Effective charge propagation and storage in hybrid films of tungsten oxide and poly(3,4-ethylenedioxythiophene)

Hybrid (composite) electroactive films consisting of such an organic conducting polymer as poly(3,4-ethylenedioxythiophene), PEDOT, and such a polynuclear inorganic compound as amorphous tungsten oxide, WO₃/H _x WO₃ were fabricated on carbon electrodes through electrodeposition by voltammetric potential in acid solution containing EDOT monomer and sodium tungstate. Electrostatic interactions between the negatively charged tungstic units (existing within WO₃) and the oxidized positively charged conductive polymer (oxidized PEDOT) sites create a robust hybrid structure which cannot be considered as a simple mixture of the organic and inorganic components. It is apparent from scanning electron microscopy that hybrid structures are granular but fairly dense. Because PEDOT and mixed-valence tungsten oxides are electronically conducting, the resulting hybrid films are capable of fast propagation. The reversible and fast redox reactions of tungsten oxide component lie in the potential range where PEDOT matrix is conductive. Furthermore, the hybrid films exhibit good mediating capabilities towards electron transfers between model redox couples such as cationic iron(III,II) and anionic hexacyanoferrate(III,II). Since the films accumulate effectively charge and show high current densities at electrochemical interfaces, they could be of importance to electrocatalysis and to construction of redox capacitors.     

Voltammetric Determination of Proguanil in Malarone and Spiked Urine with a Renewable Silver Amalgam Film Electrode

Electrochemical properties of proguanil were investigated by a voltammetric method (SWV) using a renewable silver amalgam film electrode. The influence of buffer pH as well as potential amplitude, frequency, and step potential was studied. The repeatability, precision and recovery of the developed method were examined. The reduction peak current was used for proguanil voltammetric determination in the range 1×10^?7–6×10^?6 mol L^?1, LOD=2.9×10^?8 mol L^?1, LOQ=9.7×10^?8 mol L^?1. The standard addition method was used to determine proguanil in a commercial formulation (Malarone) and in spiked urine.     

Renewable Silver Amalgam Film Electrode for the Determination of Dinotefuran in Spiked Carrot Juice Samples Using SW Voltammetry

The electrochemical properties of dinotefuran (DNF) were studied by SW voltammetry over the pH range 2.0–8.0 using a silver amalgam film electrode Hg(Ag)FE. The mechanism of electroreduction was analyzed. The dependence of the peak current on pH, buffer concentration, the nature of the buffer, amplitude, frequency, step potential and scan rate were investigated. The repeatability, precision and recovery of the developed method were checked. The detection and quantification limits were found to be 2.01×10^?7 and 6.71×10^?7 mol L^?1, respectively. The standard addition method was used to determine DNF in spiked carrot juice.     

Epoxy functionalized polymethacrylates based on various multifunctional d‐glucopyranoside acetals

The synthesis of acetal‐derived d ‐glucopyranosides with a various number of hydroxyl groups (the first step, acetalization) and their modified forms with bromoester groups (the second step, esterification) are presented here. The latter, due to the type of functional groups, can be used to initiate the controlled atom transfer radical polymerization. The copolymerizations of equimolar feed of methacrylate monomers, namely, methyl methacrylate and glycidyl methacrylate, were initiated by prepared new glycoinitiators, based on methyl α‐d ‐glucopyranoside (Meαd Glu) or 2‐(hydroxymethyl)phenyl‐β‐d ‐glucopyranoside (salicin), in the presence of the catalyst system CuCl/dNbpy in anisole at 30 °C. The conditions were sufficient for successful synthesis of well‐defined copolymers with sugar cores sheltered by two‐, three‐, four‐, or six‐polymethacrylate segments with various polymerization degrees (DP_arm = 15 – 70) and low dispersity indices (Ð = 1.15–1.30). Because of the presence of oxirane groups, the star‐copolymers can be functionalized in further steps by biologically active compounds or modified to amphipilics. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2483–2494     

Determination of Blasticidin S in Spiked Rice Using SW Voltammetry with a Renewable Silver Amalgam Film Electrode

Blasticidin S (BS) was determined in spiked rice samples by square wave voltammetry (SWV) and square wave stripping voltammetry (SWSV) using a cyclic renewable silver amalgam film electrode (Hg(Ag)FE). It was found that the compound can act as an electrocatalyst. In Britton? Robinson buffer at pH 7.0 a signal connected with the hydrogen evolution reaction was detected at ?1.2 V versus Ag/AgCl. Validation of the method was carried out. The detection and quantification limits were found to be 2.13×10^?8 mol L^?1; 7.10×10^?8 mol L^?1 for SWV and 2.65×10^?9 mol L^?1; 8.85×10^?9 mol L^?1 for SWSV, respectively.     

Polydentate chiral heteroorganic ligands/catalysts—impact of particular functional groups on their activity in selected reactions of asymmetric synthesis

The influence of each functional group in enantiomerically pure ligands 1, bearing a hydroxy moiety, a stereogenic sulfinyl group and an enantiomeric amine moiety, on ligand catalytic efficiency in enantioselective nitroaldol (Henry) reactions was investigated by subsequent transformation and/or protection of these groups. It was found that, although the absolute configuration of the amine moiety exerted a decisive influence on the stereochemical outcome of the reaction, the presence of the sulfinyl group was crucial. The hydroxy group could be replaced by a second enantiomeric amine moiety, but in order to achieve high catalytic activity of the ligand, it was necessary to retain the sulfinyl moiety in its molecule. This clearly indicated that the simultaneous presence of three coordinating centres was essential for the efficiency of the catalysts and allowed us to conclude that the original ligands 1 demonstrated a tridentate character.     

Effect of the degree of substitution on the rheology of sodium carboxymethylcellulose solutions in propylene glycol/water mixtures

The linear dynamic viscoelastic properties and non-linear transient rheology of sodium carboxymethylcellulose solutions (Na-CMC) in propylene glycol/water mixtures were investigated. Measurements were carried out for the solutions of Na-CMC with three different degrees of substitution (DS), namely 0.62, 0.79, 1.04, and the similar average molecular weight (M_w ≈ 250,000 g/mol). The strong synergism between the molecules of Na-CMC with DS of 0.62 and 0.79, and propylene glycol has been observed. The occurrence of the overshoot shear stress and the low loss tangent values indicate the physical cross-linking of the polymer chains. The increase of propylene glycol concentration over 80 wt% and sodium carboxymethylcellulose (DS = 0.7) over 1.6 wt% leads to the formation of a physical cross-link network. The absence of overshoot shear stress and terminal behaviour in SAOS flow of the Na-CMC_1.04 solutions in the PG/water mixture shows that no intermolecular cross-linking of polymer chains occurred in them.