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a sulfonamide fragment but also conformational equilibrium among these types of intramolecular interactions are essential for the manifestation of high efficiency in suppressing HIV-infection in cell culture.Introduction. Many derivatives of aminophenols (AP) are known to be effective antioxidants that are capable of changing the course of free-radical processes [1]. These compounds also have traditional applications as stabilizers of industrial organic materials and as food preservatives [2,3]. They exhibit high efficiency for prevention and treatment of pathologies due to disorders in the human antioxidant system [4] and as antiviral agents against herpes simplex and flu A virus [5][6][7][8][9]. AP derivatives that suppress HIV-infection in cell culture were recently synthesized [10].The pharmacological properties of AP are related to their effect on the course of free-radical processes in biological systems. Steady-state radiolysis and IR spectroscopic methods found that the antioxidant properties of AP are enhanced when the hydroxyls in the molecules are free and diminished upon forming various types of intramolecular hydrogen-bonds (IHB) [11]. As a rule, reactions involving active oxygen species occur nonselectively. Their occurrence in biological systems can damage both the cells themselves and viruses incorporated into them if highly active antioxidants are used.The question of which AP derivatives that are added to biological systems can change the course of free-radical reactions so that an effective and stable antiviral effect is obtained remains open. Therefore, it is important in principle to study properties of individual molecules such as the ability to form IHB because the type of IHB found in the AP is frequently related to their antiradical and antiviral activity [12,13].Herein IR-Fourier spectroscopy is used to study intramolecular interactions (IMI) in CCl 4 solutions of five structurally similar AP derivatives, 4,6-di-tert-butyl-2-(phenylamino)phenol (AP I), N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide (AP II), N-(2-hydroxy-3,5-di-tert-butylphenyl)-4-methylbenzenesulfonamide (AP III), N-(2-methoxy-3,5-di-tert-butylphenyl)-4-methylbenzenesulfonamide (AP IV), and N-(2-hydroxy-3,5-di-tert-butylphenyl) methanesulfo-namide (AP V):

The application of laser spectrochemical analysis to testing for basic compounds and nutritious/toxic elements in soil has been reviewed. A combined laser-spark approach has been applied for the rapid measurement of the carbon content in soil. Spectra have been excited both directly in a laser-ablation plume and by passing a pulsed electric discharge through the plume. The emission spectrum intensity in the combined plasma is considerably higher. The application of a complex of methods to carbon determination in soil has shown that in fact the data on the humus content usually obtained in agrochemical practice by a conventional method of carbon oxidation by potassium dichromate need to be corrected taking into account the possibility of incomplete oxidation of organic matter in soil. The efficiency of various double-pulse LIBS applications has been demonstrated in solving a number of environmental problems such as the determination of heavy and toxic metals in soil and the detection of sulfur in coal. The instrumentation and analytical procedures have been proposed and optimized for rapid control of the chlorine content in plant samples. The technique can be easily extended to ecological monitoring of toxic elements and heavy metals in any biogenic material.Introduction. Laser methods for analyzing the composition of soil, ore, minerals, and related materials have been developing rapidly for the last decade. A comprehensive review of these methods reveals that the technology for performing the analytical procedures, the equipment, and the techniques for processing results are similar. The employed methods are based on emission spectroscopy, fluorescence, Raman scattering, IR reflectance from the samples, etc. Laser-induced breakdown spectroscopy (LIBS) is promoted as a primary technique. This method was developed very early [1-4] and is sufficiently validated for solving various practical problems such as quality control of industrial products [5], processes [6], the environmental situation [7], water resources [8], and the composition of ores and minerals [9] in addition to problems in criminology for detecting explosives [10], pharmacology [11], archeology and art [12], and biological samples [13]. This method is used in agricultural chemistry to determine the soil content of carbon, which characterizes the humus content, and several nutritious elements and toxins [14][15][16]. For this, LIBS factors such as simple sample preparation for analysis, rapid processing of results and their distribution, and prospects for determining the soil composition under field conditions are important [17].Because soil has a complicated background composition, it is analyzed as a rule by calibrating instruments using certified samples (standards). These standards can differ in complexity even for solving similar problems depending on the matrix of samples subject to analysis. For example, the determination of C in chernozem and loamy soils and rocky and peaty ores cannot be carried out using single certified samples. Standards ...

The spectral-luminescence properties of a tetraazachlorin derivative with a norbornene fragment annelated to a reduced pyrrole ring and its complexes with zinc and palladium have been studied at 293 and 77 K. For the norbornene-substituted free base, differences in fluorescence from unsubstituted tetraazachlroin and its dibenzobarrelene-substituted analog are found. The fluorescence lifetime is observed to rise by ~7 times for the free base and by ~1.6 ties for the Zn complex on going from 293 to 77 K. An essential dependence of the photophysical parameters on the nature of the solvent is noted. The fluorescence polarization spectrum of the norbornene-substituted tetraazachlorin reveals in the Soret band region at least four electronic transitions. For the Pd complex, weak phosphorescence in the near IR region has been detected; the 0-0 band maximum is at 990 nm and the singlet-triplet interval amounts to 5800 cm -1 , which is larger by 400 cm -1 than for Pd tetraazaporphine. The quantum yields of the photosensitized formation of singlet oxygen have been determined using a relative luminescence method.

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We have used Fourier transform IR (FTIR) spectroscopy to study intramolecular interactions in solutions of 4,6-di-tert-butyl-2-aminophenol in n-hexane. When the hydroxyl group in the molecule is ortho to the amino group, an O-H⋅⋅⋅N intramolecular hydrogen bond is formed in the 4-6-di-tert-butyl-2-aminophenol derivatives, where the strength of the hydrogen bond depends on the type of substituent at the para position of the phenyl ring. If there are electron-donor groups on the phenyl ring, then a stronger O-H⋅⋅⋅N bond is formed in the 4,6-di-tert-butyl-2-aminophenol derivatives than in molecules containing electron-acceptor Cl and Br atoms. Formation of the above-indicated intramolecular hydrogen bond affects the course of radiation-induced reactions occurring in n-hexane with participation of these compounds and also affects their antiviral activity.

A standard-free variant of spectral laser microanalysis of the material of gold alloys for determining the standard of fineness of the specimens investigated has been implemented experimentally. A good correspondence of the results of measurements of the concentrations of gold in the materials analyzed to the specified data is shown. The basic stages and characteristic features of the procedures of the standard-free analysis are considered.Introduction. Articles made from gold alloys as well as native gold are the objects of routine technological, criminalistic, art, and other investigations. The methods and equipment used to analyze the material of gold alloys were considered to a quite satisfactory extent in [1]. The most widespread traditional method of determining the content of gold in alloys is assaying. The main drawbacks of this method are the following: the absence of information on doping components; a comparatively large mass of the laboratory sample, usually exceeding 200 mg; the slow operation of the analysis (not less than 2 h), and the necessity of recovering wastes. The most rapid method of determining the content of gold in alloys remains assaying on an assay stock. This technique has still another important advantage, that is, the mass of the sample used is fairly small (0.01-0.10 mg). The main disadvantages are the impossibility of determining the content of the remaining elements in the material and the necessity of having a highly competent operator. The simplest technique is the measurement of the material density (densitometry). Usually pure metals are suitable for the purpose. Moreover, this method cannot be used for investigating hollow specimens and articles with fragments made from other materials. Analysis of the composition of precious metals can be performed by the classical methods of "wet" chemistry. Although highly accurate, these techniques are very laborious in the case of a complete elemental analysis, and the main thing is that they require a relatively high expenditure of material.An effective investigation of the composition of the alloys of precious metals is ensured by the methods of spectral analysis: atomic absorption analysis involving a flame or electrothermal atomizer and an emission or mass spectrometric analysis with an inductively confined plasma. The procedure of measurement with the aid of the indicated methods eventually requires that the test sample be converted into a solution or a finely divided powder, although laser samples can be used for initial sampling. Here, among the drawbacks are a comparatively large expenditure of the material (except for electrothermal atomizers) and the high labor content of the full cycle of the procedure. One of the most promising methods that makes it possible to carry out a nondestructive analysis is the xray fluorescent one (XF). However, XF spectrometers yield quantitative information on the composition of the surface layers of a sample (on the order of several micrometers) and, moreover, the geometric shape of the investig...

Analysis of IR-Fourier spectra from solutions and crystals of antiviral sulfo-containing aminophenols has shown that various types of intramolecular and intermolecular interactions can occur in molecules of these compounds. Three types of intramolecular hydrogen bonds (O-H⋅⋅⋅N, O-H⋅⋅⋅O=S=O, and N-H⋅⋅⋅O=S=O) are formed in CCl 4 solutions of the sulfo-containing aminophenols. The formation of intermolecular H-bonds involving the NH-and OH-groups and the preservation of the intramolecular O-H⋅⋅⋅O=S=O H-bond are characteristic of the anti-HIV active aminophenol crystals. Spectral attributes are determined in order to distinguish between the anti-HIV active and inactive sulfo-containing aminophenols.