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You searched for subject:(aromatic aggregation). Showing records 1 – 3 of 3 total matches.

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University of Colorado

1. Perkins, Russell James. Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions.

Degree: PhD, 2017, University of Colorado

Many important chemical reactions from all branches of chemistry occur with water as a solvent. Furthermore, in environmental chemistry, biochemistry, and synthetic chemistry, key reactions occur in heterogeneous aqueous systems, where interfacial effects are particularly important. Despite the importance of aqueous environments and the tremendous amount of work done to study them, there are aspects that require further explanation and remain controversial. I have performed experimental studies to help elucidate the fundamental characteristics of aqueous systems, while examining specific phenomena across several fields. The genetic disorder phenylketonuria (PKU) can result in increased levels of the aromatic amino acid phenylalanine in human serum. Much of my work has focused on the driving forces behind partitioning of aromatic small molecules, including phenylalanine, into air-water or membrane-water interfacial regions, and the consequences of partitioning on interfacial properties. Drastically different behaviors for structurally similar aromatic molecules are observed, differences that cannot be explained by hydrophobic effects. These observations can be explained, however, through the development of a more detailed picture of interactions and partitioning, including the formation of interfacial aggregates. For phenylalanine, this partitioning appears to result in drastic changes in membrane morphology and permeability. This is a likely molecular-level cause for the damage associated with the disease state of PKU. Aqueous systems are further complicated by the reactivity of water. It often serves not only the role of a solvent, but also a reactant, a product, and/or a catalyst. I explore this reactivity using an organic molecule with relevance to environmental chemistry, zymonic acid. Zymonic acid forms spontaneously from pyruvic acid, an important atmospheric species. While zymonic acid exists as a single species in solid form when dissolved in DMSO, once in aqueous solution it quickly reacts with water and equilibrates with at least four other forms. I studied the details and kinetics of these equilibria via time-dependent NMR. Several surprising mechanistic details were uncovered, including a direct enol to geminal diol conversion and base-catalyzed lactone ring formation. The consequences of zymonic acid’s behavior are investigated in the context of environmental and prebiotic chemistry. Advisors/Committee Members: Veronica Vaida, Joel Eaves, Amy Palmer, Loren Hough, Garret Miyake.

Subjects/Keywords: aqueous interfaces; aromatic aggregation; mechanistic organic chemistry; membrane biophysics; preboitic chemistry; surfactants; Physical Chemistry

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Perkins, R. J. (2017). Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/219

Chicago Manual of Style (16th Edition):

Perkins, Russell James. “Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions.” 2017. Doctoral Dissertation, University of Colorado. Accessed April 14, 2021. https://scholar.colorado.edu/chem_gradetds/219.

MLA Handbook (7th Edition):

Perkins, Russell James. “Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions.” 2017. Web. 14 Apr 2021.

Vancouver:

Perkins RJ. Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2021 Apr 14]. Available from: https://scholar.colorado.edu/chem_gradetds/219.

Council of Science Editors:

Perkins RJ. Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/chem_gradetds/219


University of Colorado

2. Perkins, Russell James. Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions.

Degree: PhD, 2018, University of Colorado

Many important chemical reactions from all branches of chemistry occur with water as a solvent. Furthermore, in environmental chemistry, biochemistry, and synthetic chemistry, key reactions occur in heterogeneous aqueous systems, where interfacial effects are particularly important. Despite the importance of aqueous environments and the tremendous amount of work done to study them, there are aspects that require further explanation and remain controversial. I have performed experimental studies to help elucidate the fundamental characteristics of aqueous systems, while examining specific phenomena across several fields. The genetic disorder phenylketonuria (PKU) can result in increased levels of the aromatic amino acid phenylalanine in human serum. Much of my work has focused on the driving forces behind partitioning of aromatic small molecules, including phenylalanine, into air-water or membrane-water interfacial regions, and the consequences of partitioning on interfacial properties. Drastically different behaviors for structurally similar aromatic molecules are observed, differences that cannot be explained by hydrophobic effects. These observations can be explained, however, through the development of a more detailed picture of interactions and partitioning, including the formation of interfacial aggregates. For phenylalanine, this partitioning appears to result in drastic changes in membrane morphology and permeability. This is a likely molecular-level cause for the damage associated with the disease state of PKU. Aqueous systems are further complicated by the reactivity of water. It often serves not only the role of a solvent, but also a reactant, a product, and/or a catalyst. I explore this reactivity using an organic molecule with relevance to environmental chemistry, zymonic acid. Zymonic acid forms spontaneously from pyruvic acid, an important atmospheric species. While zymonic acid exists as a single species in solid form when dissolved in DMSO, once in aqueous solution it quickly reacts with water and equilibrates with at least four other forms. I studied the details and kinetics of these equilibria via time-dependent NMR. Several surprising mechanistic details were uncovered, including a direct enol to geminal diol conversion and base-catalyzed lactone ring formation. The consequences of zymonic acid’s behavior are investigated in the context of environmental and prebiotic chemistry. Advisors/Committee Members: Veronica Vaida, Joel Eaves, Amy Palmer, Loren Hough, Garret Miyake.

Subjects/Keywords: aqueous interfaces; aromatic aggregation; mechanistic organic chemistry; membrane biophysics; preboitic chemistry; surfactants; Organic Chemistry; Physical Chemistry

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Perkins, R. J. (2018). Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/273

Chicago Manual of Style (16th Edition):

Perkins, Russell James. “Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions.” 2018. Doctoral Dissertation, University of Colorado. Accessed April 14, 2021. https://scholar.colorado.edu/chem_gradetds/273.

MLA Handbook (7th Edition):

Perkins, Russell James. “Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions.” 2018. Web. 14 Apr 2021.

Vancouver:

Perkins RJ. Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Apr 14]. Available from: https://scholar.colorado.edu/chem_gradetds/273.

Council of Science Editors:

Perkins RJ. Beyond Hydrophobicity: Aqueous Interfaces, Interactions and Reactions. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/chem_gradetds/273


Louisiana State University

3. Akbay, Cevdet. Synthesis, characterization, and applications of novel pseudostationary phases in micellar capillary electrophoresis for separation of chiral and archiral compounds h.

Degree: PhD, Chemistry, 2002, Louisiana State University

The research presented in this dissertation involves the synthesis, characterization, and the use of novel surfactants, including both micelles and vesicles, as pseudostationary phases in micellar capillary electrophoresis (MCE) for the separation of achiral and chiral compounds. Separation of environmental pollutants such as 2 to 6-ring polycyclic aromatic hydrocarbons (PAHs) was achieved using poly(sodium undecylenic sulfate). A baseline separation of all 16 PAHs was possible for the first time in MCE by a single-surfactant system. In addition, a surfactant with a phosphated head group, i.e., di(2-ethylhexyl)phosphate (DEHP), was also introduced as a novel pseudostationary phase for separation of 21 weakly and strongly hydrophobic neutral compounds. Acetonitrile at a concentration of 30% (v/v) in combination with 100 mM DEHP gave optimum separation for a mixture of 21 benzene derivatives and PAHs in under 16 minutes. An application of cyclodextrin modified MCE was used for separation of twelve mono-methylbenz[a]anthracene positional isomers using a combination of poly-SUS and b-CD, g-CD or b-CD derivatives. Tartaric acid based vesicular surfactants were synthesized and utilized as novel pseudostationary phases in MCE. Linear solvation energy relationship model was applied to understand the fundamental nature of the solute-surfactant interactions and to investigate the effect of the type and the composition of pseudostationary phases on the retention mechanism and selectivity in MCE. The solute size has the largest influence on the solute retention in MCE. The hydrogen bond accepting ability of the solute is the second most important factor on retention and is the largest contributor towards the selectivity differences between pseudostationary phases used. Another study conducted was the synthesis of sodium N-undecanoyl L-leucinate and co-polymerization of SUL with SUS to make a variety of co-polymerized molecular micelles having both chiral (leucinate) and achiral (sulfate) head groups. These surfactants were applied as novel pseudostationary phases in MCE for separation of chiral and achiral compounds. Aggregation numbers and partial specific volumes of these surfactant systems were determined using fluorescence spectroscopy and densitometry, respectively. Thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy changes upon transfer of analyte(s) from aqueous phase to the pseudostationary phase were also determined.

Subjects/Keywords: micellar capillary electrophoresis; chiral surfactants; electrokinetic chromatography; ekc; aggregation number micelles; cd; benzodiazepines; enantiomeric separation; binaphthyl derivatives; cyclodextrin modified mekc; micellar electrokinetic chromatography; pah; molecular micelles; achiral surfactants; thermodynamic quantities; ce; capillary electrophoresis; copolymerized molecular micelles; partial specific volume of surfactant; enantioseparation; energy of transfer; critical aggregation concentration of surfactants; poly-sus; pseudostationary phases; enthalpy; polymeric surfactants; polycyclic aromatic hydrocarbons; mce; methylbenz[a]anthracene isomers; cyclodextrins; cmc; cac; achiral separation; entropy; lser; chiral separation; linear solvation energy relationship; cd-mekc; mekc; monomeric surfactants; vesicles; van't hoff plots

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Akbay, C. (2002). Synthesis, characterization, and applications of novel pseudostationary phases in micellar capillary electrophoresis for separation of chiral and archiral compounds h. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-0710102-230709 ; https://digitalcommons.lsu.edu/gradschool_dissertations/2131

Chicago Manual of Style (16th Edition):

Akbay, Cevdet. “Synthesis, characterization, and applications of novel pseudostationary phases in micellar capillary electrophoresis for separation of chiral and archiral compounds h.” 2002. Doctoral Dissertation, Louisiana State University. Accessed April 14, 2021. etd-0710102-230709 ; https://digitalcommons.lsu.edu/gradschool_dissertations/2131.

MLA Handbook (7th Edition):

Akbay, Cevdet. “Synthesis, characterization, and applications of novel pseudostationary phases in micellar capillary electrophoresis for separation of chiral and archiral compounds h.” 2002. Web. 14 Apr 2021.

Vancouver:

Akbay C. Synthesis, characterization, and applications of novel pseudostationary phases in micellar capillary electrophoresis for separation of chiral and archiral compounds h. [Internet] [Doctoral dissertation]. Louisiana State University; 2002. [cited 2021 Apr 14]. Available from: etd-0710102-230709 ; https://digitalcommons.lsu.edu/gradschool_dissertations/2131.

Council of Science Editors:

Akbay C. Synthesis, characterization, and applications of novel pseudostationary phases in micellar capillary electrophoresis for separation of chiral and archiral compounds h. [Doctoral Dissertation]. Louisiana State University; 2002. Available from: etd-0710102-230709 ; https://digitalcommons.lsu.edu/gradschool_dissertations/2131

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