Rearrangement of O,O’-bis(2-benzylideneaminophenyl) phenylphosphonite into 1,6,7-triphenyl-3,4:9,10-dibenzo-2,11-dioxa-5,8-diaza-1-phosphatricyclo[6.3.0.01,5]undeca-3,9-diene

Keeping of O,O’-bis(2-benzylideneaminophenyl) phenylphosphonite in a CCl4 solution for 50 days resulted in its spontaneous rearrangement into 1,6,7-triphenyl-3,4:9,10-dibenzo-2,11-dioxa-5,8-diaza-1-phosphatricyclo[6.3.0.01,5]undeca-3,9-diene, a representative of spirophosphoranes with P–N bonds.     

Effects of pyrolysis temperatures on the textural,magnetic, morphology,and catalytic properties of supported nickel nanoparticles

The development of base metal catalysts for industrially important reactions continues to be an important goal of catalysis research. Herein, the effects of pyrolysis temperature on the textural, structural, surface, magnetics properties and catalytic properties of silica-supported nickel nanoparticles (NiNPs) were thoroughly investigated. Mono-dispersed NiNPs encapsulated in graphitic shells were first successfully obtained and were characterized using a variety of methods such as BET surface area measurement, CO-pulse chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and superconducting quantum interference device (SQUID) measurement. The findings showed that all catalysts’ properties were considerably altered with change in pyrolysis temperature. Hydrogenation of diphenylacetylene was then selected as the model reaction for the evaluation of the catalytic performance of the graphitic-shelled NiNPs. After testing, pyrolysis of a nickel at 800 °C (catalyst A) displayed tremendous activity and selectivity to produce >94% of stilbene with selectivities of 99% for the Z-isomer.     

Studies on the Interaction of Some Biologically Significant Radical Scavengers on Metal‐Ion Catalyzed Phloroglucinol‐Based Chemical Oscillator

The response of the Ce(III)‐catalyzed phloroglucinol (1,3,5‐trihydroxybenzene)‐based Belousov Zhabotinsky system to the addition of various antioxidants (ascorbic acid, glutathione, inosine, N‐acetylcysteine) is monitored at 30°C under stirred batch conditions. This method is convenient and has good sensitivity for the determination of these antioxidants. The addition of these antioxidants to the BZ mixture influences the oscillatory parameter (number of oscillations) to an extent that depends on the concentration of the antioxidant. The experimental results have shown that the number of oscillations decrease on increasing the concentration of antioxidant. The calibration plots show a linear relationship (R² = 0.98 for ascorbic acid and glutathione and R² = 0.99 for inosine and N‐acetylcysteine) between the number of oscillations and the [antioxidant] over the concentration range of 0.0125‐0.5, 0.05‐0.2, 0.025‐0.1, and 0.1‐0.5 mol L^?1 with detection limits 6.9 × 10^?5, 2.762 × 10^?4, 1.381 × 10^?4, and 5.524 × 10^?4 mol L^?1 for ascorbic acid, glutathione, inosine, and N‐acetylcysteine, respectively. Some aspects of the mechanism of these antioxidants on the BZ system have been discussed.     

Growth of large La2−xSrxCuO4 single crystals using tilting-mirror-type infrared heating image furnace

Large single crystals of La_2−xSr_xCuO₄ (LSCO) high-T_c superconductors were grown by the infrared heating floating zone (IR-FZ) method using a tilting-mirror-type image furnace. The maximum diameter of the LSCO crystals increased to 10 mm in the tilting-mirror-type image furnace from 6 mm in the conventional image furnace. CuO rich feeds were required for the crystal growth using the tilting-mirror-type image furnace to compensate for the lack of CuO caused by the significant evaporation of CuO during the growth. The evaporation of CuO was affected by the tilting angle of the mirrors of the image furnace and by feed diameter. The optimized growth conditions were as follows: mirror tilting angle, 20°; feed diameter, 10 mm∅; and feed composition 50.7 mol% CuO.     

Enantioselective Syntheses of the Methylene- and Fluoromethylene-Phosphonate Analogues of 3-Phospho-D-Glyceric Acid

Abstract

The racemic methylene analogue of 3-phospho-D-glyceric acid^1–4 has been shown to be a viable substrate for the combined action of 3-phosphoglycerate kinase, PGK, and glyceraldehyde 3-phosphate dehydrogenase, GPD. We have shown that replacement of CH₂ by CHF or CF₂ in a variety of nucleotide analogues^4,5 can lead to improved Performance as enzyme substrates or inhibitors. We have therefore undertaken enantiospecific syntheses of the methylene- and fluoro-methylene-analogues of 3-phospho-D-glyceric acid to investigate their interaction with PGK and GPD and explore whether the fluorine atom in the latter can mimic an oxygen lone-pair in binding to enzymes.