First-order antiferro-ferromagnetic transition in Fe(49)(Rh(0.93)Pd(0.07))(51) under simultaneous application of magnetic field and external pressure

A magnetic field-pressure-temperature (H-P-T) phase diagram for first-order antiferromagnetic (AFM) to ferromagnetic (FM) transitions in Fe(49)(Rh(0.93)Pd(0.07))(51) has been constructed using resistivity measurements under simultaneous application of magnetic field (up to 8 T) and pressure (up to 20 kbar). The temperature dependence of resistivity (ρ-T) shows that the width of the transition and the extent of hysteresis decreases with pressure and increases with magnetic field. By exploiting opposing trends of dT(N)/dP and dT(N)/dH (where T(N) is the first-order transition temperature), the relative effects of temperature, magnetic field and pressure on disorder-broadened first-order transitions has been studied. For this, a set of H and P values are chosen for which T(N)(H(1),P(1)) = T(N)(H(2),P(2)). Measurements for such combinations of H and P show that the temperature dependence of resistivity is similar, i.e. the broadening (in temperature) of transition as well as the extent of hysteresis remains independent of H and P. Isothermal magnetoresistance measurements under various constant pressures show that even though the critical field required for AFM-FM transition depends on applied pressure, the extent of hysteresis as well as transition width (in magnetic field) remains constant with varying pressure.     

Thermal decomposition paths in A<Subscript>2</Subscript>CuCl<Subscript>4</Subscript> complexes: anilinium and its derivatives

The thermal decomposition paths of anilinium, 4-chloro anilinium tetrachlorocopper(II) complexes are compared to their benzilinium derivative. All these complexes crystallize in the layered structure, typical for a A₂MX₄ family, are studied in literature for their magnetic, semiconducting properties. TG analyses of (anilinium)₂CuCl₄ (A) and (4-chloro anilinium)₂CuCl₄ (B) loses one molecule of organic ammonium hydrochloride along with one molecule of amine, to form (H)CuCl₃, which subsequently completely decomposes to Cu above 500 °C. On the other hand, (benzilinium)₂CuCl₄ (C) loses two molecules of hydrochloride along with chlorine molecule first then two molecules of benzyl amine with formation of Cu above 300 °C. DSC studies on C have shown reversible endothermic phase transition at 130.95 °C (−1.98 J g⁻¹) while heating and exothermic phase transition at 117.07 °C (0.93 J g⁻¹) while cooling. Thus, the observed changes in the decomposition pathway can be correlated to the order–disorder phase transition occurred in the compound C.     

InCl3 catalyzed three-component synthesis of α-benzylamino coumarins and diketones

A convenient and practical InCl₃ catalyzed three-component reaction of 4-hydroxy coumarin/1,3 diones, aromatic aldehyde, and secondary amine for the synthesis of α-benzylamino coumarins and diketones in good yields has been reported.     

Catalysis by Amberlite IR-120 resin: a rapid and green method for the synthesis of phenols from arylboronic acids under metal, ligand, and base-free conditions

A clean process has been developed for the ipso-hydroxylation of aryl and heteroaryl boronic acids to the corresponding phenols using commercially available and recyclable Amberlite IR-120 resin and aqueous hydrogen peroxide as an oxidizing agent. The ion-exchange sulfonic acid resin catalyst could be readily recycled by filtration and directly reused at least four times without any significant loss of activity.     

A ring closing metathesis approach to the indole alkaloid mitralactonine

An efficient utilisation of RCM leading to a convenient synthesis of a pentacyclic indole alkaloid is described.     

PTSA–catalyzed functionalization of hydroquinones with benzhydryl alcohols in water

An intriguing and operationally simple direct benzylation of hydroquinones with benzhydryl alcohols has been developed using PTSA in water, affording functionalized hydroquinones in good to excellent yields. The advantages of being environmentally benign, metal-free, base-free, easy workup and having a wide substrate scope make it a promising process for the synthesis of symmetrically and unsymmetrically benzylated hydroquinones as well as for industrial applications.     

Biosynthetic Approaches towards the Design of Artificial Hydrogen-Evolution Catalysts

Hydrogen is a clean and sustainable form of fuel that can minimize our heavy dependence on fossil fuels as the primary energy source. The need of finding greener ways to generate H₂ gas has ignited interest in the research community to synthesize catalysts that can produce H₂ by the reduction of H⁺. The natural H₂ producing enzymes hydrogenases have served as an inspiration to produce catalytic metal centers akin to these native enzymes. In this article we describe recent advances in the design of a unique class of artificial hydrogen evolving catalysts that combine the features of the active site metal(s) surrounded by a polypeptide component. The examples of these biosynthetic catalysts discussed here include i) assemblies of synthetic cofactors with native proteins; ii) peptide-appended synthetic complexes; iii) substitution of native cofactors with non-native cofactors; iv) metal substitution from rubredoxin; and v) a reengineered Cu storage protein into a Ni binding protein. Aspects of key design considerations in the construction of these artificial biocatalysts and insights gained into their chemical reactivity are discussed.     

Development and validation of a novel high-performance thin-layer chromatography method for the quantitative estimation of neohesperidin from Citrus aurantium peel extract

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatography method was developed for the estimation of neohesperidin from Citrus aurantium peel....     

Hydrolytic degradation of polyisobutylene and poly‐L‐lactide–based multiblock copolymers

The hydrolytic degradation of a series of poly‐L ‐lactide (PLLA)‐polyisobutylene (PIB) multiblock copolymers was studied in phosphate buffer solution (pH = 7.4) at 37 °C. The multiblock copolymers were synthesized by chain extension of PLLA‐b‐PIB‐b‐PLLA triblock copolymers, which were obtained by ring‐opening polymerization of L ‐lactide initiated by hydroxyallyl telechelic PIB. The degradation strongly depended on the PLLA segment length. At constant PIB segment length, the multiblock copolymer with the shortest PLLA segment length (DPn = 10), showed significant weight loss after 8 weeks, whereas weight loss for DPn = 36 was only observed after 24 weeks. The gel‐permeation chromatographic analysis showed a similar decrease in the number‐average molecular weight (M_n) with time further supporting the weight loss data. Dynamic mechanical analysis showed a decrease in ultimate stress and modulus with time. The crystallinity of multiblock copolymers changed significantly with degradation time as indicated from differential scanning calorimetric analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3767–3774, 2010