Gas phase electron diffraction study of trimethylstannylacetylene

Trimethylstannylacetylene has been studied by gas phase electron diffraction. The bond lengths, r_a (Å), and valence angles (degrees) determined with errors represented by three times standard deviation values are as follows:

.The results are compared with the structural data on organotin compounds studied earlier. The

bond lengths are shown subject to different substituent effects.     

An X-ray spectroscopy study of CdS nanoparticles formed by the Langmuir–Blodgett technique on the surface of carbon nanotube arrays

The composition and electronic structure of cadmium sulfide (CdS) nanoparticles formed by the Langmuir–Blodgett (LB) technique on clean silicon wafers and the surface of vertically aligned carbon nanotube (CNT) arrays are studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The samples were annealed in a vacuum at 175 °C and 225 °C to remove the organic matrix of the LB film. From the analysis of the XPS data the increased concentration of sulfate groups on the surface of CdS nanoparticles formed on CNTs and the electron density transfer from CdS to CNTs are determined. An increase in the LB film annealing temperature causes an increase in the degree of crystallinity and the CdS crystallite size and a decrease in the photoluminescence intensity of a CdS–CNT hybrid.     

Atmospheric pressure ionization permanent magnet fourier transform ion cyclotron resonance mass spectrometry

A new Fourier transform ion cyclotron resonance mass spectrometer based on a permanent magnet with an atmospheric pressure ionization source was designed and constructed. A mass resolving power (full-width-at-half-maximum) of up to 80,000 in the electron ionization mode and 25,000 in the electrospray mode was obtained. Also, a mass measurement accuracy at low-ppm level has been demonstrated for peptide mixtures in a mass range of up to 1200 m/z in the isotopically resolved mass spectra.     

Development of a Generator of a Periodic Sequence of Ultrashort 8-mm Electromagnetic Pulses Based on the “Saturn” Accelerator with Two Coaxial Emitting and Absorbing Electron Beams

Radiophysics and Quantum Electronics - We analyze theoretically and model a generator of a periodic sequence of ultrashort microwave pulses in a scheme with two coaxial cylindrical electron beams...     

Initial stages of the growth and magnetic properties of cobalt films on the Si(100)2 × 1 surface

Physics of the Solid State - The initial stages of the growth of cobalt films on the Si(100)2 × 1 surface and the dynamics of variation in their phase composition, electronic structure, and...     

Prediction by 13C NMR of regioselectivity in 1,3‐dipolar cycloadditions of acridin‐9‐yl dipolarophiles

Strong correlation was found between ¹³C NMR chemical shifts of dipolarophilic CH?CH carbons and regioselectivity in 1,3‐dipolar cycloadditions of new acridin‐9‐yl dipolarophiles with stable benzonitrile oxides (BNO). Accordingly, two starting dipolarophiles, (acridin‐9‐yl)‐CH?CH‐R (R = COOCH₃ or Ph), reacted with three BNOs (2,4,6‐trimethoxy, 2,4,6‐trimethyl, and 2,6‐dichloro) to give a mixture of two target isoxazoline regioisomers in which the acridine was bound either to isoxazoline C‐4 carbon (4‐Acr) or C‐5 one (5‐Acr). Methyl 3‐(acridin‐9‐yl)propenoate afforded major 4‐(acridin‐9‐yl)‐isoxazoline‐5‐carboxylates (4‐Acr) and minor 5‐(acridin‐9‐yl)‐4‐carboxylates (5‐Acr). 9‐(2‐Styryl)acridine regiospecifically afforded only 4‐Acr cycloadducts. The ratios of regioisomers were compared with analogous reactions of acridin‐4‐yl dipolarophiles. Regioselectivity was dependent on a polarity of the CH?CH bond, donor effects in BNO, and stabilization by stacking of aromatic substituents in the products. Copyright © 2015 John Wiley & Sons, Ltd.     

Strong deshielding in aromatic isoxazolines

Very strong proton deshielding was found in di/tri‐aromatic isoxazoline regioisomers prepared from acridin‐4‐yl dipolarophiles and stable benzonitrile oxides (BNO). Three alkenes, (acridin‐4‐yl)‐CH?CH‐R (R = COOCH₃, Ph, and CONH₂), reacted with three BNO dipoles (2,4,6‐trimethoxy, 2,4,6‐trimethyl, 2,6‐dichloro) to give pairs of target isoxazolines with acridine bound to C‐4 or C‐5 carbon of the isoxazoline (denoted as 4‐Acr or 5‐Acr). Regioselectivity was dependent on both the dipolarophile and dipole character. The ester and amide dipolarophile displayed variable regioselectivity in cycloadditions whereas the styrene one afforded prevailing 4‐Acr regioisomers. 2,4,6‐Trimethoxy‐BNO was most prone to form 5‐Acr isoxazolines while mesitonitrile oxide gave major 4‐Acr isoxazolines. Basic hydrolysis of the amide cycloadduct led to an unexpected isoxazolone product. The structure of the target compounds was studied by NMR, MS, and X‐ray crystallography. Copyright © 2015 John Wiley & Sons, Ltd.     

Investigation of the radiation-protective properties of a highly filled liquid glass material

Experimental studies of the radiation-protective properties of a highly filled liquid glass composite coating are presented. Investigations are carried out by irradiating test samples of aluminum alloys with a protective coating applied to their surface. The appreciable attenuation of ionizing radiation by the coating under study up to energies of 150 keV is found.     

A gas electron diffraction study of the conformational composition of 1,3,5-trimethyl-1,3,5-triazacyclohexane

The conformational composition of 1,3,5-trimethyl-1,3,5-triazacyclohexane was studied by gas electron diffraction and quantum-chemical calculations at the density functional theory (B3LYP) and MP2 levels. Conformers with the general chair, boat, and twist ring forms were considered possible. These structures differed in the arrangement of CH₃ groups in the axial (a) and equatorial (e) positions. A chair conformer with the axial orientation of one CH₃ group was found to satisfy the electron diffraction data. Its main structural parameters (mean values) were r _g(C-N) = 1.463(3) Å, r _g(C-H) = 1.117(5) Å, ∠(C-N-C) = 110.91(1)°, and ∠(N-C-N) = 111.1(1)°.