Magnesium octa[(4′-benzo-15-crown-5)oxy]phthalocyaninate in water micellar solutions of sodium deoxycholate

Aggregation of magnesium octa-[(4′-benzo-15-crown-5)oxy]phthalocyaninate (Mgcr₈Pc) in solutions of biocompatible anionic surfactant, sodium deoxycholate (SDC), was studied. It was shown using the electron absorption spectra that formation of Mgcr₈Pc monomers in micellar solutions of SDC is affected by both increased surfactant concentration and by changes in the ionic strength of solution after sodium chloride is added. The effect of the chemical structure of biocompatible anionic surfactant on monomerization of crown-containing phthalocyanines was identified; this fact opens new possibilities for using this family of compounds for fluorescent diagnosis and photodynamic therapy.     

Alternating-current electrocontact oxidation of Kh18N10T steel

Properties of surface oxide layers formed on extended Kh18N10T steel specimens upon oxidation at residual pressure P = 10^?4–10¹ mmHg under typical heating in a furnace and alternating-current (50 Hz) electrocontact heating (300°C) are studied. A strong activating effect of alternating-current heating on the oxidation of steel at P = 0.01 mmHg is noticed. Compared to typical heating in a furnace, electrocontact heating promotes saturation of the surface oxide with chromium and homogenization of the chromium distribution in the depth of the oxide and the resulting formation of iron chromite.     

Photorefractive and nonlinear optical properties of indium(III) tetra(15-crown-5)phthalocyaninate-based composites

Photoelectric, nonlinear optical, and photorefractive properties of hybrid composite materials based on polyvinylcarbazole (PVK) and indium(III) 2,3,9,10,16,17,23,24-tetra(15-crown-5)phthalocyaninate [(15C5)₄Pc]In(OH) are studied in detail. Field dependence of the quantum efficiency in a 7.8 μm-thick layer containing 5 at % [(15C5)₄Pc]In(OH) is measured. The best approximation of the quantum efficiency with Onsager’s equation corresponds to a quantum yield of thermalized electron-hole pairs φ₀ = 0.01 at initial separation r ₀ = 9.8 Å. Z-scan measurements in a nanosecond range showed that the electric susceptibility of [(15C5)₄Pc]In(OH) solution in tetrachloroethane (TCE) with a concentration of 7 × 10^?4 mol/L is χ⁽³⁾ = 1.34 × 10^?9 esu. The maximum coupling gain coefficient found for the material composed of PVK and 5 wt % [(15C5)₄Pc]In(OH) at an electric-field intensity of 200 V/μm is Γ = 80 cm^?1, and the difference between the coupling gain and absorption coefficients is Γ ? α = 70 cm^?1. The dependence of the coupling gain coefficient on the intensity ratio of interfering beams 1 and 2 (β = I ₁(0)/I ₂(0)) in a composite containing 3 wt % [(15C5)₄Pc]In(OH) is measured. An increase in β was attained by decreasing intensity of the signal beam I ₂(0) at constant intensity of the pump beam I ₁(0) = 0.15 W/cm² and E ₀ = 214 V/μm. Within the initial segment of the curve, the coupling gain coefficient increases from 30 to 60 cm^?1; then, the coefficient drops almost to the initial value. The data obtained show that the composite materials studied can be used in practice for correcting faded images. The combined analysis of the results obtained and similar data for gallium and ruthenium tetra-15-crown-5-phthalocyaninate complexes revealed the regularities in the change of the quantum yield of thermalized electron-hole pairs and the photorefractive coupling gain coefficient in a series of complexing metals: gallium(III), ruthenium(II), and indium(III). An increase in the molecular weight of the central metal atom is found to result in a substantial decrease in Γ and φ₀ due to the increase in the spin-orbit coupling constant.     

The effect of self-organizing vinyl siloxane nanolayers on the corrosion behavior of aluminum in neutral chloride-containing solutions

The methods of quartz crystal microbalance, atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier-transform IR spectroscopy, and X-ray structural microanalysis were is used to show that adsorption of vinyl silane on an aluminum surface from an aqueous solution results in formation of a uniform, self-organizing protective vinyl siloxane nanolayer covalently bound with surface metal groups. Its thickness can be controlled by variation of application conditions. The effect of a vinyl siloxane nanolayer on dissolution of aluminum is studied in chloride-containing solutions. It is found that an ordered vinyl siloxane nanolayer with a thickness of up to 5 molecular layers causes efficient inhibition of uniform and local corrosion of aluminum. It is shown that the vinyl siloxane nanolayer is preserved on the surface of aluminum after 10 days of corrosion tests, which indicates its stability at exposure to water and corrosive components.     

Formation and Properties of Electron- and Ion-Conducting Layers of N-Substituted PVC Derivatives Grafted onto Active Carbon

Protection of Metals and Physical Chemistry of Surfaces - A systematization is presented of studies of carbon sorbent functionalization based on chemical modification of the active carbon surface...     

Supramolecular complexes: Determination of stability constants on the basis of various experimental methods

Stability constants and formation enthalpies of supramolecular complexes of crown ethers and their cyclic and acyclic analogues are determined on the basis of experimental data obtained by different physicochemical methods in the terms of a general approach developed and implemented in the ChemEqui software package. The established regularities of variation of stability of complexes are discussed as dependent on the ligand structure, nature of the cation, solvent, and anion. The applicability of the suggested method of determining complexation selectivity is shown for multicomponent equilibria in solutions.

     

Relaxation behavior of latex-polymers in frost-resistant aqueous-dispersion deep-penetration ground coats modified by water-soluble dye

The effect of a water-soluble indanthrene blue dye on the relaxation structure of styrene–acryl latex polymer with the glass-transition point below 5°C is studied in a frost-resistant aqueous-dispersion coat using the method of dynamic mechanical-relaxation spectroscopy. A significant difference is found between the change in the intensity of the maximum of α-relaxation dissipative losses of a latex-polymer binder in the ground coat and in free latex polymer when they are modified by a blue dye, which is due to the ground-coat composition. Special attention is paid to relaxation effects in the negative temperature range.     

Gravimetry, resistometry, and Fourier-transform infrared spectroscopy for monitoring the corrosivity of the atmosphere with the use of an iron-oxide nanocomposite sensor layer

The properties of a heterophase nanostructured metal-oxide layer produced by reactive sputtering in a vacuum followed by exposing to an oxidizing air environment at different evacuation degrees at 25°C are monitored with the use of diffuse reflectance Fourier transform infrared spectroscopy, resistometry, and gravimetry. According to the data of atomic force microscopy and infrared spectroscopy, as a result of the application of a metal to a glass substrate and subsequent oxidation, a metal-oxide nanocomposite film composed of metal-oxide nanoparticles with sizes of 20–30 nm covered with magnetite-hematite oxide shells is formed. It is shown that a metal-oxide nanocomposite layer can be used as a sensor in oxidizing environments. Gravimetric and resistometric sensor responses (the integral degree of oxidation) are almost proportional to the logarithmic rarefaction, which enables one to use metal-oxide sensors in broad ranges of pressure and rarefaction of the monitored atmosphere. Results of gravimetry and resistometry showed that the low-temperature oxidation of freshly sputtered iron films is accompanied by their partial oxide compaction. For overall monitoring of the formation of magnetite and its transformation into hematite, the above methods should be supplemented with a spectral method, such as Fourier-transform infrared spectroscopy.