Spatial structure of molecular complexes of zinc(II)tetraphenylporphyrin with pyridine and aniline derivatives

Structure of molecular complexes of zinc(II)tetraphenylporphyrin with 4-dimethylaminopyridine and 4-methoxyaniline has been studied by X-ray diffraction analysis. 4-Dimethylaminopyridine is coordinated almost perpendicular to the porphyrin cycle plane, whereas 4-methoxyaniline is coordinated at lower dihedral angle. The hybridization of aniline nitrogen atom in the crystal depends on donor-acceptor properties and the volume of the substituents in the aromatic ring.     

Pericyclic reactions in the synthesis of new 5-aryl-5,6-dihydroquinolino[2,1-b]quinazolin-12-ones

1. Download high-res image (52KB)
2. Download full-size image

     

The formation of dead zones in nonisothermal porous catalyst with temperature-dependent diffusion coefficient

This paper considers the formation of dead zones in the porous catalyst pellets due to the chemical reaction and diffusion. We established and investigated the model with nonisothermal reaction of fractional order and activated temperature-dependent diffusivity. The effects of process parameters, catalyst shape, and reaction and diffusion parameters on the formation of the dead zone are studied numerically and characterized by the critical Thiele modulus. The lower bounds for the critical Thiele modulus are derived analytically in terms of process parameters for exothermic and endothermic reactions and verified numerically. The critical Thiele modulus increases with increasing Arrhenius number for diffusion and decreasing Arrhenius number for reaction in the case of exothermic reactions, whereas the opposite trends hold for the endothermic reactions. The critical Thiele modulus also increases with increasing fractional reaction order as well as with decreasing energy generation function, and increasing Biot numbers for heat and mass transfer. Moreover, the critical Thiele modulus is the highest for spherical pellets and the lowest for pellets with planar shape.     

Use of allylzinc halide as a source of halide: Differential addition of nucleophiles to Ts-aziridines and aldehydes under similar reaction conditions

We have observed that the allylic zinc halide under identical reaction conditions acts in different modes for different electrophiles. For Ts-aziridines the halide part of the allylic halide has been introduced as a nucleophile and for the carbonyl compounds the simple allylation reaction occurs. To the best of our knowledge this is the first report where the allylic zinc halide is the source of halide acting as nucleophile. The main advantages of the present procedure are easy to handle, no need of inert atmosphere, mild reaction conditions, and applicability to a wide variety of substrates for aziridines and carbonyl compounds.     

Special Features of Thermal and Stress Hysteresis of B2–R–B19' Martensitic Transformations in Aged [001]-Oriented Ti–50.6 at.% Ni Single Crystals

Russian Physics Journal - Stress-induced and thermal-induced martensitic transformations (MTs) in compression were investigated in [001]-oriented Ti–50.6 at.% Ni single crystals aged at 573 K...     

Effect of the Solvent on the Coordination of Pyridine Derivatives with Zn Tetraphenylporphine

The coordination of zinc(II) tetraphenylporphine with pyridines was studied by electronic spectroscopy. Linear correlations were found between the thermodynamic and kinetic parameters of coordination in different solvents. The effect of the solvent on the stability constants of the complexes and the thermodynamics of complex formation are discussed.     

Influence of the Ohmic Contact Structure on the Performance of GaAs/AlGaAs Photovoltaic Converters

A multilayer system of ohmic contacts for GaAs/AlGaAs photovoltaic converters has been developed. A method of ohmic contact blackening is suggested with the aim of improving the coefficient of optical signal reflection from an Ag/Au/Ag multilayer contact. Owing to blackening, the reflection coefficient has been decreased more than tenfold.     

Oxygen Reaction at Carbonaceous Materials with Different Structure in Electrolytes Based on Lithium Perchlorate and Aprotic Solvents

Russian Journal of Electrochemistry - The necessity of the studying of carbonaceous materials differing in their surface area and structure is called for by the fact that these materials are used...     

Quantum-chemical study on adenine nitrosonium complexes

Adenine complexes with nitrosonium ion have been studied by the RI-MP2/L1 quantum-chemical method. Addition of nitrosonium ion to adenine tautomers produces a set of nitrosonium complexes of different types (1??C3??). n-Complexes involving NO⁺ coordination to nitrogen atoms are more energetically favorable than ??-complexes. The global minimum on the potential energy surface is occupied by the complex of 7H-adenine tautomer with nitrosonium ion coordinated at the N³ atom.     

Frequency conversion of CO laser radiation in the ZnGeP<Subscript>2</Subscript> nonlinear crystal

The experimental results of the study of CO laser frequency doubling in ZnGeP₂ and GaSe nonlinear crystals of high optical quality are presented. A multifrequency low-pressure Q-switched CO laser and a selective pulsed electroionization mode-locked CO laser with cryogenic cooling were used in the experiments. The highest external factor of radiation conversion into the second harmonic of the pulse-periodic Q-switched CO laser and pulsed mode-locked CO laser was 1% and 3.5%, respectively. Theoretical calculations showed the possibility of obtaining far IR and terahertz radiation using difference frequency generation of CO laser lines in these crystals.