Synthesis of 1-[(nitroxyalkoxy)methoxy]-1-triazene 2-oxides,new hybrid nitrogen monoxide donors

1-[(Nitroxyalkoxy)methoxy]-3,3-dialkyl-1-triazene 2-oxides were obtained by the reaction of 3,3-dialkyl-1-hydroxy-1-triazene 2-oxide sodium salts with β- or γ-nitroxyalcohol chloromethyl ethers or by the reaction of 3,3-dialkyl-1-(bromoalkoxymethoxy)-1-triazene 2-oxides with silver nitrate. These compounds can be of interest as new hybrid NO donors in living organisms.     

35Cl NQR Studies of the Geometry of Aromatic Imines

The preferred conformation of solidphase R4benzylidene3,4dichloroaniline molecules has been established by nuclear quadrupole resonance (NQR) combined with quantum chemical calculations. The conformational effect of substitutes reported previously is proved. The rotation angle of the plane of the aniline ring with respect to the plane of the azomethine bond is given.     

Subgroups of a finite group whose algebra of invariants is a complete intersection

Let G be a finite subgroup of GL(V), where V is a finite-dimensional vector space over the field K and char KG. We show that if the algebra of invariants K(V)^G of the symmetric algebra of V is a complete intersection then K(V)^H is also a complete intersection for all subgroups H of G such that H={ Gv (v)=v for all v V^H}.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 116, pp. 63–67, 1982.     

Bandgap widening of titania through semiconductor support interactions.

Silica-supported titania powders with 50, 36, 13 and 4 wt% of TiO2 (TiO2-50/SiO2, TiO2-36/SiO2, TiO2-13/SiO2 and TiO2-4/SiO2) were prepared by hydrolysis of TiCl4 in the presence of silica, followed by calcination at 500 degrees C. The formation of Ti-O-Si linkages was confirmed by diffuse reflectance infrared Fourier transform spectroscopy. Atomic force microscopy indicated the presence of titania crystals larger than 15 nm. All supported materials exhibited a blue-shift of the TiO2 absorption edge, which was attributed to an electronic semiconductor support interaction. Bandgap energies of TiO2-50/SiO2, TiO2-36/SiO2, TiO2-13/SiO2 and TiO(2)4/SiO2 were measured to be 3.28, 3.36, 3.40 and 3.42 eV, respectively, as compared to 3.15 eV for unsupported TiO2. From these values, and from the quasi-Fermi level of electrons, a high anodic shift of both the valence and the conduction band was estimated. X-ray photoelectron spectroscopy (XPS) measurements of oxygen 1s- and titanium 2p-binding energies confirmed the anodic shift of the band edges.     

Fatty acid composition of the main phospholipids of the Antarctic krill Euphausia superba

The Antarctic krillEuphausia superba Dana contains about 5% of its natural weight of extractable lipids, more than half of which are in the form of phospholipids — phosphatidylcholine (33–36% of the sum of the lipids), phosphatidylethanolamine (15–17%), lysophosphatidylcholine (3–4%), and others (2–3%) — while among the phosphorus-free components triacylglycerols predominate (32–35%). In the first two phospholipids the dominating fatty acid residue is the arachidonic acid residue (more than 40% of the sum of the acyl residues) and the amounts of residues of eicosapentaenoic acid (C_{20 : 5w3}) are about 13 and 28%, respectively. A simple procedure for isolating the phosphatidylcholine and phosphatidylethanolamine is proposed. For the analysis of the fatty acid a new method was used, consisting of the HPLC of their (7-diethylaminocoumarin-4-yl)hydrazides, with fluorometric detection.Scientific Research Laboratory of Biologically Active Substances of Hydrobionts, USSR Ministry of Health, Moscow. K. A. Timiryazev Moscow Agricultural Academy. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 181–187, March–April, 1990.     

Ring functionalization of cyclosiloxanes using electrochemically generated diorganyl silanones

Cathodic reduction of oxygen in the presence of dichloro- or dialkoxydiorganylsilanes R¹R²SiX₂ (X = Cl,OAlk) provides highly reactive intermediates, supposedly diorganyl silanones R¹R²Si=O, which readily react with cyclicpermethylsiloxanes (hexamethylcyclotrisiloxane D₃ and octamethylcyclotetrasiloxane D₄) to form ring-extended products bearing an additional R¹R²SiO fragment. In this way, various groups can beincorporated into the siloxanes framework: Ph, vinyl (Vi), Alk, OAlk, H and substituted alkyls. The process is more selective at low temperature (T ?–10°C) and when using dialkoxysilanes as starting compounds. The electrochemical activation of dichloro- and dialkoxysilanes for the reaction with siloxanes provides an alternative way to prepare functional cyclosiloxanes.     

Quantum chemical study of nickel(II) complexes with cyclic diimine ligands on the base of bis[3,3′-iminopropyl]methylamine

A quantum chemical study of spatial and electronic structures of molecules in the frame complexes, bis[3,3′(RR′)-ketiminepropyl]methylamine nickel dichlorides, where R = H, CH₃, and R′ = H, CH₃, has been performed by DFT(B3LYP/LANL2DZ) method. The molecules of these complexes were found to be in a triplet state. Energy stability of the endo form of the complex molecules was shown. In the molecule of bis[3,3′-aldiminopropyl]methylamine nickel dichloride (R = R′ = H), a considerable strengthening of the bond Ni-N(amine) takes place when passing from the diamagnetic into paramagnetic state, and all bonds Ni-N become equivalent with respect to interatomic distance values. The topology analysis of the electron density for the complexes with R = R′ =H and R = R′ = CH₃ was carried out. It is stated that all Ni-N bonds are covalent in the molecules of paramagnetic complexes.     

35Cl NQR and structural-dynamic properties of crystalline CCl3C(O)OC6H2Cl3-2,4,6

The temperature dependences of the resonance frequency and quadrupole spin-lattice relaxation time of the chlorine-35 nuclei in crystalline CCl₃C(O)OC₆H₂Cl₃-2,4,6 were studied. Owing to the presence of resonant nuclei in various fragments of the molecules, the character of dynamics of these molecular fragments and the entire molecule was established. It is shown that thermal librations of molecules are quasiharmonic over the whole temperature range from 77 K to the melting point of the crystal. The reorientational motion of the CCl₃ group bonded to the three-coordinated carbon atom was revealed. This motion causes an exponential increase in the spin-lattice relaxation time of the chlorine nuclei of this group and subsequent damping of NQR signals (chlorine-35 resonance signals of the aryl radical were observed before melting of the sample). The activation energy of the reorientational motion is found; its value, which is 27.3 kJ/mole, is considered in comparison with the activation energies obtained by the Cl NQR method in solids for CCl₃ reorientations in similar molecular structures.