The effect of curvature of Li-doped polycyclic hydrocarbon on its interaction energy with H<Subscript>2</Subscript> and H<Subscript>2</Subscript>O: DF-SAPT (DFT) calculation

In this work, the interaction of three Li⁺-doped polycyclic hydrocarbons (Li⁺-DPH) with H₂ and H₂O was calculated to investigate the effect of curvature of substrate on the interaction energy (E_int). For this purpose, the E_int and its decomposed energy components (electrostatic (E_elec), exchange (E_exch), induction (E_ind), and dispersion energy (E_disp)) were calculated using DF-SAPT (DFT) methodology for the selected systems (Li⁺-(3,3) carbon nanotube (Li⁺-CNT33), Li⁺-(6,6) carbon nanotube (Li⁺-CNT66), and Li⁺-graphene). According to the results, E_int does not change significantly with curvature for the interaction between both H₂ and H₂O gases and the selected Li⁺-DPH. Since the variation of the E_int with the curvature of Li⁺-DPH is not significant, the selection of a planar Li⁺-DPH is a trustworthy model to develop a general force field for describing the interaction between a Li⁺-DPH and adsorbed gases. The results reveal that, in the case of the H₂, the components E_elect, E_exch, E_ind, and E_disp have shown a decreasing trend with Li⁺-DPH’s curvature decrement. However, for the H₂O, E_elect, E_exch, and E_ind decrease from the Li⁺-CNT33 to the Li⁺-CNT66 while they increase from the Li⁺-CNT66 to the Li⁺-graphene. In this case, the E_disp increases with a decrease of the curvature of Li⁺-DPH. Finally, it can be seen that although the variation of the E_int with the curvature of Li⁺-DPH is not significant, the variation trend of the interaction energy components and the amount of variation depend on the gas molecule and in some cases are not negligible.     

Tri-<Emphasis Type="Italic">n</Emphasis>-butyl phosphate–ionic liquid mixtures for Li<Superscript>+</Superscript> extraction from Mg<Superscript>2+</Superscript>-containing brines at 303–343 K

Extraction of Li⁺ ions from salt lake brine into an ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₂mim][NTf₂]) mixed with tri-n-butyl was investigated. The extraction mechanism was been studied using UV–Vis spectroscopy From the temperature dependence data, the thermodynamic functions values (ΔG°, ΔH°, and ΔS°) were calculated. Furthermore, stripping of metals from ionic liquid phase to an aqueous phase by hydrochloric acid was accomplished.     

Calculation of the thermodynamic characteristics of ions in vapor over sodium fluoride

The geometric parameters, normal vibration frequencies, and thermochemical characteristics of the ions present in vapor over sodium fluoride, Na₂F⁺, Na₃F ₂ ⁺ , NaF ₂ ^? , and Na₂F ₃ ^? , were calculated ab initio by the Hartree-Fock method and taking into account electron correlation. The main equilibrium configuration of all ions was found to be the linear configuration of D _∞h symmetry. Pentaatomic ions could also exist as two isomers, planar cyclic of C _2v symmetry and bipyramidal of D _3h symmetry. Their energies were higher than that of the D _∞h isomers, and their contents in vapor were negligibly low. The energies and enthalpies of dissociation of the ions with the elimination of the NaF molecule were calculated. The enthalpies of formation of the ions were obtained.     

Electrical conductivity and ionic association of lithium and sodium perchlorates in tetrahydrofuran

The total limiting molar electrical conductivities of ions and triads of ions and the association constants of ions with the formation of ion pairs and triads of ions were calculated from the concentration dependences of the electrical conductivity of solutions of lithium and sodium perchlorates in tetrahydrofuran at 278.15–318.15 K with the use of the method specially developed earlier. The experimental total limiting electrical conductivities were used to calculate the limiting molar electrical conductivities and attraction friction factors of separate ions (Li⁺, Na⁺, ClO ₄ ^? , Li₂ClO ₄ ⁺ , Na₂ClO ₄ ⁺ , Li(ClO₄) ₂ ^? , and Na(ClO₄) ₂ ^? ). The constants of ion association into ion pairs were used to calculate the Gibbs energy of non-Coulomb interionic interaction (ΔG*_+?), and the constants of association into triads of ions, to determine the a ₃ distance parameter between the centers of the ion and the dipole of the ion pair. Positive ΔG*_+?), values and deviations of the experimental a ₃ value from the distance parameter calculated theoretically (a ₃ ⁰ ) for the triad of ions (Δa ₃ = a ₃ ? a ₃ ⁰ ) were related to non-Coulomb repulsion in the region of overlap of the solvation shells of ions and the influence of temperature and ion charge density on this repulsion.     

Evaluation of the stability of dye heteroassociates formed in aqueous solutions

The additive tetraphenylarsonium-tetraphenylborate model of interactions was found to be applicable to the problem of “preexperimental” evaluation of the stability of associates formed by dye cations (Ct⁺) and anions (An^?) in aqueous solutions. The possibility of predicting equilibrium association constants K _as from preliminarily calculated ΔG(Ct⁺) and ΔG(An^?) and of solving the inverse problem was analyzed. The invariability of the ΔG(Ct⁺) and ΔG(An^?) values and the problem of bringing calculation results in consistency with the experimental K _as values are discussed.     

Properties of solvate shells and the mobility of ions,according to molecular dynamics data

The solvate shells of an ion, its velocity autocorrelation function, and diffusion coefficient D are found, and the interrelations between them are analyzed. A single ion in the system of atoms of a liquid is considered a model system. The interaction between the ion and atoms of the liquid is described by polarization potential U(r); the interaction between atoms of the liquid alone is described by the Lennard–Jones potential. A classical molecular dynamics method is used. Five solvate shells around the ion are found, and the lifetimes of atoms on each shell are calculated. It is found that the velocity autocorrelation function is of a vibrating nature. The spectrum of the autocorrelator and the frequency of cluster vibrations in a linear approximation are compared. Dependences D on parameters of potential U(r) are found. No dependence D on the ion mass is found; this is explained by solvation. The Einstein–Stokes formula and the HSK approximation are used in discussing the results. It is shown that at small radii of the ion, dependence D on parameters U(r) is described by such a model. When the ion radius is increased, the deviation from this dependence and an increase in D are observed. The results are compared to experimental mobilities of O₂^- and Ar₂⁺ ions in liquid argon.     

Thermochemistry of the Reaction of Solvated Sodium Ion Clusters with Thymine in the Gas Phase: An Example of the Reaction in Microcosmic Environment

The thermochemistry of the reaction of the microsolvated Na⁺ such as [Na(H₂O) _n ; n?=?1?6]⁺, [Na(NH₃) _n ; n?=?1?6]⁺ and [Na(H₂O) _n (NH₃) _m ; n?+?m?=?2?6]⁺ with thymine (Thy), as an example of a reaction in the microcosmic environment, have been studied in this work, theoretically. It was found that the increase of the number of solvent molecules in the structure of microsolvated Na⁺ is accompanied by the decrease of the standard enthalpy (\(\Delta H_{r}^{^\circ }\)) and Gibbs free (\(\Delta G_{r}^{^\circ }\)) energies of the reaction (Thy?+?[Na(X) _n ]⁺→Thy-Na(X) _n ⁺ ; X?=?solvent molecule). Also, the calculations showed that the electronic intermolecular interaction (?E_int) between the Thy and microslovated Na⁺ decreased with the increase of solvent molecules. For the interaction of the [Na(H₂O) _n ; n?=?4, 5 and 6]⁺ ions with the Thy, there was the probability of forming of the hydrogen bond between water molecules in the structure of solvated Na⁺ and the Thy. The gas phase infrared (IR) spectra of the complexes of the microsolvated Na⁺ with the Thy for different values of n were calculated and compared with each other to follow the change in the frequency of the stretching vibration of the interaction path between the C=O group of the Thy and Na (O…Na) with n. Using the calculated values of \(\Delta G_{r}^{^\circ }\) of the reactions, the mole fractions of the complexes of microsolvated Na⁺ ions with the Thy were calculated at different humidity.     

Variation of the composition and properties of lithium manganese oxide spinel in lithiation-delithiation cycles

The behavior of the variable-composition spinel Li_{1 + x} Mn_{2 ? x} O₄ is examined in repeated cycles consisting of lithiation in 0.2 M LiOH and delithiation in 0.3 M HNO₃. For 0 < x < 0.33, delithiation is accompanied by the redox reaction 2Mn³⁺ → Mn⁴⁺ + Mn²⁺ and Li⁺ ? H⁺ ion exchange. The spinel undergoes partial conversion into λ-□MnO₂. Vacancies (□) build up at the 8a sites of the spinel structure. Mn²⁺ ions pass into the solution, and, accordingly, the spinel dissolves. Lithiation is accompanied by the redox reaction 4Mn⁴⁺ → 3Mn³⁺ + Mn⁷⁺ and ion exchange, and the proportion of vacancies □ at the 8a sites of the spinel structure decreases. The spinel undergoes partial dissolution because of Mn²⁺ and MnO _? ⁴ ions passing into the solution. The Li⁺ selectivity of the spinel is the property of the crystallite core. The crystallite surface is capable of sorbing Na⁺ ions.     

Enhanced lithium-ion intercalation and conduction of transparent tantalum oxide films by lithium addition with an atmospheric pressure plasma jet

An investigation is conducted on enhancing lithium-ion intercalation and conduction performance of transparent organo tantalum oxide (TaO _y C _z ) films, by addition of lithium via a fast co-synthesis onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates at the short exposed durations of 33–34 s, using an atmospheric pressure plasma jet (APPJ) at various mixed concentrations of tantalum ethoxide [Ta(OC₂H₅)₅] and lithium tert-butoxide [(CH₃)₃COLi] precursors. Transparent organo-lithiated tantalum oxide (Li _x TaO _y C _z ) films expose noteworthy Li⁺ ion intercalation and conduction performance for 200 cycles of reversible Li⁺ ion intercalation and deintercalation in a 1 M LiClO₄-propylene carbonate electrolyte, by switching measurements with a potential sweep from ?1.25 to 1.25 V at a scan rate of 50 mV/s and a potential step at ?1.25 and 1.25 V, even after being bent 360° around a 2.5-cm diameter rod for 1000 cycles. The Li⁺ ionic diffusion coefficient and conductivity of 6.2?×?10^?10 cm²/s and 6.0?×?10^?11 S/cm for TaO _y C _z films are greatly progressed of up to 9.6?×?10^?10 cm²/s and 7.8?×?10^?9 S/cm for Li _x TaO _y C _z films by co-synthesis with an APPJ.     

Electron affinity and substituent effects in radical anions

The first vertical electron affinities EA of 13 series of molecules and free radicals D(X _i ) _n are related to the inductive (σ _I ), resonance (σ _R ^? ), and polarization (σ_α) parameters of substituents X _i by the dependences EA = EA _H + aΣσ _I + bΣσ _R/? + cΣσ_α: In radical anions D^+·(X _i ) _n , compared to radical cations D^+·(X _i ) _n , the polarization interaction is weaker or similar in magnitude but has an opposite sign. The previously unknown resonance parameters σ _R ^? of substituents SiMe₃ and CH₂SiMe₃ bound to the radical anion center H₂C=CH^?· were calculated.     

Counterion effects on the isotopic properties of the Cl<Superscript>−</Superscript> and Li<Superscript>+</Superscript> ions in aqueous solutions

The reduced partition function ratios between isotopic forms (β-factors) were calculated by the ab initio RHF/6-311++G**(3df, 3p) and MP2/6-311++G**(3df, 3p) quantum-chemical methods for hydrated chloride ion and ion pair hydrates NaCl·nH₂O and LiOH · nH₂O. The influence of the Na⁺ cation on the β-factor value and the chlorine isotope separation factor in the precipitation of NaCl from concentrated aqueous solutions was found to be substantial. At the same time, the presence of OH^? counterions had no noticeable effect on the β-factor of the hydrated Li⁺ cation.     

The dynamics of nonadiabatic transitions in collisions between the I<Subscript>2</Subscript>(<Emphasis Type="Italic">E</Emphasis>) and I<Subscript>2</Subscript>(<Emphasis Type="Italic">X</Emphasis>) molecules

The paper presents the results of a theoretical study of the dynamics of nonadiabatic transitions between the ion-pair states E0 _g ⁺ and D0 _u ⁺ of the I₂ molecule induced by collisions with the I₂ molecule in the ground electronic state X0 _g ⁺ . The potential energy surfaces and diabatic coupling matrix elements of electronic states were obtained using a model based on the diatomics-in-molecule approximation. Special perturbation theory for intermolecular interaction was used to show that the large transition dipole moment between the E0 _g ⁺ and D0 _u ⁺ states caused the appearance of additional long-range corrections, an electrostatic dipole-quadrupole correction to the diabatic coupling matrix elements and induction dipole-dipole correction to the potential energy surface. The influence of these corrections on nonadiabatic dynamics was studied at the level of the semiclassical approximation. The electrostatic correction was found to sharply increase the contribution of resonance (accompanied by minimum kinetic energy changes) vibronic transitions at large distances between the colliding molecules. The induction correction had the opposite effect because of the high transition probability at short distances. The results obtained were in qualitative agreement with experimental data. The conclusion was drawn that obtaining quantitative agreement required a more balanced inclusion of interactions at short and long distances.     

The structure of dehydrated (Li<Subscript>0.7</Subscript>Na<Subscript>0.3</Subscript>)-analcime: Trigonal deformation of the ANA framework and new low coordinated non-framework positions

The dehydrated form of (Li,Na)-substituted analcime, Li_1.30Na_0.53[Al_1.83Si_4.17O₁₂], has been prepared and investigated with single crystal X-ray diffraction: a = 32.167(6) Å, b = 18.551(2) Å, c = 11.693(2) Å; β = 90.06(1)°, V = 6978(1) ų, Z = 24, space group C2. The structure was analyzed through considering the aluminosilicate framework as a system of tubes composed from corrugated 6-membered rings joint by triples of tetrahedra. Volume decrease by 6.5% and trigonal distortion of the structure are explained by the localization of the non-framework cations in new unusual positions. On dehydration of Li, Na-analcime, 67% of Na⁺ and 20% of Li⁺ migrated from the standard M-positions at the periphery of the tubes into essentially different positions Na^W and Li^L situated on the axes of the tubes. Among the total of the fixed tube positions— 12Na^W and 16Li^L — one half is aggregated in the tubes parallel to [001] and has a planar three-fold coordination by framework O-atoms. The configuration and cation population of the tubes in other directions follow the motif of the “basic” system.     

Crystal Chemistry of Lithium Intermetallic Compounds: A Survey

The structural chemistry of lithium intermetallic compounds that are formed in Li–М binary systems where М = Ca, Sr, Ba, Mg, Zn, Cd, and Hg is surveyed. It is for the first time that the crystal structures of intermetallic compounds are classified in terms of polyhedral precursor metal clusters (in the program package ToposPro). The precursor metal clusters of crystal structures are identified using the algorithms of partitioning structural graphs into cluster structures and via the design of the basal 3D network of the structure in the form of a graph whose nodes correspond to the positions of the centers of precursor clusters. Tetrahedral precursor metal clusters M₄ are identified for the crystal structures LiZn₃-oC4, LiMg₃-hP2, LiCd₃-hP2, LiHg₃-hP8, (LiMg₃)(Li₂Mg₂)-tI16, Li₂Zn₂-cF16, Li₂Cd₂-cF16, Li₂Hg₂-cP2, Li₃Cd-cF4, and Li₃Hg-cF16; tetrahedral metal clusters M₄ are found for the framework structures with spacer atoms Sr(Li₂Sr₂)-tP20, Ca₂(Li₄)-cF24, and Ca₂(Li₄)-cP12; tetrahedral metal clusters M₄ and rings M₆, for framework structures Ba₃Li₂(Li₁₀)-hP30 and Ba₃Li₂(Li₄In₆)-hP30; icosahedral metal clusters M13 for the framework structure Li(Zn₁₃)-cF112; bilayer tetrahedral metal clusters 0@М₄@M₂₂ for the framework structure Li₂₃Sr₆-cF116; and deltahedra М₁₇ and deltahedra М₃₀, for framework structures Sr₄Li₁₄ [Sr(Sr₄Li₁₂)] [(Sr₂ (Sr₈Li₁₈)]-tI252 and Ba₄Li₁₄ [Ba(Ba₄Li₁₂)][(Ba₂ (Ba₈Li₁₈)]-tI252. The scenario of crystal structure self-assembly from precursor metal clusters S₃⁰ in intermetallic compounds is reconstituted as: primary chain S₃¹→ microlayer S₃²→ microframework S₃³.     

Thermodynamic approaches for the prediction of oral drug absorption

The present study is a comparative study of three equations, namely the Clausius–Clapeyron, Van’t Hoff and Hildebrand (to calculate crystal–liquid fugacity ratio (CLFR) of drug compounds), to select the best model in predicting the intestinal absorption and develop a new classification system based on dose number (D _o) and CLFR. The required thermodynamic parameters [melting point, enthalpy of fusion (ΔH _m) and the differential molar heat capacity (?C _pm)] were experimentally obtained by differential scanning calorimetry. Pharmacokinetic data [the human intestinal absorption (F _a) and apparent permeability of Caco-2 (P _app _Caco-2)] and D _o were obtained from the literature. The highest value of CLFR was found for diclofenac with the value of 88.78, 87.29, and 87.84 mol% from Clausius–Clapeyron, Van’t Hoff, and Hildebrand approaches, respectively. The lowest CLFR value was seen for memantine with the value of 14.3 × 10^?17 and 26 × 10^?12 mol% from Van’t Hoff and Hildebrand equations, respectively. Statistical comparison with the Wilcoxon signed rank test showed that the CLFR values calculated by three equations are different. CLFR values of more than 1 mol% correspond to the complete intestinal absorption (F _a). There was a sigmoidal dependency between CLFR and F _a, similar to the dependency between P _app _Caco-2 and F _a. In these modeling, the excellent correlations were obtained in all three models as evidenced by a good coefficient of determination (r ² ) without a significant difference in the average absolute error. A new classification system from Hildebrand model based on D _o and CLFR was developed and was in agreement with the biopharmaceutics classification system (70.5%) and the biopharmaceutical drug disposition system (65.6%). This modeling approach can be a valuable tool for scientists as an alternative for intestinal permeability in the biopharmaceutical classification system to develop new oral drugs. The CLFR obtained from Hildebrand model is also more convenient than the Clausius Clapeyron model, because the former does not need to calculate ?C _pm (difficult step in calculating CLFR) for drug compounds. This new classification can help to develop the new drug product in industrial and academic research, without necessary in vivo experiments.     

Induction of radiative forbidden transitions in an oxygen molecule in O<Subscript>2</Subscript>–H<Subscript>2</Subscript>O collision complexes

By the DFT/B3LYP method the equilibrium structures of oxygen complexes with water are calculated in various geometric conformations with symmetries C _2v and C _s . By the MRCI/CASSCF method potential energy surface cross-sections of the ^1.3[O₂–H₂O] complexation reaction are constructed. With taking into account the spin-orbit coupling, the forbidden transition moments a ¹Δ _g –X ³Σ _g ^?, b ¹Σ _g ⁺–a ¹Δ _g , c ¹Σ _u ^?–a ¹Δ _g , A ³Σ _u ⁺–X ³Σ _g ^? of the complexes are calculated and changes in their intensities at different geometric configurations of the complex are revealed.     

Nickel(II) complex with 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane

A nickel(II) complex, [Ni(taetacn)](ClO₄)₂ ? H₂O, where taetacn = 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane was synthesized. The crystal structure was determined by the single-crystal X-ray diffraction method at 293 K. The complex crystallizes in the orthorhombic space group Pna2₁ with a = 16.004(2) Å, b = 10.186(1) Å, c = 13.937(2) Å, V = 2271.9(5) ų, D_x = 1.56 g cm^?3, D_m = 1.59 g cm^?3 (floatation method), and Z = 4. The R₁ [I > 2σ(I)] and wR₂ (all data) values are 0.0636 and 0.1672, respectively, for all 4845 independent reflections. The compound is composed of octahedral nickel(II) cation with three 2-aminoethyl pendant groups of taetacn, tetrahedral ClO ₄ ^? anion, and a water molecule of crystallization. Electronic spectra are consistent with the octahedral geometry. Temperature dependence of the magnetic susceptibility (4.5–300 K) can be interpreted considering the zero-field splitting of the nickel(II) ion (g = 2.14, D = 3.72 cm^?1, and Nα = 300 × 10^?6 cm³ mol^?1). Cyclic voltammetry in DMF showed quasi-reversible and irreversible oxidation waves (E_pa = 0.54 V, E_pc = 0.45 V; E_pa = 1.16 V, E_pc = 0.71 V vs. Ag/Ag⁺).     

Study on the Geometric and Electronic Structures of Al<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>Si<Subscript><Emphasis Type="Italic">m</Emphasis></Subscript> (n = 3, 4, 5; m = 1, 2, 3, 4) Clusters

Genetic algorithm combined with the semi-empirical Hamitonian AM1/PM3 is used to search the low energy isomers of Al _n Si _m (n = 3, 5, m ≤ 3 and n = 4, m ≤ 4) and the charged clusters with 20 and 28 valence electrons. The candidate structures were optimized by the density functional theory PBE0 and B3LYP models with the triply split basis sets including polarization functions. The electronic structures show that Al–Si binary clusters behave like metal clusters. The molecular orbitals accord with that predicted by the jellium model, and the electron localization function shows the valence electrons are delocalized over the entire clusters. The clusters having 20 and 28 valence electrons exhibit pronounced stabilities and large energy gaps. The 20 valence electrons of Al₄Si₂ and Al₃Si₃ ⁺, Al₅Si^? form closed shells 1S ²1P ⁶2S ²1D ¹⁰. Al₄Si₄ and Al₅Si₃ ^? have oblate structures and the P, D, F levels spilt considerably in these clusters. The electron density distributions suggest that doping silicon in the aluminum clusters enhances the stability considerably.     

X-ray diffraction study on phase transition of orthorhombic LiMnO2 in electrochemical conversions

Orthorhombic LiMnO₂ was synthesized by hydrothermal reaction. Phase transition during electrochemical process has been investigated using the high-resolution X-ray diffraction. Contrary to numerous earlier reports, phase analysis of the orthorhombic LiMnO₂ electrode cycled for three times evidences the irreversible structure transition from orthorhombic LiMnO₂ (Pmnm) to spinel LiMn₂O₄ (Fd3m) and rock salt Li_0.5Mn_0.5O (Fm \( \overline{3} \) m). Here, the spinel structure with a cell parameter a?=?8.241 (1) Å has a large cationic disorder on lithium and manganese sites, i.e., about 9% of the Li positions are occupied by Mn and vice versa. For Li_0.5Mn_0.5O, the cell parameter is a?=?4.121 (3) Å, and both Li⁺ and Mn³⁺ cations occupy the octahedral 4a sites with mole ratio 1:1. The quantity of Li_0.5Mn_0.5O phase is greatly dependent on cycling rate, namely, the higher the current density is, the larger the quantity of formed-rock salt structure is.     

The standard thermodynamic properties of 4<Emphasis Type="Italic">f</Emphasis> metal trichlorides

The enthalpies of sublimation Δ_sub H ⁰(298) of 4f metal trichlorides were calculated by the second and third laws of thermodynamics from saturated vapor pressures using the thermodynamic functions of the condensed and gaseous states suggested by us. The set of the Δ_sub H ^o(298) enthalpies was analyzed to determine the most reliable values. The enthalpies of atomization found from these values were compared with those calculated from the measured equilibrium constants of gas phase reactions with the participation of the compounds under consideration and the enthalpies of atomization found from the experimental appearance potentials AP(Ln⁺/LnCl₃). Recommended Δ_at H ^o(298) values were obtained for all the 4f metal trichlorides.