Liquid structure of vanadium tetrachloride from neutron diffraction study

Assuming the separation of the intermolecular scattering function into the radial and angular parts and using Egelstaffet al’s orientational model for tetrachlorides, the structure of liquid vanadium tetrachloride has been studied. It has been observed that such a separation is approximate for this liquid and the introduction of a third correction term is required to account for the molecular structure function. The chlorine-chlorine partial structure and effective angleaveraged intermolecular chlorine-chlorine potential in the liquid has been evaluated. Without taking the third correction term, introduced to generate theoretically the molecular structure function, the centre structure function has been obtained in an approximate way from the experimentally observed molecular structure function and from it the centre radial distribution function, centre direct correlation function and the angle-averaged vanadium-vanadium effective potential has been evaluated.     

Isopoly-molybdic acids

From the measurements of conductivity, diffusion coefficient etc., Jander indicated the presence of several isopoly-anions of molybdenum under different pH conditions. He and subsequent workers in the field dealt with solutions only. In the present work one free molybdic acid, and one ammonium acid molybdate were isolated in solid condition at pH 4.6 and 2. On analysis, their compositions were found to be H₄Mo₃O₁₁ and NH₄H₅Mo₆O₂₁ (or (NH₄)₂H₄Mo₇O₂₄) respectively.     

Inter-ring rotational potential of biphenyl and its effect on poly(p-phenylene)

Detailed ab initio studies have been done on the inter-ring torsional states of the biphenyl molecule using self-consistent field molecular orbital method. The potential goes through a minimum at an angle of 38°. The height of the potential barrier for the coplanar state is 2.01 kcal/mol. When the phenyl rings are perpendicular to each other, this height increases to 2.37 kcal/mol. The role of correlation and polarization is found to be important. The shape of the potential suggests that polyparaphenylene may possibly exist as a super helix.     

Extraction spectrophotometric determination of cobalt and nickel using ethylthioxanthate

A spectrophotometric method for the determination of cobalt and nickel using a new reagent sodium ethylthioxanthate has been described. The yellow-colored cobalt complex and red-colored nickel complex have been extracted quantitatively using carbon tetrachloride in the pH ranges 4.0–11 and 4.0–6.7, respectively. The colors of these complexes are stable and absorbances have been measured at 389 nm for cobalt and 495 nm for the nickel complexes. Few ions interfere but the method has been applied successfully for the determination of these metal ions in various complex materials.     

The Pharmaceutical Use of Captisol®: Some Surprising Observations

The purpose of this paper is to share some recent observations on the pharmaceuticaluses and properties of Captisol^® or SBE_7M--CD in controlled porosity osmotic pump tablets (CP-OPT) and the underlying mechanism/sthat lead to apparent zero-order drug release pattern. It would have been simple toattribute the apparent zero-order release mechanism/s of poorly water-soluble drugsfrom CP-OPTs and pellets utilizing Captisol^®as both a solubilizing andosmotic agent, to purely osmotic and diffusional components. However, the mechanismmay be more related to a counterbalancing of physical properties as the concentration of Captisol^®changes within the matrix. Specifically, the initial concentration of Captisol^®within a core is 0.3–0.4M. When this drops to lower values an osmotic pressure drop occurs across the membrane. Therefore, drug release should not follow apparent zero-order kinetics if all the drug is solubilized. However, as the viscosity within the tablet also drops, the apparent diffusion coefficient of both Captisol^® and drug increases. Therefore, it appears that there is an initial resistance (hydraulic pressure) to fluid flow from the tablet through the rate-limiting microporous membrane. This resistance decreases so that even as osmotic pressure and concentration differences drop with time, counterbalancing faster release occurs. Osmotic driving force appears to be the most important initial driving force but a diffusional component becomes more significant with time.     

Far infrared spectra of solid molecular nitrogen

This paper reports the observation of the far infrared absorption spectrum of a single crystal of N₂, measured over absorption paths of 4 cm (lengthwise) and 2 cm (across the crystal). The crystal chamber, with quartz windows, was immersed in a flow of cold helium gas. The spectrum from 20 to 120 cm^–1 was recorded in the liquid phase, the-phase, and over the full temperature range of the-phase (35.6–2.0 K) with a Fourier transform spectrometer. The spectral resolution, which was not instrument-limited, and the large path allowed the observation of more detailed multiphonon-transition structure in the spectrum of the-phase than has previously been observed.     

Phthalocyanines as oxidation-reduction indicators

Summary Copper phthalocyanine tetrasulphonic acid has been found to work satisfactorily as an inside indicator in the cerimetric titration of hydro-quinone and metol. It has the advantage that the indicator correction in titrations with 0.01 N solutions of ceric sulphate is much less than with the ferroin indicator, amounting to only 0.02 ml for two drops of the indicator solution.Part II: See Z. analyt. Chem. 163, 1 (1958).     

New sphingolipids and a sterol from a lobophytum species of the Indian ocean

Chemical investigation of a soft coral species of the genus Lobophytum has resulted in the isolation of three new sphingolipids--(2S,3S,4R)-2-nonadecanoylamino-octadecane-1,3,4-triol (1), (2S,3R,4E,8E)-[(2'R)-2'-hydroxyheptadecanoylamino]-4,8-octadecadiene-1,3-diol (2), 1-O-(beta-D-glucopyranosyl)-(2S,3R,4E,8E)-2-[(2'R)-2'-hydroxynonadecanoylamino]-9-methyl-4,8-octadecadiene-1,3-diol (3) and a sterol--(24S)-ergost-5-en-3beta,7beta-diol (4) along with the known sphingolipid--(2S,3R,4E,8E)-2-hexadecanoylamino-4,8-octadecadien-1,3-diol (5) which showed cytotoxicity against human peripheral blood mononuclear cells (PBMC).     

EPR and optical absorption studies on Cr3+ ions doped in KZnClSO4 x 3H2O single crystals

EPR and optical absorption spectra of Cr3+ ions doped in KZnClSO4 x 3H2O single crystals have been studied at room temperature. The EPR spectrum exhibits a group of three fine structure transitions characteristic of Cr3+ ions. From the observed EPR spectra, the spin-Hamiltonian parameters have been determined. The optical absorption spectrum exhibits two broad bands characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal field parameters have been evaluated.     

1,3,4-oxadiazolin-2-ones from carbo-t-butoxyhydrazones

5-Substituted-1,3,4-oxadiazolin-2-ones 2 were synthesized by the oxidation of carbo-t-butoxyhydrazones 1 of aromatic aldehydes with lead tetraacetate or, preferably, iodosobenzene diacetate. In some instances 5-acetoxy-1,3,4-oxadiazoles 3 were obtained along with 2 . The oxidation of carboethoxyhydrazones 4 gave 2-ethoxy-1,3,4-oxadiazoles 5 .