Synthesis,structural aspects and nonlinear optical properties of novel phthalimide derivatives: theoretical and experimental approach

Novel phthalimides ( 1 , 2 , 3 ) possessing variability of cyclic amines have been synthesized and characterized by analytical and spectroscopic techniques. Phthalimide 1 and 2 crystallized in a triclinic system with space group Pī; however, an orthorhombic system with a chiral space group of P2₁2₁2₁ was observed for 3 possessing piperidine cyclic amine. The hydrogen atoms attached to the central chiral carbon were oriented anti to each other resulting in minimum steric repulsion. The occurrence of C–H···O hydrogen bonds in 1 , 2 , 3 enabled the building of several supramolecular structures. Hyperpolarizability 197.6096 Debye Ų calculated for 1 was found to be higher than the hyperpolarizabilities, 138.0836 and 165.2521 Debye Ų measured for 2 and 3 , respectively. Subsequently, phthalimides ( 1 , 2 , 3 ) were assessed for second harmonic generation (SHG) response, and a negligible response was recorded for 1 and 2 ; however, 3 showed a significant response of 14.2 mV. In addition to acentric structure, helical structural motifs identified in 3 could be responsible for its enhanced SHG response. Copyright © 2014 John Wiley & Sons, Ltd.     

Rationalizing fragment based drug discovery for BACE1: insights from FB-QSAR,FB-QSSR,multi objective (MO-QSPR) and MIF studies

The ability to identify fragments that interact with a biological target is a key step in FBDD. To date, the concept of fragment based drug design (FBDD) is increasingly driven by bio-physical methods. To expand the boundaries of QSAR paradigm, and to rationalize FBDD using In silico approach, we propose a fragment based QSAR methodology referred here in as FB-QSAR. The FB-QSAR methodology was validated on a dataset consisting of 52 Hydroxy ethylamine (HEA) inhibitors, disclosed by GlaxoSmithKline Pharmaceuticals as potential anti-Alzheimer agents. To address the issue of target selectivity, a major confounding factor in the development of selective BACE1 inhibitors, FB-QSSR models were developed using the reported off target activity values. A heat map constructed, based on the activity and selectivity profile of the individual R-group fragments, and was in turn used to identify superior R-group fragments. Further, simultaneous optimization of multiple properties, an issue encountered in real-world drug discovery scenario, and often overlooked in QSAR approaches, was addressed using a Multi Objective (MO-QSPR) method that balances properties, based on the defined objectives. MO-QSPR was implemented using Derringer and Suich desirability algorithm to identify the optimal level of independent variables (X) that could confer a trade-off between selectivity and activity. The results obtained from FB-QSAR were further substantiated using MIF (Molecular Interaction Fields) studies. To exemplify the potentials of FB-QSAR and MO-QSPR in a pragmatic fashion, the insights gleaned from the MO-QSPR study was reverse engineered using Inverse-QSAR in a combinatorial fashion to enumerate some prospective novel, potent and selective BACE1 inhibitors.     

Study of effects of polishing and etching processes on Cd1−xZnxTe surface quality

The effect of surface preparation on CdZnTe properties was investigated. Surface etching using bromine solutions enhances Te elemental composition, resulting in a Te rich surface layer that is prone to oxidize. This oxidation degrades the performance of the fabricated CZT gamma detector. Roughness results were identical for samples polished with 1 and 3 μm and subsequently etched in 2% Br-MeOH. The optimal concentration of etching was 2% Br-MeOH.     

Perchlorate in seawater: bioconcentration of iodide and perchlorate by various seaweed species

There has been no reliable published data on the presence of perchlorate in seawater. Seaweeds are among the most important plant life in the ocean and are good sources of iodine and have been widely used as food and nutritional supplement. Perchlorate is known to inhibit the transport of iodide by the sodium iodide symporter (NIS), present e.g., in the thyroid and mammary glands. With perchlorate being increasingly detected in drinking water, milk and various other foods, increasing the iodide intake through inexpensive natural supplements may be an attractive solution for maintaining iodine assimilation. We report here measurable concentrations of perchlorate in several samples of seawater (detectable in about half the samples analyzed). We also report the iodide and perchlorate concentrations of 11 different species of seaweed and the corresponding bioconcentration factors (BCF) for perchlorate and iodide, relative to the seawater from which they were harvested. All seaweed samples came from the same region, off the coast of Northeastern Maine. Concentrations of iodide and perchlorate in four seawater samples collected from the region near harvest time were 30 ± 11 and 0.16 ± 0.084 μg l⁻¹, respectively. Concentrations of both iodide and perchlorate varied over a wide range for different seaweed species; iodide ranging from 16 to 3134 mg kg⁻¹ and perchlorate from 0.077 to 3.2 mg kg⁻¹. The Laminaria species had the highest iodide concentration; Laminaria digitata is the seaweed species most commonly used in the kelp tablets sold in health food stores. Our sample of L. digitata contained 3134 ± 15 mg iodide/kg dry weight. The BCF varied widely for different species, with Laminaria species concentrating iodide preferentially over perchlorate. The iodide BCF (BCF_i) to perchlorate BCF (BCF_p) quotient ranged from 0.66 to 53; L. digitata and L. saccarina having a BCF_i/BCF_p value of 45 and 53, respectively, far greater than a simple anion exchange process will allow. Although most seaweed samples contain some amount of perchlorate, the great majority contains iodide in so much higher amount that at least for the commonly used Laminaria species, the iodide/perchlorate ratio is greater than the square of the perchlorate to iodide selectivity factor reported for the mammalian NIS and should thus lead to net beneficial iodine nutrition even in a two-stage mother-infant scenario.     

A simple catalytic method for the regioselective halogenation of arenes

This paper describes a mild palladium-catalyzed method for the regioselective chlorination, bromination, and iodination of arene C-H bonds using N-halosuccinimides as oxidants. These transformations have been applied to a wide array of substrates and can provide products that are complementary to those obtained via conventional electrophilic aromatic substitution reactions. [reaction: see text]     

Preparative and mechanistic studies toward the rational development of catalytic, enantioselective selenoetherification reactions

A systematic investigation into the Lewis base catalyzed, asymmetric, intramolecular selenoetherification of olefins is described. A critical challenge for the development of this process was the identification and suppression of racemization pathways available to arylseleniranium ion intermediates. This report details a thorough study of the influences of the steric and electronic modulation of the arylselenenyl group on the configurational stability of enantioenriched seleniranium ions. These studies show that the 2-nitrophenyl group attached to the selenium atom significantly attenuates the racemization of seleniranium ions. A variety of achiral Lewis bases catalyze the intramolecular selenoetherification of alkenes using N-(2-nitrophenylselenenyl)succinimide as the electrophile along with a Br?nsted acid. Preliminary mechanistic studies suggest the intermediacy of ionic Lewis base-selenium(II) adducts. Most importantly, a broad survey of chiral Lewis bases revealed that 1,1'-binaphthalene-2,2'-diamine (BINAM)-derived thiophosphoramides catalyze the cyclization of unsaturated alcohols in the presence of N-(2-nitrophenylselenenyl)succinimide and methanesulfonic acid. A variety of cyclic seleno ethers were produced in good chemical yields and in moderate to good enantioselectivities, which constitutes the first catalytic, enantioselective selenofunctionalization of unactivated olefins.     

Development of electroluminescence cell using a Eu0.5Y0.5(TTA)3Phen organic luminescent complex

Novel red emitting organic luminescent complexes, namely Eu_0.5Ln_0.5(TTA)₃ Phen (Eu: europium, Ln: Y/Tb, Y: yttrium, Tb: terbium, TTA: thenoyl tri fluoro acetone, Phen: phenanthroline) were synthesized by solution technique, maintaining stoichiometric ratio. These complexes were characterized by various techniques such as XRD, optical absorption and photoluminescence (PL) spectra. Electroluminescence cells were designed by sandwiching Eu_0.5Ln_0.5(TTA)₃Phen between indium tin oxide (ITO) and aluminum (Al). Voltage?current characteristics and voltage?brightness characteristics of the developed electroluminescent cell were carried out. Turn on voltage of both the devices was found to be 9 V. These devices emit intense red emission at 611 nm, proving their potential applications as organic light emitting diodes and displays.     

Inventory models with a mixture of backorders and lost sales under fuzzy cost

Continuous review and periodic review inventory models in which a fraction of demand is backordered and the remaining fraction is lost during the stockout period are considered under fuzzy environment. Fuzziness is introduced by allowing the cost components imprecise and vague to certain extent. Trapezoidal fuzzy numbers are used to represent these characteristics. The optimum policies of these models under fuzzy costs are derived. Numerical results highlighting the sensitivity in the decision variables are also described.     

Preparation and surface charge studies of bio-magnetoelectrets of l-serine

This paper reports the study of surface charge characteristics of bio-magnetoelectrets of amino acid l-serine. Electrets were prepared under the combined effect of heat and magnetic field. Three different forming temperatures and five different magnetic fields were used for the study. The bio-magnetoelectrets prepared this way were observed to have a surface charge of the order of 10^?9 C. The decay of surface charge was studied continuously for 20 days and corresponding time constant was calculated. The comparative studies of surface charge characteristics were done by preparing bio-magnetoelectrets using homogeneous and inhomogeneous magnetic fields.