Solubility of tadalafil in aqueous mixtures of Transcutol® and PEG 400 revisited: correlation, thermodynamics and preferential solvation

Article analyzing mole fraction solubilities of tadalafil (3) in aqueous mixtures of Transcutol® and PEG 400 at temperatures from 298.15 to 333.15 K following Hildebrand solubility parameters

Effect of N-Methyl-pyrrolidone (NMP) on the Equilibrium Solubility of Meloxicam in Aqueous Media: Correlation, Dissolution Thermodynamics, and Preferential Solvation

Article describes a study of the drug Meloxicam in N-methyl-pyrrolidone (NMP)–aqueous mixtures at several temperatures to expand the solubility database about pharmaceutical compounds in aqueous–mixed solvents. Meloxicam is preferentially hydrated in water-rich mixtures but preferentially solvated by NMP in the composition interval of 0.16 < x1 < 1.00

Solubility behavior and thermodynamic modeling of inosine (form β) in four cosolvency systems at T = 278.15 to 323.15 K

N,N-Dimethylformamide (DMF) as the main solvent with strong dissolving power was blended with four secondary solvents (ethanol, n-propanol, isopropanol, and propylene glycol) with relatively weak dissolving power to form many new solvents. The dispersion index (inosine (form β) mole fraction) in five organic solvents such as DMF and in the newly formed solvent was also obtained one by one with the static method commonly used in solid–liquid equilibrium. The temperature environment includes the high temperature set at 323.15 K, the low temperature set at 278.15 K, and an interval between each temperature of 5 K. The pressure environment was the atmospheric pressure in the natural state, and the usual value was 101.0 kPa. In a mixed system, temperature was a non-negligible influencing factor from beginning to end, and its increase often led the solute to the trend of high solubility. In addition, the proportion of the main solvent also dominated the solubilization trend of the inosine (form β); the larger the proportion of DMF, the easier the dissolution process. When both of the above factors were fixed at a certain point, the dispersing ability of the dispersing liquid composed of DMF and ethanol was undoubtedly the first. Three models (Jouyban–Acree model, van’t Hoff–Jouyban–Acree model, and modified Apelblat–Jouyban–Acree model) were used to correlate the solubility data. The largest relative average deviation and root-mean-square deviation values were 4.66 × 10–2 and 7.27 × 10–4, respectively. The dispersion data of inosine (form β) obtained through this experimental process and related thermodynamic parameters obtained through thermodynamic calculations have important application significance for its industrial production and further purification

Design nanostruktur založených na klastrových sloučeninách bóru ve vodných roztocích

Náplní této disertační práce bylo studium roztokového chování klastrových sloučenin bóru a jejich interakce s polymery, s důrazem na pochopení zákonitostí vedoucích k tvorbě příslušných nano-struktur. Kromě polymerního systému obsahujícího o-karboran, byl výzkum zaměřen zejména na chování kobalt bis(dikarbollidového) aniontu (COSAN). Hlavní myšlenkou bylo pochopit některé dosud nejasné aspekty micelizace COSANu v souladu s dlouhodobými badatelskými plány v naší skupině. Z toho důvodu byla provedena detailní kalorimetrická studie, která umožnila kromě dalších termodynamických parametrů stanovit hodnotu agregačního čísla solí COSANu při koncentracích blízkých kritické micelární koncentrace (KMK), což je obtížně dostupné pomocí jiných experimentálních technik. Použití acetonitrilu jako příměsi ve vodném roztoku COSANu se ukázalo jako velmi účinný prostředek pro získání alespoň přibližné představy o vnitřní struktuře micel COSANu, což je z experimentálního hlediska jinak velmi obtížné. Z provedených fyzikálně chemických experimentů plyne, že C-H skupiny COSANu pravděpodobně směřují dovnitř nano-agregátů. Dále byla studována solubilizace COSANu v micelách s hydrofobním jádrem a polyelektrolytovou slupkou, kde byl použit COSAN jako modelové léčivo kombinující elektrostatický náboj s hydrofobním...Thesis The main objective of this thesis is the study of boron cluster compounds in solution, their interaction with polymers and the formation of nanostructures. Most of the work was focused around cobalt bis(dicarbollide) (COSAN) but the incorporation of carborane into polymers was also studied. The idea was to close the knowledge gap around the way COSAN aggregates and continue the line of the laboratory in leading this topic. Therefore, we performed in-depth analysis of isothermal titration calorimetry curves to determine the aggregation number at concentrations around the critical micellar concentration (CMC). Thus, the aggregation number obtained was an improvement over previous data obtained a much higher concentration. The use of acetonitrile as a cosolvent in the micellization process helped formulate a model describing how C-H bonds in the COSAN micelles are directed towards the inside of the micelle. Furthermore, COSAN was used as a model drug for loading nanocarriers composed of hydrophobic core and charged corona. The importance of this work relies on the creation of guidelines for drug loading into similar polymeric vectors in order to determine how the nanocarrier will be affected. With the help of coarse-grained simulations, we determined that changes in the hydrophobicity of the...Katedra fyzikální a makromol. chemieDepartment of Physical and Macromolecular ChemistryPřírodovědecká fakultaFaculty of Scienc

13th International Chemical and Biological Engineering Conference (CHEMPOR 2018): book of short abstracts

University of Aveiro and Ordem dos Engenheiros proudly welcome all participants to the 13th International Chemical and Biological Engineering Conference - CHEMPOR 2018. Welcome to Aveiro! During three days, from October 2nd to 4th, more than 370 participants from Industry and Academia gathered at Centro Cultural e de Congressos de Aveiro to discuss recent developments and future directions in different areas of chemical engineering, materials science and engineering, biotechnology and biological engineering. CHEMPOR 2018 aims to be a forum for the debate of societal challenges related to energy, the environment, and the efficient use of natural resources and materials, all of which require innovative solutions complying with sustainability criteria. In 2017 Portuguese exports increased circa 11 % reaching the highest value of the Gross Domestic Product (in a time horizon of 23 years). Portugal’s Ministry of Economy estimates that capital-intensive industries (such as chemicals and polymers producers) and manufacturing industries (including food, textile, paper, cork, wood panels and metal producers) account for over 50 % of the overall value of the exportations. In this context, CHEMPOR 2018 emerges as a privileged forum to discuss technological and scientific issues that will promote economic growth through innovation. The Organizing Committee accepted more than 345 communications, of which 83 oral presentations, after peer reviewing. Internationally recognized scientists were invited to deliver 6 Plenary Lectures and 6 Keynote Speeches. On the opening day of CHEMPOR 2018, the Portuguese Minister of Economy, Professor Manuel Caldeira Cabral, made a communication in the presence of dozens of industrial sponsors. Just before the closing session, the Professor Almiro Castro Award (sponsored by PARALAB) was granted , for the second time, and prizes were awarded to the best Oral and Poster Communications presented during the Conference. The Organizing Committee of CHEMPOR 2018 acknowledges all authors for their contributions, all colleagues involved in the organization of the program, and the generosity of all sponsors. We wish you a memorable Conference both scientifically and socially.publishe

Micellar chromatographic partition coefficients and their application in predicting skin permeability

The major goal for physicochemical screening of pharmaceuticals is to predict human drug absorption, distribution, elimination, excretion and toxicity. These are all dependent on the lipophilicity of the drug, which is expressed as a partition coefficient i.e. a measure of a drug’s preference for the lipophilic or hydrophilic phases. The most common method of determining a partition coefficient is the shake flask method using octanol and water as partitioning media. However, this system has many limitations when modeling the interaction of ionised compounds with membranes, therefore, unreliable partitioning data for many solutes has been reported. In addition to these concerns, the procedure is tedious and time consuming and requires a high level of solute and solvent purity. Micellar liquid chromatography (MLC) has been proposed as an alternative technique for measuring partition coefficients utilising surfactant aggregates, known as micelles. This thesis investigates the application of MLC in determining micelle-water partition coefficients (logPMW) of pharmaceutical compounds of varying physicochemical properties. The effect of mobile phase pH and column temperature on the partitioning of compounds was evaluated. Results revealed that partitioning of drugs solely into the micellar core was influenced by the interaction of charged and neutral species with the surface of the micelle. Furthermore, the pH of the mobile phase significantly influenced the partitioning behaviour and a good correlation of logPMW was observed with calculated distribution coefficient (logD) values. More interestingly, a significant change in partitioning was observed near the dissociation constant of each drug indicating an influence of ionised species on the association with the micelle and retention on the stationary phase. Elevated column temperatures confirmed partitioning of drugs considered in this study was enthalpically driven with a small change in the entropy of the system because of the change in the nature of hydrogen bonding. Finally, a quantitative structure property relationship was developed to evaluate biological relevance in terms of predicting skin permeability of the newly developed partition coefficient values. This study provides a better surrogate for predicting skin permeability based on an easy, fast and cheap experimental methodology, and the method holds the predictive capability for a wider population of drugs. In summary, it can be concluded that MLC has the ability to generate partition coefficient values in a shorter time with higher accuracy, and has the potential to replace the octanol-water system for pharmaceutical compounds

Extraction of Bio-based Organic Acids using Supported Liquid Membranes with Novel Solvents

A thesis submitted to The University of Manchester for the degree of Doctor of Philosophy in the Faculty of Science and Engineering.Novel green solvents and supported liquid membranes were studied for the recovery of bio-based organic acids from model fermentation broths. As fundamental building blocks for the chemical industry, the production of organic acids from renewable feedstock have been broadly developed. Among them, succinic acid, levulinic acid, and fumaric acid have been highlighted as leading representatives. Nevertheless, their downstream separation and purification still require further research to build a suitable green production route. This turns the development of environmentally-friendly extractants as well as efficient separation methods into priority key research areas for bio-separations. The growing number of available green solvents, such as ionic liquids, eutectic solvents, and bio-based solvents, makes unbearable the experimental screening process to find the most appropriate extractant. In this work, the molecular interactions driving the overall extraction performance for the organic acids were systematically analysed. Experimental measurements of the liquid-liquid extraction and solid-liquid equilibria, as well as thermodynamic modelling using the quantum chemistry-based COSMO-RS method, were carried out. Organic acids extraction yields and solubilities, systems excess energies, activity coefficients, and energies of solutions are reported. The combination of structurally different acids and extraction solvents arise complex interactions; however, hydrogen bonding showed to determine the overall behaviour. As a result, a straightforward selection guide was developed based on the organic acids partition coefficients in the extractant/water system, ln(K), system's water affinity, ln(y), and separation process spontaneity, G. Furthermore, the dissolution process of the organic acids in green solvents displayed an endothermic and spontaneous process with an enthalpy-entropy compensation effect. The separation is driven by the new and stronger interactions formed, increasing the order of the systems. The state-of-the-art on sustainable applications of liquid membrane technology was thoroughly reviewed. Despite its high potential to replace conventional liquid-liquid extraction processes, some operational issues must be overcome and better predictive models developed. The feasibility of green-supported liquid membranes for succinic acid recovery was explored. As suggested by previous results, the solvent-phase affinities became key in the extraction performance. Experimental extractions were carried out to assess the effect of the green solvents and receiving phase. Commercial polyvinylidene fluoride (PVDF) porous membranes were impregnated with four different green solvents: the eutectic solvents DL-menthol:OctA and N4444Cl:OctA, the bio-based solvents eucalyptol, and the ionic liquid [C4pyrr][Tf2N]. The acid recovery for all liquid membranes was 50%, 51% and 59% with pure water and alkaline aqueous solutions of 0.1M and 0.5M NaOH in the stripping phase, respectively. It was found that extraction yield indeed depends on the pH of the stripping phase and that the solute permeation rate depends on the extraction solvent. For the first time, a permeability model based on experimental data and activity coefficients computed using the COSMO-RS method was developed. Moreover, the novel Permeability Activity-Based Linear Operation (PABLO) method was developed and proposed to determine the theoretical stages number and mass transfer area in a countercurrent cascade extraction system. Overall, this thesis comprehensively covers two research needs for the bioseparations of key building blocks. The contributions will certainly enhance the development and design of green production routes, boosting the next generation of sustainable chemicals and biorefinery industries.This work was funded by the CONICYT PFCHA/ DOCTORADO BECAS CHILE/2017−72180306.Peer reviewe

Solubility and preferential solvation of some n-alkyl-parabens in methanol + water mixtures at 298.15 K

This article describes methyl, ethyl and propyl parabens equilibrium solubility as determined in (methanol + water) binary mixtures at 298.15 K