Expedient synthesis of α-substituted fluoroethenes

A mild and efficient synthesis of 1-aryl-1-fluoroethenes from benzothiazolyl (aryl)fluoromethyl sulfones and paraformaldehyde, under DBU- or Cs(2)CO(3)-mediated conditions at room temperature, is described. A comparable diethyl fluoro(naphthalen-2-yl)methylphosphonate reagent does not react with paraformaldehyde under these mild conditions. The utility of the methodology for synthesis of terminal α-fluoroalkenes bearing electron-withdrawing functionalities is also shown.     

Unprecedented dithiolation of enals via their NHC-catalysed umpolung reaction with organic disulfides

A novel one-pot N-heterocyclic carbene (NHC)-catalysed dithiolation of α,β-unsaturated aldehydes (enals) with organic disulfides is reported. The protocol involves homoenolate reactivity of enals, where the homoenolate attacks on the disulfide as a d(3) nucleophile followed by thioesterification to afford β-aryl/alkylsulfanyl thioesters with complete atom economy.     

Recent progress in the synthesis of inorganic nanoparticles

Nanoparticles probably constitute the largest class of nanomaterials. Nanoparticles of several inorganic materials have been prepared by employing a variety of synthetic strategies. Besides synthesizing nanoparticles, there has been considerable effort to selectively prepare nanoparticles of different shapes. In view of the great interest in inorganic nanoparticles evinced in the last few years, we have prepared this perspective on the present status of the synthesis of inorganic nanoparticles. This article includes a brief discussion of methods followed by reports on the synthesis of nanoparticles of various classes of inorganic materials such as metals, alloys, oxides chalcogenides and pnictides. A brief section on core-shell nanoparticles is also included.     

Bromodimethylsulfonium bromide (BDMS)-catalyzed multicomponent synthesis of 3-aminoalkylated indoles

Bromodimethylsulfonium bromide (BDMS)-catalyzed three-component coupling reaction between indoles, aldehydes, and N-alkylanilines is reported to access substituted 3-aminoalkylated indoles at room temperature in high yields (82-96%) within 1.5-3.5 h. The salient features of this protocol are the simplicity of the procedure, the ready accessibility of the catalyst, its cost effectiveness, and higher yields in relatively short reaction times.     

Effect of gamma radiation on organic ion exchangers

Effects of gamma radiation on indigenous strong cation and anion exchange resins have been studied in HCl medium up to a dosage of 3600 kGy. The ion exchange capacities of cation and anion exchangers decreased by around 20% at 2400 kGy of absorbed dose. Decrease in salt-splitting capacity and total exchange capacity for both cation and anion exchangers were comparable up to 2400 kGy. Above 2400 kGy, a marginal loss in the capacity was observed for cation exchangers whereas a drastic reduction was noticed for the anion exchangers. The distribution coefficients for zirconium, antimony and cobalt, measured in HCl medium, did not change significantly for 2400 kGy of absorbed dose. Crushing strength and moisture retention capacity did not exhibit any specific trend with the absorbed dose.     

Sb2S3 quantum dots: diffusion‐controlled growth and characterization

The quantum dots of antimony trisulphide, a potential semiconductor for various applications, are grown in glass matrix for the first time and are characterized by various techniques. The dependence of the average dot size on growth parameters like growth temperature and time is systematically studied for the dot size range of 5–80 nm. The linear blue shift of band gap of dots with inverse square of dot size clearly indicates the typical behavior of quantum dots in a strong quantum confinement regime. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparison of structure factors and pair correlation functions obtained using coulomb attractive potential and screened coulomb potential for the suspended macroions

The structure factors and pair correlation functions have been calculated for the macroions suspended in water using coulomb attractive potential (CAP) and the results have been compared well with the results obtained from the RMSA and MMSA using screened coulomb potential (SCP). Differences among the values of compressibility in the limit of zero momentum transfer, excess energy per macroion and coordination number for both the potentials have been reported. Liquid like ordering of the FCC type has been obtained using both CAP as well as SCP potentials between suspended macroions.     

Fabrication of high aluminium containing rare-earth doped fiber without core-clad interface defects

The unwanted core-clad interface defect generation and related scattering loss in rare-earth doped optical fibers containing Al-oxide is up to now an unsolved problem as it cannot be avoided without modifying fiber design or composition. Here a simple technique is proposed to eliminate the problem without affecting fiber parameters. The method comprises addition of fumed silica in appropriate amount under dispersed condition to the soaking solution containing Al and rare-earth salts during the solution impregnation stage. This facilitates the networking between Al₂O₃ and SiO₂ during sintering. The method leads to an improvement in optical properties of the fibers and enables doping of high concentration of Al-oxide even in presence of GeO₂ in the core.     

Fractional vortex lens

The properties of a fractional vortex lens are discussed and its focal plane intensity distribution is investigated. The azimuthal phase pattern of a fractional topological charge vortex and the quadratic phase variation of the lens are displayed on a spatial light modulator (SLM) that is used in the phase mode. The intensity distribution possesses a low intensity radial opening in contrast to the doughnut pattern formed by a vortex beam with integer charge. The presence of multiple singularities in the radial opening of the doughnut structure is detected interferometrically.