Nanostructural Approach to Proton Ordering in Gas Hydrate Cages

A nanostructural approach to analysis of proton ordering in gas hydrate cages has been worked out within the framework of the topological model of strong and weak H-bonds. The approach involves rejection of the periodic boundary conditions, decomposition of the H-bond net into spherical layers, and two-dimensional drawing of the structure of spherical (spheroidal) fragments in the form of conjugate Schlegel diagrams. To analyze proton ordering in the spherical fragments composed of gas hydrate voids, we used the simulated annealing procedure and the correlation extension method proposed earlier.     

C5,5—取代基对海因质子亲合能的影响

文章对５种碳五位（Ｃ５）的不同取代基海因的质子北合能（ＰＡ）,在亚稳状态下采用“动能法”进行了研究。以５,５－甲基海因作为参照,确定了５种样品亲质子能的顺序。     

Thermodynamic properties of lithium chloride ammonia complexes for application inahigh-lifthigh temperature chemical heat pump

Ammonia absorption by and desorption from lithium chloride at different pressures has been studied using high-pressure differential scanning calorimetry, for application in a high-lift high temperature chemical heat pump. The measurements were performed under isobaric as well as under isothermal circumstances. Clausius–Clapeyron plots were constructed and used to calculate the thermodynamic parameters and to determine the stability regions of the different complexes. Controversies in literature as to the real existing phases are resolved.     

Tetrakis(thiadiazolo)porphyrazines. 3. Acid-base Properties and Stability of Tetrakis-3,4-(1,2,5-thiadiazolo)porphyrazine in Sulfuric Acid Solutions

AM1 calculations gave the proton affinities of different types of donor sites in tetrakis-3,4-(1,2,5-thiadiazolo)porphyrazine, H₂{[SN₂)₄PA}, and protonation of the meso-nitrogen atoms was found to be favored. A spectrometric study showed that the basicity of the meso-nitrogen atoms of the porphyrazine macrocycle is strongly diminished and these atoms in CF₃CO₂H are involved in an incomplete acid-base interaction (ABI) to give acid solvates, while a complete ABI (protonation) is found only in the presence of sulfuric acid. The basicity constants of the meso-nitrogen atoms were determined spectrophotometrically in CF₃CO₂H-H₂SO₄. The kinetics of decomposition of the macrocyclic chromophore in concentrated sulfuric acid was studied and a possible mechanism for this process was proposed.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 278–287, February, 2005.     

Preparation of Polycrystalline Antimonic Acid Films by Electrophoretic Deposition

Cubic antimonic acid (Sb₂O₅·nH₂O) films were successfully prepared on stainless steel and Si(100) substrates by electrophoretic deposition (EPD) using two types of sols. The sols were prepared by reacting an H₂O₂ aqueous solution with Sb(O-i-C₃H₇)₃ or metallic Sb powder. The resulting films were found to consist of fine particles of cubic Sb₂O₅·nH₂O single crystals with uniform particle sizes of 30 nm and 150 nm. The weight of the Sb₂O₅·nH₂O deposit on the anode Si(100) substrate by EPD increased linearly with the current density in the range of 0–0.67 mA cm^–2, when the sol pH was over 7. The proton conductivity of the polycrystalline Sb₂O₅·nH₂O discs, formed from the two types of sols, was evaluated by an ac impedance method at room temperature under controlled levels of relative humidity.     

Exploration on regulating factors for proton transfer along hydrogen-bonded water chains.

Proton transfer along a single-file hydrogen-bonded water chain is elucidated with a special emphasis on the investigation of chain length, side water, and solvent effects, as well as the temperature and pressure dependences. The number of water molecules in the chain varies from one to nine. The proton can be transported to the acceptor fragment through the single-file hydrogen-bonded water wire which contains at most five water molecules. If the number of water molecule is more than five, the proton is trapped by the chain in the hydroxyl-centered H(7)O(3) (+) state. The farthest water molecule involved in the formation of H(7)O(3) (+) is the fifth one away from the donor fragment. These phenomena reappear in the molecular dynamics simulations. The energy of the system is reduced along with the proton conduction. The proton transfer mechanism can be altered by excess proton. The augmentation of the solvent dielectric constant weakens the stability of the system, but favors the proton transfer. NMR spin-spin coupling constants can be used as a criterion in judging whether the proton is transferred or not. The enhancement of temperature increases the thermal motion of the molecule, augments the internal energy of the system, and favors the proton transfer. The lengthening of the water wire increases the entropy of the system, concomitantly, the temperature dependence of the Gibbs free energy increases. The most favorable condition for the proton transfer along the H-bonded water wire is the four-water contained chain with side water attached near to the acceptor fragment in polar solvent under higher temperature.     

DFT study and Monte Carlo simulation on proton transfers of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water

Density functional theory (DFT) and Monte Carlo (MC) simulation with free energy perturbation (FEP) techniques have been used to study the tautomeric proton transfer reaction of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water. Two reaction pathways were considered: the direct and water-assisted transfers. The optimized structures and thermodynamic properties of stationary points for the title reaction system in the gas phase were calculated at the B3LYP/6-311+G(d, p) level of theory. The potential energy profiles along the minimum energy path in the gas phase and in water were obtained. The study of the solvent effect of water on the proton transfer of 2-amino-2-oxozoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline indicates that water as a solvent is favorable for the water-assisted process and slows down the rate of the direct transfer pathway.     

Oxygen diffusion in SrCe<Subscript>0.95</Subscript>Yb<Subscript>0.05</Subscript>O<Subscript>3−δ</Subscript>

¹⁸O/¹⁶O isotope exchange depth profiling (IEDP) combined with secondary ion mass spectrometry (SIMS) has been used to measure the oxygen tracer diffusivity of SrCe_0.95Yb_0.05O_3– between 800 °C and 500 °C at a nominal pressure of 200 mbar. The values of D* (oxygen tracer diffusion coefficient) and k (surface exchange coefficient) increase steadily with increasing temperature, and the activation energies are 1.13 eV and 0.96 eV, respectively. Oxygen ion conductivities have been calculated using the Nernst–Einstein equation. The transport number for oxide ions at 769 °C, the highest temperature studied, is only ~0.05. Moreover, SrCe_0.95Yb_0.05O_3– has been studied using impedance spectroscopy under dry O₂, wet O₂ and wet H₂ (N₂/10% H₂) atmospheres, over the range 850–300 °C. Above ~550 °C, SrCe_0.95Yb_0.05O_3– shows higher conductivity in dry O₂ than in wet O₂ or wet H₂; below that temperature the results obtained for the three atmospheres are comparable. Dry O₂ shows the highest activation energy (0.77 eV); the activation energies for wet O₂ and wet H₂ are identical (0.62 eV).Abbreviations HTPC high-temperature proton conductor - IEDP isotope exchange depth profiling - SIMS secondary ion mass spectrometryPresented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003     

DFT investigation of sites of protonation of antitumor of 2‐(4‐aminophenyl)benzazoles in the gas phase and in solution

The proton affinity on each of the possible sites in the antitumor 2‐(4‐aminophenyl)benzazoles has been calculated at the B3LYP/6‐311G** level of theory in the gas phase and in solution. The N₃‐site of protonation is found to be strongly favored over the NH₂‐site for the studied compounds both in gas phase and in solution. The stability of N₃‐protonated species is explained by the resonance interaction of the NH₂‐group with the heterocyclic ring. The potential energy surface (PES) for the protonation process was studied at the density functional theory (DFT)/B3LYP/6‐311++G** level of theory. Solvent effects on the PES were also examined using two models: Onsager self‐consistent field and polarizable continuum model (PCM). © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

peri-Naphthylenediamines. 36. 5,6-Bis(dimethylamino)acenaphthylene in [4+2] cycloaddition reactions. Synthesis and characteristic features of protonation of “proton sponges” with the 8,9-diazafluoranthene structure

5,6-Bis(dimethylamino)acenaphthylene is readily involved in [4+2] cycloaddition reactions with symm-tetrazine derivatives to form new proton sponges with the diazafluoranthene skeleton. Under analogous condition, 1,8-bis(dimethylamino)-4-vinylnaphthalene gave 4-pyridazinyl derivatives. The relative reactivities of 5,6-bis(dimethylamino)acenaphthylene, 1,8-bis(dimethylamino)-4-vinylnaphthalene, 5-dimethylaminoacenaphthylene, and acenaphthylene in the reactions with 3,6-diphenyl-symm-tetrazine are in a ratio of 32 : 17 : 14 : 1. The site of protonation of 3,4-bis(dimethylamino)-7,10-diphenyl-8,9-diazafluoranthene is controlled by the basicity of the solvent. The reaction in acetonitrile afforded the cation stabilized by an intramolecular hydrogen bond, whereas the reaction in dimethyl sulfoxide gave rise to the resonance-stabilized cation. 6,7-Bis(dimethylamino)phenalen-1-one was protonated only at the carbonyl group.