Solid State Oxidation of Thiols to Disulfides Using Ammonium Persulfate

A solid state method for the oxidation of thiols is described that uses benign oxidant, ammonium persulfate.     

Microwave Thermolysis with Clayfen: Solvent-Free Oxidation of Sulfides to Sulfoxides

Alkyl, aryl and cyclic sulfides are rapidly oxidized to the corresponding sulfoxides in high yields upon microwave thermolysis with iron(III) nitrate impregnated on clay (clayfen) under solvent-free conditions; the conversion also occurs in refluxing methylene chloride but requires much longer reaction time.     

Bio-inspired sustainable synthesis of silver chloride nanoparticles and their prominent applications

Advanced nanotechnology is an enormously growing area due to its massive scope of applications for diverse domains of applied science and engineering. Numerous types of synthetic procedures are utilized for the creation of nanoparticles (NPs) due to their myriad application scenarios. However, known conventional physical and chemical strategies have a number of shortcomings. Consequently, the designs of facile, clean, safer, non-noxious, reliable, inexpensive and eco-friendly processes for manufacturing of NPs are being explored actively to circumvent these barriers. The phytogenic fabrication of NPs is much safer, one-pot, facile, and a sustainable methodology. Hence, divergent biological means like the use of plants, biopolymers, fungi, fibres, bacteria, enzymes, etc., are pursued the procurable biogenic fabrication of metallic NPs. In this review paper, current findings on the bio-inspired fabrication of silver chloride nanoparticles (AgCl-NPs) are deliberated, which have with their useful appliances in assorted sectors. The experimental protocols, advanced characterization techniques along with diverse applications of biogenically synthesized AgCl-NPs have been highlighted.     

Normality and sharing functions

In this paper, we proved some normality criteria for a family of meromorphic functions, where a holomorphic function is shared by every function from the family and a linear differential polynomial generated by the members of the family.     

Observability of the effects of curl-free magnetic vector potential on the macroscale and the nature of the ‘transition amplitude wave’

We discuss here the prediction, based on a formalism by the author, on the observable effects of a curl-free magnetic vector potential on the macroscale as against the microscale of the Aharonov-Bohm effect. A new quantum concept — the ‘transition amplitude wave’ — postulated in the formalism has already been shown to exhibit matter wave manifestations in the form of one-dimensional interference effects on the macroscale. It was predicted by the formalism that the same entity would lead to the detection of a curl-free magnetic vector potential on the macroscale. We describe here the manner of generation of this quantum entity in an inelastic scattering episode and work out an algorithm to observe this radically new phenomenon, the detection of a curl-free magnetic vector potential on the macroscale. We determine the various characteristic features of such an observation which can then be looked for experimentally so as to verify the predicted effect, establishing thereby the physical reality of the new quantum entity, and to fully validate the formalism predicting it. It is also shown that this ‘transition amplitude wave’ can be regarded as a novel kind of ‘quasiparticle’ excited in the charged particle trajectory as a consequence of the scattering episode.     

On the study of pH effects in the microwave enhanced rapid synthesis of nano-ZnO

The rapid synthesis of ZnO nanostructures by microwave treatment of aqueous solutions of different pH values is reported for the first time. Microwave in various wattages was used as the source of heating or energy feeding the aqueous precursors. The pH of the zinc metal source was altered by a suitable amount of mineralisers. The considered pH values are 8, 10, 12 and 13.5. Microwave dielectric heating is dependent on the ability of the material to absorb microwave. This is responsible for molecular friction and dielectric loss, which as a result produce internal heating of the dielectric medium, in this case the solution. In typical microwave assisted synthesis, the total exposure to the microwave treatment was near about 25 to 35 minutes. The ZnO nanostructures obtained were studied by XRD, SEM and TEM characterisations. From the XRD pattern and the full width half maximum of the dominant reflections, microstructural parameters of the nanostructures are calculated and compared for the different pH values. Flower petal like flakes and hexagonal nanorods are formed for the lower and higher pH solutions, respectively. From the SEM images, the size distributions for the pH 12 and 13.5 cases are compared by drawing a histogram.     

Spectroscopic and spectrometric studies of anion recognition with calix[4]pyrroles in different reaction conditions

The binding studies of calix[4]pyrroles (1–6) with fluoro, chloro, bromo, iodo and sulphato anions generated from normal-tetrabutylammoniumfluoride, normal-tetrabutylammoniumchloride, normal-tetrabutylammoniumbromide, normal-tetrabutylammoniumiodide, and normal-tetrabutylammoniumsulphate respectively were investigated by electrospray ionization mass spectrometry (ESI-MS) in dichloromethane–acetonitrile in negative ion mode. The efficacy of a particular calix[4]pyrrole to bind with anions was found maximum at low cone voltage of the instrument, at high cone voltage the binding was suppressed due to removal of anion from the cavity of the macrocycles. The binding strength was found inversely proportional to the size of anion for a particular calix[4]pyrrole. The fragmentation pattern of calix[4]pyrrole was observed at higher cone voltage of ESI-MS and was interpreted. The association constants of calix[4]pyrroles and anions obtained from electronic transition studies were in good agreement with that observed from ¹H NMR titration studies.     

Enantiomeric Separation of Moxifloxacin and Its (R,R)-Isomer by Ligand-Exchange Chiral Chromatography

A new stereospecific LC method for the separation and quantification of moxifloxacin and its (R,R)-enantiomer in bulk drug was developed and validated by ligand-exchange liquid chromatography on a reversed phase column using aqueous mobile phase containing the chiral reagent l-isoleucine-Cu(II). The UV detector was operated at 293 nm. The flow rate of mobile phase was set at 0.9 mL min^?1. The achiral ODS column offers good separation of the two enantiomers in less than 20 min. The test concentration was 1,000 μg mL^?1 in the mobile phase. This method was capable of detecting the (R,R)-enantiomer of moxifloxacin up to 0.1 μg mL^?1 for a 20 μL injection volume. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. There was no interference of degradants with the (R,R)-enantiomer in the developed method. The developed chiral RP-LC method was validated with respect to linearity, accuracy, precision and robustness. The percentage recovery for the (R,R)-enantiomer in bulk drug samples ranged from 98.1 to 104.4%. The test solution was found to be stable in the mobile phase for 48 h after preparation.     

Solution conformation of longifolene and its precursor by NMR and ab initio calculations

We describe the conformation and stereospecific 1H and 13C chemical shift assignments of longifolene 1 and its penultimate precursor 2 through the combined use of ab initio calculations and experimental NMR techniques. The predicted stable conformation for both compounds was similar and adopts a twisted chair conformation at the seven-membered ring where C4 lies on top of the exocyclic double bond. The calculated chemical shifts for the stable conformation agree well with the experimental values.