Specific features of the synthesis and the physicochemical properties of nanocomposite polymer electrolytes based on poly(ethylene glycol) diacrylate with the introduction of SiO<Subscript>2</Subscript>

The specific features of the synthesis and the physicochemical properties of new nanocomposite polymer electrolytes (NPE) based on poly(ethylene glycol) diacrylate, a liquid electrolyte, and silicon dioxide were studied. The kinetics of polymerization of the system in question were studied by isothermal calorimetry and the optimal conditions for the hardening of the NPE were selected. The dependence of the conductivity of the electrolyte samples on the amount of SiO₂ nanopowder introduced, the presence of preliminary ultrasonic treatment of the nanocomposite mixture before the synthesis, and the storage duration of the samples was studied using the electrochemical impedance method. The maximum conductivity (4.3?10^–3 S cm^–1 at 20 °C) was observed for samples without preliminary treatment with the introduction of 6 wt.% of SiO₂ and for the samples after ultrasonic treatment with 8 wt.% of SiO₂. The electrolyte films with the optimal SiO₂ content of 4 wt.% maintained their properties for 24 months.     

Synthesis,spectral-luminescent properties of B(III) and Zn(II) complexes with alkyl- and aryl-substituted dipyrrins and azadipyrrins

Effect of complexing atom, molecular structure of dipyrrolylmethene and its aza analog on spectral-luminescent properties of heteroleptic boron(III) and homoleptic zinc(II) complexes with 3,3′,5,5′-tetramethyl-2,2′-dipyrrolylmethene, 3,3′,5,5′-tetraphenyl-2,2′-dipyrrolylmethene, and 3,3′,5,5′-tetraphenyl-ms-aza-2,2′-dipyrrolylmethene in organic solvent solutions was studied. The complexes were found to exhibit strong chromophore (λ = 350–690 nm, ? ～ 10⁵ L/mol cm) and fluorescent properties. Quantum yield (γ^fl) for fluoroborate complexes reaches 100% and is weakly dependent on medium nature. The value of γ^fl for phenyl- and alkyl-substituted zinc(II) dipyrrolylmethenates in nonpolar solvents is not higher 0.3 and 0.03, respectively; complete fluorescence quenching is observed in electron-donating solvents. Aza-substitution at the meso spacer causes considerable shift of electronic absorption and fluorescence spectra to the red region but completely quenches fluorescence of zinc(II) chelates and decreases γ^fl of boron(III) complex to 0.04.     

Thermochemistry of ethyl acetate solvation in the 1-octanol-N,N-dimethylformamide system

The thermal effects of ethyl acetate (EtOAc), 1-octanol (OctOH), and N,N-dimethylformamide (DMF) solution in a OctOH-DMF model system were measured using a calorimeter of variable temperature with an isothermal shell at 298 K. The standard enthalpies of solution and ester transfer from an alcohol to a binary mixture, and partial mole enthalpies of mixed solvent components were determined. The state of non-electrolyte molecules in OctOH-DMF and OctOH-DMF-EtOAc systems were studied using extended coordination model. It was found that the binary solvent is subjected to microclusterization, since the fraction of the single-type molecules in the solvation sphere of both components of a mixture is significantly higher than in the liquid phase volume. The conclusion was drawn that in the triple system, the ethyl acetate solvation sphere in the whole range of compositions is significantly enriched with amide owing to stronger esteramide dipole-dipole interaction.     

Thermal stability of porphyrins with chemicaly active NH bond and their associates with electron-donor solvents

The composition and stability of the crystalline H associates of NH active tetrapyrroles with electron-donor solvents were investigated by thermogravimetry. It was found that common porphyrins and their analogs can form 1: 1 and 1: 2 macrocycle solvent H associates whose energy of formation depends on their composition and ranges from 20 to 115 kJ/mol. Based on the results from an analysis of the Stokes shifts, we concluded that the formation of H associates in a solution is accompanied by variations in the degree of macrocycle nonplanarity. The stability of a series of tetrapyrroles with regard to thermal destruction in argon atmosphere and in the presence of atmospheric oxygen was shown to drastically vary.     

Spectroscopic and laser characteristics of new efficient luminophores for a wide spectral range based on complexes of dipyrrolylmethene derivatives with difluorine borate

We have studied the spectral-luminescent, lasing, photochemical, and endurance characteristics of a series of new efficiently emitting difluorine borate complexes with dipyrrolylmethenes of different structures. Experimental data have been obtained in polar and nonpolar organic solvents and in solid polymer films involving the participation of silicate structures. We have discussed relations of the structure of investigated compounds and formed solvates with their optical characteristics, and have given guidelines on the use of particular compounds as active media of tunable lasers for determining spectral ranges.     

Thermodynamics of redox reactions involving nicotinamide adenine dinucleotide

Literature data on the thermodynamics of redox nicotinamide adenine dinucleotide (NAD) dependent reactions have been analyzed. It has been established that for the redox reaction of NAD

where all substances except H₂ are in the aqueous buffer with the ionization enthalpy equal to zero, the most reliable thermodynamic parameters should be considered as: ΔH(298.15 K; pH 7)=?27.4±1.7 kJ mole^?1; ΔG (298.15K; pH 7)=±17.8 kJ mole^?1. From the above thermodynamic parameters of the reaction ΔH, ΔG and ΔS for reactions of NAD with natural substrates, synthetic mediators and some inorganic compounds have been calculated.     

Transformations of <Emphasis Type="Italic">N</Emphasis>-ethylamines into amide derivatives under the action of sulfur monochloride

Tertiary N-ethylamines were converted into amide derivatives by reactions with sulfur monochloride and DABCO at 0 °C. Depending on the nature of the substituents in the amine, the reaction can be accompanied by unexpected transformations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1135–1140, June, 2007.     

Kinematic and electrooptical anharmonicity in the semiempirical intensity theory of IR and raman spectra of polyatomic molecules

Saratov State University, 83 Astrakhanskaya Str., Saratov, 410601, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 6, pp. 49–57, November–December, 1995.     

Calculation of the Normal Vibrations of Benzene in the First Singlet Electron-Excited State 1 B 2u

Using the CIS/6-311+G^** method, the normal vibrations of the benzene molecule in the first singlet electron-excited state ¹ B _2u have been calculated. The algorithm of calculation of the force field in dependent coordinates by the method of generalized inversion is described. A method of autoscaling in dependent natural coordinates is suggested. For six groups of natural coordinates scaling factors have been obtained, the use of which has led to agreement between the calculated and experimental frequencies of the vibrations of benzene. The frequencies of the B _1u -symmetry-type vibrations, for which there is no experimental assignment, have been calculated. The problem of selection of the force field in dependent coordinates is discussed.