Univ, Diss--Leipzig, 2006.

Univ, Diss--Leipzig, 2006.

Determination of whether ion specific potassium halides binding with BSA occurred within the experimental conditions was the aim of the study. Ultrasound velocity measurements using a Resoscan system and density measurements using a DMA 5000M density meter were made to analyse BSA conformation in the presence of potassium salts of the Hofmeister series. It was found that the density and the adiabatic compressibility of BSA-potassium halide mixed aqueous solutions cannot be predicted from the density and the adiabatic compressibility of potassium halide solutions and that of BSA solutions. Interaction occurs between BSA and Br-, I- and F- ions in mixed aqueous solutions of BSA-KBr, BSA-KI and BSA-KF, but there is no interaction between BSA and Cl- ion in BSA-KCl mixed aqueous solution. The interaction of ion to BSA is ion non-specific to the Hofmeister series.

Determination of whether ion specific potassium halides binding with BSA occurred within the experimental conditions was the aim of the study. Ultrasound velocity measurements using a Resoscan system and density measurements using a DMA 5000M density meter were made to analyse BSA conformation in the presence of potassium salts of the Hofmeister series. It was found that the density and the adiabatic compressibility of BSA-potassium halide mixed aqueous solutions cannot be predicted from the density and the adiabatic compressibility of potassium halide solutions and that of BSA solutions. Interaction occurs between BSA and Br-, I- and F- ions in mixed aqueous solutions of BSA-KBr, BSA-KI and BSA-KF, but there is no interaction between BSA and Cl- ion in BSA-KCl mixed aqueous solution. The interaction of ion to BSA is ion non-specific to the Hofmeister series.

Zugl.: Leipzig, Univ., Diss., 2006

Les catasurfs sont des tensioactifs cationiques à contre-ion catalytiques qui ont été conçus pour la formulation de systèmes de microémulsion oxydante triphasiques utilisés comme milieux réactionnels pour l’oxydation de substrats organiques par H2O2. Les propriétés physicochimiques en solution aqueuse (solubilité, température de Krafft, cmc) d’ammonium quaternaires amphiphiles ont été déterminées pour une série de contre-ion, mettant en évidence l’importance de la polarisabilité et de l’hydratation de l’anion sur le caractère amphiphile du tensioactif. Le comportement de phase des systèmes ternaires eau/solvant/tensioactif a été étudié en fonction de divers paramètres (contre-ion, solvant, structure de l’ammonium quaternaire, addition de tensioactif non ionique) et notamment le comportement des tensioactifs catalytiques à base de molybdate et tungstate en présence de H2O2. La peroxydation de l’anion, en modifiant la polarisabilité de celui-ci, modifie radicalement le caractère hydrophile/hydrophobe du tensioactif et son comportement de phase. Les diverses considérations ont conduit à la conception de milieux réactionnels triphasiques à base de molybdate ou tungstate d’ammonium quaternaires, avec divers solvants (aromatiques, acétates d’alkyles) et contrôle du pH. Ce type de milieu présente plusieurs avantages majeurs en termes d’application : large interface eau/solvant dans la phase microémulsion, simplicité de mise en œuvre avec seulement trois constituants, facilité de traitement du milieu après réaction avec le catalyseur localisé en phase microémulsion et le(s) produit(s) en phase organique, séparation instantanée des phases grâce aux tensions de surface ultra-basses. L’efficacité de ces systèmes a été évaluée et validée dans le cas de l’oxydation des sulfures par le système catalytique H2O2/MoO42-, et dans le cas de l’époxydation d’alcènes par H2O2/WO42- en milieu acide. / Catasurfs are cationic surfactant bearing a catalytic counterion and have been designed for the formulation of three-phase oxidative microemulsion systems whose purpose is the H2O2 oxidation of organic substrates. Physicochemical properties of amphiphilic quaternary ammonium in aqueous solution have been investigated with various counterions, showing the dependence of anion polarisability and hydration on the amphiphilic properties of the surfactant. The phase behavior of water/solvent/surfactant ternary mixtures has been examined according to various parameters (counterion, solvent, quaternary ammonium structure, addition of non ionic surfactant), and particularly the behavior of catalytic surfactants with H2O2. Anion peroxydation, by a variation of its polarisability, radically changes its water and oil affinities, and its phase behavior. The various observations led us to elaborate three-liquid-phase reaction media based on quaternary ammonium molybdate or tungstate, with various solvents (aromatic and alkyl acetates) and under pH control. This type of medium has several practical major advantages: large water/oil interface in the microemulsion phase, simplicity of implementation with only three components, ease of reaction medium treatment with the catalyst lying in the middle phase and the product(s) in the organic phase, instantaneous phase separation thanks to ultra-low interfacial tensions. The efficiency of these three-phase microemulsion systems has been evaluated and validated for the oxidation of sulfides by the H2O2/MoO42- catalytic system, and for the epoxidation of alkenes with H2O2/WO42- in acidic media.

Dissertation--Fakultät für Geschichte, Kunst und Orientwissenschaften--Universität Leipzig, 2006. / Bibliogr. p. 403-407.

acase@tulane.edu / Rational, synthetic design is implemented in a systematic study of the effect of host shape and properties and manifestations of the reverse Hofmeister effect. Hofmeister specific effects were observed at the molecular level wherein it was shown that key to the effectiveness of some “salting-in” anions is their complementarity to hydrophobic cavities and other binding surfaces. A gamut of responses was observed across a range of hosts possessing different structural and functional motifs. These observations were typically manifest at a relatively low (<20 mM) critical precipitation concentration (CPC). Furthermore, it was shown that at low concentrations, typical observations of screening effects are not observed, and binding-site competition is a predominant factor when multiple anions are present in solution. In terms of quantifying the ion recognition sites of different, similarly charged hosts there is little difference in anion affinity, but large differences are observed in 1/CPC values. Thus, subtle changes in the recognition site have dramatic changes in terms of manifestations of the reverse Hofmeister effect. This is (to the authors best knowledge) the first example of a systematic study sequentially modifying small molecular hosts and utilizing them to study reverse Hofmeister trends. In total 12 hosts and 6 host-guest complexes were examined. These studies demonstrate applications of the reverse Hofmeister effect to generate single crystal X-ray structures, with potential applications in protein and small molecule purifications, separations, and crystallizations. / 1 / Jacobs Jordan

archives@tulane.edu / Solubility is the ability of a molecule to favorably interact with a solvent. While seemingly simple in application many phenomena arise from knife-edge like conditions between solubility and insolubility. Herein, three of these phenomena; co-non-solvency, the hydrophobic effect, and the direct and reverse Hofmeister effects are investigated in detail to parse out a mechanistic view of solubility in each case. The first phenomenon, co-non-solvency, is the insolubility of a thermo-responsive polymer and a mixture of two good cosolvents. Host-guest systems are used to probe small molecule interactions in the presence of cosolvents for co-non-solvent effects. The second phenomenon, the hydrophobic effect, is often colloquially described as “oil and water do not mix.” However, this is much more complex when diving into the energetic contributions. Host-guest systems are used to determine structural effects novel hosts and guests have on the hydrophobic effect in collaboration with the computational community. The third phenomenon, the Hofmeister effects, are explored through the fine tuning of solubility of lysozyme through the addition of sodium perchlorate in varying pHs. This is used to determine a mechanistic view of protein solubility in the presence of salts. / 1 / Nicholas Ernst

The technique of phase labeling has the ability to greatly enhance synthetic protocol by simplifying purification and increasing efficiency. Traditional insoluble supports offer efficient and simple recovery of the “phase tagged” material but suffer from problems inherent to their heterogeneous nature. A solution to these problems has been to utilize phase separable soluble polymers in the design of “smart” responsive systems that offer the option of homogenous reaction conditions with heterogeneous separation conditions. The subject of this dissertation focuses on the application of soluble polymeric phase tags in systems where the miscibility between solid-liquid and liquid-liquid systems is thermally induced. Low molecular weight poly(ethylene glycol) (PEG) oligomers were investigated as phase anchors for SCS palladacycle catalysts. The oligomeric PEG chains were sufficient to engender polar phase solubility in a heptane-DMA thermomorphic system. Microwave irradiation of these thermomorphic mixtures of palladium complexes and substrates was a viable scheme to recycle and significantly shorten reaction times for simple Heck reactions of aryl iodides. Soluble polymeric supports possessing a lower critical solution temperature (LCST) were utilized in the sequestration of the S-triazine herbicide, atrazine, from contaminated water samples. The ability of poly(N-isopropylacrylamide) to sequester hydrophobic guests like atrazine was examined. A functionalized PNIPAM derivative containing secondary cyclic amines exhibited superior sequestration ability that was credited to the covalent binding of the atrazine. In order to facilitate the design of tailored, thermally responsive, smart polymers, a high throughput temperature gradient microfluidic device was used to obtain LCST data in a fast, accurate manner. The specific ion effects of various alkali metal halide salts on the LCST of PNIPAM were investigated. The high precision in the measurements enabled more subtle effects such as changes in solvent isotope, polymer microstructure, molecular weight, and importance of end group effects on the LCST of poly(N-alkylacrylamide)s to be evaluated.