Electronic structure of monosubstituted benzenes and X-ray emission spectroscopy

The electronic structure of fluorobenzene was investigated by X-ray emission spectroscopy (using the F−Kα- and C−Kα-spectra) and quantum-chemical MNDO calculations. Molecular orbitals of fluorobenzene were compared with those of benzene and hydrogen fluoride. The P_π−p_π-interaction between the phenyl ring and the fluorine atom in the fluorobenzene molecule is weak for both the outer and inner π levels. For Part 2, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1454–1460, August, 1997.     

Chemical modification of usnic acid 2. Reactions of (+)-usnic acid with amino acids

The condensation of amino acids with (+)-usnic acid involves the 2-positioned acetyl group of the latter and gives derivatives containing an enamine fragment. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1203–1205, June, 2007.     

Isolation and Properties of a Biocidal Peptide from Hibiscus cannabinus Seeds

The fungitoxicity of a biocidal peptide from kenaf Hibiscus cannabinus L. seeds was investigated. Its influence on the distribution of calcium ions in mycelial cells of the fungus Verticilluim dahliae Kleb. was examined.     

Host-guest complexes of carotenoids with beta-glycyrrhizic acid

The structure, stability, and reactivity of the host-guest complexes between a set of carotenoids and the triterpene glycoside, beta-glycyrrhizic acid (GA), were investigated by different physicochemical techniques: high-performance liquid chromatography, optical absorption, and fluorescence spectroscopy. It has been demonstrated recently that the molecular complexes of GA with a number of drugs are characterized by reduced toxicity and increased therapeutic activity of these drugs. In the present work it was found that carotenoids form 1:2 complexes with GA in aqueous solutions as well as in polar organic solvents, methanol, acetonitrile, and dimethylsulfoxide. We assume that the structure of the complex is a cycliclike dimer of GA encapsulating a carotenoid molecule. The stability constants in all solvents are near 10(4) M(-1). In addition, GA forms inclusion complexes with carotenoid radical cations, which results in their stabilization. Complex formation (a) decreases the rate of electron transfer from carotenoids to electron acceptors (Fe3+ or quinone) and (b) considerably increases the lifetime of the carotenoid-quinone charge-transfer complex and the yield of the major product (a carotenoid-quinone adduct). A thermodynamic study shows that hydrophobic interactions are the main driving force of the carotenoid-GA complex formation. These results are important for understanding both the nature of GA complexes and the influence of GA on the therapeutic activity of some drugs. Furthermore, carotenoid-GA complexes could be used for the design of artificial light-harvesting, photoredox, and catalytic systems.     

Measurement of Electron Emission Spectra from Micropinch Discharge Plasma

Physics of Atomic Nuclei - In this paper, we describe a small-size magnetic spectrometer of electrons that allowed studying the spectral composition of electron emission in the energy range of...     

Synthesis of new chiral schiff bases from (+)-3-carene and their use in asymmetric oxidation of sulfides catalyzed by metal complexes

A number of new chiral Schiff bases were synthesized starting from accessible monoterpene (+)-3-carene, and the products were used as ligands in metal complex-catalyzed oxidation of sulfides to chiral sulfoxides. The optical purity and the sign of optical rotation of chiral sulfoxides were found to strongly depend on the oxidation temperature.     

Complexes of Zn(II) and Сu(II) with the Amino Derivatives of Deoxycholic Acid: Syntheses,Structures, and Properties

Russian Journal of Coordination Chemistry - Complexes [Zn(L)Cl2] (I), Cu(L)Cl2 ? H2O (II), Zn(L1)Cl2 ? 0.5H2O (III), and Cu(L1)Cl2 ? 0.5H2O (IV) (where L and L1 are the...     

Synthesis of (1S)-(+)-camphor-10-sulfonic acid derivatives and investigations in vitro and in silico of their antiviral activity as the inhibitors of fi lovirus infections

Russian Chemical Bulletin - N-Heterocycle-containing (1S)-(+)-camphor-10-sulfonamide derivatives were synthesized. Their antiviral activity against the Ebola and Marburg viruses was estimated using...     

Synthesis of new (+)-usnic acid derivatives with the flavone structure

Reactions of a chalcone derivative (synthesized earlier from usnic acid) with various oxidants (hydrogen peroxide, tert-butyl hydroperoxide, and dichlorodicyanobenzoquinone) gave new flavonols, dihydroflavonols, and flavones. Treatment of the starting chalcone with a nucleophilic reagent (NH₂NH₂·H₂O) afforded a dihydropyrazole-containing derivative.