Fluorescence quenching of laser grade dye coumarin 440 in presence of hydrogen peroxide

Fluorescence quenching of coumarine 440 in ethanol due to the presence in aqueous solution of hydrogen peroxide is reported here. The Stern-Volmer plot is very much linear and quencher concentration could easily be estimated. An optical sensor for the detection of aqueous hydrogen peroxide could thus be easily constructed using the dye solution.     

Controlling dynamical behavior of drive-response system through linear augmentation

Unidirectionally coupled chaotic systems give rise to driver induced bistability in response system under certain parameters setting. Such a system is studied here with augmented dynamics. A linear augmentation provides a controlled dynamical behavior of response system in two different ways: augmented drive system brings the stabilization of the steady state where as augmented response system is able to control the bistability. We present a detailed analysis of Lorenz–Rössler system with linear augmentation for controlled dynamical behavior.     

Effects of CdCl2 concentration on the structural,thermal and ionic conductivity properties of HPMC polymer electrolyte films

Ionics - The present study illustrates cadmium chloride (CdCl2)-doped hydroxypropyl methylcellulose (HPMC) polymer electrolyte films. Solution cast method is employed to prepare polymer electrolyte...     

Effect of gamma-irradiation on thermal decomposition kinetics,X-ray diffraction pattern and spectral properties of tris(1,2-diaminoethane)nickel(II)sulphate

Tris(1,2-diaminoethane)nickel(II)sulphate was prepared, and characterised by various chemical and spectral techniques. The sample was irradiated with ⁶⁰Co gamma rays for varying doses. Sulphite ion and ammonia were detected and estimated in the irradiated samples. Non-isothermal decomposition kinetics, X-ray diffraction pattern, Fourier transform infrared spectroscopy, electronic, fast atom bombardment mass spectra, and surface morphology of the complex were studied before and after irradiation. Kinetic parameters were evaluated by integral, differential, and approximation methods. Irradiation enhanced thermal decomposition, lowering thermal and kinetic parameters. The mechanism of decomposition is controlled by R₃ function. From X-ray diffraction studies, change in lattice parameters and subsequent changes in unit cell volume and average crystallite size were observed. Both unirradiated and irradiated samples of the complex belong to trigonal crystal system. Decrease in the intensity of the peaks was observed in the infrared spectra of irradiated samples. Electronic spectral studies revealed that the M–L interaction is unaffected by irradiation. Mass spectral studies showed that the fragmentation patterns of the unirradiated and irradiated samples are similar. The additional fragment with m/z 256 found in the irradiated sample is attributed to S₈⁺. Surface morphology of the complex changed upon irradiation.     

Structural elucidation of manganese(II), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of a new multidentate dihydrazino quinoxaline derivative

Summary Manganese(II), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of a new multidentate oxygen-nitrogen donor, bis(N-salicylidene)-2,3-dihydrazino-1,4-quinoxaline (H₂BSDHQ) were prepared and characterised by elemental analysis, conductance, thermal, spectral and magnetic data. H₂BSDHQ deprotonates to give a dibasic ONNO donor set in a trivalent iron(III) complex, which binds to the divalent metal ions in a bis-tridentate fashion, using two monobasic ONN donor sets, and resulting in polymeric complexes. Octahedral geometries are proposed for all these complexes, and preliminary studies show that they possess potential antimicrobial activity.     

Total lipids of the intramuscular tissue of fallow deer

In this study non-isothermal non-oxidative and oxidative TG analysis was applied as a method for determining the thermal stability of the total lipids extracted from raw and maturing intramuscular tissue of fallow deer (Cervus Dama Dama L.). The total lipids were extracted from intramuscular tissue, according to the Folch method and stored for nine months at +4 and −18°C. The changes in the thermal stability of the total lipids during non-oxidative and oxidative TG analysis were correlated with the lipid composition, i.e. fatty acid composition. The Flynn-Wall method was used to determine the values of the activation energy of thermal degradation of the total lipids in a defined mass loss range.     

Kinetics and mechanism of the oxidative cleavage of ketones by quinolinium dichromate

The kinetics of the oxidation of ketones (cyclic and arylalkyl) by quinolinium dichromate (QDC), in an acid medium, has been investigated. The rate of the reaction was proportional to the concentrations of the ketone, QDC, and acid. The order of reactivity for the cyclic ketones was C₆ > C₈ > C₅ > C₇ (ring size) and acetophenone > propiophenone > butyrophenone > valerophenone (arylalkyl ketones). A kinetic isotope effect, k _H/k _D = 5.80, was observed (cyclohexanone and cyclohexanone-d₄). The rate data have been rationalized using conformational considerations. The mechanism involved the attack of the protonated QDC on the enol form (of the ketone), in the rate-determining step, forming a cyclic chromate ester. Subsequent cleavage of the carbon-carbon bond of the ester yielded carboxylic acids as the products. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 3, pp. 403–411 This article was submitted by the authors in English.     

Novel approach for the conversion of natural Δ3 cephalosporin derivatives into corresponding Δ2 cephalosporin derivatives

A simple one pot synthetic method for the isomerization of cephem double bond from the natural 3‐position to 2‐cephem positions is affected by silylation. Thus cephalosporin acids are treated with Ntrimethylsilylacetamide (MSA) or N,O‐bis(trimethylsilyl)acetamide (BSA) and the resulting silyl esters are treated with triethylamine at ambient temperature in the same pot to afford Δ²‐cephalosporins, which are potentially related compounds in cephalosporin antibacterial compounds.     

Antioxidant and Biochemical Activities of Mixed Ligand Complexes

Novel 4-aminoantipyrine based mixed ligand metal complexes with the Schiff bases ofL¹(L¹-4(furanylmethyleneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one and L²/ L³/ L⁴are 2-(2-chlorobenzylideneamino)phenol, 2-(3-chlorobenzylideneamino)phenol, 2-(4-chlorobenzylideneamino)phenol were synthesized. The structures of the mixed ligand complexes were established by analytical and spectral techniques. They were screened for in vitro antimicrobial activity against bacteria and fungi by disc diffusion method. The interaction of metal complexes with CT-DNA was investigated by UV–vis, cyclic voltammetry, viscosity and thermal denaturation studies.DNA interaction studies suggest that metal complex binds to calf thymus DNA (CT-DNA) through intercalation mode. Superoxide dismutase activity of these complexes has also been studied. The free ligands and their metal complexes have been tested for in vitro antioxidant activity by the reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH).The antioxidant activities of the complexes were studied and compared with the activity of ascorbic acid. Cu(II) complex showed superior antioxidant activity than other complexes. The solvatochromic behaviour of complexes was also performed in various solvents.     

Spectroscopic and quantum chemical studies on 4-acryloyl morpholine

Fourier transform infrared (FTIR) and FT-Raman spectra have been recorded and an extensive spectroscopic investigations have been carried out on 4-acryloyl morpholine (4AM). Theoretical quantum chemical studies have also been performed. From the ab initio and DFT analysis using HF, B3LYP and B3PW91 methods with 6-31G(d,p) and 6-311G++(d,p) basis sets the energies, structural, thermodynamical and vibrational characteristics of the compound were determined. The energy difference between the chair equatorial and chair axial conformers of 4AM have been calculated by density functional theory (DFT) method. The optimized geometrical parameters, theoretical wavenumbers and thermodynamic properties of the molecule are compared with the experimental values. The effect of acryloyl group on the characteristic frequencies of the morpholine ring has been analysed. The mixing of the fundamental modes with the help of potential energy distribution (PED) through normal co-ordinate analysis has been discussed.