PTAB mediated open air synthesis of sulfonamides,thiosulfonates and symmetrical disulfanes

A facile methodology has been described which has successfully simplified the generation of sulfonamides, thiosulfonates and symmetric disulfanes. This “trio” of reactions occur in an open air metal free atmosphere and has also been scaled up to grams making it suitable for commercialization. The reactions also have been successfully carried out with asymmetric variants, thus contributing to the chiral pool. The user friendly “trio” enables easy generation of these versatile sulfur analogues and the reaction condition employed depict an economic outline.     

Copper ferrite nanoparticle-mediated N-arylation of heterocycles: a ligand-free reaction

The synergistic effects of iron and copper in copper ferrite nanoparticles for the N-arylation of heterocycles with aryl halides were demonstrated. The magnetic nature of the catalyst facilitates its removal from the reaction medium for further use. Negligible leaching of Cu and Fe in consecutive cycles makes the catalyst economical and environmentally benign for C-N cross-coupling reactions.     

Room temperature ferroelectricity in multiferroic HoMnO3 ceramics

We have observed good ferroelectric loops at room temperature in hexagonal HoMnO₃ (HMO) bulk ceramics sintered at 1250 °C. Microstructure and ferroelectric hysteresis loops are observed to be dependent on sintering temperature. It is observed that with an increase of sintering temperature, hexagonal a-axis is compressed and c-axis is marginally dilated with overall contraction of the hexagonal unit-cell volume. We explain the origin of ferroelectricity through relative movement of Ho ion and Mn ion within its unit-cell volume, resulting in the distortion of unit-cell volume. We argue that ferroelectric origin of hexagonal HMO at room temperature may be due to the marginal displacement of Ho ion along a-axis, that influences the exchange interaction among the Mn³⁺ and Ho³⁺ ions, causing magnetically induced ferroelectricity at room temperature.     

Effect of pressure on itinerant magnetism and spin disorder in cubic FeGe

The results of ab initio calculations of the pressure dependence of Fe magnetism in cubic FeGe are presented. We find that when the pressure-volume scale is set by means of generalized gradient approximation total energies and magnetism is described by means of the local density approximation, the critical pressure at which the magnetic phase transition occurs is estimated at ≈18 GPa, which is in good agreement with experiments. Using the disordered local moment method we find a localized to itinerant model cross-over of Fe magnetism in cubic FeGe, as a function of volume. Moreover, our calculations also suggest subtle signatures of longitudinal spin fluctuations in cubic FeGe, and that the stiffness parameter softens with increasing pressure. We associate the retention of metallicity in FeGe under pressure with the spin-disorder scattering. The effect of spin-orbit coupling on the electronic structure is also discussed.     

Hydrogen sensors based on ZnO nanoparticles

Hydrogen sensing characteristics of thick films of nanoparticles (∼35 nm diameter) of ZnO, 3% Co doped ZnO, 1% Pt-impregnated ZnO and 1% Pt-impregnated 3% Co-ZnO have been investigated. The last composition exhibits the highest sensitivity for 10-1000 ppm H₂, reaching values upto 1700 as well as good response and recovery times at 125 °C or lower. The sensor is not affected significantly upto 50% relative humidity.     

A formal total synthesis of (+/-)-neplanocin A

Stereoselective formal synthesis of (+/-)-neplanocin A from a cyclopentane derivative employing an elegant strategy involving reiterative usage of an already existing acetonide protecting group is reported. The acetonide protecting group that is carried forward intact right from the starting adduct to an advanced intermediate is shuffled around twice as in a "relay race" through the synthetic sequence, thus avoiding unnecessary employment of additional protecting groups.     

Kinetics and mechanism of interaction of hexaaquachromium(III) with <Emphasis Type="SmallCaps">l</Emphasis>-Dopa in aqueous medium: comparative antiparkinsonian studies

The kinetics and mechanism of the substitution reaction between [Cr(H₂O)₆]³⁺ and l-Dopa in aqueous medium has been studied over the range 1.8 ≤ pH ≤ 2.6, 1.68 × 10⁻² mol dm⁻³ ≤ [Dopa] ≤ 5.04 × 10⁻² mol dm⁻³, I = 0.1 mol dm⁻³ (KNO₃) at 50 °C. The reaction takes place via an outer sphere association between Cr³⁺ and l-Dopa followed by chelation. The product was characterized by physicochemical and infrared spectroscopic methods. The antiparkinsonian activity of the product was found to be higher than that of l-Dopa.     

A simple Schiff base as selective and sensitive fluorescent-colorimetric hydrazine chemosensor

ABSTRACT

A new fluorescent-colorimetric chemosensor L has been synthesised by Schiff base condensation reaction between 1,8-diaminooctane and 4-nitro-benzaldehyde in very good yields. Its photo-luminescent properties and selective detection properties for hydrazine have been examined. The synthesised chemosensor exhibited highly selective fluorescence on-off response for hydrazine amongst a wide range of different metal cations, anions and amines, along with the bare eye colour change from colourless to yellow based on intermolecular hydrogen-bond interaction. The limit of detection of the chemosensor L was estimated as 9.77 × 10^?8 M or 3.12 × 10^?6 g L^?1 for hydrazine which is extremely below the limit set by the World Health Organization (WHO) and the binding stoichiometry was proposed to be 1 : 2 based on ¹H NMR spectroscopic techniques and the Job’s plot analysis. The proposed sensing mechanism is the hydrogen-bonding interaction which has further been established by Density Functional Theory (Functional Density Theory (DFT)) studies. This recognition feature of sensor L makes it an efficient chemosensor for hydrazine detection in different water samples.