Vol 52, No 5 (2018)

The structure formation in xerogels of aqueous solutions of products of the UV-initiated formose reaction has been studied in the context of the problem of the spontaneous formation of prebiological structures. Of the 11 variants of xerogels, only in the talopyranose xerogel show the presence of anisometric strings with distinct periodic (in particular, helical) structure, which form characteristic elements of biomimetic structures by interlacing. Under the conditions simulating the primitive Earth’s atmosphere (formaldehyde, water, UV), spontaneous formation of anisometric superhelical structures has been modeled and the type of the sugars forming these structures has been identified.

The effective rate constants for the photoreduction (k_H) of 9,10-phenanthrenequinone (PQ) in the presence of dimethacrylate monomers (ethylene glycol dimethacrylate (DMEG), triethylene glycol dimethacrylate (TGM-3), and oligocarbonate dimethacrylate (OKM-2)) and porous polymers based on them have been spectrophotometrically determined. The values of k_H in the presence of DMEG and TGM-3 in benzene solutions and in the monomer media are two times greater than in the presence of OKM-2. The values of k_H for PQ in pores of polyDMEG, polyTGM-3, and polyOKM-2 are approximately identical and do not depend on the pore size (up to hundreds of nanometers) and the specific surface area.

Modern quantum-chemical methods have been used to model and assign the bands of the electronic spectrum in the near UV–visible region of a structurally intricate metal complex with organometallic σ and π bonds. The properties of the frontier and nearest molecular orbitals and the nature of the electronic transitions with ligand-to-metal charge transfer have been estimated.

It has been shown that in addition to the conventional mechanism of photovoltaic effect in organic solar cells (OSCs), which is the ionization of molecular excitons on impurities, a new mechanism is possible in nanoscale cells, namely, tunneling autoionization in a strong electric field of the pn junction. Its quantum yield for molecular excitons and charge-transfer excitons becomes higher than for ionization on impurities with a cell length of less than 20–25 or 60–80 lattice periods (~10 and ~25 nm), respectively. The possibility of creating cascades of series-connected OSCs with a quantum yield close to 1 on the basis of the new mechanism is discussed.

Energy characteristics of the irradiated surface of a polytetrafluoroethylene film depend on the energy and fluence of bombarding MeV protons. Irradiation with 2–4 MeV protons leads to an increase in the surface free energy; 4 MeV protons at a fluence of 10¹⁵ proton/cm² increase the polarity of the polymer surface by 40 times due to the appearance of functional groups, the polarity enhancement being manifested in an increase in the acid–base component of the surface energy by more than a factor of 50. There is a correlation between the dispersion component of the surface energy and the degree of crystallinity of the near-surface layer of the polymer a period. They both grow symbatically in the case of bombardment with 1–2 MeV protons and decrease upon irradiation with 4 MeV protons. It has been found that dehydrofluorination results in carbonization of the irradiated surface, a decrease in the fluorine content, and an increase in the proportion of oxygen due to oxidation of the radicals generated by proton bombardment.

The effect of irradiation of copper films with low-energy He²⁺ ions on their structural properties has been studied. The surface morphology and structural properties of the samples before and after irradiation have been examined by scanning electron microscopy, energy dispersive analysis, and X-ray diffraction. Bombardment of the initial samples with He²⁺ ions at a fluence of 1 × 10¹⁶ion/cm² alters the surface morphology of copper films and leads to the formation of nanoscale inclusions of hexagonal shape. An increase in the fluence to 1 × 10¹⁷ ion/cm² and higher results in the formation of cracks and amorphous oxide inclusions on the sample surface.

The flow of vortex-stabilized argon–hydrogen plasma in a radiofrequency induction (RFI) plasma torch has been investigated using modern methods of computational fluid dynamics. Optimal values of the torch power and energy release in plasma have been found at various argon to hydrogen ratios in the plasma gas mixture. The heat and kinetic fields determined by calculation for a plasma-chemical reactor can be of use in designing an RFI plasma torch in part concerning the determination of the optimum zone for feeding the reactants to the reactor.

Materials based on organic–inorganic hybrid perovskites MAPbX₃ (X = I, Cl, or Br) having unique adsorption characteristics have been considered. Theoretical investigation data obtained by molecular modeling and results of X-ray diffraction measurements of the hybrid organic–inorganic perovskite structures based on methylammonium lead trichloride in different temperature ranges have been analyzed.Z

The yield of singlet oxygen (¹О₂) in the decomposition of a number of hydrotrioxides of alcohols (cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, L-menthol, 1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol, 1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol, heptan-4-ol, propanol-2, and 1-cyclopropylethanol) has been determined using the IR chemiluminescence technique. It has been shown that cyclopentanol, 1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol and 1-cyclopropylethanol hydrotrioxides are efficient sources of singlet oxygen; the yield of ¹О₂ reaches up to 58%.