Hexamolybdoaluminates and Hexamolybdochromates of Some Trivalent Lanthanides and Americium

The reactions of some rare-earth elements (La, Ce, Sm, Lu, Gd) and Am(III) with heteropolymolybdate anions are studied. The complexation rate constants of Am(III) in a solution with Al(OH)₆Mo₆O₁₈ ^3- and Cr(OH)₆MoO₁₈ ^3- ₆ (₁ = 18 ± 6 and 25 ± 5, respectively) are determined by spectral methods. The Ln[Al(OH)₆Mo₆O₁₈] · nH₂O, Eu[Cr(OH)₆Mo₆O₁₈] · nH₂O, and Am[Al(OH)₆Mo₆O₁₈] · nH₂O isostructural compounds are synthesized. The crystal structure of the Sm[Al(OH)₆Mo₆O₁₈] · 11H₂O complex was determined by the X-ray diffraction analysis. The results of spectroscopic and thermogravimetric studies of the obtained compounds are presented.     

Intramolecular charge transfer processes in a series of styryl derivatives of pyridine and quinoline N-oxides

Intramolecular charge transfer processes in a series of thetrans-isomers of styryl derivatives of pyridines and quinolines, their hydrochlorides and molecular complexes with BF₃ have been studied by electronic and IR spectroscopy. Electron donor groups involved in direct resonance conjugation with the N-oxide group intensify these processes, while electron acceptor nitro groups somewhat weaken them. Protons and BF₃ coordinate to the oxygen of the NO group to form strong 11 complexes, except in the cases of 4-(4-dimethylaminostyryl)quinoline and pyridine N-oxides, in which a second acceptor molecule adds to the amino group.Petrozavodsk State University, Petrozavodsk 185640, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, 1093–1102, August, 1998.     

Electroinjection analysis. The introduction of a new variant of flow-injection analysis and comparison with electrophoretically-mediated microanalysis

A new method of mixing sample and reagent due to the difference in their electrophoretic mobilities is introduced. Unlike electrophoretically-mediated microanalysis, sample and reagent are injected from the opposite ends of a capillary tube. This method is compared with electrophoretically-mediated microanalysis. Experiments are performed showing the possibilities of this new method.     

Waveguide propagation of intense electromagnetic radiation in slightly inhomogeneous nonlinear media

The propagation of self-localizing beams of electromagnetic waves in the form of nonlinear waveguides in a slightly inhomogeneous medium is studied analytically and numerically. The trajectories of the axial ray are studied as a function of its direction and the field strength at the initial point on the basis of a nonlinear scalar Helmholtz equation. Analytic expressions are derived. The longitudinal refractive index, the field intensity, and the waveguide radius are plotted as functions of the instantaneous position of the point on the axial ray. Deep penetration of the beam into the opaque region and the position of the screening surface are studied as functions of the parameters of the beam and the medium. A steady-state 3D problem is analyzed for a power-law nonlinearity with an arbitrary power. A 2D problem is analyzed for the case of a ponderomotive nonlinearity with saturation.     

Influence of the adsorption potential on the composition of formaldehyde chemisorption products on platinum

The influence of the adsorption potential on the composition of formaldehyde chemisorption products on platinum has been investigated by the radioactive tracer method in conjunction with electrochemical methods. It is shown that in the potential range 0.0–0.3 V the main adsorption product of formaldehyde is a particle of composition COH, and at the potential 0.4 V a particle of composition CO. It has been found that at E<0.3 V adsorbed CO particles are reduced to COH particles. The electrochemical properties of these particles have been studied.     

Environmetric modeling of emission sources for dry and wet precipitation from an urban area

Monitoring data from chemical analysis of rainwater and aerosol samples collected in an urban area have been interpreted by the use of environmetric approaches. An attempt was done to compare the data set structures of both type of precipitation and to estimate the contribution of different anthropogenic and naturally occurring emission sources to the total mass of the wet and dry precipitation. It was found that three latent factors explaining over 80% of the total variance of the set are responsible for the rainwater set structure-'sea spray', 'soil dust', and 'anthropogenic'. Only two were the latent factors explaining the dominant part of the variance in the case of aerosol samples-'anthropogenic' and 'natural'. It is shown that the anthropogenic influence for aerosol samples is more complex that that of rainwater samples and represents interaction between typical anthropogenic sources and natural emitters. Additionally, a source apportioning using multiple regression on absolute principal component scores is performed in order to obtain qualitative information about the impact of the different identified emission sources on the urban environment.     

Raising the conductivity of crystalline polymer electrolytes by aliovalent doping

Polymer electrolytes, salts dissolved in solid polymers, hold the key to realizing all solid-state devices such as rechargeable lithium batteries, electrochromic displays, or SMART windows. For 25 years conductivity was believed to be confined to amorphous polymer electrolytes, all crystalline polymer electrolytes were thought to be insulators. However, recent results have demonstrated conductivity in crystalline polymer electrolytes, although the levels at room temperature are too low for application. Here we show, for the first time, that it is possible to raise significantly the level of ionic conductivity by aliovalent doping. The conductivity may be raised by 1.5 orders of magnitude if the SbF6- ion in the crystalline conductor poly(ethylene oxide)6:LiSbF6 is replaced by less than 5 mol % SiF6(2-), thus introducing additional, mobile, Li+ ions into the structure to maintain electroneutrality.     

Oxidation of 2,4-Dinitrotoluene with an Ozone-Oxygen Mixture

Oxidation of 2,4-dinitrotoluene to 2,4-dinitrobenzoic acid with an ozone-oxygen mixture in glacial acetic acid was studied.     

Molecular and Electronic Structure of Trimethylsilylpropiolamides

The specific features of molecular and electronic structure of trimethylsilylpropiolic acid amides were studied by means of IR spectroscopy and quantum chemistry (AM1). The competition between p,-conjugation in the amide fragment and ,-conjugation in the ethynylcarbonyl group CC-C=O was established. The prevailing conformers were revealed, their geometrical parameters were established, the barriers to internal rotation around the amide C-N bond were calculated for acyclic (13 kcal mol^-1) and heterocyclic (8.12 kcal mol^-1) amides.     

Carvone epoxidation by system “hydrogen peroxide-[Mn2L2O3][PF6]2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane)-carboxylic acid”: a combinatorial approach to the process optimization?

Summary Epoxidation of natural terpene (+)-carvone by the system consisting of a catalyst, oxalic acid (co-catalyst) and H₂O₂ (70% aqueous solution; oxidant) was studied and factorial design methods were applied for the optimization of this reaction. A dinuclear manganese(IV) complex [LMn(O)₃MnL](PF₆)₂ (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) was used as a catalyst, and acetonitrile was employed as a solvent. An analysis by methods of the complete 2⁴ factorial design showed that an increase in the catalyst concentration gives a strong positive effect on the carvone conversion and selectivity. Hydrogen peroxide has a smaller positive effect on the conversion, but at high concentration, H₂O₂ leads to some decrease in the selectivity. An increase in the oxalic acid concentration has a beneficial effect on the conversion, but does not affect the selectivity.