Regiochemistry of the addition of mercury salts to bornylene

The dependence of the regiochemistry of the mercuration of bornylene on the nature of the mercurating reagent and on the solvent has been found. The structures of the intermediate and transition state in these reactions have been proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 501–505, March, 1994.     

A. A. Il’yushin’s postulate for anisotropic materials and a version of constitutive relations

The particular isotropy postulate proposed by A. A. Il’yushin permits stating and implementing programs for construction and experimental justification of relations determining the thermomechanical properties of initially isotropic materials for trajectories of various degree of complexity.     

Spectral and luminescent properties of sensitizers based on psoralen substitutes

Psoralens (furocoumarines) are photosensitizers of vegetative origin increasing the sensitivity of biological objects to near-ultraviolet radiation (UV-A, 320–400 nm). In the present work, the influence of substitution on the energy level diagram is considered for the first element of the series-psoralen. The absorption and fluorescence spectra are investigated with the use of an SM-2203 spectrofluorimeter, and theoretical calculations are carried out. In addition, the results obtained are compared with the calculated and experimental results of other authors. The employed method of intermediate neglect of differential overlap (INDO) yields such parameters as an oscillator force, nature and energy of the transition, positions of triplets and singlets, etc. The geometry is optimized by the semi-empirical PM3 method of the program Hyperchem 6.03. A comparison of the calculated results for the examined compounds demonstrates that after the substitution, the absorption spectra are shifted toward the red range. The lower excited singlet of the 21,22-dimethyl-10,11-cyclohexylpsoralen compound lies higher than that of psoralen and 10,11-phenyl-21,22-cyclohexylpsoralen; it is located at 332 nm. The absorption spectra from the excited states undergo a bathochromic shift after the substitution. The most intensive T-T absorption bands are also indicated in this work. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 43–49, July, 2008.     

Phase equilibrium in binary liquid-crystal mixtures of 4-n-pentyl-4′-cyanobiphenyl and phenyl benzoates

Differential scanning calorimetry and polarization microscopy were used to study the phase diagram of a mixture of nematic liquid crystals, 4-n-pentyl-4′-cyanobiphenyl and 4-n-octyloxyphenyl-4′-hexylbenzoate.     

Fluorescent analysis of photoinduced biodegradation of cresol isomers

We have used fluorescence spectroscopy to study photoinduced biodegradation of ortho-cresol, para-cresol and mixture of them in water when excited by different UV radiation sources. We show that the efficiency of photolysis for both the individual isomers and the mixture of cresols is higher for excitation by radiation at λ ∼ 222 nm. Pre-irradiation of aqueous cresol solutions slows down subsequent biodegradation. Using a combination of UV irradiation and the strain Penicillium tardum H-2 for utilization of the cresol mixture led to complete degradation of para-cresol and partial degradation of ortho-cresol. Spectral and chromatographic study of the qualitative composition of the metabolites formed during biodegradation of para-cresol showed that preparatory metabolism of such compounds occurs both through oxidation of the methyl group with formation of 4-hydroxybenzoic acid and through hydroxylation with formation of 4-methylcatechol. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 250–255, March–April, 2008.     

Kinetics and mechanism of azidomercuration of alkenes,cycloalkenes, and their derivatives with a mercuric acetate-sodium azide system

The kinetics of azidomercuration of alkenes, cycioalkenes, and their derivatives with a Hg(OAc)₂-NaN₃ system (1 1, 1 2, and 1 3) was studied. Based on the data on the product structure and kinetic results, it was concluded that HgOAcN₃ and Hg(N₃)₂ play the role of azidomercuration reagents. The reactions with alkenes having a strained double bond occur by a concerted scheme. With nonstrained alkenes, a multistep mechanism is realized, its first reversible step involving the formation of a mercurinium intermediate with an ion pair structure.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No.12, pp. 2479–2485, December, 1995.     

The Integrative Approach to Study of the Structure and Functions of Cardiac Voltage-Dependent Ion Channels

Crystallography Reports - Membrane proteins, including ion channels, became the focus of structural proteomics midway through the 20th century. Methods for studying ion channels are diverse and...