Electrochemical impedance spectroscopic studies on aging-dependent electrochemical degradation of p-toluene sulfonic acid-doped polypyrrole thin film

The conducting polymer polypyrrole thin film was galvanostatically polymerized on stainless steel substrate for the supercapacitor electrode. The electrochemical stability of the electrode was monitored each 30 days of aging up to 90 days. The FTIR analysis showed an increase in intensity of the absorption peaks, especially high growth of the carbonyl peaks after 90 days of aging. The electrochemical capacitance degradation of the electrode was studied using cyclic voltammetric and galvanostatic charge/discharge analysis in 1 M Na₂SO₄ electrolyte, which showed ~?53% of fading in the initial specific capacitance value after 90 days. Further, the electrochemical degradation of polypyrrole electrodes was analyzed in detail using electrochemical impedance spectroscopy. The analysis showed a large increase in the internal resistance and low-power deliverability of the electrode with respect to aging as the main reasons for the degradation of specific capacitance of the polypyrrole electrode.     

Rapid and cleaner synthesis of 1,4‐dihydropyridines in aqueous medium

The present investigation deals with a novel water soluble Lewis acid complex, Zn[(L)proline]₂ catalyzed Hantzsch 1,4‐dihydropyridine derivatives syntheses in aqueous medium assisted by microwave irradiation. The microwave promoted syntheses in aqueous medium afforded moderate to excellent yield (up to 98%) within short reaction time and allowed the reaction to take place with low microwave power (200 W). This synthetic methodology provides easier separation of products and the catalyst exhibits recycling ability without loss of its catalytic activity up to five reaction cycles. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:267–271, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20197     

Influence of Host Lattice in Interstital Dopant Sites: EPR Studies on Cu (II) Doped Sarcosine Cadmium Bromide Single Crystals

EPR study of Cu(II) doped in sarcosine cadmium bromide single crystals are carried out at room temperature. The impurity ions occupy the interstitial position in this crystal lattice. Crystalline field around the Cu(II) ion in this low symmetry crystal is rhombic. The transitions arise from a single paramagnetic site with g_xx = 2.1082, g_yy = 2.0005, g_zz = 2.2071, and A_xx = ‐64 x 10^‐4 cm^‐1, A_yy = ‐23 x 10^‐4 cm^‐1, A_zz =‐185 x 10^‐4 cm^‐1. The ground state is an admixture of dx2‐y2 and dz2 states. The observed molecular orbital coefficient value a2 = 0.85 reveals a moderate covalency of the s bonding and b2 = 0.967 indicates the weak pi bonding. A strong interaction between Cu(II) and nitrogen ligands is found to exist.     

Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey–Seebach Reaction

A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C−H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.     

Bioactive mono/bis (carboxyamide) based Co (II), Ni (II) and Cu (II) complexes: Synthesis,Characterization, DNA binding and Anticancer Potentials

Bioactive carboxyamide ligated Cu^II ( 1 ), Co^II ( 2 ) and Ni^II ( 3 ) complexes have been synthesized and characterized using various physico‐chemical techniques. In particular, the occurred slightly distorted square planar geometry in complex 1 was confirmed by single X‐ray crystal structure. Their ( 1 , 2 and 3 ) potential interactions with herring sperm DNA (HS‐DNA) have been investigated using spectral and electrochemical techniques. All these studies suggested that the complex 1 could partially penetrated in the sugar phosphate backbone and stacked in between the DNA base pairs, while the other complexes 2 & 3 could bound only on the grooves of HS‐DNA due to their bi‐ligated architecture around the metal centre. The potent cytotoxicity of L and its complexes 1–3 was also evaluated against AGS human gastric cancer cells. Hoechst 33342/PI double staining images revealed that the complexes significantly induced cell death through apoptosis. In vivo administration of complex 1 remarkably inhibits the tumor growth in male Swiss albino mice, moreover it did not show any hepatotoxicity in mice. All these observed results suggested that these complexes may utilized as good conventional therapeutic agents in the near feature after a series of biological assessments.     

NiWO3 Nanoparticles Grown on Graphitic Carbon Nitride (g‐C3N4) Supported Toray Carbon as an Efficient Bifunctional Electrocatalyst for Oxygen and Hydrogen Evolution Reactions

Catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are at the heart of water oxidation reactions. Despite continuous efforts, the development of OER/HER electrocatalysts with high activity at low cost remains a big challenge. Herein, a composite material consisting of TC@WO₃@g‐C₃N₄@Ni‐NiO complex matrix as a bifunctional electrocatalyst for the OER and HER is described. Though the catalyst has modest activity for HER, it exhibits high OER activity thereby making it a better nonprecious electrocatalyst for both OER and HER and is further improved by g‐C₃N₄. The catalytic activity arises from the synergetic effects between WO₃, Ni‐NiO, and g‐C₃N₄. A Ni‐NiO alloy and WO₃ nanoparticles decorated on the g‐C₃N₄ surface supported toray carbon (TC) matrix (TC@WO₃@g‐C₃N₄@Ni‐NiO) by a facile route that show an excellent and durable bifunctional catalytic activity for OER and HER in the alkaline medium are developed. This carbon nitride with binary metal/metal‐oxide matrix supported with TC exhibit an overpotential of 0.385 and 0.535 V versus RHE at a current density of 10 mA cm^?2 (Tafel slopes of 0.057 and 0.246 V dec^?1 for OER and HER, respectively), in 0.1 m NaOH . The catalyst is tested in water electrolysis for 17 h.     

An efficient synthesis of the opioid analgesic (R)-phenampromide via an aziridinium ion

A simple and efficient synthesis of the opioid analgesic agent (R)-phenampromide with high enantiopurity (>99% ee) via the formation of an aziridinium ion as a key step using commercially available starting material is described.     

A sensitive liquid chromatography–mass spectrometry bioanalytical assay for a novel anticancer candidate – ZMC1

ZMC1 {azetidinecarbothioic acid, [1‐(2‐pyridinyl) ethylidene] hydrazide} is a lead compound being developed as one of the first mutant p53 targeted anti‐cancer drugs. Establishing a precise quantitative method is an integral component of this development. The aim of this study was to develop a sensitive LC/MS/MS assay suitable for assessing purity, stability and preclinical pharmacokinetic studies of ZMC1. Acetonitrile protein precipitation extraction was chosen for plasma sample preparation with satisfactory recovery (84.2–92.8%) for ZMC1. Chromatographic separation was achieved on an Xterra C₁₈ column (50 × 4.6 mm, 3.5 µm) using a gradient elution with mobile phase of 0.1% formic acid in water and acetonitrile. ZMC1 and internal standard 2‐amino‐6‐bromobenzothiazole were identified using selected‐ion monitoring mode at m/z 235.2/178.2 and m/z 231.0/150.0 at retention times of 5.2 and 6.3 min, respectively. The method was validated with a linearity range of 3.9–500.0 ng/mL in human plasma and showed acceptable reproducibility with intra‐ and interday precisions <5.9 and 10.5%, and accuracy within ±5.4% of nominal values. This analytical method together with basic stability data in plasma and plasma binding experiments provides a reliable protocol for the study of ZMC1 pharmacokinetics. This will greatly facilitate the pre‐clinical development of this novel anti‐cancer drug. Copyright © 2015 John Wiley & Sons, Ltd.     

Solvent-free protocol for amide bond formation via trapping of nascent phosphazenes with carboxylic acids

A solvent-free synthesis of amides via the coupling of phosphazenes with carboxylic acids is reported. Increasing the rate of heating either by microwave irradiation or conventional heating results in multifold increase in the rate of amide bond formation. Synthesis of a library of amides including a potent antitumour candidate has been accomplished.     

Contrasting electronic requirements for CH binding and CH activation in d6 half‐sandwich complexes of rhenium and tungsten

A computational study of the interaction half‐sandwich metal fragments (metal = Re/W, electron count = d⁶), containing linear nitrosyl (NO⁺), carbon monoxide (CO), trifluorophosphine (PF₃), N‐heterocyclic carbene (NHC) ligands with alkanes are conducted using density functional theory employing the hybrid meta‐GGA functional (M06). Electron deficiency on the metal increases with the ligand in the order NHC < CO < PF₃ < NO⁺. Electron‐withdrawing ligands like NO⁺ lead to more stable alkane complexes than NHC, a strong electron donor. Energy decomposition analysis shows that stabilization is due to orbital interaction involving charge transfer from the alkane to the metal. Reactivity and dynamics of the alkane fragment are facilitated by electron donors on the metal. These results match most of the experimental results known for CO and PF₃ complexes. The study suggests activation of alkane in metal complexes to be facile with strong donor ligands like NHC. © 2015 Wiley Periodicals, Inc.