Synthesis and photochemical degradation of copper(II) <Emphasis Type="Italic">ortho</Emphasis>-azidobenzoate

An aqua complex of copper(II) ortho-azidobenzoate was synthesized. The formula of this complex, [Cu(OH)ABA 2H₂O]₂ (ABA is ortho-azidobenzoate), was determined by IR, UV, and EPR spectroscopy and volumetric analysis (from the amount of nitrogen released upon dissolving the aqua complex in dry DMF). It was found that, in this aqua complex, the azido group is not coordinated to the copper(II) ion. On the dissolution of the aqua complex in dry organic solvents, such as DMF, DMSO, dioxane, and methanol, it underwent dehydration followed by the coordination of the azido group to copper(II) to convert into a chelate complex. The chelate complex in the solid state was stable at room temperature; however, it slowly degraded in solutions to liberate nitrogen. Dissolution in dry THF did not result in the dehydration of the complex. In the photolysis of the aqua complex in dry THF or a THF-water mixture, photochemical dehydration yielding the chelate complex occurred along with the degradation of the azido group and the formation of copper(II) anthranilate.Translated from Khimiya Vysokikh Energii, Vol. 39, No. 2, 2005, pp. 135–139.Original Russian Text Copyright © 2005 by Budruev, Levina, Karyakina, Oleinik.This revised version was published online in April 2005 with a corrected cover date.     

Photolysis of ortho-Azidobenzoic Acid in Aqueous Solutions and Water–Organic Solvent Mixtures

The photolysis of o-azidobenzoic acid and its potassium salt in water, ethanol, tetrahydrofuran (THF), and ethanol–water and THF–water mixtures was studied by IR and UV spectroscopy and thin-layer chromatography. It was found that the photolysis of o-azidobenzoic acid and potassium o-azidobenzoate in aqueous solutions mainly resulted in 2,1-benzisoxazolone, the intramolecular cyclization product. The process of azepine formation in ethanol or an ethanol–water mixture depends on the nucleophilic nature of ethanol; in this case, water is practically of no importance. The presence of THF in an aqueous solution shifted the singlet nitrene–dehydroazepine equilibrium toward dehydroazepine, which reacts with water to give azepines.     

Determination of glucose and lactose in food products with the use of biosensors based on Berlin blue

The immobilization of enzymes into polyelectrolyte membranes with the use of organic solvents was applied to the development of the biosensing elements of biosensors. The following domestically produced preparations were used: the enzymes glucose oxidase and β-galactosidase and a perfluorosulfonated polymer. The compositions of mono-and bienzymic polyelectrolyte membranes were optimized. The glucose and lactose biosensors based on Berlin blue (as a signal transducer) and polyelectrolyte membranes exhibited high sensitivity, low detection limits, and fast response. The results of the analysis of milk whey in a flow-injection system that included biosensors completely correlated with measurement data obtained by a standard chromatographic technique.     

Supramolecular structure and incipient cracks in three-dimensional stitched amorphous polymers

The electron-microscopic method was used to study the structure of unsaturated polyester films. The initial submicrocracks developing in the loaded films were studies by the low-angle x-ray diffraction method. It is shown that for these polymers a typical feature is the globular structure with a globule diameter of 10³–3·10³ Å, and the transverse dimension of the submicrocracks developing under the action of a load practically coincides with the globule diameter.     

Electrochemical polymerization of N-substituted pyrrols for the development of novel lactate biosensor

Lactate oxidase from the species Pediococcus is immobilized in a conducting polymer film on the surface of planar electrodes modified with Prussian blue. Polypyrrole ammonium is electropolymerized to obtain the conducting polymer. The analytical characteristics of the resulting biosensor are as follows: a sensitivity of 190 ± 14 mA M⁻¹ cm⁻², a linear dynamic range of 5 × 10⁻⁷ to 5 × l0⁻⁴ M, and high operational stability. The applicability of a lactate biosensor for food quality control (for example, quality control of kvass) is shown. Effective and inexpensive biosensors for lactate analysis may be applied in clinical diagnostics, sports medicine, quality control of food and farm products, as well as for biotechnology processes.     

Photolysis of <Emphasis Type="Italic">para</Emphasis>-azidobenzoic acid in solutions and in the crystalline state

Photolysis of para-azidobenzoic acid (p-ABA) in the crystalline state, organic solvents, and water at different pH values was studied by means of IR spectroscopy, electronic absorption spectroscopy, and TLC. The nature of L-ABA photolysis products is determined by the character of solvation or hydration of the acid in solutions and the relative arrangement of azide molecules in the crystalline state or highly concentrated solutions.     

Direct Bioelectrocatalysis by NADP‐Reducing Hydrogenase from Pyrococcus furiosus

The direct bioelectrocatalysis by an NAD(P)‐reducing hydrogenase is reported for the first time. In contrast to previous attempts to involve similar enzymes in bioelectrocatalysis [1–4], which were in fact unsuccessful, in our report an effective electrocatalysis by Pyrococcus furiosus hydrogenase is convincingly shown by (i) achievement of the hydrogen equilibrium potential and (ii) a high current of hydrogen oxidation (0.3 mA cm^?2 at 100 mV overpotential and at 75 °C). The latter is just a few times lower compared to enzyme electrodes based on NAD(P)‐independent hydrogenases.     

Investigation of magneto-anisotropy field for system of particles with near superparamagnetic volume

We obtained the temperature dependence for low-field boundary of the anisotropy field distribution in a system of barium hexaferrite nanocrystals in the temperature range from 300 to 700 K. We treated the experimental data taking into account the influence of thermal fluctuations on the anisotropy field and the transition of particles into the paramagnetic state, stimulated by external magnetic field. We showed that the dependence under consideration is formed by particles of different volume, which increased from 3.5×10⁻¹⁸ to 40×10⁻¹⁸ cm³ while the particles lost their magnetic stability with the temperature growth.     

Photolysis of <Emphasis Type="Italic">meta</Emphasis>-azidophenol in solutions

The photolysis of meta-azidophenol in various organic solvents and aqueous solutions is studied by IR spectroscopy, electronic absorption spectroscopy, thin-layer chromatography (TLC), and analytical spot-test reactions. The polymeric derivatives of hydroxylamine are formed in organic solvents (benzene, chloroform, acetonitrile) via the interaction of nitrene with the phenol group of a neighboring m-azidophenol molecule. N-(meta-Hydroxyphenyl)hydroxylamine,—the product of the nitrene reaction with water, is formed in ethanol and aqueous solutions.