Chemistry Commons^™

Density Functional Theory Of Samarium(Ii) Reactivity In Thf And Water, Parisa Fasihianifard

Dissertations and Theses

Sm(II) diiodide is widely used in organic synthesis for the reduction of functional groups such as esters, anhydrides, amides, carbonyls, and arenes. Moreover, in aqueous systems and in mixtures of water and THF, the addition of Sm(II) diiodide can reduce water directly resulting in the formation of hydrogen gas. However, the mechanism of these reactions is not completely understood, making it difficult to improve experimental design. The reaction can proceed either through subsequent electron-transfer proton-transfer (ET-PT), subsequent proton transfer electron-transfer (PT-ET), or via proton coupled electron transfer (PCET). Density functional theory (DFT) calculations were performed to understand the speciation of …

Computational Study On The Nucleation Of Polyoxovanadate-Alkoxide Clusters, S M Gulam Rabbani

Dissertations and Theses

Polyoxovanadate-alkoxide (POV-alkoxide) clusters are a new class of electroactive species with potential electrochemical applications in redox catalysis, energy storage, and optoelectronics. These clusters' redox properties can be tuned by the functionalization via heterometallic installation and changing alkoxide ligands. However, the formation mechanism of these POV-alkoxides in the solvothermal process is unknown, limiting the rational design to improve their electronic properties. This dissertation reports the speciation study of POV-alkoxide clusters, which is fundamental to controlling and manipulating the evolution of transient species during their nucleation and tuning the final product's properties. Chapter 2 and chapter 3 describe our computational study of …

Semiconducting Polymer Dots-Based Ratiometric Fluorescent Probes For Detection Of Biomarkers, Shuyi He

Dissertations and Theses

Biomarkers serve a key role in illness diagnosis and treatment. Importantly, early detection can boost the therapy success rate greatly. However, traditional approaches to detect biomarkers based on fluorescence intensity changes of individual fluorophores did not completely realize the potential due to several technical problems such as low sensitivity. Ratiometric fluorescent methods use changes in the intensity of two or more emission bands (caused by the analyte) to create an internal reference that improves detection sensitivity. Due to their unique photophysical properties, such as high fluorescence intensity, high quantum yield, and low toxicity, semiconductor quantum dots (Pdots) are an ideal …

Selective Oxidation Of Alkenes In Air Catalyzed By Mn3o4 Nanoparticles, Brojo Kishor Shachib Dhali

Dissertations and Theses

Catalytic oxidation is a process where compounds are oxidized using catalysts. Solid catalysts exhibit several advantages over homogeneous systems, such as catalyst recovery and excellent stability. Various supported transition-metal oxides (for example: CuO, ZnO, CeO2, Fe2O3 and WO3), metal nanoparticles (for example: Pd and Ru) and polyoxometalate clusters (for example: [W10O32]4-, [Mn2ZnW(ZnW9O34)2]10- and [XW12O40]n- (X = P, Si)) have been applied to selective oxidation of organic compounds, but high associated product conversion still remains a challenge. Recently, a number of materials containing Mn3O4 have been used successfully in different catalytic applications, such as degradation of phenols, reduction of nitrobenzenes, and …

Exploring The Potential Use Of Porous Silica Nanoparticles In Cest-Mri, Lydia Makotamo

Dissertations and Theses

Magnetic resonance imaging (MRI) is a widely used modality in diagnostics, treatment, and monitoring various conditions due to its ability to generate high-resolution images using non-ionizing radiation. The advent of contrast agents, which generally work by increasing the spin relaxation rate constants of water protons, has led to image enhancement. Despite the usefulness of this class of agents in diagnostic medicine, their inability to provide in-depth functional and anatomical information, coupled with their high detection limits, has led to new agents being explored.

Chemical exchange saturation transfer (CEST) presents an alternative route to generate signals via repetitive saturations transfers between …

Designing Environmentally Responsible And Highly Effective Bioorthogonally Functionalized Chiral Mri Contrast Agents, Karley Breann Maier

Dissertations and Theses

Magnetic resonance imaging (MRI) revolutionized diagnostic imaging and modernized the characterization of numerous diseases. The clinical success of MRI is in large part due to the employment of gadolinium-based contrast agents (GBCAs). Due to sensitivity limitations, GBCAs are indicated at markedly high dosages (~1 g Gd³⁺ per exam). The routine use of such large quantities of gadolinium poses significant health and environmental risks. There are growing concerns over the effects of dechelation of the metal in vivo and the possible effect of resulting gadolinium deposition. Concurrently, there is a rising awareness of gadolinium anomalies borne by GBCAs which undergo …

Selenium Probes For The Detection Of Thioredoxin Reductase Activity, Tendai Joseph Mafireyi

Dissertations and Theses

The identification and quantification of proteins and enzymatic activity in living tissues frequently requires the use of invasive procedures such as biopsy. These techniques can inhibit measurements of protein levels in real-time, and the disruption of tissue can lead to the loss of important information concerning the spatial distribution and differential activities in various cell types. The use of small organic fluorescent probes that rely on activation or accumulation within a tissue embody robust methods of detection that address these issues. This dissertation describes the design, synthesis and evaluation of fluorescent probes that can detect the enzyme thioredoxin reductase (TrxR). …

Mechanistic Investigation Of Neuropeptide S-Nitrosylation By Nitric Oxide Moieties: A Kinetic And Thermodynamic Approach, Vusumuzi Leroy Sibanda

Dissertations and Theses

This dissertation focuses on providing quantitative insights regarding kinetic, thermodynamic and mechanistic parameters of neuropeptide S-nitrosylation by nitrous acid (HNO₂), peroxynitrite (ONOO^-) and S-nitroso-N-acetyl-D,L-penicillamine (SNAP) to produce S-nitrosothiols (SNOs). Peptide thiol stability and the formation of SNOs from neuropeptides; arginine vasopressin (AVP), somatostatin-14 (SST-14) and urotensin II (U-II) was studied. Investigations into the effects of temperature, copper chelators and pH on peptide thiol autoxidation show that AVP, SST-14 and U-II thiols have half-lives of 30, 44 and 28.2 mins respectively at physiologically relevant temperature and pH in the absence of metal chelators. Target peptide thiols were …

The Development And Application Of Instrumental Methods For The Identification Of Materials And Processes Used In The Manufacture Of Orotone, Hand-Colored Orotone, And Silvertone Photographs, Ivanny Jeannette Jácome-Valladares

Dissertations and Theses

Orotone photographs are positive photographic images on glass with a gold-colored metallic coating or backing. Although the materials and process used in the production of orotones have been previously documented, there is limited published scientific research on the subject. This study focused on expanding those published works by analyzing a greater number of photographs, including eleven orotones, four hand-colored orotones, two silvertones, and one uncoated orotone. The photographs, dating from the early to mid-20^th century, were from the University of Washington (UW) Libraries' collection, except for one orotone that was from the Portland Art Museum.

X-ray Fluorescence (XRF) spectroscopy, …

Tellurorhodamine Photocatalysts In Aerobic Oxidation Reactions: Development Of Synthetic Methods And Reaction Mechanisms, Irving D. Rettig

Dissertations and Theses

Aerobic oxidation photocatalysis involves the use of oxygen as an oxidant species, coupled to a light driven catalyst to achieve useful chemical transformations. Catalytic aerobic oxidation reactions can be defined as either oxidase-like, in which O₂ acts as an electron donor/acceptor but is not incorporated into the reaction products, or oxygenase-like where O₂ acts as an electron donor/acceptor and is incorporated into the reaction products. A multitude of inorganic catalysts have been developed that can achieve a wide scope of oxidase-like or oxygenase-like reactivity, however, it is rare for a catalyst to be capable of both. We report …

Investigations Into Size And Surface Control Of Silicon Nanocrystals For Improved Optical Properties, James Donald Barnes

Dissertations and Theses

The discovery of visible photoluminescence (PL) from nanocrystalline porous silicon in 1990 led to extensive research into the mechanisms of the emergent properties, and optimization of these properties, for use in applications. The widespread use of silicon nanoparticles (Si NPs) in commercial applications is currently limited by three main factors: 1) poor radiative recombination efficiency of the interband transition, 2) instability of the interband photoluminescence, and 3) a lack of scalable methods for producing Si NPs that are both highly crystalline and size monodisperse.

To address these limitations, this dissertation correlates changes in the photoluminescence properties of hydrogen passivated silicon …

Steady-State Transmembrane Water Exchange In Proliferating Cultures Of Saccharomyces Cerevisiae, Joseph O'Malley Armstrong

Dissertations and Theses

Cellular water exchange is often considered in terms of a change in volume, where a net flux of water moves across the cell membrane due to a change in osmotic pressure. Osmotic pressure can cause a cell to shrink or swell, however, rapid water exchange persists across the membrane even when the volume of the cell is constant. Steady-state transmembrane water exchange describes the exchange of water across the cell membranes which results in no net change in cell volume. This exchange is astonishingly rapid; the entire pool of intracellular water of a Saccharomyces cerevisiae cell may exchange 2-5 times …

Chemical Characterization Of Toxicologically Relevant Molecules In Cannabis Concentrates And Vaporizer Aerosols, Jiries Meehan-Atrash

Dissertations and Theses

Consumption of cannabis concentrates using the relatively novel non-combustion methods dabbing and vaping has steadily grown in popularity as cannabis legalization in North America has allowed increased access to sophisticated cannabis products and technology. In order to assess the safety of these products, it is necessary to gain a chemical understanding of the decomposition reactions that occur when the active ingredients are heated in the conditions seen when dabbing or vaping. This dissertation contains a manuscript that details efforts to structurally characterize a toxic cannabis concentrate adulterant, and three manuscripts that studied the chemical decomposition of the two primary cannabis …

Complex Fluid Dynamics: Chemo-Hydrodynamics Driven By Autocatalytic Reaction Fronts, Matthew Walter Eskew

Dissertations and Theses

Chemo-hydrodynamics generated from reaction-diffusion-convection processes of autocatalytic chemical systems are extensively studied for their applications in modeling complex systems. Compared to the more extensively studied autocatalytic systems, chlorite-tetrathionate and chlorite-trithionate, the chlorite-thiourea systems is relatively unexplored. Compared to the two previous systems, chlorite-thiourea has more straightforward chemical kinetics. To narrow the gap between chlorite-thiourea and the other systems a combination of experimental study and numerical simulation were employed to quantify this system.

Compared to established literature, experiments were performed at five orders of magnitude lower concentration of indicator, minimizing confounding effects of indicator on hydrodynamic motion. To accurately image the …

Thermodynamics Of Ligand Binding And Global Structural Stability Of Human Serum Albumin, Matthew Walter Eskew

Dissertations and Theses

Protein structure is integral to its function. For the past 70 years differential scanning calorimetry has been used to measure protein structural stability. More recently it has been used to study macromolecular interactions. Interactions between proteins and ligands can manifest on differential scanning calorimetry melting curves or thermograms. Utilizing differential scanning calorimetry thermograms to detect or diagnose diseases has been a major goal in disease diagnostics. However, correlating specific ligand-protein interactions, as manifested in a thermogram, with a disease-specific plasma thermogram, has proven elusive.

Modified human serum albumin was utilized to develop a process to capture and retrieve ligands from …

Comparison Of Calculated Normal Mode Molecular Vibrations With Experimental Gas-Phase Infrared Spectroscopy, Anila Renis Sutar

Dissertations and Theses

Computational vibrational spectroscopy serves as an important tool in the interpretation of experimental infrared (IR) spectra. Analysis of computational results provides a perspective over broader wavelength ranges and at higher precision. Although there are issues regarding accuracy, this can be approximated by using a scaling factor. High-resolution gas-phase FTIR spectroscopy at a resolution of 0.125 cm^-1 can partially resolve rovibrational transitions in the P, Q, and R bands and therefore identify fundamental frequencies with approximately 1 cm^-1 precision.

This research has compared high-resolution gas-phase FTIR absorption peaks to calculated vibrational frequencies. In the calculation of normal mode frequencies, …

Aryne-Guided C-H Functionalization Of Benzenoid Rings Using Diaryliodonium Salts, Aleksandra Nilova

Dissertations and Theses

The benzenoid core is a frequent and irreplaceable component of biologically active molecules. Structure function relationship of these compounds has been broadly analyzed and presented in numerous literature reports. Herein, we augmented existing knowledge by a broad analysis of the benzenoid substitution patterns in small molecule active pharmaceutical ingredients approved by the FDA. Our findings reveal a strong correlation that the most represented substitution patterns are those achieved via S_EAr. Despite the rapid development of methods to functionalize benzenoid rings, the lack of synthetic methodologies to access sterically and electronically unfavorable positions is highlighted. We sought to establish …

Designing A More Effective Mri Contrast Agent: Investigation Into Various Functionalization Strategies For Targeted Imaging, Lauren Nicole Rust

Dissertations and Theses

Magnetic resonance imaging (MRI) is a medical imaging technique that provides high-resolution images used for diagnostic medicine while maintaining a superior safety profile compared to other radiative techniques. The administration of gadolinium-based contrast agents (GBCAs) improves the diagnostic power of MRI and have been used clinically for over three decades. Although GBCAs are effective at improving the contrast in the image, their detection limits are high and require a large dose to generate an observable effect. This high dose is the consequence of the current available designs of clinical GBCAs; their structures are not tuned to generate optimal efficacy. Efficacy …

Synthesis And Assessment Of Radiotherapy-Enhancing Nanoparticles, Hayden Winter

Dissertations and Theses

Radiation Therapy (RT) is a common treatment for cancerous lesions that acts by ionizing matter in the affected tissue, causing cell death. The disadvantage of RT is that it is most often delivered via an external beam of radiation which must pass through healthy tissues to reach the target site, ionizing matter within healthy tissues as well. To address this drawback, techniques are being developed for increasing RT-induced cell death in a target tissue while minimizing cell death in surrounding tissues. This effect is known as radiation dose enhancement or RT enhancement.

The approach to RT enhancement studied in this …

Optimized Xanthene-Based Probes For Pancreatic Cancer Imaging, Ian Ruramai Munhenzva

Dissertations and Theses

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest human malignancies with an extremely poor 5-year survival rate of below 5%. Surgical resection is the most effective treatment of choice because chemotherapy and radiation therapy do not improve life expectancy. Residual tumor after PDAC surgery is common due to a lack of PDAC targeted intraoperative contrast agents to confirm clear margins.

Fluorescence imaging has the potential to improve surgery outcome and PDAC patients' survival rate via the use of highly PDAC-specific molecular probes to facilitate tumor identification. This thesis describes the application of a focused library of benzoxanthene fluorophores for …

Applications Of Triplet-Photosensitizers And Development Of Photochemical Methods, Luke V. Lutkus

Dissertations and Theses

Photochemistry focuses on various aspects of the interaction of light with molecules. This work entails new methodology for fundamental measurements of photochemistry along with novel applications of triplet-photosensitizers. Herein described are two separate methodologies developed for the determination of the quantum yield. A method for the singlet oxygen quantum yield was developed that utilizes the reaction between singlet oxygen and dimethyl sulfoxide (DMSO) to produce dimethyl sulfone. The rate of the reaction is measured by the pressure decrease that results from the consumption of oxygen from the headspace of a sealed system. It was found that the rate of pressure …

Sugar-Derived Oleogels In Cosmetics And Food Applications: A Case Study Of Trehalose- And Mannitol-Based Gelators, Polina Tsupko

Dissertations and Theses

Gels represent an indispensable part of our everyday lives with direct applications in food, medicine, cosmetics and other industries. Amphiphilic molecules have been shown to act as low molecular weight gelators (LMWGs) and are becoming the main focus of several research groups. Their ability to self-assemble into various morphologies from micelles to bilayer sheets, and remain stable due to noncovalent forces responsible for the formation of the 3D network—Self-Assembled Fibrillar Network (SAFiNs)—is in the core of their ability to produce molecular gels. Those amphiphilic molecules capable of adsorbing at the interface and behaving as surface active agents are known as …

Reductions By Cobalt-Catalyzed Production Of Hydrogen Gas From Nabh4 In A Two-Chamber System, Joshua K. Mitchell

Dissertations and Theses

The work outlined in this thesis describes a bench-scale methodology involving a two-chamber system for conducting catalytic hydrogenation reactions by obtaining hydrogen (H₂) gas from stable sodium borohydride (NaBH₄). Whereas NaBH₄ is widely used for a variety of reductions and is known to produce H₂ gas in protic media, to our knowledge, there has been scant use of NaBH₄ in catalytic hydrogenation chemistry where it has been used as a source of H₂ gas. In this work, addition of a catalytic amount of CoCl₂•6H₂O as an aqueous solution …

Analysis Of E-Cigarette Liquids And Aerosols By Nmr Spectroscopy: Compositions, Boiling Points, And Degradation Profiles, Anna Katherine Duell

Dissertations and Theses

Electronic cigarettes (e-cigarettes) are an increasingly popular tobacco product used by ~3% of adults and 21% of 12th grade students (as reported for the prior 30-days in surveys) in the United States in 2018. As of 2019, this number went up to ~25% for 12th grade students. Due to how quickly e-cigarettes gained popularity and the rapid design changes that have ensued, there has not been enough time to accurately assess the effects of e-cigarettes, particularly for long-term use. The liquids used in e-cigarettes (e-liquids) can degrade when vaped in an e-cigarette, so understanding the variables that can modulate degradation …

The Process Of Establishing Theoretically Grounded Measures Of Science And Chemistry Identity For Use In Undergraduate Chemistry Courses, Kathryn Nicole Hosbein

Dissertations and Theses

Identity has been theorized to aid in student persistence toward science, engineering, technology, and math (STEM) degrees. However, before we can explore the impacts of learning environments on identity, and subsequently persistence, robust measures that can aid in understanding how identity is fostered need to be available. This research study aims to create measures of identity by expanding an existing physics identity framework and contextualizing it to science and chemistry identities. Development of the measures was carried out through two distinct phases that provided evidence for reliability and multiple aspects of validity.

The first phase of the study used qualitative …

Assessing The Efficacy Of Virtual Experiments In The General Chemistry Laboratory, Cory Jerome Hensen

Dissertations and Theses

As more students enroll in chemistry courses, institutions are faced with increasing costs and limited laboratory space to keep up with the demand. One solution some institutions have turned to is the incorporation of virtual experiments into the curriculum, as this can lower costs and increase the availability of laboratory space. Some institutions have offered sections that complete all of their experiments in a virtual environment, others have offered sections that alternate between a traditional hands-on experiment and a virtual experiment, and some institutions have replaced only select experiments throughout the curriculum with a virtual experiment. To begin to be …

Investigating The Origins Of Toxins Present In Electronic Cigarette Aerosols, Shawna Vreeke

Dissertations and Theses

The purported safety of electronic cigarettes has come under scrutiny with the significant increase of lung related illnesses starting in the summer of 2019. Public view has started to shift towards understanding the potential negative health impact associated with these devices. While many investigations indicate probable hazards present in e-cigarette aerosols, inter-laboratory assessments are wide ranging and can be contradictory. Due to the novelty of this field, relatively little is known about these products. In this work, the identification and quantification of inhalation toxicants such as formaldehyde, acrolein, acetaldehyde and dihydroxyacetone are reported. Results of the investigation of the ability …

Spontaneous Recombination Of Short Rnas To Increase Length And Complexity In Prebiotically Plausible Conditions, Benedict Arthur Smail

Dissertations and Theses

The RNA World hypothesis is an influential theory of how life arose on earth which posits that the earliest life forms carried out essential activities with RNA catalysts instead of proteins. Substantial evidence to support this theory comes from among others, the fact that the ribosome is a ribozyme, the existence of small RNA catalysts capable of high activity, and self-assembling ribozymes such as the Azoarcus ribozyme. Additional support has been provided by the directed evolution of various ribozymes and the reputed prebiotic synthesis of nucleotides and small RNA oligomers. However, it has long been challenging to show how long …

Photoelectrochemical Catalysis Of Hydrogen Peroxide With Tellurium Containing Chromophores, James Eliott Lohman

Dissertations and Theses

Growing concerns over climate change and demand for energy worldwide have made development and implementation of alternative energy sources more necessary than ever. Many of the leading energy alternatives suffer from inconsistent energy production due to fluctuations in availability of natural resources, and the current methods of addressing the issue have tremendous ecological and social ramifications of their own. While fuels like hydrogen gas are providing some promise of relief, the scope of infrastructure changes necessary for implementation and the implicit hazards of the use of such fuels complicate their application as an immediate solution. However, hydrogen peroxide carries far …

Copper-Mediated N1-Arylation Of Benzotriazoles, Magdalena R. Andrzejewska

Dissertations and Theses

Benzotriazoles are group of bicyclic heterocyclic compounds that contain three nitrogen atoms fused to a benzene ring. Along with their derivatives, they possess a wide range of properties. They are used in medical field, as they exhibit such properties as antibacterial,antiplasmoidal,antiprotozoal, antifungal and anti-inflammatory activities, among others. They are also used in various industries as herbicides, UV absorbers, deicing and antiicing agents and corrosion inhibitors, to list a few. Because of their wide range of applications, we designed a new two-step synthesis for the formation of N-1-aryl benzotriazoles. 1-Hydroxy-1H-benzotriazole N-oxides were synthesized using phenylboronic acid (PhB(OH) …