Synthesis and Photochromic Properties of 2-(3-Nitro-2-pyridylmethyl)benzazoles

2-(3-Nitro-2-pyridylmethyl)benzazoles were synthesized, and their photochromic properties were studied by flash photolysis. Introduction of a nitropyridyl instead of the nitrophenyl moiety into the 2-methyl group insignificantly increases the basicity of the methylene group. Nitropyridyl-substituted benzazoles give rise to three detectable photoinduced forms: the corresponding anion at pH > 10, azamerocyanine at pH 4 , and monomethinecyanine at pH 1. Irradiation of solutions of weakly basic benzoxazole and benzothiazole derivatives at pH 4 results in formation of neutral chelate structures in which the hydrogen atom is linked simultaneously to two nitrogen atoms: one in the pyridine ring, and the second, in the azole ring.     

First example of a click-reaction on the aminate copper complexes: effect of reaction parameters

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Passage of the discharge current through the plasma–electrode interface in the electromagnetic rail accelerator channel

We investigate the phenomena that accompany the acceleration of a free plasma piston (without a striker) in the electromagnetic rail accelerator channel filled with different gases (argon, helium). An intense glow appears in the shock-compressed layer (SCL) in the case of strong shock waves that produce a high electron concentration (~10¹⁷–10¹⁸ cm^–3) behind the front. We have proposed that explosive electron emission (EEE) ensures the high-intensity emission of electrons, the passage of a part of the discharge current through the SCL, and the glow of the SCL. The velocity of a shock wave for which the strong electric field in the Debye layer at the cathode causes EEE from its surface and the passage of the current in the SCL has been determined. It has been concluded that, for high velocities of the plasma, the EEE is a universal mechanism that ensure the passage of a strong current through the interface between the cold electrode and the plasma.     

Supersonic flow about a body exposed to electric and magnetic fields

The feasibility of using nonmechanical (electrogasdynamic, EGD, and magnetohydrodynamic, MHD) methods to control shock-wave configurations emerging in supersonic flows is investigated. In the EGD method, the flow is heated by a gas discharge; in the MHD one, the flow is influenced by a Lorentz force arising in a gas discharge upon applying a magnetic field. The influence of the gas discharge and MHD interaction on the position of a detached shock wave appearing in a supersonic xenon flow about a semicylindrical body is studied. A discharge is initiated in the immediate vicinity of the leading edge of the body, and the variation of the shock wave position with the intensity of the discharge (discharge current density) is traced when the influence of the EGD action increases and/or an external magnetic field is applied (the influence of the MHD action increases). Preliminary data for a supersonic air flow about a body are presented.     

Pressure variation by a magnetohydrodynamic method at the surface of a body placed in a supersonic flow

This study is aimed at investigating the possibility of pressure variation near the surface of a body placed in a supersonic flow as a model of an aerofoil or the nose of an aircraft by organizing a surface gas discharge in a magnetic field transverse to the flow. The flow parameters and pressure are mainly affected by the ponderomotive Lorentz force acting on the gas in the direction orthogonal to the direction of the organized discharge current and leading to the removal or compression of the gas at the surface of the body and, hence, a variation of pressure. Experimental data on the visualization of the flow and on the pressure at the surface of the body are considered for various configurations of the current and intensities of the gas discharge and magnetic field; it is demonstrated that such configurations of the current and magnetic field near the surface of the body under investigation can be organized in such a way that the pressure at the front part as well as the upper and lower surfaces of the body under investigation can be increased or decreased, thus changing the aerodynamic drag and the aerofoil lift. Such a magnetohydrodynamic control over aerodynamic parameters of the aircraft can be used during takeoff and landing as well as during steady-state flight and also during the entrance into dense atmospheric layers. This will considerably reduce the thermal load on the surface of the body in the flow.     

Photochromic Properties of ortho-Methylnitrobenzothiazoles in Solution

Isomeric benzothiazoles having the nitro and methyl groups ortho to each other are converted into tautomeric aci-nitro derivatives on irradiation in heptane solution; in water, the corresponding more deeply colored anions are formed. The efficiency of photochromic transformations strongly depends on the position of the nitro and methyl groups in the benzene ring of the benzothiazole molecule.     

Investigation of a Rail Electromagnetic Plasma Jet Source

Technical Physics - We report the results of investigation of elements of a rail-type electromagnetic accelerator (railgun), which are aimed at analysis of the mechanism of formation of a dense...     

Phosphonomethylated Acetoxymethyl Derivatives of Acetylfurans and Alkyl Furoates with Neighboring Location of Substituents: Synthesis and Following Transformations

Russian Journal of General Chemistry - Methods of synthesis of phosphonmethylated acetoxymethyl derivatives of acetylfurans and alkyl furoates have been developed and their methanolysis was...     

Alkylation of CH-Acids with 3-Halomethyl Derivatives of Ethyl (Diethoxyphosphorylmethyl)furoates

Russian Journal of General Chemistry - Alkylation at the carbon atom of the active methylene group of 3-halomethyl derivatives of phosphonocarboxylic acid esters of the furan series with...