Characterization and Reactivity of the [N,N-Dimethyl(thioformamidyl)]-9-fluorenyl Cation(1)

The 9-[N,N-dimethyl(thioformamidyl)]-9-fluorenyl cation was generated under stable ion conditions and characterized by UV/visible and NMR spectroscopy and methanol trapping reactions. The same cation was generated by laser excitation of the appropriate chloride precursor in 2,2,2-trifluoroethanol, and rate constants for nucleophilic quenching by alcohols and several anions were measured. The quenching data for this and other 9-fluorenyl cations demonstrate that the reactivity decreases for 9-substituents in the order H > carbomethoxy > N,N-dimethyl(thioformamidyl), demonstrating that the thioamidyl group imparts substantial kinetic stabilization to an adjacent cationic center. Both steric and electronic factors are suggested to be important in determining this reactivity order.     

The Briggs-Rauscher oscillatory reactions catalyzed by nickel macrocyclic complexes

The investigation of Briggs-Rauscher reactions (BRR) with nickel complexes have shown that the range of the standard redox potentials of BRR catalysts is at least 0.7–1.7 V. An inner-sphere interaction of metal ions with hydrogen peroxide is a prerequisite of the oscillatory behavior. The unique catalytic properties of the nickel compounds are probably due to their lower redox potential.     

Julia sets for the gamma recursion in nonlinear psychophysics

Julia sets for the map za(z–ie)(1–z)(z+ie) are illustrated for some attractors of interest. This work extends previous analyses of the cubic complex polynomial and considers dynamics in regions which may be associated with the modelling of the results of overload in sensory inputs.Work supported by grant No. A7881403 (1988) from the Australian Research Council.     

Solvothermal synthesis of nanocrystalline copper nitride from an energetically unstable copper azide precursor

Nonaqueous solvothermal chemical reactions have found extensive utility in the growth of inorganic non-oxide materials. This report describes the successful use of organic solvothermal environments to synthesize energetically unstable copper azide precursors that are then decomposed in situ to crystalline metastable copper nitride at temperatures below 200 degrees C. A comparison of Cu3N products formed from nonpolar (toluene) and coordinating (THF) solvents is described. The cubic Cu3N products are nanocrystalline with aggregated particle-like extended structures and were characterized by X-ray diffraction, electron microscopy, IR spectroscopy, and mass spectrometry. The thermal stability and composition of Cu3N was examined by thermogravimetric analysis and bulk elemental analysis. The particle surfaces contain bound residual solvent species that can be removed by heating. The poorly coordinating solvent, toluene, lead to a more crystalline product containing less residual organic content. Benchtop reactions were performed to follow the temporal formation and decomposition of metal azide intermediates. These studies provided more detailed information on the progression of metal azide to metal nitride materials in a solvothermal environment.     

Geometries and excited-state dynamics of van der Waals dimers and higher clusters of 1-cyanonaphthalene

Mass-selected resonant two-photon ionization and infrared-ultraviolet double-resonance spectroscopies are combined with correlated (second Moller-Plesset perturbation) quantum chemistry calculation to probe electronic spectra and ground-state geometries of the jet-cooled dimer and higher clusters of 1-cyanonaphthalene. The results indicate that the dimer and trimer have stacked geometries, consistent with the highly efficient, rapid excimer formation that follows photoexcitation of the ground-state clusters.     

Optimization of energy consumption for NOx removal in multistage gas irradiation process

Previously reported results of the tests performed on industrial pilot plant for EB flue gas treatment has proved the theoretical assumption that multistage gas irradiation leads to power consumption savings in comparison with single gas irradiation process. In this paper the results of theoretical and experimental studies are presented concerning optimization of the ratio of dose distribution between the particular stages. Nonuniform dose distribution causes further decrease in power consumption for NO_x removal.     

Influence of relative humidity on electrical properties of alpha-Al2O3 powders: resistivity and electrochemical impedance spectroscopy

The influence of humidity on the electrical properties of alpha-Al2O3 powders has been investigated using adsorption isotherms, DC resistivity, and electrochemical impedance spectroscopy. Samples of two alpha-Al2O3 particle sizes were examined, both individually and mixed together. The results show that the grain-bed resistivity decreases with humidity, whereas the grain capacitance is almost constant. The resistivity difference between the two particle sizes is of several orders of magnitude, while the capacitance values are not very different. These results are interpreted in terms of the layer-by-layer growth of water adsorbed on the grain surfaces. The first, more tightly bound adsorbed layer does not provoke the same effects as those layers adsorbed at higher relative humidity.     

Rayleigh–Schrödinger perturbation expansions for a hydrogen atom in a polynomial perturbation

Rayleigh–Schrouml;dinger (RS ) perturbation expansions for the eigenvalues E(λ) of a hydrogen atom in the general polynomial perturbation V(r) = aλr + b>²r², a, b > 0, are studied. When a² = 2b, the ground state energy is exactly E(λ) = -(1/2) + (3/2)a>, i.e., the RS series is truncated. In the case a² > 2b, the RS series is negative Stieltjes. In general, when λ < 0, a well of depth ω ≈ -a²/(4b²) (note the λ independence) is situated at r_ω = a/(2b|λ|). When a² > 2b/N², and interaction between this well and the hydrogenic state ψ_NLM(λ) is possible, thus creating a pair of asymptotically degenerate eigenstates separated by a “gap” δE(λ). The large order behavior of the RS coefficients E may be computed from the asymptotics of δE(λ), which is, in turn, related to the tunnelling integral. For excited states, stricter inequalities must be obeyed for Stieltjes behavior. The E⁽ⁿ⁾_NLM may be calculated either numerically or in closed form via the “so(4, 2) Lie algebra technology” for such hydrogenic problems.     

Studies towards the total synthesis of Sch 56036; isoquinolinone synthesis and the synthesis of phenanthrenes

The isoquinolinone hemisphere of Sch 56036 has been prepared using a modified Pomeranz-Fritsch reaction and the synthesis of the phenanthrene core has been modelled via a Suzuki coupling and subsequent ring closing metathesis.