Synthesis and Reactivity of a Strained Silicon‐Bridged [1]Ferrocenophanium Ion

Not blue but red‐brown : A [1]ferrocenophanium ion has been synthesized and isolated as a red‐brown crystalline salt, surprisingly different in color from characteristically blue‐green unstrained ferrocenium ions. Compared to the neutral iron(II) counterpart, the [1]ferrocenophanium ion displays a considerably higher ring tilt and an increased propensity for ring‐opening reactions.

     

Synthesis and optical properties of new polyurethane cationomers with anchored stilbene chromophores

An ionic diol bearing a one‐sided urethane‐stilbene group located on the ammonium quaternary structure was prepared and proposed as an intermediate for polyurethane ionomer synthesis. Polyurethane cationomers with stilbene ionic groups based on poly(tetramethylene oxide) diols, 4,4′‐diphenylmethane diisocyanate and the aforementioned ionic diol, were synthesized and characterized. Some aspects of the trans–cis photoisomerism and fluorescent emission of the stilbene chromophore in polyurethane cationomers were studied comparatively with the urethane‐stilbene diol. The stilbene polycations absorbed at λ_A = 316 nm and emitted violet‐blue light with an emission maxima at λ_F = 444 nm (dimethylformamide solution) and λ_F = 465 nm (film). These polymers are known for their elastomeric properties and are assumed to be of great interest for some future applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1918–1928, 2002     

Potentiometric microanalysis of soaps and mixtures of soaps with anionic surfactants

Summary An attempt was made to find a method for potentiometric titration of soaps and mixtures of soaps and anionic surfactants. A liquid-membrane electrode based on bis(dimethylglyoxime)-l,10-phenanthrolinecobaltate(III) dodecyl sulphate was used. The effects of pH, ionic strength, and temperature on the titration were studied.

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Zusammenfassung Eine Methode zur potentiometrischen Titration von Seifen und Gemischen von Seifen und anionischen Schaummitteln wurde auszuarbeiten versucht. Eine Flüssigmembran-Elektrode aus Bis-(dimethylglyoxim)-l,10-phenanthrolincobaltat(III)-Dodecylsulfat wurde dazu verwendet. Die Wirkung von pH, lonenstärke und Temperatur auf die Titration wurden untersucht.

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Paper presented at the International Symposium on Microchemical Techniques, Davos, May 1977.     

13C NMR and infrared evidence of a dioctyl-disulfide structure on octanethiol-protected palladium nanoparticle surfaces

On 13C1-labeled octanethiol-protected 2.7 nm Pd nanoparticle surfaces, it has been observed that the 13C1 NMR of the alpha-carbon shows a peak centered around 38 ppm (with respect to tetramethylsilane (TMS)), which virtually coincides with that of the alpha-carbons in a dioctyl-disulfide molecule (39.3 ppm), and the corresponding 13C1 spin-spin relaxation becomes nonexponential. In addition, the infrared spectrum of the same sample shows that the ligands have a 100% gauche conformation, which is also consistent with a dioctyl-disulfide arrangement. By comparing with data obtained on 13C1-labeled octanethiol-protected 2.8 nm Au nanoparticles, we propose that a dioctyl-disulfide structure of the ligands is formed on the octanethiol-protected Pd nanoparticle surface, in contrast to the thiolate structure proposed on the Au nanoparticles. In addition, CO adsorption experiments show no sign of a PdS layer formed on the Pd nanoparticle surface. Furthermore, data taken over a period of more than 1 year show that the Pd nanoparticles are rather stable in organic solvents (for instance benzene), although slow degradation does happen and oxygen seems to play an important role in accelerating the degradation.     

Dilute solutions of polyelectrolytes—IV. Unperturbed dimensions of N,N-diethylacrylamide-N,N-dimethyldiallylammonium chloride copolymers

The behaviour of copolymers of N,N-diethylacrylamide with N,N-dimethyldiallylammonium chloride in aqueous NaCl solution has been studied by light-scattering. The parameters characterizing the short- and long-range interactions have been calculated. The influence of copolymer composition on the gyration radius and unperturbed dimensions shows that the macromolecules have maximum flexibility for a composition near equimolar. This behaviour was attributed to decrease of both the electrostatic repulsions and the steric hindrance of the structural units, as a result of pronounced alternation.     

Stabilization of solid/liquid suspensions

The stability of colloidal graphite dispersions was investigated. A mixed stabilizer (CELAD) consisting of a non-ionic cellulose derivative and an anionic polymer was used to facilitate the grinding process and to stabilize the aqueous dispersions. Measurements of turbidity, ultramicroscopy and scanning electron microscopy were carried out to determine the size of the particles. Adherent films were obtained by spraying the dispersions onto glass plates. The 20 μm thick films had an electrical resistance within the 20–40 Ω cm range. They proved to be suitable for spray application onto the exernal glass cone of cathode ray tubes.     

Simultaneous Determination of 4‐Chlorophenol and Oxalic Acid Using an Expanded Graphite‐Epoxy Composite Electrode

An expanded graphite‐epoxy composite electrode (EG‐Epoxy) was employed for the simultaneous determination of 4‐chlorophenol (4‐CP) and oxalic acid (OA) by using cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV). The results indicated that OA could be determined in the presence of the same concentrations of 4‐CP within the concentration range of 0.1 mM to 0.5 mM with a relative standard deviation (RSD) smaller than 5%. Electrode fouling occurred during CA for 4‐CP concentrations larger than 0.5 mM. The DPV method was used for the simultaneous determination of 4‐CP and OA before and after electrochemical oxidation by chronopotentiometry under galvanostatic conditions (j=0.04 mA cm^?2, t=2 h) of a tap water sample spiked with 0.19 mM 4‐CP and 0.1 M Na₂SO₄.     

A study of the interaction of natural polymers — surfactants I. International of catalase (EC 1.11.1.6) with ionic surfactants

Summary Catalase interaction with anionic type (sodium laurate and sodium dodecylsulfate) and cationic type (dodecylpyrimidinium chloride) surfactants was investigated. Viscosity, electric conductivity, enzyme activity and kinetics depend on surfactant concentration. Corroborating data demonstrate the existence of interaction between catalase and anionic surfactants. Results were interpreted in the terms of non-polar interactions, taking into account both the physicochemical properties of surfactants in aqueous solutions and the better known structure of haemic proteins (haemoglobin) similar to catalase.

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Zusammenfassung Die Interaktion der Katalase mit anionischen (Natriumlaurinat und Natriumdodezylsulfat) und kationischen (Dodezylpyrimidiniumchlorid) Tensiden wurde untersucht, indem die Variation der Viskosität, der elektrischen Leitfähigkeit, der Enzymaktivität und-kinetik in Abhängigkeit von der Tensidkonzentration beobachtet wurden. Gegenseitig sich bekräftigende Angaben weisen auf das Vorhandensein von Interaktionen zwischen Katalase und den untersuchten anionischen Tensiden hin. Die Ergebnisse wurden unter Annahme nichtpolarer Interaktionen und unter Berücksichtigung der physiko-chemischen Eigenschaften der Tenside in Wasserlösungen sowie der Struktur Katalase-ähnlicher Haem-Proteine (Hämoglobin) gedeutet.

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With 4 figures and 1 table     

Beiträge zum Studium einiger Heterocyclen. XLIV—Massenspektrometrische Untersuchungen einiger 2-(p-X-Phenyl)-5-Y-4-acetylthiazole

The fragmentation under eletron impact of some new 2-phenyl-4-acetyl-thiazoles has been studied. The compounds investigaed exhibit molecular ion peaks. Substituents in the para position of the bensene ring do not influence the fragmentation patterns but only the relative abundances of the molecular ion and some fragment ions. However, by introdicing CI and Br in position 5 of the thiazole some signifiecant differences appear (‘ortho effect’). A rearrangement also occurs involving a 5-membered cyclic transition state. Intense doubly charged ions are obseved a fact which is attributed to the presence of two easily ionizable centres.     

Magnetic and optical properties of Cu(II)-bis(oxamato) complexes: combined quantum chemical density functional theory and vibrational spectroscopy studies

Vibrational spectroscopies are shown to be highly sensitive to the structural modifications of paramagnetic mono- and trinuclear Cu(II)-bis(oxamato) complexes. The vibrational bands are assigned using density functional theory (DFT) calculations. Moreover, Raman spectroscopy investigations for different temperatures of thin films show that the onset of superexchange interactions at low temperatures does not involve a modification of the structural parameters. The influence of packing effects, however, on the magnetic properties is significant, as demonstrated by means of DFT using the broken symmetry approach.