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Abstract: We have prepared hybrid materials of azobenzene and chiral Schiff base Ni(II), Cu(II), and Zn(II) complexes and investigated their linearly or circularly polarized UV (ultraviolet) light-induced supramolecular orientation with polarized electronic and IR spectra or CD (circular dichroism) spectra. The experimental FT-IR (Fourier transfer-infrared) spectra of azobenzene molecules were recorded at room temperature, and the results were compared with quantum chemical theoretical values using B3LYP, M052X, and M062X DFT (density functional theory) methods. The interaction of azobenzene with PMMA was simulated. Molecular geometry, vibrational wavenumbers, and thermodynamic parameters were calculated in all these systems. With the help of specific scaling procedures for the computed wavenumbers, the experimentally observed FT-IR bands were analyzed and assigned to different normal modes of the molecule. Most modes had wavenumbers in the expected range, and the error obtained was in general very low. Several general conclusions were deduced. Keywords: Chirality, azobenzene, polarized light, IR spectra, DFT.Download Full Article |
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Abstract: The effect of temperature on the two types of multilamellar structures, LI and LII, formed by the complexes of DNA with a cationic lipid, cholesteryl 3β-N-(dimethylamionethyl) carbamate (DC-Chol), in the bulk state has been investigated by small angle X-ray scattering (SAXS). LI phase composing of A-DNA intercalated between the lipid bilayers with tilted tails was formed at lower lipid-to-base pair molar ratio (x < 2), while LII phase consisting of B-DNA bound to untilted lipid was formed at x > 2. In addition to the differences in lipid packing state and DNA conformation, these two lamellar phases also displayed different thermal stability. LI phase was highly thermally stable as its interlamellar distance remained essentially unperturbed even after the denaturation of A-DNA in the complex at elevated temperature. By contrast, the interlamellar distance of LII phase decreased with increasing temperature due to the release of bound water and B-DNA denaturation. Keywords: DNA-lipid complex, Lipid, DNA condensation, DC-Chol, SAXS.Download Full Article |
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Abstract: Many intermolecular forces and parameters affect the solubility of a compound in a solvent. Various thermodynamic models are presented to predict these parameters and determine solid liquid equilibrium data. By selecting suitable thermodynamic model for solubility modeling, calculation error is reduced and the results will be closer to the experimental data. Herein, the ability of two predictive and two correlative models in solubility modeling of chiral compounds is investigated. Thus, solubility of pure and racemic forms of chiral Ketamine, Mandelic acid and 3-Chloromandelic acid is evaluated using UNIQUAC and NRTL models. The solubility modeling of pure and racemic forms of Ketamine in Ethanol is also determined by UNIFAC and NRTL-SAC models. There are good agreement between experimental data and results of NRTL and UNIQUAC models. Predictive NRTL-SAC model shows smaller deviation than UNIFAC in solubility determination of pure and racemic form of Ketamine. Keywords: Solubility, Chiral compounds, Thermodynamic modeling, NRTL-SAC, UNIFAC, UNIQUAC, NRTL.. Download Full Article |
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Abstract: Using the evaporating method, the solubility of sodium chlorate was determined in the various mixed solvents (water + ethanol + propanol) at various temperatures. The results showed that the solubility of NaClO3 decreases with increasing the mass percent of ethanol and propanol. On the other hand, the solubility of NaClO3 increases with increasing the temperature .In addition, the equilibrium constant of ion pair formation, KIP, for the reaction Na+(aq) + ClO3-(aq) Na+ClO3- (Ion Pair) was estimated upon Fuoss contact ion pair model and then, the values of ion-pair concentrations were determined by using the extended Debye-Hückel model and iteration calculations in various mixed solvents and various temperatures . Finally the value of thermodynamic solubility product constant, Ksp(th), and the values ΔH°, ΔS° and ΔG° of and of ion-pair formation were estimated in the mixed solvent media. Keywords: Mixed solvent, The extended Debye-Hückel model, Ion- pair, Thermodynamic function.Download Full Article |
 To the Mathematical Theory of the Temkin Adsorption Model - Pages 6-12Michael Vigdorowitsch, Liudmila E. Tsygankova and Pavel N. Bernatsky DOI: https://doi.org/10.6000/1929-5030.2020.09.02 Published: 04 April 2020 |
Abstract: This study expands the mathematical theory of the Temkin adsorption model and demonstrates the way experimental data are to be additionally treated. A functional complement property of the Temkin isotherm has been studied as a particular case of the common theory of asymptotic complement. This property is shown to give rise to various analytical strategies to be employed for processing or interpretation of the experimental results, e.g. to perform mapping of data obtained in experiments onto a conjugated part of the true isotherm, to judge if presupposed energetic heterogeneity type of the surface really takes place, etc. Experimental data for adsorption of carbon monoxide on gold and of sodium oleate on steel with and without a magnetite coating have been extensively analysed. |