Supramolecular Association between γ-Cyclodextrin and Preyssler-Type Polyoxotungstate

The development of hybrid materials based on polyoxometalates constitutes a strategy for the design of multifunctional materials. The slow evaporation of an aqueous solution of [NaP₅W₃₀O₁₁₀]¹⁴⁻ in the presence of γ-Cyclodextrin (γ-CD) led to the crystallization of a K₆Na₈{[NaP₅W₃₀O₁₁₀]•(C₄₈H₈₀O₄₀)}•23H₂O (NaP₅W₃₀•1CD) supramolecular compound, which was characterized by single-crystal X-ray diffraction, IR-spectroscopy, thermogravimetric and elemental analyses. Structural analysis revealed the formation of 1:1 {[NaP₅W₃₀O₁₁₀]•[γ-CD]}¹⁴⁻ adduct in the solid state. Studies in solution by cyclic voltammetry, electrochemical impedance spectroscopy, ¹H NMR spectroscopy, and ³¹P DOSY, have demonstrated weak interactions between the inorganic anion and the macrocyclic organic molecule.     

The intramolecular S = O···H-O hydrogen bond in a chiral cyclic sulfite ester: How it affects the reaction behavior and spectral properties

The intramolecular S = O···H?O hydrogen bond in a chiral cyclic sulfite ester, which affects the reaction behavior and spectral properties considerably, was studied.     

Self-supported interconnected Pt nanoassemblies as highly stable electrocatalysts for low-temperature fuel cells

In it for the long haul: Clusters of Pt nanowires (3D Pt nanoassemblies, Pt?NA) serve as an electrocatalyst for low-temperature fuel cells. These Pt nanoassemblies exhibit remarkably high stability following thousands of voltage cycles and good catalytic activity, when compared with a commercial Pt?catalyst and 20?%?wt Pt?catalyst supported on carbon black (20?% Pt/CB).     

REACTIONS OF 1,3-OXAZOLIDINE-2-THIONE WITH ZINC(II), CADMIUM(II) AND MERCURY(II) HALIDES

Abstract

The reactivity of 1,3-oxazolidine-2-thione towards II B group metals is considered. Cadmium halides, mercury chloride and bromide react to give coordination compounds, whose stereochemistry is tentatively assigned by their i.r. spectra.

Otherwise zinc halides and mercury iodide induce a ring opening.     

Application of Adsorptive Stripping Voltammetry for the Nano‐Level Detection of Tramadol in Biological Fluids and Tablets Using Fast Fourier Transform Continuous Cyclic Voltammetry at an Au Microelectrode in a Flowing System

Abstract

A novel adsorptive fast Fourier transform cyclic voltammetry (AFFTCV) technique for the fast determination of tramadol in flow‐injection systems has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping, and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 µm in radius). The proposed detection method has some advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, it is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the tramadol were considered. The method was linear over the concentration range of 1.5–900,000 pg/ml (r=0.9968) with a limit of detection and quantitation 0.32 and 1.5 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay tramadol in tablets and in biological fluids.     

Electrochemical Investigation of Ascorbic Acid Interacting with Bovine Serum Albumin

Abstract

Electrochemical investigation of the interaction of Ascorbic acid (AA) with bovine serum albumin (BSA) on a glassy carbon electrode is reported for the first time. In a 0.1 mol/l, pH 7.3 NaCl solution, AA had a well‐defined voltammetric oxidative peak at +0.2086 V (versus Ag/AgCl) on a GC electrode. After the addition of BSA into the AA solution, the oxidative peak current decreased significantly without a shift of the peak potential, and no new peak appeared. The experimental results showed that a new nonelectrochemical supramolecular complex was formed after the interaction of BSA with AA, which resulted in a decrease of the diffusion coefficient, and then a decrease of the oxidative peak current. The interaction conditions and the electrochemical detection conditions were carefully investigated. The stoichiometry of this supramolecular complex was calculated based on voltammetric data with a binding number of two and a binding constant of 1.38×10⁷.     

Analytical Determination of Methionine by Complex Formation with the Pentacyanoferrate(II) Ion

Abstract

An analytical method of determination of methionine is proposed, based on electrochemical detection of the S-bound complex generated in the presence of the amminepentacyanoferrate (II) ion.     

Corrosion protection performance of ceria‐copolymer bilayer coating on low nickel stainless steel in 0.5 M H2SO4 medium

In this paper, we have reported the anti‐corrosion performance of ceria / poly (indole‐co‐pyrrole) (Ce/(poly(In‐co‐Py)) bilayer coating on low nickel stainless steel (LN SS). Electrochemical polymerization of (poly (In‐co‐Py)) was achieved on ceria‐coated LN SS (CeO₂/LN SS) in acetonitrile medium containing LiClO₄ (ACN‐LiClO₄) by cyclic voltammetric technique. The coatings were characterized by analytical techniques like Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive analysis of X‐ray, respectively. The mechanical behavior of the coatings was studied using peel test, hardness and wear resistance tests. The corrosion defensive performance of this bilayer coating on LN SS was investigated using electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy in 0.5 M H₂SO₄. These results show that the bilayer coating on LN SS lowered the permeability of corrosive ions present in the acidic medium and thus acts as a barrier against the attack of corrosive environment. Copyright © 2012 John Wiley & Sons, Ltd.