Raman scattering from Pt(CN)42− adsorbed on Pt colloids

Raman scattering from Pt(CN)₄^2? adsorbed on Pt colloids (average diameter of 16 A) is compared with the Raman signal from the same amount of Pt(CN)₄^2? in solution. The wavelength dependence of the adsorbate Raman intensity is measured from 308 to 647 nm and compared with a Lorenz/Mie calculation of the enhancement factor for the electromagnetic field intensity on the surface of a Pt sphere as a function of sphere radius and incident wavelength.     

Equilibrium studies of Mn(II), Mg(II), Ca(II), Sr(II) and Ba(II) withp-fluoro-,p-chloro-,p-bromo-,p-methyl-benzoylacetones and 1-(4-fluorophenyl)-1,3-pentanedione

The rawpH-data, obtained from the potentiometric titrations of the titled ligands with NaOH in 75% (v/v) dioxane-water mixture performed at 20, 30 and 40°C at constant ionic strength (=0.1M-NaClO₄), have been adequately corrected for dilution, and solvent effects in order to evaluate thermodynamic dissociation constants. Variance of the latter as a function of temperature has also been accounted for. The differing magnitudes of thermodynamic dissociation constants of the titled ligands have been explained on the basis of the non coplanar orientation of the phenyl ring in the ligands and a comparison has been made with those of unsubstituted benzoylacetone, dibenzoylmethane and acetylacetone.Following similar technique, thermodynamic stepwise and overall formation constants of the titled metal-ligand systems have been obtained and the results correlated with ligand basicity inverse metal crystal radii and second potentials of metals. Decrease in the free enthalpy (–G) of complexation reaction has also been evaluated.

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Untersuchung der Gleichgewichte von Mn(II), Mg(II), Ca(II), Sr(II) und Ba(II) mit p-Fluor-, p.-Chlor-, p-Brom-, p-Methyl-benzoylaceton und 1-(4-Fluorphenyl)-1,3-pentanedion

Zusammenfassung Aus der potenitometrischen Titration der Titelverbindungen mit NaOH in 75 (v/v) Dioxan—Wasser bei, 20, 30 und 40°C bei konstanter Ionenstärke (=0,1M-NaClO₄) wurden die thermodynamischen Dissoziationskonstanten ermittelt. Verdünnungs-, Lösungsmittel-und Temperatureffekte wurden berücksichtigt. Die unterschiedlichen Dissoziationskonstanten werden mit der Nichtplanarität des Phenylrings in den Liganden erklärt. Außerdem wurden die Komplexbildungskonstanten bestimmt; sie sind in die Diskussion miteinbezogen.

     

Synthesis and transformations of metallacycles. 23. Cp2TiCl2-Catalyzed cyclometallation of fullerene C60 with EtAlCl2

1-Ethyl-2,3-fullerenoaluminacyclopropanes (EtAl)_n(²-C₆₀) were synthesized by the reaction of fullerene C₆₀ with an excess of EtAlCl₂ in the presence of Mg and using Cp₂TiCl₂ as the catalyst in a THF--toluene solution at 20 °C. Deuterolysis of fullerenoaluminacyclopropanes afforded a mixture of deuteriofullerenes C₆₀D_m, where m = 6--12.     

Supramolecular structures of macromolecules containing bipyridine–copper(I) complexes as revealed from transmission electron microscopy studies

Transmission electron microscopy (TEM) studies on bipyridine (bpy) containing block copolymer systems showed the formation of nanoscopic polymer–ion complexes through complexation with copper(I) ions which segregated to highly ordered columnar domains of mesoscopic dimensions. The domains, i.e. stacks of [(bpy)₂Cu(I)] complex moieties could be visualized by complementary TEM techniques. First, electron energy loss spectra (EELS) showed the absorption edges of copper and nitrogen, which are specific for the bipyridine copper complexes. The element spectroscopic imaging (ESI) technique allowed the imaging of the net copper and net nitrogen distribution, and the coinciding pictures exhibited a microphase separated system in the case of a 3-block copolymer with complexed end segments. High resolution elastic bright field images showed interference lines with a line to line distance of about 8 A which could be related to the Cu–Cu distance in staggered Cu(I)–bipyridine complexes. Received: 6 August 1997 Accepted: 28 April 1998     

Copolymer of Di (methacryloyloxymethyl) naphthalene and divinylbenzene as a column packing for high-performance liquid chromatography

Summary A new porous polyaromatic ester packing was synthetized for high performance liquid chromatography. The relationship between retention and chain length of the members of homologous series of alkylbenzenes, N-alkylanilines, alkylarylethers, alkylbenzoates and alkylarylketones on this new stationary phase using different eluents was investigated. Using the alkylarylketone scale the retention indices of the homologues and test compounds were calculated. The results were compared with those obtained for poly (styrene-divinylbenzene) polymers. For both types of packing the first members of each homologous series gave non-linear behaviour. The methylene group index increments are different for the studied homologous series; thus there is no simple additivity of the retention indices. The efficiency of the porous polymeric columns is a function of the capacity factor of the solute and the organic component of the eluent.     

Molecular aggregation in the ternary system deca glycerol dioleate/heptane/water

The phase diagram for the ternary system deca glycerol dioleate(DGD)/heptane/water was established at 25 °C. In this phase diagram it was seen that the reverse micellar solution phase extends in its area until the water content reaches 35–45 wt%, at which a liquid crystalline phase begins to appear. On the basis of the experimental results of specific conductivity, viscosity, etc. for the samples containing a definite amount of DGD (0,1 M), and varying relative amounts of heptane and water, the mechanism of the transition of reverse micellar structures to liquid crystalline phase is discussed.     

Photometric determination of malathion with molybdenum

A photometric method for the determination of malathion is described. Malathion dissolved in carbon tetrachloride is hydrolysed at room temperature with sodium ethoxide to dimethyl dithiophosphate (DMDTP) and fumarate. The DMDTP is converted into a molybdenum-DMDTP complex and determined spectrometrically.     

Composition and inhibiting action of a fraction of secondary metabolites from cotton plant leaves

The qualitative and quantitive compositions of fractions from the leaves of two self-pinching-out lines of cotton plant and of the standard variety 108-F have been determined in parallel by mass chromatography, and differences in their contents of the main metabolites have been determined. A fraction of the secondary metabolites (SMs) obtained from mature leaves of a cotton plant of the self-pinching-out line L-49 has shown a retardant activity in treatment of the growth points of plants of the Tashkent-1 variety. Deceased.