Study of local properties of liquid solutions of non-electrolytes using the reverse method to calculate the Kirkwood-Buff integrals and Koga's differential approach

Orientador: Pedro Luiz Onófrio VolpeDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: O objetivo deste trabalho é o estudo das propriedades locais de soluções líquidas binárias de não-eletrólitos. Para se alcançar tal objetivo, executou-se o cálculo dos valores das integrais de Kirkwood-Buff a partir de grandezas termodinâmicas, elaborado por Ben-Naim. Foram calculados valores para as integrais KB de uma solução de etanol em água a 298,15 K, dando-se especial ênfase a regiões de alta concentração de água. Outras grandezas locais, como o desvio da idealidade em relação a uma solução simétrica, também foram calculadas a partir dos resultados obtidos para as integrais KB. O enfoque diferencial de Koga foi utilizado de maneira a complementar a análise realizada com as integrais de Kirkwood-Buff, possibilitando um estudo mais aprofundado do sistema. Até onde o autor desta dissertação está familiarizado, a utilização conjunta destas duas ferramentas teóricas está sendo implementada pela primeira vezAbstract: The objective of this work is the study of local properties of binary liquid solutions of non-electrolytes. To achieve this goal, Kirkwood-Buff integrals from thermodynamic quantities were obtained, as Ben-Naim has demonstrated. We obtained the values of Kirkwood-Buff integrals for a solution of ethanol in water at 298.15 K, with particular emphasis on areas of high concentration of water. Other local qantities, as the deviation of ideality with respect to a symmetric solution, were also calculated from the results obtained from KB integrals. Koga¿s Differential approach was used in order to complement the analysis provided by Kirkwood-Buff integrals, allowing further understanding of the system. As far as the author of this thesis is familiar, the joint useMestradoFísico-QuímicaMestre em Químic

Study of Kirkwood-Buff integrals of selected polar and nonpolar amino acids in aqueous-streptomycin sulphate solutions at 298.15 K

The Kirkwood-Buff (K-B) integrals can play pivotal role in understanding the physiochemical action of drugs on proteins. The Kirkwood-Buff theory can be used to characterize the intermolecular interactions of amino acids with drug by directly calculating G11, G22 and G12 parameters which represents solute-solute, solvent-solvent and solute-solvent interaction respectively. The K-B integrals of nonpolar amino acids glycine, l-alanine, l-valine, l-isoleucine and polar amino acids l-histidine and l-arginine in aqueous-streptomycin sulphate solutions (1% and 2% streptomycin sulphate in water, w/w) have been calculated from experimental data of ultrasonic speed and density at 298.15 K. All the results obtained by theoretical calculations are in good agreement with that of experimental results

Thermodynamic factor of quaternary mixtures from Kirkwood–Buff integration

Expressions for the thermodynamic factor matrix Γ of quaternary mixtures are derived in terms of Kirkwood–Buff integrals and implemented into the massively parallel simulation tool ms2. To assess these expressions, a liquid-like supercritical quaternary Lennard–Jones mixture is sampled throughout its entire composition range, employing molecular dynamics in the canonical ensemble. Good agreement is found between numerical chemical potential derivatives and the results from the present Kirkwood–Buff integral expressions. Moreover, the limits of the thermodynamic factor matrix for pure, binary and ternary subsystems are discussed.BMBF, 01IH16008E, Verbundprojekt: TaLPas - Task-basierte Lastverteilung und Auto-Tuning in der Partikelsimulatio

Microstructures of negative and positive azeotropes

Azeotropes famously impose fundamental restrictions on distillation processes, yet their special thermodynamic properties make them highly desirable for a diverse range of industrial and technological applications. Using neutron diffraction, we investigate the structures of two prototypical azeotropes, the negative acetone–chloroform and the positive benzene–methanol azeotrope. C–H⋯O hydrogen bonding is the dominating interaction in the negative azeotrope but C–Cl⋯O halogen bonding contributes as well. Hydrogen-bonded chains of methanol molecules, which are on average longer than in pure methanol, are the defining structural feature of the positive azeotrope illustrating the fundamentally different local mixing in the two kinds of azeotropes. The emerging trend for both azeotropes is that the more volatile components experience the more pronounced structural changes in their local environments as the azeotropes form. The mixing of the acetone–chloroform azeotrope is essentially random above 20 Å, where the running Kirkwood–Buff integrals of our structural model converge closely to the ones expected from thermodynamic data. The benzene–methanol azeotrope on the other hand displays extended methanol-rich regions and consequently the running Kirkwood–Buff integrals oscillate up to at least 60 Å. Our study provides the first experimental insights into the microstructures of azeotropes and a direct link with their thermodynamic properties. Ultimately, this will provide a route for creating tailored molecular environments in azeotropes to improve and fine-tune their performances

Preferential Solvation Study of Rosuvastatin in the {PEG400 (1) + Water (2)} Cosolvent Mixture and GastroPlus Software-Based In Vivo Predictions

Article claims that rosuvastatin (RST) is a poorly water-soluble drug responsible for limited in vivo dissolution and subsequently low oral systemic absorption (poor bioavailability). The results of inverse Kirkwood–Buff integrals showed the PS of RST by PEG400 as observed in all studied ratios of the binary mixture