Kinetic study and analytical application of the iodate-hypophosphite reaction in strongly acidic solutions

The iodate—hypophosphite reaction in strongly acidic solutions was studied spectrophotometrically. Reaction rate constants and the activation energy of the reaction are reported. A method for determining hypophosphite on the basis of this reaction is described. Hypophosphite in the range 0.06–4 mg (10^-3–6·10^-2 M) can be determined with a relative error and relative standard deviation of 2—3%.     

Phase-controlled atom-photon entanglement in a three-level Λ-type closed-loop atomic system

We study the entanglement of dressed atom and its spontaneous emission in a three-level Λ-type closed-loop atomic system in a multi-photon resonance condition and beyond it.It is shown that the von Neumann entropy in such a system is phase-dependent,and it can be controlled by either the intensity or relative phase of applied fields.It is demonstrated that for the special case of the Rabi frequency of applied fields,the system is disentangled.In addition,we take into account the effect of Doppler broadening on the entanglement and it is found that a suitable choice of laser propagation direction allows us to obtain the steady state degree of entanglement(DEM) even in the presence of the Doppler effect.     

Spectrophotometric determination of oxalic acid in presence of glyoxylic acid and chloride

Glyoxylic acid gives a yellow 1:1 complex, [FeCHOCOO]²⁺ with iron(III). The dissociation contant, measured by two spectrophotometric methods, is K = 9.7 ± 1 mol l^?1. Oxalic acid gives two complexes with iron(III) which absorb in the same range around 400 nm. With appropriate precautions and corrections, oxalic acid concentrations of about 10^?1–10^?2 M can be determined in the presence of glyoxylic acid and chloride.     

Zirconium triflate: An efficient catalyst for the synthesis of quinolines and quinoxalines

An environmentally friendly method is described for the preparation of substituted quinoline and quinoxaline derivatives using Zr(OTf)₄ as an efficient catalyst. The method is based on using 1,3-diketones, ketones and 2-aminoaryl ketones under solvent-free conditions and also on using 1,2-diketone, 1,2-diamine in EtOH/H₂O at room temperature for quinloine and quinoxaline synthesis, respectively. The advantages in using this method, include its environmental friendliness, simple operating process and good yields.     

The synthesis of water soluble decalin-based thiols and S-nitrosothiols--model systems for studying the reactions of nitric oxide with protein thiols

The syntheses of three decalin-based tert-thiols displaying varying degrees of solubility in aqueous milieu are described. The S-nitroso derivatives of these compounds have also been prepared and the structures of two of these determined by single crystal X-ray diffraction. These compounds have been designed for studying the interaction of nitric oxide (NO) with thiols under physiological conditions.     

Microwave-Assisted Synthesis of Coumarins via Pechmann Condensation in Wet Phosphoric Acid Imidazolium Dihydrogenphosphate

Phosphoric acid imidazolium dihydrogenphosphate was found to work well as a catalyst and excellent reaction medium in the Pechmann condensation of substituted phenols or α-naphthol with ethyl acetoacetate to give 4-methyl coumarins under microwave irradiation. This method is simple, cost effective, requires short reaction times, and gives very good to excellent yields.     

Preparation of Cu (II) imprinted polymer electrode and its application for potentiometric and voltammetric determination of Cu (II)

The Cu (II) imprinted polymer glassy carbon electrode (GCE/Cu-IP) was prepared by electropolymerization of pyrrole at GCE in the presence of methyl red as a dopant and then imprinting by Cu²⁺ ions. This electrode was applied for potentiometric and voltammetric detection of Cu²⁺ ion. The potentiometric response of the electrode was linear within the Cu²⁺ concentration range of 3.9 × 10^?6 to 5.0 × 10^?2 M with a near-Nernstian slope of 29.0 mV decade^?1 and a detection limit of 5.0 × 10^?7 M. The electrode was also used for preconcentration anodic stripping voltammetry and results exhibited that peak currents for the incorporated copper species were dependent on the metal ion concentration in the range of 1.0 × 10^?8 to 1.0 × 10^?3 M and detection limit was 6.5 × 10^?9 M. Also the selectivity of the prepared electrode was investigated. The imprinted polymer electrode was used for the successful assay of copper in two standard reference material samples.     

Warfarin Induced Quenching of the Carbon Quantum Dots: Mechanism Study and Warfarin Sensor Construction

Journal of Fluorescence - The mechanism of the fluorescence quenching of the CQDs by warfarin was determined and based on this study a simple, low cost and highly sensitive nanosensor was developed...     

Synthesis of chiral non-racemic substituted vinyl aziridines

Synthesis of a range of chiral non-racemic vinyl aziridines with varying substitutions on the alkene has been achieved by the reaction of (S_S)-tert-butylphenylsulfinimine with a range of ylides derived by deprotonation of substituted allyltetrahydrothiophenium salts. Yields of the substituted vinyl aziridines range from 0% to 90%, with trans:cis ratios between 1:1 and 0:100 and diastereomeric excesses of up to 99%.