Chemistry Commons^™

Functional Emulsions Via Thiol-Ene Chemistry, Douglas Amato

Dissertations

Polymer particles (micro to nano) with tunable functionality have emerged as a promising and viable technology platform for applications including coatings, cosmetics, nanomedicine, and imaging. Unfortunately, the lengthy polymerization time and lack of intrinsic functionality in the monomers used to fabricate particles is an industrial challenge. Thiol-ene chemistry cirmcumvents these limitations with very rapid polymerization kinetics, high reaction yields, with supressed side reactions and inherent functionality. This dissertation demonstrates the utility of thiol-ene/yne polymerization in miniemulsion and microfluidics to generate functional materials in a one-pot-method. The functionality is typically generated via off-stoichiometry thiol-ene (OSTE) resins which allow for either excess …

Photoelectrochemical Studies On Non-Noble Metal Based Catalysts Towards Tandem Solar Water Splitting, Arun Siddarth Sridhar

Dissertations

Photoelectrochemical (PEC) water splitting makes direct use of solar energy incident on semiconductor photoelectrodes, and it is a convenient, economic option to produce high purity hydrogen at low temperatures. The use of multiple light absorbers can increase overall solar energy utilization and provide a solution to the trade-off between overall band gap and band edge positioning of photoelectrodes specific to solar water oxidation and water reduction. The study of non-noble metal based catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) are essential for economic practical commercialization of photo-electrolyzers. This dissertation focuses on the use of a variety …

An Exploration Of Pyrrole Groups On The Enantioselectivity Of Pig Liver Esterase, Brian Long

Honors Theses

Pig Liver Esterase (PLE) is a serine protease enzyme that can interact with one side of a diester to hydrolyze the ester to a carboxylic acid, and research has found that the level of hydrophobicity of side groups can impact the enantioselectivity of PLE hydrolysis.1, 2 The Jones Model is what current researchers use to model the active site of PLE, but the nature of its binding pockets, namely the Hydrophobic Long (HL) pocket, has been called into question.3 Dimethyl 2-((pyrrole-2-yl)methyl)-2-methylmalonate was prepared to be subjected to PLE hydrolysis to see whether enantioselectivity was found. Chiral HPLC revealed 25.32% enantiomeric …

Pro-Antimicrobial Networks Prepared Via Degradable Thiol-Ene Acetal Photopolymerization, Sarah Swilley

Honors Theses

A degradable, antimicrobial polymer network with acetal crosslink junctions derived from p-anisaldehyde (pA), a common constituent found in star anise extract, is reported. The p-anisaldehyde was converted into a bis-functional acetal alkene monomer, which serves as a pro-antimicrobial form of the active aldehyde and a building block for materials referred to as pro-antimicrobial polymer networks via degradable acetals (PANDAs). Subsequently, the bis-functional acetal alkene monomer was photopolymerized with a multifunctional thiol to yield a thiol-ene network. PANDAs exhibit surface erosion behavior and yield sustained release of pA over 38 days when exposed to neutral or biologically relevant conditions. The pA …

Investigation Of The Effects Of Hydrogen Bonding On The Enantiomeric Excess Of Pig Liver Esterase Hydrolysis Products, Matthew Hasler

Honors Theses

Pig Liver Esterase (PLE) is an effective enzyme used in the Masterson Research Group due to its ability to hydrolyze only one ester in a malonic diester. PLE is employed for creating chiral molecules for the synthesis of unnatural amino acid precursors. Previous research in the group found that malonic half esters with hydrogen bonding capable substrates yielded varying degrees of enantiomeric excess, and non-hydrogen bonding substrates yielded racemic mixtures.1,2 The compounds synthesized contained substrates consisting of thiophene rings in the second and third position, and these molecules act as a control for the other research done in the group. …

Understanding The Coating-Substrate Interface Changes And Degradation Caused By Environmental Acclimation With Water And Electrolytes, Russell Vick

Honors Theses

While it is well known that polymeric coatings are used to protect metals from corrosion, efficient and reliable protocols for quantifying and estimating protective coatings’ lifetimes have yet to match real-time results in rate or in detected mechanisms of material failure. Alkoxysilane pretreatments are widely utilized for substrate preparation and improved coating system performance by changing the metal substrate surface morphology to improve adhesion at the coating-substrate interface by creating a foundation and excluding water from the system. Three pretreatments used were 3-aminopropyltriethoxy silane (APS), tetraethylortho silicate (TEOS), N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAS). They were investigated to improve the understanding of the relationships …

Photoelectrochemical Investigations On Novel Earth Abundant Solid State Catalysts For Solar Water Oxidation, Nathaniel Branimir Kurtz

Honors Theses

In light of a looming fossil fuel scarcity, many forms of alternative, clean energy production are being researched in order to provide a more sustainable source of energy production for the future. One area of research is on using novel, abundant catalytic materials in conjunction with semiconducting materials to drive the splitting of water in order to produce hydrogen gas, an energy-rich fuel. Currently, efficiency is limited by the energy bottleneck posed by the oxygen evolution reaction (OER) half of water splitting. In this work, cobalt selenide (CoSe) catalyst paired with the semiconductor iron oxide (Fe2O3) has been identified as …

Diastereoselective Synthesis Of 2,4,6-Trisubstituted Piperidines Via Aza-Prins Cyclization, John A. Hood

Honors Theses

The nitrogen heterocycles are shared amongst 59% of Food and Drug Administration (FDA) approved small molecule pharmaceuticals with the six-membered piperidine representing the most common moiety. Given the versatility and potential to yield derivatives with broad biological activities, the discovery of new chemical methods to generate these heterocycles in a more time and cost-efficient manner is desired. While there are existing racemic methods to access this class of molecule, the objective of this research is to pioneer a new novel six-step method to generate 2,4,6-trisubstituted piperidines with stereoselective control.

The first step is a condensation between a nonenolizable aldehyde and …

Biocompatible, Responsive Polysoaps Via Raft Copolymerization For The Delivery Of Model Cancer Therapeutics, Mason Dearborn

Honors Theses

Many chemotherapeutic drugs are small, hydrophobic molecules that require water-soluble, biocompatible nanocarriers for enhanced vascular circulation. Existing polymeric carriers either conjugate the drug along a copolymer backbone or sequester drugs within a protected interior domain to be delivered to specific sites in the body. Such therapeutic systems must overcome a myriad of hurdles, beginning with complex, multi-step syntheses, followed by other inherent barriers that limit the efficiency of drug delivery at the targeted site. This work aims to circumvent a number of these issues using biocompatible, stimuli-responsive polysoaps that are capable of unimeric micelle formation, hydrophobic drug delivery, and triggered …

Detection And Assay Of Isoniazid Utilizing Isocratic High-Performance Liquid Chromatography, Cassandra Nguyen

Theses/Capstones/Creative Projects

To demonstrate an analysis for isoniazid from aqueous mixtures and solid tablets, utilizing isocratic conditions, with high performance liquid chromatography (HPLC) and UV detection. Isoniazid in solid and liquid samples is assayed utilizing HPLC. Isoniazid is a tuberculostat, that is assayed by high performance liquid chromatography that utilizes a reversed-phase C-18 column. The eluent solvent is 5.3% ethanol, 93.7% water, and 1% acetic acid. Aqueous samples are prepared in distilled water as the solvent. The ultraviolet-visible detection of isoniazid is accomplished at 265 nm, which is the wavelength having the highest sensitivity for isoniazid. Having a column pump pressure at …

Phospholipid Membrane Remodeling Through Exogenous Fatty Acid Incorporation In Certain Bacterial Species, Josh Herndon

Honors Theses

Multi-drug resistant bacteria have become problematic in healthcare settings. Recent studies have documented the ability of some bacteria, such as Vibrio species, to assimilate exogenous fatty acids into their membrane phospholipids. Therefore, the current research was performed to determine whether the three virulent, multi-drug resistant bacteria Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli can remodel their cell membranes following exposure to a range of exogenous polyunsaturated fatty acids (PUFAs). Furthermore, we hypothesized that PUFAs would influence phenotypes associated with growth and virulence. Extracted phospholipids were examined by UPLC/MS analysis to confirm assimilation of exogenous PUFAs into the bacterial phospholipids. A. …

Sds-Page Analysis Of Modified Lysozyme By Substituted Benzoquinones And Naphthoquinones, Neethu Kurien

Honors Theses

Quinones are molecules that are commonly found in the environment, as cofactors for proteins or an electron carrier in the mitochondrial electron transport chain. However, quinones also can come from polycyclic aromatic hydrocarbons as their metabolites, harming cellular integrity. In this study, we investigated protein modification of lysozyme in the presence of substituted benzoquinones and naphthoquinones. To simulate physiological conditions, all reactions used phosphate buffer (50.0 mM). While the majority of the experiments were performed at 37 C and pH 7.0, there were also temperature dependence (27 C and 42 C) and pH dependence (6.0 and 8.0) reactions included. SDS-PAGE …

Computational Modeling Of Electronically Excited States In Cobalamin-Dependent Reactions., Brady D. Garabato

Electronic Theses and Dissertations

The current understanding of the photolytic properties of Vitamin B12 derivatives or cobalamins are summarized from a computational point of view. The focus is on two non-alkylcobalamins, cyanocobalamin (CNCbl) and hydroxocobalamin (HOCbl), two alkylcobalamins, methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), as well as the stable cob(II)alamin radical. Photolysis of alkylcobalamins involves low-lying singlet excited states where photo-dissociation of the Co-C bond forms singlet-born alkyl/cob(II)alamin radical pairs (RPs). Potential energy surfaces (PESs) of low-lying excited states as functions of both axial bonds provide the most reliable tool for analysis of photochemical and photophysical properties. Due to the size limitations associated with the …

Long-Range Electrostatic Interactions In Gold Catalysis And Fluorinating Reagent Development., Zhichao Lu

Electronic Theses and Dissertations

Our research focus is on applying two long range electrostatic interactions--coulombic interaction between ion pairs and hydrogen bonding—to two tasks: exploring counterion effects in gold catalysis and utilizing hydrogen bonding for fluorinating reagent development. Cationic gold catalysis is considered one of the most important breakthroughs in organic synthesis over the past two decades. A wealth of empirical information on counterion effects is now available regarding homogeneous gold catalysis. However, the rational understanding of the counterion effect on reactivity is still elusive. We proposed a widely applicable model to rationalize the kinetic effect in gold catalyzed reaction. We first solved the …

The Effects Of Passive Integrated Transponder Tagging On Cortisol Release In The Gulf Killifish, Fundulus Grandis, Ariel Marcelo Hernandez

Senior Honors Theses

Due to its ease of use, low cost, and essentially limitless number of unique codes, PIT tagging has become the favored technique for tagging individuals in biological studies. However, studies employing PIT tagging generally assume that stress due to the implantation and presence of a PIT tag has no influence on the experimental results. This study investigated the effects of PIT tagging on levels of the stress hormone cortisol in the Gulf Killifish, Fundulus grandis, an estuarine fish of the Gulf of Mexico that is prone to daily or seasonal environmental stressors. Cortisol was measured non-invasively by extracting and …

Ultrafast Affinity Extraction And High-Performance Affinity Chromatography Applications For Measuring Free Drug Fractions: Interactions Of Sulfonylurea Drugs With Normal And Glycated Human Serum Albumin, Bao Yang

Department of Chemistry: Dissertations, Theses, and Student Research

Ultrafast affinity extraction was used with microcolumns containing human serum albumin (HSA) to measure the free fractions of several sulfonylurea drugs in the presence of solution-phase HSA and for the analysis of these drugs at therapeutic levels or determining their binding strengths with this protein. This approach was first used with normal HSA and the drugs glibenclamide, glipizide and glimepiride. This work used both one- and two-dimensional affinity systems based on HSA microcolumns. The first microcolumn was used to extract the free drug fractions in injected drug/protein mixtures. As the retained drug eluted from the first microcolumn, it was passed …

Polymer Nanocomposites Containing High Aspect Ratio Particulates: Innovation In Co-Extruded Multilayer Barrier Films, Kevin Meyers

Dissertations

Delaminated montmorillonite (MMT) clay/ maleic anhydride grafted LLDPE nanocomposite multilayer films with alternating layers of LDPE were produced through multilayer co-extrusion. The MMT concentration within the nanocomposite layers was increased through annealing the films in the melt due to a mismatch in interdiffusion rates of the polymer layers. Analysis of the nanocomposite layers upon annealing revealed that the platelets impinged upon one another resulting in significant improvement in oxygen barrier in the multilayer system, exceeding the results of bulk nanocomposites.

Model analysis demonstrated that increasing the nanoplatelet aspect ratio or initial concentration in the filled layers would lead to even …

Experimental And Computational Studies Of Rotation And Proton Tunneling In Organic Molecules And Molecular Dimers, Agapito Serrato Iii

Theses and Dissertations

An introduction to the relations of classical and quantum mechanics are presented in brief. As is an overview of the instrumentation and quantum chemical analysis performed to characterize the molecules presented in in this thesis. The pure rotational spectrum of 3,3,3-trifluoro-2(trifluoromethyl)propanoic acid, perfluorobutyric acid–formic acid dimer, and tropolone–formic acid dimer were measured using high-resolution microwave spectroscopy. The spectra have been observed using a cavity-based Fourier-transform microwave (FTMW) spectrometer and/or a chirped-pulse FTMW.

Microwave-Assisted Ring-Opening Polymerization Of Poly(Ε-Caprolactone), Nancy Obregon

Theses and Dissertations

Poly(ϵ-caprolactone) (PCL) is a biodegradable polyester notorious by its promising properties and applications in the biomedical field. In this work, microwave-assisted ringopening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) was performed. Stannous octoate [Sn(Oct)2] was used as catalyst with and without an alcohol initiator. The different initiators tested were glycerol, diethylene glycol (DEG) and poly(ethylene) glycol (PEG). Aiming to establish reaction parameters, the influence of different reaction times, temperatures, and monomer:initiator:catalyst ratios were examined. It was observed that the reaction was obtained and high molecular weight PCL was achieved successfully without an initiator. However, mixed results were obtained using an initiator. Products …

Singlet Oxygen Oxidation Of Guanine, 9-Methylguanine And Guanine-Cytosine Base Pair: Dynamics And Kinetics Revealed By Parallel Gas- And Solution-Phase Experiments And Computations, Wenchao Lu

Dissertations, Theses, and Capstone Projects

Singlet oxygen (¹O₂) oxidatively generated damage of DNA gives rise to mutagenesis, carcinogenesis, and cellular death. Guanine is the most susceptible DNA target of ¹O₂. The related process has been studied over three decades but the mechanism has remained elusive. My thesis research has focused on reaction mechanism, dynamics and kinetics of ¹O₂ oxidation of guanine, 9-methylguanine and guanine-cytosine base pair, from the gas-phase bare ions, through hydrated clusters, to aqueous solution. Various techniques have been adapted in the work, including ¹O₂ generation and detection, guided-ion beam tandem mass …

Computational Study Of Lawesson’S Reagent Mediated Fluorenone Dimerization Forming 9,9’-Bifluorenylidene, Andrew Jourdan Eckelmann

Graduate Theses/Dissertations

The ambition of this work is to start a path to the a priori rational design of high yield production for electron acceptors with finely tuned band gaps, from the comfort of an armchair. To this end, organic photovoltaics offer a cheap and sustainable means of manufacture using readily available materials and avoids the toxicity of some of the heavy metals used in first and second-generation solar cells such as cadmium. The microwave assisted Lawesson’s reagent mediated one-pot one-step solventless synthesis takes less than 3 minutes and results in an 84% yield of 9,9’-bifluorenylidene from two equivalents of fluorenone. While …

Highly Flame Retardant And Bio-Based Rigid Polyurethane Foams Derived From Orange Peel Oil, Chunyang Zhang

Electronic Theses & Dissertations

Polyurethane is an important class of polymer which is being used for various industrial applications in the form of rigid foams, flexible foams, thermoplastic, elastomer, coating, and adhesive. Especially there is a huge market for rigid polyurethane foams for their applications as thermal insulating material in building and housing. In general, polyurethanes are prepared using polyols and diisocyanates. Most of the polyols used by industries are petrochemical based. In this project, a novel polyol from an orange peel oil-based derivative, limonene dimercaptan, was synthesized using one step photochemical thiol-ene reaction. The synthesized polyol was used to prepare flame retardant polyurethane …

Kinetics And Activation Energy Parameters For Hydrolysis Of Acetic Anhydride In A Water-Acetone Cosolvent System, Samson Olowoyo

Electronic Theses and Dissertations

The hydrolysis of acetic anhydride is a widely-studied liquid phase reaction studied since 1906. Different approaches have been used to study the kinetics of this reaction. Approaches used by researchers have involved the use of sophisticated experimental set-ups. In this work, the pH technique has been adopted which involves the use of a pH meter to monitor the hydrolysis reaction. Analysis of the hydrolysis reaction has been performed for water/acetone cosolvent systems over a range of temperatures and mole fractions. Eyring analysis was performed under isomole fraction conditions and activation enthalpy, entropy, and Gibbs free energy for hydrolysis of acetic …

Multivalency Regulates Activity In An Intrinsically Disordered Transcription Factor, Sarah Clark, Janette B. Myers, Ashleigh King, Radovan Fiala, Jiri Novacek, Grant Pearce, Steve L. Reichow, Elisar J. Barbar

Chemistry Faculty Publications and Presentations

The transcription factor ASCIZ (ATMIN, ZNF822) has an unusually high number of recognition motifs for the product of its main target gene, the hub protein LC8 (DYNLL1). Using a combination of biophysical methods, structural analysis by NMR and electron microscopy, and cellular transcription assays, we developed a model that proposes a concerted role of intrinsic disorder and multiple LC8 binding events in regulating LC8 transcription. We demonstrate that the long intrinsically disordered C-terminal domain of ASCIZ binds LC8 to form a dynamic ensemble of complexes with a gradient of transcriptional activity that is inversely proportional to LC8 occupancy. The preference …

Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, Randy Espinal Cabrera

Graduate Theses and Dissertations

A new microdialysis sampling method and microfluidic device were developed in vitro. The method consisted of using up to four microdialysis sampling probes connected in series to evaluate the relative recovery (RR) of different model solutes methyl orange, fluorescein isothiocyanate (FITC)-dextran average mol. wt. 4,000 (FITC-4), FITC-10, FITC-20, and FITC-40. Different flow rates (0.8, 1.0, and 1.5 µL/min) were used to compare experimentally observed relative recoveries with theoretical estimations. With increasing the number of probes in series, the relative recovery increases and ~100% (99.7% ± 0.9%) relative recovery for methyl orange was obtained. For larger molecules such as fluorescein isothiocyanate …

Eyring Activation Energy Analysis Of Acetic Anhydride Hydrolysis In Acetonitrile Cosolvent Systems, Nathan Mitchell

Electronic Theses and Dissertations

Acetic anhydride hydrolysis in water is considered a standard reaction for investigating activation energy parameters using cosolvents. Hydrolysis in water/acetonitrile cosolvent is monitored by measuring pH vs. time at temperatures from 15.0 to 40.0 °C and mole fraction of water from 1 to 0.750. This work utilizes a temperature controlled water bath and a Vernier glass-body pH probe with Vernier Logger Pro 3.10.1 software for automated data collection. Data analysis is used to determine observed kinetic rate constants under the assumption that hydrolysis is a pseudo-first-order reaction. Eyring plots were used to compare activation energy parameters under iso-mole fraction conditions. …

Removal Of Chromium(Vi) And Chromium(Iii) Ions From Aqueous Solution Using Bio-Char Generated From Agricultural Waste Products, Diego Fernando Gonzalez

Theses and Dissertations

Heavy metals are one of the most persistent and prevalent contaminants in the aquatic environment. The removal of chromium from aqueous solution, especially in the hexavalent form is difficult. New technologies, techniques and/or new materials have been designed in order to effectively and efficiently remove chromium from the aqueous environment. The project focuses on the comparison of the effects of pH, time, temperature, binding capacity on bio-char’ generated from agricultural waste produces vs an amino modified derivative of the bio-char. Pineapple skins were dried, ground, sieved, and pyrolyzed to produce a bio-char material. The bio-char was analyzed using FTIR to …

Investigations Into Ring-Opening Polymerization Of Functionalized Ε-Caprolactones, Danielle N. Coderre, Matthew K. Kiesewetter

Senior Honors Projects

Polymers are defined as large molecules constructed from small, repeating units (monomers) which make up everyday items, such as: plastic bags and bottles, waterproof coatings, pipes, etc. H-bonding urea (U) or thiourea (TU) catalysts paired with base cocatalysts used for organocatalytic ring-opening polymerization (ROP) of cyclic esters have been shown to exhibit fast rates of polymerization and result in polymers with controlled molecular weights (Mn) and low polydispersity indexes (PDI). Additionally, organocatalytic ring-opening polymerization (ROP) techniques have been shown to be tolerant of the incorporation of functional groups into the monomer feed, which is vital for the catalytic synthesis of …

Tmsotf Assisted Synthesis Of 2’-Deoxy-2’-[18f] Fluoro-Β-D-Arabinofuranosylcytosine ([18f] Fac), Kishore K. Gangangari, John L. Humm, Steven M. Larson, Naga Vara Kishore Pillarsetty

Publications and Research

[¹⁸F]FAC (2’-deoxy-2’-[¹⁸F]fluoro-β-D-arabinofuranosylcytosine, 1) is a versatile probe for imaging deoxycytidine kinase (dCK) expression levels in vivo. dCK is responsible for phosphorylation of deoxycytidine (dC, 2) and other nucleoside analogs, plays a key role in immune activation and has demonstrated to be one of the key enzymes in activating nucleoside based drugs including gemcitabine. Reported synthesis of [¹⁸F]FAC is high yielding but is quite challenging requiring bromination using HBr and careful drying of excess HBr which is critical for successful synthesis. Here in we report a simplified trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted synthesis …

Elucidating Molecular Interactions Of Shigella Type Three Secretion System Components Critical For Pathogenesis, R. Alan Burgess

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Shigella are pathogenic bacteria which commonly infect human hosts through the fecal-oral route. As the causative agent of shigellosis, a disease characterized by severe diarrhea, nausea, and vomiting, Shigella are responsible for an estimated 90 million infections and 100,000 deaths each year. With the emergence of antibiotic resistant strains of Shigella, the need for alternative treatments methods has become critical to fighting outbreaks of shigellosis and drug resistant strains. One such method is to target the infection system of the bacteria, called the type three secretion system (T3SS). The T3SS includes a complex needle and syringe-like apparatus that is …