NISCAIR Online Periodicals Repository Collection: IJC-A Vol.51A(07) [July 2012]

Kinetic study of oxidation of nitrite with a metallo superoxide

Title: Kinetic study of oxidation of nitrite with a metallo superoxide

Authors: Gain, Sekhar; Mukhopadhyay, Subrata; Banerjee, Rupendranath

Abstract: Bridging superoxide in [(en)(dien)Co^III(O₂)Co^III(en)(dien)]⁵⁺ quantitatively oxidizes N(III) to N(V), itself being reduced to hydroperoxo group. Kinetic study and solvent isotope effect indicate two parallel paths: (a) electron transfer and (b) proton coupled electron transfer. The present study also indicates that the ancillary ligands affect the reaction rate substantially. Studies on redox behavior of metal bound superoxide are not many and this study is expected to shed some light on the redox nature of metal bound superoxide.

Page(s): 949-953

Copper modified iron oxide as heterogeneous photo-Fenton reagent for the degradation of coomasie brilliant blue R-250

Title: Copper modified iron oxide as heterogeneous photo-Fenton reagent for the degradation of coomasie brilliant blue R-250

Authors: Ameta, Noopur; Sharma, Jyoti; Sharma, Sanyogita; Kumar, Sudhish; Punjabi, Pinki B

Abstract: The heterogeneous photo-Fenton degradation of coomasie brilliant blue R–250 under visible light has been investigated using copper modified iron oxide, which has been prepared by coprecipitation method and characterized by IR spectroscopy, scanning electron microscopy and X-ray diffraction. The rate of photocatalytic degradation of dye follows pseudo-first order kinetics. The effects of various parameters like pH, concentration of dye, amount of photocatalyst, amount of H₂O₂ and light intensity on the rate of the photo-Fenton degradation has also been studied. Chemical oxygen demand of the reaction mixture before and after exposure has been determined. A tentative mechanism for the photocatalytic degradation has been proposed, wherein involvement of ^•OHradicals has been confirmed by the drastic reduction in the reaction rate in the presence of ^•OH radical scavengers such as isopropanol and butylated hydroxy toluene. The retardation with butylated hydroxy toluene is much higher than with isopropanol. Under similar conditions, efficiencies of Fe₂O₃and copper modified Fe₂O₃ have been compared for the photocatalytic degradation of coomasie brilliant blue R-250.

Page(s): 943-948

Synthesis of new iridium complexes with substituted 1,3,4-oxadiazole and β –diketones as ligands for OLED application

Title: Synthesis of new iridium complexes with substituted 1,3,4-oxadiazole and β –diketones as ligands for OLED application

Authors: Kumar, Amit; Srivastava, Ritu; Kamalasanan, Modeeparampil N; Singh, Ishwar

Abstract: New iridium(III) complexes, viz., (OctOXD)₂Ir(tta) and (OctOXD)₂Ir(tmd) [OctOXD = 2-(4-butyloxyphenyl)-5-phenyl-[1,3,4]oxadiazolato-N4,C2, tta = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, tmd = 2,2,6,6-tetramethylheptane-3,5-dione] have been synthesized and characterized. These complexes have two cyclometalated ligands (C^N) and a bidentate diketone ligand {[(C^N)₂Ir(X)], where X is a β-diketone with trifloromethyl, theonyl or t-butyl groups} and show good thermal stability in air up to 400 ^oC. The photoluminescence spectra of the two complexes show peak emissions at 537 and 557 nm, respectively. The electroluminescent properties of these complexes have been studied by fabricating multilayer devices. The electroluminescence spectra also show peak emission at 541 and 564 nm for (OctOXD)₂Ir(tta) and (OctOXD)₂Ir(tmd), respectively.

Page(s): 937-942

Effect of glycine concentration on the properties of LaCoO₃ perovskite prepared by the glycine-nitrate process

Title: Effect of glycine concentration on the properties of LaCoO₃ perovskite prepared by the glycine-nitrate process

Authors: Kondakindi, Rajender R

Abstract: LaCoO₃ nanocrystals have been prepared by the glycine-nitrate process. The effect of glycine content in the synthesis solution on various properties of LaCoO₃ has been studied in the glycine-to-nitrate molar ratio between 0.75 and 2.0. The samples are characterized by X-ray diffraction for phase purity and particle size, by transmission electron microscopy for particle size, by BET for surface area and by temperature-programmed reduction for reducibility of Coⁿ⁺. XRD reflections show the presence of impurities in the as-prepared samples while only rhombohedral phase could be identified in the samples after calcination at 700 °C. For all the glycine-to-nitrate ratios tested, the particle size estimated from XRD data ranges from 58-69 nm, which are systematically lower than those determined by BET which ranged from 97-118 nm. TPR profiles of the samples show two major peaks; one due to the reduction of Co³⁺ to Co²⁺ and the other due to the reduction of Co²⁺ to Co⁰. The samples prepared under fuel-deficient and fuel-rich conditions show higher reducibility as compared to that of the sample prepared under stoichiometric conditions.

Page(s): 931-936

NISCAIR Online Periodicals Repository Collection: IJC-A Vol.51A(07) [July 2012]

Kinetic study of oxidation of nitrite with a metallo superoxide

Copper modified iron oxide as heterogeneous photo-Fenton reagent for the degradation of coomasie brilliant blue R-250

Synthesis of new iridium complexes with substituted 1,3,4-oxadiazole and β –diketones as ligands for OLED application

Effect of glycine concentration on the properties of LaCoO3 perovskite prepared by the glycine-nitrate process

Effect of glycine concentration on the properties of LaCoO₃ perovskite prepared by the glycine-nitrate process