Ionic liquid mediated 1,3-dipolar cycloaddition of azomethine ylides: a facile and green synthesis of novel dispiro heterocycles

A greener, facile and efficient one-pot, three-component procedure for the synthesis of novel dispiropyrrolidine-bisoxindole derivatives by cycloaddition trapping of azomethine ylides generated in situ, via decarboxylative condensation of isatin with sarcosine (α-amino acid), has been reported in [bmim]PF₆, an ionic liquid as a recyclable solvent in excellent yield without using any catalyst. This protocol provides mild reaction conditions, high yields of product in short reaction time, high regio- and stereoselectivity, operational simplicity and environmentally benign procedure.     

Characterization of α and γ polymorphs of glycine crystallized from water‐ammonia solution

Crystallization of metastable α and stable γ polymorphs of glycine was carried out from aqueous solution in the presence of ammonia. Pure aqueous solution and solution with lower concentration of ammonia yield α nucleation and solution with a critical concentration of ammonia yield γ nucleation. Variation in the solubility of glycine in double distilled water and pH of the resulting solution due to the ammonia incorporation was studied in a range of temperatures. The induction period for the α and γ nucleation in the solution was determined and its variation due to the ammonia incorporation was also studied. Single crystals of both the polymorphs were grown by slow evaporation method. Effect of ammonia concentration and the resultant pH of the solution on the nucleation, growth and morphology of the grown polymorphs were investigated. The unidirectional growth of the γ polymorph along the polar axis was revealed. X‐ray powder diffraction method was employed to distinguish both the polymorphs structurally. Their thermal stability above room temperature was studied by differential scanning calorimetry which revealed that the as‐grown γ polymorph transforms to α at 179.6 °C while the as‐grown α retains its phase until melting. The optical transmittance of the grown γ polymorph was studied in the UV‐Vis‐Near IR region. The second harmonic generation (SHG) efficiency of the grown γ polymorph was studied with a Nd:YAG laser source and is about 6.8% higher than that of the inorganic standard KDP. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Interaction of an Endosomolytic Polyamidoamine ISA23 with Vesicles Mimicking Intracellular Membranes: A SANS/EPR Study

The mechanism of ISA23 · HCl interaction with model membrane vesicles (80–100 nm in diameter) was investigated using EPR in conjunction with SANS. For EPR, 16‐DSE was dissolved in the vesicle membrane to measure its dynamics and polarity, whereas a spin‐labeled (Tempo)‐ISA 23 analogue was used to give a measure of the polymer flexibility. When ISA23 was added to the external vesicle surface, no interaction was found. This observation conflicts with the reported ability to lyse RBC, but is in agreement with recent studies that showed no effect on membrane permeability when a PAA was added to an incubation medium containing isolated lysosomal vesicles. The vesicle‐mimetic models used here provide a new and useful tool for studying endosomolytic polymer/membrane interactions.

     

Low level Pu and Am estimation in liquid waste from nuclear reactor

Estimation of very low amount up to pico-gram of Am and Pu in the liquid waste of U–Pu fuel cycle of the irradiated U fuel from the nuclear reactor has been carried out using combined method of α- and γ-ray spectrometric techniques. ²⁴¹Am was estimated by γ-ray spectrometry from a plancheted source. In spite of the same α energy of 5.49 MeV for ²⁴¹Am and ²³⁸Pu, the amount ²³⁸Pu was estimated by α spectrometry from the same plancheted source after subtracting amount of the ²⁴¹Am obtained from γ-ray spectrometry. The amount of Am and Pu obtained by this technique is found to be superior compared to other techniques even in the presence of Th, U and fission products.     

Possible intermolecular association in triphenyltin chloride in the solution state as detected by NMR spectroscopy

NMR measurements ((119)Sn chemical shift, line width and (13)C relaxation) were made on triphenyltin chloride in two solutions, 2.5 and 0.75 mol% in CDCl(3), at several temperatures. The (13)C spin-lattice relaxation time and NOE data for the phenyl carbons provide the corresponding correlation times for the overall molecular reorientational motion and the internal rotation of the phenyl groups. The results are indicative of a weak intermolecular association of the triphenyltin chloride molecules in solution and are discussed with reference to a model for intermolecular phenyl ring π-π stacking interactions.     

One-Pot Green Synthesis of 3'-(2-Aminobenzimidazolyl)-2-Phenyl Spiro[4H-Benzopyran-4,2'-Thiazolidin]-4-Ones and Acylation Using Trifluoroacetic Anhydride

Abstract

An expeditious one-pot synthesis of a novel heterocyclic system, 3′-(2-aminobenzimidazolyl)-2-phenyl spiro[4H-benzopyran-4,2′-thiazolidin]-4-ones, has been accomplished by condensing substituted hydrazinobenzimidazole, flavanone, and mercaptoacetic acid by conventional heating in ethanol or toluene, and in an ionic liquid, viz., 1-butyl-3-methyl-imidazolium hexafluorophosphate. Excellent yields (85%–90%) and higher purity are obtained in the ionic-liquid-mediated synthesis as compared with the conventional procedure (55%–60%). Further, these compounds were acylated with trifluoroacetic anhydride. The structures of the compounds were confirmed by IR, ¹H NMR, ¹³C NMR, mass spectral data, and elemental analysis. The compounds, upon evaluation for their antibacterial, antifungal, and insecticidal activities, exhibited excellent results.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Table S1, S2, and S3]

GRAPHICAL ABSTRACT      

Optimization of Fiber-Water Dispersion Process Using Box-Behnken Design of Experiments Coupled with Response Surface Methodology of Analysis

In this work, the fiber-water dispersion process with reference to the wet-lay technology was optimized in order to improve the uniformity of the wet-laid webs by using Box-Behnken design of experiments coupled with response surface methodology of analysis. A series of wet-laid webs were prepared by using cotton fibers of 7 mm cut length and 5.6 micronaire linear density and employing different combinations of three process variables of interest namely stirring rate, dispersion time, and surfactant concentration. The resulting webs were tested for their area-based uniformity by means of quadrat analysis. The response surface model was found to be statistically significant at a P value as low as 0.0213. The experimental results were found to be in good agreement with the model results. The single effect of surfactant concentration, interaction effect of surfactant concentration and stirring rate, and quadratic effect of dispersion time were found to be statistically significant at 0.05 level of significance. The optimum level of coefficient of variation of the area occupied by the fibers in the web was predicted as 10.50% at stirring rate of 250 rpm, dispersion time of 5 minutes, and surfactant concentration of 0.10 and this was experimentally observed as 11.02%.     

Synthesis,bulk growth,polarizability and nonlinear optical properties of γ‐glycine single crystals

The role of sodium acetate, sodium nitrate, sodium hydroxide and malonic acid as additives in assisting the nucleation of γ‐polymorph from solution has been investigated. For the first time large dimensional bulk single crystals of γ‐glycine have been grown at the optimized concentration of the additives by the top seeded slow cooling technique. The bulk growth of single crystals elucidates well the unidirectional growth characteristics and the existence of merohedral twinning in γ‐ glycine. Polarizability, plasmon energy and Fermi energy has been evaluated for the first time for γ‐glycine single crystals based on an analytical approach. Structural affirmation of the nucleated polymorph has been carried out by Powder x‐ray diffraction and the thermal characteristics of the nucleated polymorph are well revealed by Differential Scanning Calorimetry. The non linear optical characteristics of γ‐glycine studied by Kurtz and Perry technique revealed increased SHG efficiency with the highest of about 2.2 in the presence of malonic acid compared to the standard Potassium dihydrogen orthophosphate (KDP).