NOPR Collection:

Catalytic effect of CTAB reverse micelles on the reduction of toluidine blue by ascorbic acid

2016-07-20T04:55:13Z

Title: Catalytic effect of CTAB reverse micelles on the reduction of toluidine blue by ascorbic acid Authors: Padma, M; Shyamala, P; Satyanarayana, A; Rao, P V Subba; Mathew, Asha Abstract: The kinetics of the reduction of toluidine blue by ascorbic acid has been studied in the presence of CTAB/CHCl₃/hexane/water reverse micelles. In the absence of added acid, the reaction obeys simple first order kinetics with respect to both the reactants. The second order rate constant in the presence of reverse micelles, k_w(0.027 M^-1 s^-1) was found to be about sixty times greater than that in aqueous medium, k_o (4.50×10^-4 M^-1 s^-1) under identical experimental conditions. The significant increase is attributed to the concentration effect in the reverse micelles, and, lower micro-polarity due to the reverse micelles, which facilitates the reaction between oppositely charged ions. The effect of variation of W (= [H₂O]/[CTAB]) at constant [CTAB] and variation of [CTAB] at fixed W has been studied. The kinetics at W < 6 is explained on the basis of the special properties of the entrapped water, while the kinetics at W > 10 is explained on the basis of ionic strength. Page(s): 221-225

Electrocatalytic oxidation of hydroquinone with Cu²⁺ modified gold-L-cysteine self-assembled monolayer electrodes

2016-07-20T04:54:13Z

Title: Electrocatalytic oxidation of hydroquinone with Cu²⁺ modified gold-L-cysteine self-assembled monolayer electrodes Authors: Barman, Kaushik; Jasimuddin, Sk Abstract: Electrocatalytic activity of a new catalyst towards the oxidation reaction of hydroquinone as a model compound is described. The catalyst is formed by immobilizing Cu(II) ion on the top side of a gold-L-cysteine self assembled monolayer electrode. Preparation steps and the electrocatalytic activity of Au-L-cysteine-Cu²⁺ have been studied by cyclic voltammetry and electrochemical impedance spectroscopy. The Au-L-cysteine-Cu²⁺ electrode exhibits better electrocatalytic activity than Au-L-cysteine and bare Au electrode for the oxidation of hydroquinone. Page(s): 217-220

Excimer formation in inclusion complexes of antihypertensive drugs with HP-α- and HP-β-cyclodextrins

2016-07-20T04:48:43Z

Title: Excimer formation in inclusion complexes of antihypertensive drugs with HP-α- and HP-β-cyclodextrins Authors: Jenita, M Jude; Venkatesh, G; Subramanian, V K; Rajendiran, N Abstract: The inclusion complexation behavior of three antihypertensive drugs, viz., salbutamol, sotalol and atenolol with hydroxypropyl-α-cyclodextrin (HP-α-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) is investigated by UV-visible, steady state/time resolved fluorescence and PM3 methods and compared with complexation with α-CD and β-CD. In the presence of any of the CDs, dual emission is observed in these drugs, whereas in the absence of CDs, single emission is seen. Addition of CD to aqueous solutions of the drugs results in excimer emission. In CD solutions, the monomer emission intensity decreases regularly while excimer emission intensity increases. The excimer emission is concluded to be due to a 1:2 inclusion complex between the CD and the drugs. Page(s): 207-216

Oxidation of glycine by diperiodatocuprate(III) in aqueous alkaline medium

2016-07-20T04:43:40Z

Title: Oxidation of glycine by diperiodatocuprate(III) in aqueous alkaline medium Authors: Gowda, Jayant I; Hanabaratti, Rohini M; Pattanashetti, Nandini A; Nandibewoor, Sharanappa T Abstract: Oxidation of the amino acid, glycine, by diperiodatocuprate(III) is studied spectrophotometrically in alkaline medium at constant ionic strength (0.20 mol dm^-3) and at varying temperatures (298-318 K). The reaction between diperiodatocuprate(III) and glycine in aqueous alkaline medium exhibits 1:4 stoichiometry. Intervention of free radicals is observed in the reaction. Mechanism involving monoperiodatocuprate(III) as the reactive oxidant species, proceeding through the formation of a complex is proposed. The reaction constants involved in the different steps of the mechanism and activation parameters with respect to the slow step of the mechanism are computed and discussed. The thermodynamic quantities are also determined for the various equilibrium steps. The isokinetic temperature is found to be 381 K. Page(s): 200-206

NOPR Collection:

Catalytic effect of CTAB reverse micelles on the reduction of toluidine blue by ascorbic acid

Electrocatalytic oxidation of hydroquinone with Cu2+ modified gold-L-cysteine self-assembled monolayer electrodes

Excimer formation in inclusion complexes of antihypertensive drugs with HP-α- and HP-β-cyclodextrins

Oxidation of glycine by diperiodatocuprate(III) in aqueous alkaline medium

Electrocatalytic oxidation of hydroquinone with Cu²⁺ modified gold-L-cysteine self-assembled monolayer electrodes