Preparation and characterization of poly-N-vinyl carbazole langmuir-blodgett films

Langmuir monolayers of poly-N-vinyl carbazole (PNVK) were obtained by dispensing PNVK dissolved in tetrahydrofuran onto an air-water interface. Surface pressure-area isotherms of mixed monolayer of the PNVK were studied under different subphase conditions such as temperature and pH of the subphase. It was demonstrated that the monolayer of PNVK remained stable over a temperature range of 10–40°C. The area per molecule of the solid phase was found to be 31Ų. These monolayers were transferred onto indium-tin-oxide-coated glass plates and characterized by spectroscopic and electrochemical techniques.     

Synthesis and Antiinflammatoryand Anticancer Activity Evaluation of Some Condensed Pyrimidines

Summary.  Upon condensation with 4-isothiocyanato-4-methyl-2-pentanone, 2,3-diaminonaphthalene and N-aminoethyladenosine gave in good yields substituted pyrimidonaphthoimidazole and imidazopyrimidine thione. Refluxing pyrimidobenzthiazole with methanol H₂SO₄ at pH∼1 resulted in S-methyl pyrimidobenzthiazole in moderate yield. Pyrimidobenzimidazole derivatives could be reacted to S-alkylated and N-acylated derivatives by refluxing with ethyl bromoacetate in the presence of anhydrous potassium carbonate in THF and by heating in an acetic acid/acetic anhydride mixture. Heating of pyrimidobenzimidazole with 75% aqueous H₂SO₄ on a water bath ended up in a rearranged product. All compounds gave correct ¹H NMR, IR, and HR mass spectra. Results of antiinflammatory, analgesic, and anticancer activity screening of the new compounds are described. Received October 29, 1999. Accepted (revised) January 13, 2000     

Synthesis of Nanocrystalline Ni0.5Zn0.5Fe2O4 by Aerosol Route and Its Characterization

Hyperfine Interactions - Nano-size particles of Ni0.5Zn0.5Fe2O4 ferrite were prepared through aerosol route. The solutions of iron, nickel and zinc nitrates were mixed in stoichiometric proportion,...     

XANES and EXAFS in Cu-Ti and Ni-Zr glasses

X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements have been done at the K-edge of Cu in Cu-Ti glasses and on the K-edges of Ni and Zr in Ni-Zr glasses using a synchrotron radiation source. The results are discussed in terms of the shape shift and intensity of the absorption edge as well as the principal absorption maximum. The values of bondlength calculated by the one-electron multiple scattering XANES theory as well as the graphical analysis EXAFS technique show good agreement.     

Cation distribution and magnetic properties in chromium-substituted nickel ferrites prepared using aerosol route

Cation distribution have been investigated using X-ray diffraction, magnetic and Mössbauer spectral studies in chromium-substituted nickel ferrites prepared by aerosol route. Cation distribution indicates that the chromium atom occupy octahedral site upto x=0.8, and then also enters into tetrahedral site. The saturation magnetization decreases linearly with the increase of chromium concentration due to the diamagnetic nature of the Cr³⁺. However, interesting behaviour is observed in the coercivity. Initially it increases slowly with the chromium concentration but when x>0.8 a very large increase has been observed. This was attributed to the specific cation distribution of Cr³⁺ which results an unquenched orbital angular momentum and a large anisotropy. Room temperature Mössbauer spectra of as obtained samples exhibited a broad doublet resolved into two doublets corresponding to the surface and internal region atoms. The samples annealed at 1200 °C show broad sextets, which were fitted with different sextets, indicating different local environment of both tetrahedral and octahedral coordinated iron cation.     

Laser Raman and IR spectra and force fields for 2,6-difluorobenzonitrile

Raman spectrum of 2,6-difluorobenzonitrile in the powder form has been recorded in the region 50–4000 cm⁻¹ on a Jasco K-500 spectrophotometer using the 488.0 nm radiation from an argon laser. IR spectra in the region 200–4000 cm⁻¹ have been recorded in KBr pellet and nujol mull on a Nicolet DX spectrometer and in liquid and vapour phases on a Jasco FTIR/7000 spectrometer. Using these observed frequencies force field calculations for the planar and non-planar modes have been carried out assuming a general valence force field.     

Synthesis of dirhodium[3H]tetraacetate

Realizing a need for labeled dirhodium tetraacetate [Rh₂/OAc/₄] for binding studies by the equilibrium dialysis procedure, we have established a method for the preparation and purification of [³H]Rh₂/OAc/₄. This is obtained with a tritium label of a sufficiently high specific activity in the methyl group of acetate residues. The method consists of replacement of the existing acetate bridge by [³H]OAc^–. A typical preparation involves refluxing Rh₂/OAc/₄ with [³H]NaOAc in dry ethanol at 80°C for 6 h. The reaction time is critical for obtaining the product with a high specific activity. A simple purification of reaction products yields the compound of interest with a high specific activity, i. e., 315±10 Ci per mol of Rh₂/OAc/₄ and in satisfactory yield /87% of the starting material., This labeled material can be synthesized with greatly increased specific activity /of tritium in acetate groups/ by employing [³H]NaOAc without prior dilution. The labeled Rh₂/OAc/₄ is stable and yields a characteristic product with adenylic acid.     

Studies on metallochromic indicators--II. Zincon and its mercury and zinc complexes as indicators in EDTA titrations

Zincon has been found to be an excellent indicator in the titration of mercury(II) with EDTA at pH 5.5-7. Moreover the mercury(II)-Zincon and zinc-Zincon systems have been found to be suitable indicators in the direct EDTA titrations of Pb(2+), Cd(1+) and Ca(2+). Interference studies of a number of cations and anions have been made. Chloride and bromide can be tolerated in the titration of mercury(II), up to equivalent concentrations.     

Facile conversion of lactols to lactones using IBX

Lactols, which are insoluble or only sparingly soluble in most of the organic solvents that are generally employed for oxidation, are converted to lactones using o-iodoxybenzoic acid (IBX) in a facile manner under modified experimental conditions [EtOAc-DMSO (9:1) mixture at reflux] in good to excellent isolated yields (66-91%).