Chemistry Commons^™

Stepwise Solvation Of Organic Radical Cations By Ionic Hydrogen And Halogen Bonding In The Gas Phase, Kyle Mason

Theses and Dissertations

The ability to characterize the interactions between ions and solvent molecules plays a critical role in understanding fundamental aspects of thermodynamics in solution chemistry. These interactions are often difficult if not impossible to observe in solution due to the number of solvent molecules far exceeding that of the ions. However, this challenge can be circumvented in the gas phase which enables the isolation and study of reactions between a single ion and single solvent molecule.

Within the field of ion-molecule chemistry are two sub-categories of interactions known as ionic hydrogen bonds (IHBs) and ionic halogen bonds (IXBs). In these interactions, …

Engineering High Reaction Economy Or, An Intensification/Scoring Program For The Preparation Of Simple And Complex Molecules, Caleb J. Kong

Theses and Dissertations

Success of newly discovered chemistry in academia is often scored in terms of its novelty and level of scholarship. In industrial settings, cost, safety and quality are often times the ruler by which new processes are measured. Our group has identified that there is a gap between these two measures of success and has sought to develop principles in order formalize an approach to synthetic strategy and developing ready-to-implement manufacturing processes for molecules, simple and complex.

Some of these principles include (1) the development and application of new chemical methods and reactor technologies (2) recognition of globally amenable chemical environments …

An Enzymology And Inhibition Study Of A Camp-Dependent Protein Kinase Linked To Acth-Independent Cushing's Syndrome, Nicole Luzi

Theses and Dissertations

Cyclic-AMP dependent protein kinase (PKA) is a key intracellular signal transduction kinase that is modulated by G_s- and G_i-coupled GPCRs. Under normal physiological conditions, PKA exists as an inactive holoenzyme made up of two catalytic subunits and two regulatory subunits. Upon cAMP binding to the regulatory subunits, the catalytic subunits (PKACa) are released to perform various downstream phosphorylation events. However, aberrant PKA activation can cause various diseases including Cushing’s Syndrome, which is an endocrine disorder caused by the overproduction of cortisol by the hypothalamus-pituitary-adrenal hormone system. This disorder can be caused by pituitary adenomas that release …

Expansion Of The Genetic Code To Include Acylated Lysine Derivatives And Photocaged Histidine, William D. Kinney

Theses and Dissertations

The genetic code of all known organisms is comprised of the 20 proteinogenic amino acids that serve as building blocks on a peptide chain to form a vast array of proteins. Proteins are responsible for virtually every biological process in all organisms; however, the 20 amino acids contain a limited number of functional groups that often leaves much to be desired. The lack of diversity addresses the need to increase the genetic repertoire of living cells to include a variety of amino acids with novel structural, chemical, and physical properties not found in the common 20 amino acids. In order …

Biometal-Induced Structural Consequences Of Α-Synuclein – The Parkinson’S Disease Protein, Dinendra L. Abeyawardhane

Theses and Dissertations

The pre-synaptic protein α-Synuclein (αS) is often linked to the pathology of Parkinson’s disease (PD), an age-related neurodegenerative disorder. Lewy bodies, the cytopathological hallmarks of PD, are found to be rich in aggregates of misfolded αS protein. Metal dyshomeostasis has also been linked to PD due to the accumulation of iron in the substantia nigra pars compacta, and diminished copper levels reported in this same region. Metal dyshomeostasis in the brain coupled with oxidative stress can enhance the aggregation of αS. Recently, it was confirmed that mammalian αS is universally acetylated at the N-terminus, a common post-translational modification in …

The Development Of Intrinsically Cell-Permeable Peptide Libraries Using Mrna Display, Nicolas A. Abrigo

Theses and Dissertations

Peptides are emerging as promising therapeutics due to their inhibitory affinity towards protein-protein interactions (PPI). However, peptides have been limited mainly by their poor bio-stability and lack of cell permeability. Efforts to generate drug-like peptides have led to the development of macrocyclic peptides, which exhibit improved stability. Yet, most macrocyclic peptides still require the assistance of a cell penetrating peptide (CPP) for cellular entry.

High throughput technologies have been exceptional tools for the discovery of peptides to interrupt PPIs. This work details the recent advancements we have made to improve our high throughput technique, mRNA display, to yield more therapeutically …

Nanostructured Materials For Photocatalysis, Water Treatment And Solar Desalination, Hiran D. Kiriarachchi

Theses and Dissertations

Maintaining a constant supply of clean drinking water is among the most pressing global challenges in our time. About one-third of the population is affected by the water scarcity and it can only get worse with climate change, rapid industrialization, and the population growth. Even though nearly 70 percent of the planet is covered by water, the consumable freshwater content is only 2.5 percent of it. Unfortunately, the accessible portion of it is only 1 percent. Even so, most of the freshwater bodies are choked with pollution. Considering the vast availability of saline water on the planet and the increasing …

Metallic Systems At The Nano And Micro Scale: Bimetallic Nanoparticles As Catalysts And Mcraly Bond Coats In Thermal Barrier Coatings, Kenneth Kane

Theses and Dissertations

The dissertation is split into two parts. The first part will be focused on changes in material properties found at the nanoscale, as miscibility and electronic structure can change significantly with size. The formation of classically-immiscible bimetallic nanoparticles (BNPs) becomes favorable at the nanoscale and novel catalytic properties can emerge from the bimetallic alloying. The formation of alloyed and non-alloyed BNPs is achieved through pulse laser ablation (PLA) and a significant increase in catalytic activity is observed for both. Recently discovered, the increased activity in the non-alloyed BNPs, deemed multicomponent photocatalysis, is examined and the proposed mechanism discussed. The second …

Development And Characterization Of Stationary Phase Gradients For High Performance Liquid Chromatography, Anna Forzano

Theses and Dissertations

Choosing a stationary phase is the first step in developing a liquid chromatography (LC) separation method, where the selectivity is governed by the differential interactions of the analytes with the stationary and mobile phases. Introducing a gradient in stationary phase functionality allows for tuning of analyte retention, translating to a possible improvement in selectivity and an increase in resolution versus that offered by uniform stationary phases.

In this work, C₁₈-silica, phenylbutyl-silica, and phenylbutyl-ammonium opposed continuous stationary phase gradients were fabricated using controlled rate infusion (CRI) on particle packed LC columns. Characterization of the stationary phase was carried out …

Non-Covalent And Covalent Interactions Between Phenylacetylene And Quinoline Radical Cations With Polar And Non-Polar Molecules In The Gas Phase, Adam C. Pearcy

Theses and Dissertations

Gas phase molecular clusters present an ideal medium for observing factors that drive chemical reactions without outside interferences from excessive solvent molecules. Introducing an ion into the cluster promotes ion-molecule interactions that may manifest in a variety of non-covalent or even covalent binding motifs and are of significant importance in many fields including atmospheric and astronomical sciences. For instance, in outer space, molecules are subject to ionizing radiation where ion-molecule reactions become increasingly competitive to molecule-molecule interactions. To elucidate individual ion-molecule interaction information, mass spectrometry was used in conjunction with appropriate theoretical calculations.

Three main categories of experiment were conducted …

Metal Nanoparticle Synthesis By Photochemical Reduction With A High-Intensity Focused Laser Beam, Victoria K. Meader

Theses and Dissertations

Colloidal, metallic nanoparticles have myriad applications, but they are most ideal when they are monodisperse, and demonstrate maximum catalytic utility when they are small (< 5 nm) and uncoated; because their surface area is accessible and maximized. Laser- assisted metal nanoparticle synthesis is a ‘green’ method that has become a topic of active research because it is able to produce uncoated or ‘naked’ products. The nanoparticles synthesized in this work were formed through the reduction of metal salts in aqueous solutions; but the reducing agent is an electron-dense microplasma generated by the laser pulse interacting with the media. Because no chemical reducing agents or stabilizers are needed, the products have no surfactants.

The underlying reaction mechanisms that drive this type of synthesis are generally understood, however, there is insufficient detail that would allow control over the formation of ultimate product morphologies and size distributions. The metals examined in this thesis are: gold, whose formation follows an autocatalytic rate law; and silver, whose formation follows a first-order rate law. Through my research, I was able to …

2nd Tier Assay For The Detection Of Congenital Adrenal Hyperplasia By Virginia’S Newborn Screening Laboratory: Steroid Profile By Hplc-Ms/Ms, Christopher E. Nixon

Theses and Dissertations

Congenital Adrenal Hyperplasia (CAH) encompasses several disorders related to disruptions in the adrenal steroid production pathway. These disruptions may cause virilization of the external female sex organs, incorrect gender assignment, precocious puberty, and in the most severe form, may cause life-threatening salt wasting and adrenal crisis if not detected and treated early in the newborn period.

17α-Hydroxyprogesterone (17-OHP) is the primary target for immunofluorescence detection of CAH from dried blood spots in newborn screening (NBS). Unfortunately, current immunoassay techniques for the detection of CAH suffer from high false positive rates. The primary factors contributing to false positive determinations can include …

Adhesion At Solid/Liquid Interfaces, Neda Ojaghlou

Theses and Dissertations

The adhesion at solid/liquid interface plays a fundamental role in diverse fields and helps explain the structure and physical properties of interfaces, at the atomic scale, for example in catalysis, crystal growth, lubrication, electrochemistry, colloidal system, and in many biological reactions. Unraveling the atomic structure at the solid/liquid interface is, therefore, one of the major challenges facing the surface science today to understand the physical processes in the phenomena such as surface coating, self-cleaning, and oil recovery applications. In this thesis, a variety of theory/computational methods in statistical physics and statistical mechanics are used to improve understanding of water adhesion …

Computational Studies Of Fullerene-Porphyrin Dyads, Sumreen Gul

Theses and Dissertations

Fullerene (C60) has generated much scientific interest since its discovery due to its novel optical, electronic, and physical properties. Fullerene has been shown to be an excellent electron acceptor and as a result is the acceptor of choice in organic photovoltaics. Porphyrins are excellent electron-donors due to their stability, low ionization potential, and excellent light absorption properties. As a result, fullerene-porphyrin dyads form unique donor-acceptor systems that can be useful for a variety of photoactive applications. In this research, computational studies have been performed on different varieties of C60-Porphyrin dyads and the relationship between molecular topology and the properties of …

Synthesis, Characterization And Enhanced Electrochemical Performance Of Amide-Based Metal Complexes As Electrocatalysts In Energy Devices And Non-Enzymatic Sensor, Charlette Parnell

Theses and Dissertations

The use of metal catalysts supported on the carbon nanomaterials as electrocatalysts has propelled the development of modified electrodes for electrochemical studies. They have been shown to increase sensitivity and electrical conductivity making them advantageous in applications for fuel cells, sensors and supercapacitors. In this dissertation, the synthesis and characterization of metal catalysts supported on carbon nanomaterials will be discussed and their electrochemical activity towards fuel cells, sensor and supercapacitor studies will be explored. Due to the great need for energy efficient and environmentally benign energy devices that can replace the use of fossil fuels in energy production, fuel cells …

Photocatalytic Degradation Of Simazine Using Zno/Go Composites, Kenneth Ray Flores

Theses and Dissertations

The photocatalytic degradation of simazine (SIM) by Zinc oxide/graphene oxide (ZnO/GO) composites, under visible light irradiation, was investigated to determine various reaction parameters, of initial pH, ZnO loading on GO, and catalyst mass. A pH of 2 was determined to be the optimal reaction pH for all ZnO/GO catalysts. A loading mass of 40mg for the 20 & 30mmol composites; whereas a 10mg mass was determined to be most effective for the 10mmol composite. The reaction followed second order kinetics for the degradation process, the reaction dependence was determined to be on the concentration of SIM in solution. All ZnO/GO …

Oxidation Of Carbon Monoxide Over Ceria And Alumina Supported Palladium Catalysts, John Davis Gary

Theses and Dissertations

Palladium catalysts on both Al2O3 and CeO2, supports were studied for efficacy in low temperature carbon monoxide oxidation. Calcination temperatures were varied between 500-900°C for alumina supported catalysts and shown to have no significant difference in activity. X-Ray Photoelectron Spectroscopy studies revealed structural changes associated with palladium states and reacted catalysts and displayed a change from palladium oxide (PdO) to native palladium oxide (PdOx) and elemental palladium (Pd). Activity studies were conducted on all catalysts synthesized and indicated that Pd/Al2O3 achieved 100% CO conversion at 150°C when calcined at 500°C and pretreated with reduction process. Pd/CeO2 showed higher activity and …

Green Synthesis/Biosynthesis Of Silver Nanoparticles By Using Orange Peel Extract, Leela Joshi

Theses and Dissertations

Joshi, Leela, Green Synthesis/Biosynthesis of Silver Nanoparticles by Using Orange Peel Extract. Master of Science (MS), December, 2018, 40 pages, 23 figures, references, 36 titles. In this work, we report synthesis of silver nanoparticles (AgNPs) with an average size of ~6 nm. The aqueous solution of Ag+ ions is reduced using an aqueous extract from orange peel (Citrus Sinensis) at varying pHs. Reduction of Ag+ ions in solution was monitored using UV-visible absorption spectroscopy, and the corresponding surface plasmon resonance of AgNPs at 435 nm. The solution changed color from yellow to reddish-brown upon bioreduction of silver nitrate in orange …

Three Dimensional Carbon Nanotube Yarn Based Perovskite Solar Cells, Istiak Hussain

Theses and Dissertations

Perovskite solar cells (PSC) have emerged as a promising photovoltaic technology in lab scale with a short time of research due to their high power conversion efficiency, simple device fabrication, all solid-state structure and the possibility to ingrate the traditional device into fiber format. In this work, a three-dimensional (3D) perovskite solar cell is demonstrated using functionalized carbon nanotube yarn (CNT) as both cathode and anode. TiO2 and 2,2,7,-7-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) are used as the electron transporting and hole transporting material respectively. The TiO2 oxide layer is deposited on the top of the twisted carbon nanotube yarn and annealed with TiCl4 …

Effects On Altering Reaction Conditions In Suzuki Cross Coupling Reactions Using The Microwave, Javier Alejandro Perez

Theses and Dissertations

Over the last few decades, Suzuki coupling has become a common process for the synthesis of intermediates in pharmaceutical and industrial applications. It is well known that palladium is an effective catalyst for the formation of cross-coupled products. Therefore, this catalyst was tested in a series of reactions. Also, it is believed that other catalyst with similar properties to palladium can work, for example cerium. Therefore, a cerium hydroxide catalyst was synthesized in lab and used as a potential catalyst for the Suzuki reaction. For this study, some bases were investigated (NaOH, Na2CO 3, K3PO4, NaNO3, NaHCO3, etc) for the …

1. Synthesis And Characterization Of A Vanadium Based Transition State Mimic For Organophosphate Hydrolase 2. Catalytic Oxidation Of Thioanisole And 2-Chloroethyl Ethyl Sulfide Using Resin Bead Supported Oxoperoxidovanadium(V) Complexes, Efram Goldberg

Theses and Dissertations

Two vanadium(V) complexes were prepared for different projects. First the ONS tridentate ligand 14 was prepared according to literature procedure. This ligand was chosen to make the ONS dioxovanadium complex 15 for conjugation to a protein and to eventually elicit catalytic antibodies for the hydrolysis of the chemical weapon VX. Complex 15 was prepared in 65% overall yield and a full characterization was performed including X-ray diffraction. Initial screening performed at the Naval Research Laboratory indicated an IC50 of 84 nM for inhibition of a bacterial cholinesterase. It was also found to be 50% as effective as the control antiobiotic …

Photoremediation Of Organic Compounds With Fullerene (C60) Modified Tio2 Nanoparticles, Raymond Patey

Theses and Dissertations

Historically the populations of many developing countries have been subjected to potable water shortages through drought and those of developed nations from pollution because of industrialization. Recently parts of our own country were in dire straits when it comes to the availability of clean drinking water due to severe drought. Existing inert processes involving activated carbon and titanium dioxide (TiO2) coated particles and membranes have shown to be effective at water purification. However, processes such as these typically require expensive infrastructure and filtration systems and consequently are not expected to be found in developing countries, where clean water is severely …

Development Of Betulinic Acid Triazole Conjugates As Potential Anti-Cancer Agents, Gayathri Jampana

Theses and Dissertations

Betulin and betulinic acid are pentacyclic triterpenoid natural product isolated from the bark of birch trees. While betulin is abundantly available in the bark, betulinic acid is present in scarce quantities in nature. However, betulinic acid can be conveniently synthesized from betulin via simple redox manipulations. Betulinic acid shows selective cytotoxicity profile against cancer cells in vitro while being relatively safe for normal cells. One of the challenges for the clinical development of betulinic acid is its lack of aqueous solubility. The three key structural features of betulin/betulinic acid that have been routinely exploited for structural modifications to enhance their …

Synthesis And Characterization Of A Series Of Vanadium ( Iv ) Complexes With The Kläui Ligand, Xiao Wu

Theses and Dissertations

Cyclopentadienyltris (dibutyl phosphito-P) cobaltate, {(C5H5)Co[(OR)2PO]3}– (R=Bu), is a tripodal ligand and also called Kläui ligand (R=Bu). The synthesis and characterization of several vanadium(III) and vanadium(IV) complexes containing Kläui ligand (R=Bu) as the catalytic models to catalyst the oxidation reaction of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butyl-o-benzoquinone (3,5-DTBQ) are detailed here. Chapter II details the synthesis of the supersandwiches and Kläui ligand (R=Bu). Chapter III details the synthesis of vanadium monomeric complexes containing Kläui ligand (R=Bu). Chapter IV details the vanadium dimeric bridging complexes synthesized by different vanadium monomers from Chapter III. Chapter V details the catalytic activities of these vanadium complexes.

Synthesis And Characterization Of Transition Metal Based Nanocomposites For Orr In Fuel Cell Applications, Hunter Austin Wayland

Theses and Dissertations

Development of economically viable platinum alternatives for polymer electrolyte membrane fuel cells is a fundamental step towards large-scale commercialization efforts, which aim to reduce reliance on non-renewable energy resources. This work explores the synthesis, characterization, and application of graphene supported cobalt(III) and iron(III) based MN4 complexes for oxygen reduction, and farther investigates the potential for gains in performance and enhanced stability following coating with a bioinspired self- assembling polymer, polydopamine. The nanocomposites were characterized using a variety of electron microscopy and spectroscopy techniques, and their electrochemical performance was assessed using a potentiostat/galvanostat. The polymer-uncoated nanocomposites were found to reduce oxygen …

Development Of A Fluorescence Imaging Photometer-Based Method For Characterization Of Phytoplankton Communities, Cameron Maxwell Rekully

Theses and Dissertations

The development of methods for real-time characterization of phytoplankton community structure has important implications for environmental monitoring and the prediction of harmful algal blooms. Our research group has developed an instrument, the Fluorescence Imaging Photometer (FIP), which is capable of rapid classification of phytoplankton via imaging single-cell chlorophyll a fluorescence under different excitation conditions. Discrimination of cells from different taxonomic groups is achieved using optical bandpass filters that have been chosen to selectively excite pigments which occur in characteristic ratios that vary from one group to the next. The relative fluorescence intensity emitted by cells under these different excitation conditions …

Hierarchical Corannulene-Based Materials, Allison M. Rice

Theses and Dissertations

Merging the intrinsic properties of fullerene (buckyball) and corannulene (buckybowl) derivatives with the inherent properties of crystalline metal- and covalent- organic frameworks (MOFs and COFs), including their modularity, porosity, versatility, high surface area, and structural tunability, opens a pathway to unlock a novel class of fulleretic materials. Despite the great interest in MOFs and COFs, as well as fullerene derivatives, this dissertation is focused on crystalline fullerene- and corannulene- containing frameworks, highlighting their potential contributions in the fields of optoelectronic devices, electrodes, and photosensitizers. We have revealed a dual role of fullerene- and corannulene-containing building blocks showing their versatility to …

Efforts Towards The Discovery Of Novel Methods For The Synthesis Of Pharmacologically Relevant Molecular Scaffolds, Graham Joseph Haun

Theses and Dissertations

With the introductions of pharmaceuticals into modern day society many people have been using them to improve their lives. Due to this high increase in demand along with the ever-growing concern of environmental impact pharmaceutical companies have been pressed to synthesis new and existing drugs at a higher rate. This increased rate can cause low yield drugs or have a heavy environmental impact. As the use of pharmaceuticals becomes more widespread the need for greener and simpler organic synthesis methods to make these pharmaceuticals becomes more needed.

Herein is reported the methodological development of different pharmacologically relevant scaffolds. This work …

Functionalized And Nanostructured Fibers For Photocatalysis And Energy Conversion, Jared R. Jaksik

Theses and Dissertations

Fiber-type / flexible materials present a unique opportunity for the incorporation of photocatalytic / energy generating technology, as they typically have a broad surface area exposed to light (clothing, curtains, carpet). In this work, several methods of harvesting incident light striking a flexible substrate to perform useful work are examined. In the first section a gold and silver nanoparticle augmented TiO2 thin film textile coating is evaluated for its self-cleaning / UV-protective / anti-microbial properties, and stability of the film / substrate over time is examined. In the second section a dye sensitized / hybrid type solar cell architecture based …

Design And Characterization Of Composite Membranes For Solar Fuel Generating Devices, Ibtehaj Fahad Alshdoukhi

Theses and Dissertations

Currently, there is a great need for research and development on new sources of energy in order to meet energy demands in a clean, efficient, sustainable, economical and environmentally friendly way. A system that promises to meet these requirements is water splitting through artificial photosynthesis, generating hydrogen and oxygen, effectively storing light energy in the form of fuel such as H2. One main limitation in artificial photosynthesis is that the membrane must be able to conduct the ions involved in redox reactions, as well as the electrons/hole carriers produced by light absorption, while being mechanically stable and optically transparent. No …