Correlating the Solvating Power of Solvents with the Strength of Ion-Dipole Interaction in Electrolytes of Lithium-ion Batteries

The solvation structure of Li⁺ plays a significant role in determining the physicochemical properties of electrolytes. However, to date, there is still no clear definition of the solvating power of different electrolyte solvents, and even the solvents that preferentially participate in the solvation structure remain controversial. In this study, we comprehensively discuss the solvating power and solvation process of Li⁺ ions using both experimental characterizations and theoretical calculations. Our findings reveal that the solvating power is dependent on the strength of the Li⁺-solvent (ion-dipole) interaction. Additionally, we uncover that the anions tend to enter the solvation sheath in most electrolyte systems through Li⁺-anion (ion-ion) interaction, which is weakened by the shielding effect of solvents. The competition between the Li⁺-solvent and Li⁺-anion interactions ultimately determines the final solvation structures. This insight into the fundamental understanding of the solvation structure of Li⁺ provides inspiration for the design of multifunctional mixed-solvent electrolytes for advanced batteries.     

Synthesis and characterization of three new fluorovanadate complexes: N(C2H5)4[VOF4], N(CH3)4[VOF3Cl], N(C4H9)4[VOF3Br] and theoretical calculations of VOF4, VOF3Cl and VOF3Br ions

The reaction of VOF₃ with (C₂H₅)₄NF, (CH₃)₄NCl and (C₄H₉)₄NBr salts in anhydrous CH₃CN produced new complexes with the anion general formula [VOF₃X]⁻ in that (X = F⁻, Cl⁻, Br⁻). These were characterized by elemental analysis, IR, UV/Visible and ¹⁹F NMR spectroscopy. The optimized geometries and frequencies of the stationary point are calculated at the B3LYP/6-311G level of theory. Theoretical results showed that the VX (X = F, Cl, Br) bond length values for the [VOF₃X]⁻ in compounds 1-3 are 1.8247, 2.4031 and 2.5595 Å, respectively. Also, the VF₅ bond length values in [VOF₃X]⁻ are 1.824, 1.812 and 1.802 Å, respectively. These results reveal that the bond order for VX bonds decrease from compounds 1 to 3, while for VF₅ bonds, the bond orders increase. It can be concluded that the decrease of VX bonds lengths and the increase of VF₅ bond lengths in compounds 1-3 result from the increase of the hyperconjugation from compounds 1 to 3. Harmonic vibrational frequencies and infrared intensities for VOF₄⁻, VOF₃Cl⁻ and VOF₃Br⁻ are studied by means of theoretical and experimental methods. The calculated frequencies are in reasonable agreement with the experiment values. These data can be used in models of phosphoryl transfer enzymes because vanadate can often bind to phosphoryl transfer enzymes to form a trigonal-bipyramidal structure at the active site.     

Effects of pressure ratio on population inversion in a DF chemical laser with concurrent lasing

A numerical simulation is presented for investigating the effects of pressure ratio of D₂ injector to supersonic nozzle on the population inversion in the DF chemical laser cavity, while a lasing concurrently takes place. The chemical laser is generally used for the industrial process and manufacturing as well as the military weapon system, which requires high power characteristic of laser system rather than the others. The population inversion is absolutely needed to generate the laser beam and is non-equilibrium process. The laser beam is generated between the mirrors in the cavity and it is important to obtain stronger population inversion and more uniform distribution of the excited molecules in the laser cavity in order to produce high-power laser beam with good quality. In this study, these phenomena are investigated by means of analyzing the distributions of the DF excited molecules and the F atom used as an oxidant, while simultaneously estimating the maximum small signal and saturated gains and power in the DF chemical laser cavity. For the numerical solution, a fully conservative implicit method and a second order total variation diminishing (TVD) scheme are used with the finite-volume method (FVM). An 11-species (including DF molecules in various excited states of energies), 32-step chemistry model is adopted for the chemical reaction of the DF chemical laser system. The results are discussed by comparison with two D₂ injector pressure cases; 192 and 388.64 torr. Major results reveal that in the resonator, stronger population inversions occur in the all transitions except DF(1)-DF(0), when the D₂ injection pressure is lower. But, the higher D₂ injection pressure provides a favorable condition for DF(1)-DF(0) transition to generate the higher power laser beam. In other words, as the pressure of D₂ injector increases, the maximum small signal gain in the v_1-0 transition, which is in charge of generating most of laser power, becomes higher. Therefore, the total laser beam power becomes higher.     

NON-REACTIVE ORIENTATIONS OF MOLECULES AT SURFACES

The role of the orientation of a molecule in its interaction with a surface is examined for the specific case of NO interaction with Pt(111). For this system molecular chemisorption occurs, mediated by a strong chemisorption well. Experimental results concerning sticking, angular distributions of scattered molecules, steric effects in scattering, and rotational excitation will be presented. Classical trajectory calculations using a model potential energy hypersurface can reproduce most experimental findings. Analysis of the trajectories shows that there is a strong orientation dependence of rotational excitation and sticking. The O-end of the molecule turns out to be non-reactive. The N-end of the molecule is very reactive. Its behaviour can almost be described using statistical methods.     

5‐Substituted Benzothiophenes: Synthesis,Mechanism, and Kinetic Studies

The kinetics of the reaction of 4‐methoxythiophenoxyacetaldehyde diethyl acetal, 4‐nitrothiophenoxyacetaldehyde diethyl acetal, and 3‐methoxythiophenoxyacetaldehyde diethyl acetal in polyphosphoric acid has been explained. The kinetic behavior has been explained on the basis of aided simulation and on the basis of density functional theory calculations showing a different pathway for 4‐nitrothiophenoxyacetaldehyde diethyl acetal and for 4‐methoxythiophenoxyacetaldehyde diethyl acetal. In this last case, a very fast competing reaction to the dimerization product was observed.     

Density Functional Study of the Reaction Mechanism of Two Oxiimine Alcohol Formations and Their Novel Rearrangements

In this study, the reaction mechanisms of isonitrosoacetophenone (inapH) with ethanolamine (ea) and 1‐phenylethanolamine (pea) have been investigated theoretically using B3LYP/6‐311G(d,p) method to explain why the formation and unexpected rearrangement products occur or not occur. While the reaction between isonitrosoacetophenone (inapH) with ethanolamine gives oximine alcohol ( Ib ), the reaction of 1‐phenylethanolamine with inapH results in the formation of oximine alcohol with a different substituent ( Ia ) and amido alcohol ( IIa ), which is the unexpected rearrangement product. The rearrangement driving forces of compounds from Ia to IIa are calculated as ca. 28 and 23 kJ/mol in the gas and EtOH phases, respectively. These driving forces have been calculated ca. 46 and 45 kJ/mol for the rearrangement of compound Ib to obtain IIb in the same phases, respectively. This high driving force shows that the compound IIb cannot be obtained from rearrangement of compound Ib as described experimentally in the literature. In addition, as the DFT functionals poorly describe dispersion effects, dispersion correction for reaction heat and free‐energy barrier was estimated using the wB97X‐D/6‐311G(d,p). In general, the relative free energies of all molecules calculated from wB97XD method are lower than performed from B3LYP level. The changes of thermodynamic properties for all molecules with temperature ranging from 100 to 500 K have been obtained using the statistical thermodynamic method.     

On Some Problems of Grothendieck Concerning (F) and (DF) Spaces

This is an expository article devoted to the answers to the 10 open problems of the fundamental paper of Grothendieck (Summa Res. Math. 1954; 3:57–123), some of which were given in the recent years.     

Frequency Regime of Generation of a Holographic Distributed Feedback Dye Laser

We carried out an experimental investigation of the frequency regime of generation of a holographic distributed feedback (DF) dye laser. We show that the convection induced in liquid by heating-up a solution in the excitation zone ensures self-pumping of the solution through this zone that is sufficient for stable operation of the laser in the regime of frequently repeating pulses without forced circulation of the solution through the cuvette. It is found that the main condition for the operation of a DF-laser in this regime is the sharp focusing of pumping radiation, which ensures transverse dimensions of the generation zone of less than 1 mm. In experiments, we produced stable generation of a holographic DF dye laser in the regime of self-pumping of a solution with a pulse repetition rate of up to 1 kHz with an efficiency of 10% and a spectral line width of 0.01 nm.     

Book Reviews

Abstract

Restoration of Environments with Radioactive Residues International Atomic Energy Agency, Proceedings of an International Symposium, Arlington, Virginia, USA, 29 November -3 December 1999. Vienna 2000.697 pp. Proceedings Series, ISSN 0074-1884

Regularity Control of Radioactive Discharches to the Environment. Safety Guide Safety Standards Series No. WS-G-2.3. International Atomic Energy Agency, Vienna 2000. 43 pp.     

Vibrational frequencies of CO adsorbed on silica supported Mo atoms from density functional calculations

The interaction of CO with silica supported molybdenum atoms has been studied by means of density functional calculations and cluster models. Experimentally two bands in the IR spectra of adsorbed CO have been observed at 2170 and 1990 cm⁻¹ with vibrational shifts of +27 and −153 cm⁻¹, respectively, with respect to the gas-phase molecule, the peak at +27 cm⁻¹ has been related to the presence of neutral Mo atoms anchored to two oxygen atoms of the SiO₂ substrate. Possible reactive sites at the Mo/SiO₂ interface have been explored as candidates for CO adsorption. Mo atoms in various formal oxidation states, from +II to +VI, have been considered. Both molecular and cluster models of the Mo/SiO₂ interface have been employed. The analysis shows that a neutral Mo(II) atom, proposed to be responsible for the blue-shift of ν(CO), is not likely to be the origin of the IR band at 2170 cm⁻¹. Only Mo atoms in high oxidation states or Mo cations carrying a real positive charge can account for the positive shifts in the CO frequency.