresponding ion radicals are given.See [1] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 523–527, April, 1982.     

Simultaneous determination of cefazolin in rat blood and brain by microdialysis and microbore liquid chromatography

A sensitive microbore liquid chromatographic method combined with the minimally invasive technique of microdialysis was devised for simultaneously and continuously monitoring the levels of unbound blood and brain cefazolin in rats. Microdialysis probes were inserted into the jugular vein and brain striatum for blood and brain sampling, respectively. Chromatographic conditions consisted of a mobile phase of methanol-acetonitrile-100 mM monosodium phosphoric acid (20:10:70, v/v, pH 4.5) pumped through a microbore reversed-phase column at a flow rate of 0.05 mL/min. The ultraviolet detection wavelength was set at 270 nm. An on-line design allowed direct and continuous analysis of protein-free samples in the dialysate. Microdialysis probes, being home-made, were screened for acceptable in vivo recovery. Chromatographic resolution and detection were validated for response linearity as well as intra-day and inter-day variabilities. This method was then applied to pharmacokinetic profiling of protein unbound cefazolin in both the blood and brain following intravenous administration (10 mg/kg, i.v., n = 6). Rapid appearance of cefazolin in the rat brain striatal dialysate following drug injection suggested good blood-brain barrier penetration. According to a non-compartmental pharmacokinetics model, the area under the concentration (AUC) vs time ratio of cefazolin in rat brain and blood was 6%.     

Protein profiling of rat cerebella during development

Protein profiles of developing rat cerebella were analyzed by means of two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). The analysis of adult rat cerebellum gave rise to a protein map comprising approximately 3000 spots detectable by silver staining following high resolution 2-DE with a pH range of 3-10 and a mass range of 8-100 kDa. To obtain landmarks for comparison of developmental profiles of cerebellar proteins, 100 spots were subjected to peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and 67 spots were assigned on the map. Analysis of profiles of the developing cerebella revealed significant changes in the expression of proteins during development. In most cases the expression levels of proteins increased as the cerebellum matured, while the expression of 42 spots appeared specific or remarkably abundant in the immature cerebellum. Peptide mass fingerprinting of these spots allowed us to identify 29 proteins, which include, in addition to proteins of unknown function, many proteins known to have roles in the development of the central nervous system. These results suggest that the proteomic approach is valuable for mass identification of proteins involved in cerebellar morphogenesis.     

Plasma-Enhanced Chemical Vapor Deposition of Silicon Carbonitride Films from Volatile Silyl Derivatives of 1,1-Dimethylhydrazine

Silicon carbonitride films were synthesized from new volatile precursors by plasma-enhanced chemical vapor deposition. Based on a detailed study of the morphology of film surfaces, it was found that the layer material was an amorphous matrix with inclusions of nanosized crystals. Calculation of the structure of the crystalline phase from synchrotron X-ray diffraction patterns demonstrated that the entire set of the diffraction peaks detected is indexed by a tetragonal structure with the lattice parameters a = 9.6 Å and c = 6.4 Å. This is consistent with the fact that the carbon 1s and nitrogen 1s core level X-ray photoelectron spectra exhibited only sp ³ bonding, which was expected for superhard carbon nitride phases.     

Tetraphenylbismuth 2,4-Dimethylbenzenesulfonate: Synthesis and Structure

Tetraphenylbismuth 2,4-dimethylbenzenesulfonate was synthesized by reacting pentaphenylbismuth or bromine with diphenylbismuth 2,4-dimethylbenzenesulfonate and its structure was established using X-ray diffraction analysis. The Bi atom has a distorted trigonal bipyramidal coordination. The Bi–C bond lengths are equal to 2.199(4)–2.227(4) Å the Bi–O distance and axial CBiO angle are equal to 2.665(3) Å and 174.2(1)°, respectively.     

Migration of 99Tc in a Weak Loess Aquifer: A Field Column Experiment

The migration of ⁹⁹Tc in a weak loess aquifer was investigated in-situ with undisturbed aquifer medium columns. The columns were obtained horizontally at a depth of 3236 m in an Underground Research Facility (URF). Quartz containing ³H (HTO) and ⁹⁹Tc (in the form of ⁹⁹TcO₄ ^-) was introduced into one end of the columns and the columns were covered tightly. Aquifer water was introduced into the columns directly from an experimental shaft in the UFR. Effluents from the columns were collected and the activity of ³H and ⁹⁹Tc were determined with a liquid scintillation analyzer. The breakthrough curves of ³H and ⁹⁹Tc indicate that ⁹⁹Tc migrates a little faster than that ³H does in the aquifer.     

Diverse redox-active molecules bearing O-, S-, or Se-terminated tethers for attachment to silicon in studies of molecular information storage

A molecular approach to information storage employs redox-active molecules tethered to an electroactive surface. Attachment of the molecules to electroactive surfaces requires control over the nature of the tether (linker and surface attachment group). We have synthesized a collection of redox-active molecules bearing different linkers and surface anchor groups in free or protected form (hydroxy, mercapto, S-acetylthio, and Se-acetylseleno) for attachment to surfaces such as silicon, germanium, and gold. The molecules exhibit a number of cationic oxidation states, including one (ferrocene), two [zinc(II)porphyrin], three [cobalt(II)porphyrin], or four (lanthanide triple-decker sandwich compound). Electrochemical studies of monolayers of a variety of the redox-active molecules attached to Si(100) electrodes indicate that molecules exhibit a regular mode of attachment (via a Si-X bond, X = O, S, or Se), relatively homogeneous surface organization, and robust reversible electrochemical behavior. The acetyl protecting group undergoes cleavage during the surface deposition process, enabling attachment to silicon via thio or seleno groups without handling free thiols or selenols.     

Polymeric Formulations Based on Iron and Cobalt Molybdophosphates and Polyacrylates

The possibility of using synthesized iron(III) and cobalt(II) molybdophosphates as dyes in dyeing of copolymers and polymeric formulations based on methacrylic acid and methyl methacrylate and also as pigments deposited onto natural and inorganic supports for heterogeneous dyeing of polymeric materials was studied.