Effect of Temperature and Composition on the Transport and Thermodynamic Properties of Binary Mixtures of Ionic Liquid <Emphasis Type="Italic">N</Emphasis>-Butyl-<Emphasis Type="Italic">N</Emphasis>-methylpyrrolidinium bis(Trifluoromethanesulfonyl)imide and Propylene Carbonate

The thermodynamic and transport proprieties have been determined for the whole concentration range of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P₁₄) and propylene carbonate (PC) binary mixtures in the temperature range 293.15–318.15 K. Strong effects of the mole fraction and temperature on these properties have been observed. The isobaric expansivities and excess properties have been evaluated. Their corresponding coefficients were positive but the excess volume had both negative and positive values. The viscosity parameter was found to be temperature-dependant and followed the Arrhenius law. The variation of activation energies for viscous flow E _a,η versus the ILs concentration exhibited a change in the medium structure. The conductivity-temperature relationship was found to have a better fitting on the Vogel-Tammann-Fulcher model than on the Arrhenius law. In addition, the variation of conductivity with the molar fraction was well described by the Casteel-Amis equation. Finally, the Walden product showed significant dependence of the conductivity on the viscosity of the medium. The results allowed good characterisation of both the ruling interactions and the medium structure.     

Effect of humidity and UV-assistance on the preparation of erbium doped alumina by aerosol MOCVD process

The effect of deposition temperature, relative humidity of carrier gas and UV-assistance on the growth of Erbium-doped aluminium oxide films has been studied. The films were prepared from aluminium acetylacetonate (Al(C₅H₇O₂)₃) and erbium (III) Tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Er(TMHD)₃) by UV and aerosol-assisted metal-organic chemical vapour deposition, using air with controlled humidity as carrier gas. Amorphous transparent films were deposited between 350 and 460 °C. It was observed that UV assistance allows a large decrease down to 5 kJ/mol of the activation energy of the deposition reaction for deposition temperatures lower than 420 °C. More over, depositing under high air humidity induced higher deposition rate, lower level of organic contamination and higher film density. Under these conditions Er-doped aluminium oxide films with a refractive index value of 1.71 were obtained at 460 °C.     

1-Soliton solution of the generalized Zakharov equation in plasmas by He’s variational principle

This paper obtains the 1-soliton solution to Zakharov equation with power law and dual-power law nonlinearities. The He’s variational principle is used to carry out the integration of this equation.     

Theoretical investigation of a single erbium center in hexagonal gallium nitride

A theoretical energy-level analysis was based on parametric Hamiltonian for the 4f¹¹ electronic configuration of Er³⁺ ions in C_3v center, and it permitted a phenomenological characterization of crystal-field (CF) Hamiltonian parameters. This characterization allowed us to calculate the energy of the missing stark levels of the ⁴I_15/2 and ⁴I_13/2 states and to confirm the presence of a single emission center with C_3v symmetry. The calculated CF and strength parameters are compared with those obtained for Sm³⁺, Pr³⁺ and Yb³⁺ ions in the same host and with Er³⁺ in other isostructural hosts.     

Cross-coupling reactions of organosilicon compounds: new concepts and recent advances

This review highlights the rapid evolution of the newly-developed class of palladium-catalyzed cross-coupling reactions of organosilicon compounds. A myriad of heteroatom-containing silicon moieties (silyl hydrides, siletanes, silanols, silyl ethers, orthosiliconates, di- and polysiloxanes and pyridylsilanes) undergo mild and stereospecific cross-coupling. The diversity of methods for introduction of silicon groups into organic molecules and the range of organic electrophiles that can be used are emphasized.     

Combined experimental and theoretical investigation of the CO2 adsorption on LaMnO3+y perovskite oxide

The surface interaction of CO₂ with the perovskite-type oxide LaMnO_3+y has been investigated by means of density functional theory calculations and experimental measurements of adsorption isotherms in the temperature range 298-473 K. A (1 0 0) oriented slab of the cubic structure was used for modeling CO₂ adsorption. The reference unit cell contains alternating LaO⁺ layers and layers; one slab is LaO⁺-terminated and the opposite surface is terminated. A Freundlich isotherm fitted the experimental data satisfactorily. Analysis of the isosteric heat revealed an energetically heterogeneous character for the lanthanum manganite oxide surface, mainly due to the degree of heterogeneity of the adsorption center and due to the adsorbate-adsorbate lateral interactions. Considering theoretical calculations and thermodynamical approaches, two types of active sites were found to be responsible for irreversible and reversible adsorption of CO₂ as a function of surface coverage and O₂ treatment. Strong adsorption takes place on the surface containing La cations. The strongest adsorption is associated with surface oxygen vacancies, center. The next strongest adsorption, a flat adaptation of CO₂ molecules with respect to the surface sites, with a strong binding to a surface oxygen, leads to chemisorbed carbonate species. These adsorption modes are chiefly indicative of a high basic character of the lanthanum manganite oxide surface. Several cationic sites formed by lanthanum and manganese cations are able to weakly adsorb CO₂ molecules in perpendicular or bridged forms. The latter adsorption modes suggest a weak acidic character of the manganite adsorbent.     

Template‐Free Synthesis and Selective Filling of Janus Nanocups

We report on the formation of shape‐ and surface‐anisotropic Janus nanocups (JNCs) by evaporation‐induced confinement assembly (EICA) of ABC triblock terpolymers. During microphase separation in spherical confinement, the triblock terpolymer spontaneously adopted a hemispherical shape with an inner concentric lamella–lamella (ll) morphology. Cross‐linking and disassembly of the microparticles resulted in well‐defined JNCs with different chemistry on the inside and outside. By synthesizing polymers with increasing length of the cross‐linkable block, we tuned the mechanical stability of the nanocups, which is relevant to control opening and closing of the cup cavity. We utilize the Janus properties for selective uptake of cargo exemplified by the filling of JNCs with polymer or gold nanoparticles. The directional properties of JNCs suggest applications in locomotion, oil‐spill recovery, storage and release, templating, and as nanoreactors with attoliter volume.     

Fluoride-promoted cross-coupling reactions of alkenylsilanols. Elucidation of the mechanism through spectroscopic and kinetic analysis

The mechanism of the palladium-catalyzed cross-coupling reaction of (E)-dimethyl-(1-heptenyl)silanol ((E)-1) and of (E)-diisopropyl-(1-heptenyl)silanol ((E)-2) with 2-iodothiophene has been investigated through spectroscopic and kinetic analysis. A common intermediate in cross-coupling reactions of several types of organosilicon precursors has been identified as a hydrogen-bonded complex between tetrabutylammonium fluoride (TBAF) and a silanol. The order in each component has been determined by plotting the initial rates of the cross-coupling reaction at varying concentrations. These data provide a mechanistic picture that involves a fast and irreversible oxidative insertion of palladium into the aryl iodide and a subsequent turnover-limiting transmetalation step achieved through a fluoride-activated disiloxane derived from the particular silanol employed. The inverse order dependence of TBAF at high concentration is consistent with a pathway that proceeds through a hydrogen-bonded complex which is the lowest energy silicon species in solution.     

Crystal-field analysis for d ions at D4h symmetry sites: Electronic states in trans-NiCl2(H2O)4 complex

The polarized absorption spectra of trans-NiCl₂(H₂O)₄ complex were measured by Bussière et al. [Coord. Chem. Rev. 219-221 (2001) 509-543] at low-temperature. Using the experimental spectroscopic data, semiempirical calculations of the crystal-field levels of trans-NiCl₂(H₂O)₄ chromophore are carried out, based on the Racah theory. We used idealized D_4h point group symmetry to analyse the observed crystalline-field splitting of this chromophore. As a result, Racah and crystal-field parameters have been reliably obtained. A good agreement between the theoretical and experimental energy levels of trans-NiCl₂(H₂O)₄ complex has been obtained. The region of ³T_1g/¹E_g(O_h) bands is of great interest and it is useful to use the tetragonal symmetry to understand the features of this spectral region.     

Synthesis,Crystal Structure,Hirshfeld Surface Analysis,and Physicochemical Study of an Anhydrous Organic Acidic Cyclohexaphosphate

The new organic–inorganic hybrid [5-Cl-2-(CH₃)C₆H₃NH₃]₄H₂P₆O₁₈ has been synthesized by the slow evaporation method. X-ray diffraction on a single crystal shows that this acidic cyclohexaphosphate crystallized in the monoclinic space group C _2/c with a?=?33.89(11) Å, b?=?9.16(16) Å, c?=?13.68(3) Å, β?=?91.35(2)°, V?=?4244.9(19) ų and Z?=?4. ³¹P MAS-NMR and ¹³C CP/MAS-NMR results are in accordance with X-ray findings. Fluorescent study shows the blue photoluminescence. Furthermore, FT-IR analysis was studied and the complete vibrational assignments were done. Intermolecular interactions were analyzed using Hirshfeld surface analysis and the associated 2D fingerprint plots.