Intramolecular copper(I)-catalyzed 1,3-dipolar cycloaddition of azido-alkynes: synthesis of triazolo-benzoxazepine derivatives and their biological evaluation

Synthesis of a series of [1,2,3] triazolo [5,1-c] [1,4]benzoxazepine derivatives have been accomplished by the intramolecular Cu(I)-catalyzed cycloaddition of azido-alkynes derived from salicylaldehyde. The biological profile of these heterocyclic structural scaffolds toward anti-bacterial as well as anti-fungal activity has also been illustrated.     

Photo-neutron cross-section of 100Mo

The ¹⁰⁰Mo(γ, n) reaction cross-section was experimentally determined at end point bremsstrahlung energy of 10 and 12.5 MeV using off-line γ-ray spectrometric technique. It was also found that ¹⁰⁰Mo(γ, n) reaction cross-section increases sharply from the end point bremsstrahlung energy of 10 MeV to 12.5 MeV, which may be because of GDR around the energy region of 12–16 MeV. The ¹⁰⁰Mo(γ, n) reaction cross-section as a function of photon energy was calculated theoretically using TALYS 1.2 computer code. The flux-weighted average values of ¹⁰⁰Mo(γ, n) reaction cross-section for bremsstrahlung having end point energy of 10 and 12.5 MeV were also calculated using the experimental and theoretical data of mono-energetic photon. The present experimental ¹⁰⁰Mo(γ, n) reaction cross-sections were compared with the bremsstrahlung flux-weighted average values of experimental and theoretical data and found to be in the lower side for 10 MeV and in the higher side for 12.5 MeV.     

Cell inactivation studies on yeast cells under euoxic and hypoxic condition using electron beam from microtron accelerator

In the case of sparsely ionizing radiation such as electron, the dose rate and the pattern of energy deposition of the radiation are the important physical factors which can affect the amount of damage in living cells. In the present study, the differences in the cell survival efficiency and dose rate effect in diploid yeast strains Saccharomyces cerevisiae X2180 and Saccharomyces cerevisiae D7 under euoxic and hypoxic condition have been quantified. Irradiation was carried out using 8 MeV pulsed electron beam from Microtron accelerator. The dose per pulse and pulse width of the beam used was 0.6 Gy and 2.3 μs, respectively, which correspond to an instantaneous dose rate of 2.6 × 10⁵ Gy s⁻¹. For survival studies doses were delivered at a rate of 50 pulses per second (an average dose rate of 1,800 Gy s⁻¹). Fricke and alanine dosimeters were used to measure the dose delivered to the sample. A significant difference in the dose response has been observed under euoxic and hypoxic condition. Dose rate effect has been studied by changing the pulse repetition rate of the Microtron and the dose rate used was from 180 to 1800 Gy min⁻¹. A significant dose rate effect was observed under euoxic condition for Saccharomyces cerevisiae X2180 but the same was absent under hypoxic condition. The dose rate effect was absent for Saccharomyces cerevisiae D7 under both irradiation condition. The survival curves are found to be sigmoidal in shape under both condition but with a wider shoulder under hypoxic condition. The D₀ value and the Oxygen Enhancement Ratio (OER) at that point have been derived.     

Potentiometric determination of free acidity in presence of hydrolysable ions and a sequential determination of hydrazine

A simple potentiometric method for the determination of free acidity in presence of hydrolysable ions and sequential determination of hydrazine is developed and described. Both free acid and hydrazine are estimated from the same aliquot. In this method, free acid is titrated with standard sodium carbonate solution after the metal ions in solutions are masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. This method is especially applicable to all ranges of nitric acid and heavy metal ion concentration relevant to Purex process used for nuclear fuel reprocessing. The overall recovery of nitric acid is 98.9% with 1.2% relative standard deviation. Hydrazine content has also been determined in the same aliquot with a recovery of nitric acid is 99% with 2% relative standard deviation. The major advantage of the method is that generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal.     

Copper catalyzed Gomberg-Buchmann-Hey reaction using aryldiazonium tosylate

Copper catalyzed modification of Gomberg-Bachmann-Hey reaction to synthesize symmetrical/unsymmetrical biaryls via diazotization of anilines with p-TSA and NaNO₂ system at 50 °C, in aromatic liquids as solvents and second partners was successfully developed. Aniline and 3-nitronaniline gave biphenyl and 3-nitrobiphenyl, respectively, with moderate yields. All para-substituted anilines gave comparatively higher yields while in the other cases including ortho-substituted anilines yields were lower. Except anilines with o-NHCOCH₃ and o-CONH₂ which gave symmetrical biaryls, all others gave selectively unsymmetrical biaryls.     

Acrylamide based proton conducting polymer gel electrolyte for electric double layer capacitors

A new class of polymer gel electrolyte (PGE) was synthesized using acrylamide as host polymer and LiClO₄ as dopant. The polymer gel was subjected to electrochemical AC impedance analysis and thermal analysis. The polymer has conductivity in the order of 10⁻³ S cm⁻¹ at ambient temperature. Thermogravimetric analysis (TGA) revealed the effect of dopant on host polymer matrix. A supercapacitor was fabricated using acrylamide based polymer gel electrolyte with activated carbon as electrode material and it was subjected to various electrochemical techniques like cyclic voltammetry, electrochemical AC impedance analysis and galvanostatic charge–discharge tests at various current densities. From cyclic voltammetry a specific capacitance of 28 F/g was obtained at a scan rate of 10 mV/s. The capacitor had good self-discharge behavior and good cycle life of more than 10,000 cycles. The coulombic efficiency was more than 95%. These results indicate that this acrylamide-based polymer gel electrolyte doped with LiClO₄ is a potential electrolyte for electric double-layer capacitors (EDLCs).     

Crystal and Molecular Structure of 9-Methyl-3,4,6,7,910-hexahydro-2,2,8,8-tetramethyl 1,8-(2H,5H)- acridine-dione

The crystal structure of the title compound was determined from X-ray diffraction data using direct methods. The crystals are tetragonal, a = b = 17.618 (1) A, c = 10.121(2) A, Z = 8, V = 3141.5(7) A³, space group P4(2)/n. The structure was refined by full-matrix least-squares to a final R value of 0.052. The central dihydropyridine ring is nearly planar while the outer two rings adopt half chair conformation.     

Synthesis,growth and characterization of single crystals of pure and thiourea doped L‐glutamic acid hydrochloride

L(+)Glutamic acid hydrochloride [HOOC (CH₂)₂CH(NH₂) COOH·HCl], a monoamino dicarboxylic acid salt of L‐Glutamic acid was synthesized and the synthesis was confirmed by FTIR analysis. Solubility of the material in water was determined. Pure and Thiourea doped L‐Glutamic acid hydrochloride crystals were grown by low temperature solution growth using solvent evaporation technique. XRD, UV‐Vis‐NIR analyses were carried out for both pure and thiourea doped crystals. The crystals were qualitatively analyzed by EDAX analysis and the presence of thiourea was confirmed. The cell parameters of L‐Glutamic acid hydrochloride have been determined as a = 5.151 Å, b = 11.79 Å, c = 13.35 Å by X‐ray diffraction analysis and it crystallizes in orthorhombic space group P2₁2₁2₁. UV‐Vis‐NIR spectra analysis showed good optical transmission in the entire visible region for both pure and doped crystals. Micro hardness of both pure and doped crystals has been determined using Vickers micro hardness tester. The SHG efficiencies of both pure and doped crystals were determined using Kurtz powder test and pure L‐Glutamic acid hydrochloride crystal was found to possess better efficiency than thiourea doped L‐Glutamic acid hydrochloride crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)