Liquid-Phase Oxidation of Some Aromatic Aldehydes,Hydrocarbons, and Alcohols by Cerium(IV) Catalyzed by Iridium(III) in Acidic Medium

Addition of traces of iridium(III) chloride with cerium(IV) sulfate (catalyst–substrate ratio (1:2994 to 1:10,000) in traditional water-bath heating resulted in the oxidation of p-chlorobenzaldehyde, p-nitrobenzaldehyde, benzyl alcohol, p-methoxy benzyl alcohol, p-xylene, and p-nitrotoluene dissolved in acetic acid to give 77%, 90%, 21.7%, 88.6%, 86.2%, and 18% yields of the products, respectively, while catechol and resorcinol polymerized. Oxidation of aldehydes and alcohols resulted as usual in the corresponding acids and aldehydes, respectively, while p-xylene and p-nitrotoluene gave p-tolualdehyde and p-nitrobenzoic acid. Conditions were obtained for getting the highest yields under the experimental conditions.     

Green procedure for highly efficient,rapid synthesis of imidazo[1,2-a]pyridine and its late stage functionalization

We unfold a rapid synthetic protocol for the preparation of imidazo[1,2-a]pyridine in cyclohexane. This methodology includes several advantages like shorter reaction time, catalyst free, broader substrate scope, and good yields of the desired products. Late stage functionalization of imidazo[1,2-a]pyridine has also been performed through C–H bond activation and C–C cross-coupling reactions.     

Effect of processing on dielectric properties of (0.95)PbZr0.52Ti0.48O3–(0.05)BiFeO3

An effort has been made to synthesize solid solution of a composition with x=0.05 in the system (1?x)PbZr_0.52Ti_0.48O₃–(x)BiFeO₃ by the sol–gel method. XRD patterns of the pure PZT and BFO modified PZT samples have shown single phase formation. The effects of substitution of BFO on dielectric properties of PZT have been studied in the frequency range 10 Hz to 100 kHz and temperature range from RT to 773 K. The density was optimized by sintering the BFO modified PZT samples at different temperatures in four batches, S1, S2, S3 and S4. P–E hysteresis loop measurements for all the samples have shown almost saturated polarization. It has been observed that sample S2, sintered at 950 °C, exhibits superior dielectric properties of the four samples. The occurrence of weak ferromagnetism, observed in the M–H hysteresis loop, indicates coupling between ferroelectricity and magnetism. Impedance analysis has revealed that all the samples, sintered at different temperatures, have a different grain resistance. A large change in ac conductivity around T _c has been observed in all the samples.     

Iridium(III) catalyzed oxidation of cyclic ketones by cerium(IV)

IrCl₃which is considered to be a sluggish catalyst in alkaline media, was found to surpass the catalytic efficiency of even osmium and ruthenium in acidic media in the oxidation of cyclopentanone and 2-methylcyclohexanone by cerium(IV) sulphate in aqueous sulphuric acid medium. It was observed that the order of the reaction shows direct proportionality with respect to low concentrations of the oxidant and alcohols, but tends to become independent of concentration at higher concentrations. On increasing the concentrations of externally added Cl^-, H⁺ and Ce^IIIions, the rate of the reaction decreases sharply initially but the decrease in rate becomes less prominent as their concentration is increased. The rate of reaction is directly proportional with respect to IrCl₃concentrations. Kinetic data suggest that the production of Ce^III ion occurs before the rate-determining step. Parameters such as the energy of activation, free energy of activation and entropy data collected at five different temperatures suggest that cyclopentanone forms the activated complex more easily.     

Multifractal analysis of sputtered CaF2 thin films

The surface morphologies of CaF₂ thin films prepared by electron beam evaporation technique were measured by atomic force microscopy. The films were bombarded by energetic ion beams of different fluences, which modified the surface morphology predominantly via the process of erosion. The dependence of the surface morphology on ion fluence was explored using multifractal analysis. It was found that the roughness of the film first decreased with ion fluence but increased at higher fluences. Copyright © 2013 John Wiley & Sons, Ltd.     

Voltammetric behavior of cefdinir in solubilized system

The voltammetric behavior of cefdinir has been studied in different surfactant media viz. anionic, neutral, and cationic surfactants over the pH range 2.5-12 in phosphate buffer (0.2 M). Addition of cationic surfactant (citrimide) to the cefdinir containing electrolyte enhanced the reduction current signal while anionic surfactant (sodium lauryl) and neutral surfactant (Tween-20) showed an opposite effect. The reduction process was irreversible over the entire pH range studied (2.5-12). The mechanism of reduction has been postulated on the basis of controlled potential electrolysis, coulometry and spectral analysis. An analytical method with adequate precision and accuracy was developed for the determination of cefdinir in linear concentration range 2x10(-4)-1x10(-5) mol L(-1) with detection limit 0.3x10(-6) mol L(-1). The analysis of cefdinir in its pharmaceutical formulation resulted in mean recoveries of 99 and 98% for both the reduction peaks.     

Discogen-DNA complex films at air-water and air-solid interfaces

We have studied films of an ionic discogenic (discotic mesogenic) molecule (pyridinium salt tethered with hexaalkoxytriphenylene (PyTp)) and DNA complex at air-water (A-W) and air-solid interfaces. We have formed an PyTp monolayer on an aqueous subphase containing a small amount of DNA to obtain a PyTp-DNA complex at the A-W interface. Compared to the pure PyTp monolayer, the PyTp-DNA complex monolayer exhibits a higher collapse pressure and lower limiting area, indicating condensation and better stability. A Brewster angle microscope was used for in situ observation of the morphology of the film at the A-W interface. The PyTp-DNA complex films on silicon wafers were prepared using the Langmuir-Blodgett (LB) technique. We find that several tens of layers of the PyTp-DNA complex monolayer can be transferred with good efficiency. Fourier transform infrared spectroscopy studies confirm the presence of DNA in the LB films of the PyTp-DNA complex. Nanoindentation measurements using atomic force microscope reveal that the PyTp-DNA complex films are about two times harder as compared to the pure PyTp films.     

Electron induced modification in polypropylene

The effect of 23 kGy dose of 2 MeV electron irradiation on polypropylene has been studied by different characterisation techniques, viz. Fourier transform IR spectroscopy, electron spin resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction analysis. The thermal stability of the polymer was found to be increasing due to electron irradiation. The thermal decomposition temperature as well as the melting temperature in case of irradiated polypropylene was found to increase due to electron bombardment. The isotactic nature of the polymer was found to be unaffected by electron irradiation. An increase in crystallinity of the polymer has also been observed after irradiation.     

Aqueous extract of <Emphasis Type="Italic">Argemone mexicana</Emphasis> roots for effective protection of mild steel in an HCl environment

The inhibition effect of aqueous Argemone mexicana root extract (AMRE) on mild steel corrosion in 1 M HCl has been studied by weight loss, Tafel polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy techniques. Results indicate that inhibition ability of AMRE increases with the increasing amount of the extract. A maximum corrosion inhibition of 94 % is acknowledged at the extract concentration of 400 mg L^?1. Polarization curves and impedance spectra reveal that both cathodic and anodic reactions are suppressed due to passive layer formation at the metal–acid interface. It is also confirmed by SEM micrographs and FTIR studies. Furthermore, the effects of acid concentration (1–5 M), immersion time (120 h) and temperature (30–60 °C) on inhibition potential of AMRE have been investigated by the weight loss method and electrochemical techniques. An adsorption mechanism is also proposed on the basis of weight loss results, which shows good agreement with the Langmuir isotherm.     

Green approach for the synthesis of 4-coumarin-4H-pyrans from 4-formylcoumarins and their antibacterial study

A series of 4H-pyranocoumarin derivatives have been successfully synthesized under eco-friendly condition using triethylamine as a catalyst in short reaction time with excellent yield at room temperature. All the synthesized compounds were characterized by spectral analysis and screened for their antibacterial activity against Escherichia coli and Staphylococcus aureus, the results are quite promising.