Chemistry Commons^™

Fast Scan Cyclic Voltammetry For Real-Time Metal Speciation Analysis, Hettige. M. Thushani Siriwardhane

Theses and Dissertations

Electrochemistry is a powerful analytical tool that has been widely used to detect trace metals in natural systems. However, studying the speciation of metals during dynamic events, such as storms and floods, is analytically challenging due to the limited temporal resolution of traditional electrochemical techniques. Additionally, most techniques report the total metal concentration (both complexed and free) that does not reflect the toxicity of these metals, which arise mostly from the free state. To overcome these issues, we previously pioneered the use of fast scan cyclic voltammetry (FSCV) to measure free copper (Cu(II)) and lead (Pb(II)) in real-time in laboratory …

Development Of An Electrochemical Method To Study Real-Time In Vivo Neurotransmitter Modulation, Srimal Aminda Samaranayake

Theses and Dissertations

Histamine and serotonin are important biogenic amines that regulate vital brain functions. These two transmitters are thoughts to be involved in neurodegenerative diseases such as Parkinson’s and Alzheimer’s and affective disorders including depression. Histamine and serotonin are believed to regulate each other but their fundamental neuromodulation mechanisms are not well understood. This lack of understanding makes brain disorders implicating these two transmitters difficult to diagnose and treat. Our lab extensively investigates the serotonergic system to understand serotonin’s neurochemistry in the brain. However, histamine is relatively understudied with respect to other biogenic amines because of an absence of suitable analytical tools. …

Fluorescence Polarization Measurements To Probe Alignment Of A Bithiophene Dye In One-Dimensional Channels Of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals, Preecha Kittikhunnatham

Theses and Dissertations

This thesis describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up …

Synthesis, Characterization And Application Of Polymer-Grafted Nanoparticles, Yang Zheng

Theses and Dissertations

This work focused on the synthesis and characterization of polymer-grafted nanoparticles for various applications including drug-delivery, directed self-assembly and mechanical reinforcement applications. The surfaces of inorganic particles were modified with polymers of different composition, chain length, graft density and polymer architecture depending on the specific needs of each project. The surface modifications were mainly achieved by surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization, which is a very versatile technique to prepare nanocomposites with desired properties.

The first part of this work (Chapters 2 & 3) focused on novel self-assembly techniques. Chapter 2 described the design and characterization of a …

Materials Discovery Of Reduced Early Transition Metal Compounds: Crystal Growth And Characterization, Dileka Abeysinghe

Theses and Dissertations

Materials discovery via crystal growth is an active area of research that has led to the preparation of many novel materials along with the determination of their crystal structures. One sub-category in this diverse field of materials is the preparation of early transition metal reduced oxides. These reduced oxides often exhibit unusual electronic and magnetic properties. Due to the synthetic challenges associated with early transition metal reduction, new and facile methods to prepare reduced oxides is of great interest. These limitations can be overcome by using a carefully selected redox neutral flux, a vacuum sealed fused silica tube, and metal …

Kinetic-Control Of Block Copolymer Micelles For Tunable Nanomaterials Towards Energy Devices, Hasala Nadeesini Lokupitiya

Theses and Dissertations

Nano-scale inorganic porous materials are crucial for numerous applications ranging from electronics to energy conversion. The ability to control the morphology and the key architectural parameters of nanomaterials largely determines the transport characteristics and performance of such devices. But, there is very little understanding and development to tune these key architectural parameters such as inorganic wall-thickness and pore diameter. Even though there are numerous examples available on the fabrication of porous nanomaterials via block copolymer co-assembly, there is limited understanding on independent control over key architectural parameters. Because of that the major focus of this thesis is to explore and …

Coordination Chemistry Of Carboranes And Furan Ligands On Transition Metal Cluster Complexes, Emmanuel Joseph Kiprotich

Theses and Dissertations

Chapter 1 presents the most relevant literature in the field of carborane chemistry. The focus is on icosahedral carboranes and the different methods of boron or carbon atoms substitution and functionalization. The direct addition of transition metal to boron atoms is covered in detail as well as strategies for cage opening of icosahedral carboranes.

Chapter 2 reports the preparation of some of the first polynuclear metal carbonyl cluster complexes where the closo-carborane cage: o-C₂B₁₀H₁₂ serves as a ligand on the face of one (Os₃(CO)₉(µ₃-4,5,9-C₂B₁₀H_{10 …}

Elucidation Of Protein Interactions And The Re-Tuning Of Porphyrin Electronics For Hydroxylases, Steven Charles Ratigan

Theses and Dissertations

Non-Ribosomal Peptide Synthetases (NRPSs) and their exogenous tailoring partners have been heavily studied but not in the context of non-cognate systems. Orf78, a dinuclear iron β-hydroxylase from the lysobacter pathway and homologous to CmlA from the chloramphenicol pathway, is used to test affinities for one native and two non-native T-domains. Results indicate that there is enough difference between Type I and Type II NRPS systems to disfavor common recognition motifs. Additionally, the β-hydroxylase P450sky, from the skyllamycin biosynthetic pathway, is used in conjunction with the NRPS ATdomain NikP1AT from the nikkomycin biosynthetic pathway, in lieu of the homolog P450nikQ. The …

Silylation-Based Kinetic Resolution Of 2-Arylcyclohexanols And Understanding Internal Chirality Transmission Via Circular Dichroism, Li Wang

Theses and Dissertations

This work described herein focuses on the silylation-based kinetic resolution methodology developed by the Wiskur group in 2011. It is a powerful method for the separation of a single enantiomer from a mixture of racemic secondary alcohols. Chapter one is a summary of the background and related works of this methodology.

In chapter two, the silylation-based kinetic resolution of various trans 2-arylcyclohexanols will be discussed by employing a p-isopropyl triphenylsilyl chloride as the derivatizing reagent with (-)-benzotetramisole as the catalyst. The diastereoselective and enantioselective of trans alcohols over the cis will be investigated and a facial one-pot reaction sequence will …

Redirecting P450 Ferryl-Oxo Intermediates From Oxygenation To Decarboxylation, Job Logan Grant

Theses and Dissertations

A recently discovered cytochrome P450 has garnered much interest for its ability to oxidatively decarboxylate n length fatty acids to n-1 terminal olefins using hydrogen peroxide as an oxidant. This enzyme (P450 OleT) is mechanistically peculiar, as it seemingly abrogates the oxygen insertion chemistry that typifies the P450 superfamily. In this work we explore the origin of this deviant catalysis.

Using stopped-flow and transient kinetic methodologies the ferryl-oxo pi-cation radical and ferryl-hydroxo intermediates, known as compound-I (Cpd-I) and compound-II (Cpd-II) respectively, were isolated in high yield. This is the first time either species has been observed in a substrate bound …

Polymer Grafted Nanoparticles For Designed Interfaces In Polymer Nanocomposites, Mohammad Mohammadkhani

Theses and Dissertations

This dissertation presents the design, synthesis, and characterization of polymer nanocomposite interfaces and the property enhancement from this interface design. Through the use of reversible addition fragmentation chain transfer (RAFT) polymerization for the grafting of polymer chains to silica nanoparticles, the surface of silica nanoparticles can be manipulated to tune the properties of nanocomposites by controlling the interface between the particles and the polymer matrix.

In the first part of this work, compatibility of 15 nm silica nanoparticles grafted with different alkyl methacrylates with linear low density polyethylene was investigated. SI-RAFT polymerization of hexyl, lauryl, and stearyl methacrylate on silica …

Disinfection By-Products: Formation In Pool Water And The Role Of Iodinated Medical Imaging Compounds As A Potential Precursor In The Formation Of Iodo-Dbps, Christina Marie Joseph

Theses and Dissertations

Disinfection by-products (DBPs) are the unintended consequence of using chemical disinfectants to kill pathogens in water. 1-11 They are formed from the reaction between disinfectants and natural organic matter (NOM), anthropogenic contaminants, and bromide/iodide present in the raw source water. DBPs are cause for concern because studies have found them to be toxic.11-16 This research focuses on identifying and studying the formation of DBPs. Specifically, the presence of DBPs in chlorinated pool water and tap water from Barcelona, Spain was studied to better understand which DBPs are formed in the pool as compared to those that enter the pool from …

Structural And Functional Studies Of Proteins From The Agricultural Pests Tetranychus Urticae And Aspergillus Fumigatus, Caleb Schlachter

Theses and Dissertations

Agricultural pests are a worldwide problem and cause billions of dollars in crop loss. In the United States alone, an estimated $40 billion USD is lost per year due to insecticide resistance [1]. Studied here are proteins (potentially new pesticide targets) from the agricultural pests Tetranychus urticae and Aspergillus fumigatus. T. urticae, or twospotted spidermite, is a polyphagous pest, and three proteins from this pest, a cyanase, a glutathione S-transferase and an intradiol ring-cleavage dioxygenase are described [2]. Cyanase is involved in the conversion of bicarbonate and cyanate, a toxic self-defense metabolite produced by plants, into ammonia and carbon dioxide. …

Metal-Organic Frameworks: A Versatile Platform For Light Harvesting And Energy Transfer, Derek E. Williams

Theses and Dissertations

The global energy demand is undoubtedly rising at an alarming rate, and as a result, humanity faces the problem of finding alternative energy supplies. Approximately 80 percent of the world’s energy currently comes from fossil fuels, and only a small fraction, 10 percent, from renewable energy sources. The study of energy transfer (ET) processes is a rapidly developing area of interest due to the necessity for more efficient photovoltaic devices, which are crucial to meet the growing energy demand. A promising approach to further advance organic photovoltaics is to precisely arrange many lightharvesting chromophores (e.g., porphyrin derivatives), attainable through a …

Mechanistic Studies Of Nucleic Acid Chaperone Activities Of Retroviral Nucleocapsid Protein, Lichao Sun

Theses and Dissertations

In this dissertation, I have used single molecule Fluorescence Resonance Energy Transfer (sm-FRET), as a nanoscale spectroscopic ruler to gain quantitative, molecular-level understanding about the kinetics and mechanism of NC-chaperoned TAR sequence rearrangements. Firstly, I have resolved the complex kinetics and underlying reaction pathways of TAR sequence annealing in the presence of HIV-1 NC over a broad NC concentration by performing the time-resolved sm-FRET measurements in a unique aggregation-free environment. I have further gained the insights that the NC-induced secondary structural changed of TAR hairpins modulate the annealing pathways and consequently affect the overall kinetics of the TAR sequence annealing. …

Assessing Aberrant Glycosylation With Synthetic Lectins To Detect And Stage Prostate Cancer, Anna Veldkamp

Theses and Dissertations

Aberrant glycosylation takes place during the onset of cancer and throughout the progression of the disease allowing certain glycans to serve as biomarkers1. Boronic acid functionalized synthetic lectins (SLs) have been shown to bind selectively and crossreactively to certain glycoproteins through covalent yet reversible interactions between the boronic acids and 1,2- or 1,3-diols found on saccharides2. This project focuses on 1) data acquisition optimization of an existing SL array; 2) the identification, isolation, and characterization of new SLs that interact with proteins and glycoproteins targeting the prostate and prostate cancer; and 3) the utilization of new SLs in cross-reactive sensor …

Characterization Of The Suf Fe-S Pathway In Escherichia Coli, Naimah Bolaji

Theses and Dissertations

Iron is an essential transition metal required by almost all organisms for use as a cofactor in many metabolic processes such as respiration and photosynthesis. Iron can be combined with elemental sulfur to form an iron-sulfur (Fe-S) cluster. In bacterial pathogens, Fe-S cluster cofactors carry out critical functions and the Fe-S cluster biogenesis pathway is essential for their survival. In E. coli, the Suf pathway assembles Fe-S clusters under conditions of iron starvation and oxidative stress. While some mechanistic details of the Fe-S cluster biogenesis have been well-characterized, the process of in vivo iron donation remains unclear. Iron storage proteins …

Investigation Of Iron(Ii) Autoxidation Rate And Iron Mediated Geochemical Production Of Reactive Oxygen Species At Oxic-Anoxic Interfaces, Dewamunnage Muditha Chathurangani Dias

Theses and Dissertations

Biogeochemical cycles in ecosystems regulate the flow of energy between reduced species (typically carbon compounds) and a variety of oxidants via both biotic and abiotic reactions. A key class of chemical compounds that can link these cycles through abiotic pathways are Reactive Oxygen Species (ROS). The production of ROS via photochemical pathways is well known. More recently, the non-photochemical production of ROS via the one electron oxidation of ferrous iron (Fe(II)) by dioxygen (O2) has been detected in a range of environments. The oxidation of Fe(II) initiates a pathway that generates an array of ROS as Fe is cycled between …

Chemical Sensing In Harsh Environments By Multivariate Optical Computing, Christopher Michael Jones

Theses and Dissertations

Multivariate optical computing (MOC) is a compressive sensing technique for which an analyte concentration is detected in an interfering mixture by direct detector output. The detector measures the dot product of a linear regression vector with a sample spectrum, as an analog optical computation. The computation is accomplished with the multivariate optical element (MOE), to which the optical regression vector is encoded as a transmission pattern. As a spectrum of light emanates from a sample and passes through the MOE, the dot product naturally occurs when light strikes the detector. The MOC platform allows a simple, robust, and direct measurement …

Sustainable Polymeric Materials Derived From Plant Oils: From Synthesis To Applications, Xinzhou Zhang

Theses and Dissertations

In this thesis, monomers and polymers derived from high oleic soybean oil are investigated. The properties of these monomers and polymeric materials are characterized and discussed. Chapter 1 describes an overall background of bio-based resources, monomers, polymers, and their potential impact on society. The overall objective of my research is described. Chapter 2 outlines a new large-scale preparation of a soybean based monomer and the use of this monomer in thermoplastic elastomers. The synthetic procedures and characterizations of the monomers and polymers are discussed. In Chapter 3, potential applications of soybean oil monomers in both supramolecular polymers and poly(phosphoester)s are …

Targeting Aberrant Glycosylation In Colon And Prostate Cancer With An Improved Synthetic Lectin Array, Tanya Hundal

Theses and Dissertations

Cancers of the colon and prostate, though treatable, necessitate early detection to improve patient outcomes. Current diagnostics, (visual methods or biopsies) besides being invasive, are subjective towards interpretation, thus decreasing accuracy. Alternatively, blood-based tests involving measuring of specific biomarkers (like CEA and PSA for colon and prostate cancers, respectively) are associated with high false-positive rates and are more useful for monitoring post-treatment patient health, thus driving efforts to identify better screening and diagnostic techniques.

Abnormal glycosylation of integral membrane and secreted glycoproteins is known to take place at the onset of many diseases, including cancer, and presents as the over, …

Fulleretic Well-Defined Scaffolds: Donor–Fullerene Alignment Through Metal Coordination And Its Effect On Photophysics, Derek E. Williams, Ekaterina A. Dolgopolova, Danielle C. Godfrey, Evgeniya D. Ermolaeva, Perry J. Pellechia Dr., Andrew B. Greytak Prof. Dr., Mark Smith Dr., Stanislav M. Avdoshenko, Dr., Alexey A. Popov Dr., Natalia B. Shustova Prof. Dr.

Faculty Publications

Herein, we report the first example of a crystalline metal–donor–fullerene framework, in which control of the donor–fullerene mutual orientation was achieved through chemical bond formation, in particular, by metal coordination. The 13C cross-polarization magic-angle spinning NMR spectroscopy, X-ray diffraction, and time-resolved fluorescence spectroscopy were performed for comprehensive structural analysis and energy-transfer (ET) studies of the fulleretic donor–acceptor scaffold. Furthermore, in combination with photoluminescence measurements, the theoretical calculations of the spectral overlap function, Förster radius, excitation energies, and band structure were employed to elucidate the photophysical and ET processes in the prepared fulleretic material. We envision that the well-defined fulleretic donor–acceptor …

Quantum Dot Metrics For Preparative Chemistry And Fluorescence Applications, Yi Shen

Theses and Dissertations

Colloidal semiconductor quantum dots (QDs) are considered to be a promising candidate for bio-imaging and solar cells because of their extraordinary photo-physical properties. The ultimate goal of this dissertation is to design a reliable matrix and a reproducible method to prepare QDs-based biocompatible probe for fluorescence applications. Synthesis of quantum dots requires a large amount of ligands to improve the stability at high temperature. However, for further application and surface modification of QDs, excess ligands must be removed. In this dissertation, I will first describe using gel permeation chromatography (GPC) as a media to purify different types of QDs. A …

Iron Uptake And Accumulation Is A Target Of Nickel Toxicity During The Lag Phase In Escherichia Coli, Geoffrey Tuttle Ford

Theses and Dissertations

Various transition metals are essential to all forms of life, and are only required in trace amounts. But this dependence comes as a double-edged sword. All organisms must maintain a careful intracellular quota that does not traverse outside an acceptable range. One transition metal in particular is nickel. The importance of this transition metal has been debated widely and its function varies greatly between organisms, including bacteria. However, the adverse effects caused by over exposure to this metal have been the center of much experimentation in recent years. Still, the mechanisms of nickel toxicity and the subsequent effects on cellular …

The Development Of A High Resolution Deep-Uv Spatial Heterodyne Raman Spectrometer, Nirmal Lamsal

Theses and Dissertations

Raman spectroscopy is a light scattering technique that has a huge potential for standoff measurements in applications such as planetary exploration because a Raman spectrum provides a unique molecular fingerprint that can be used for unambiguous identification of target molecules. For this reason, NASA has selected a Raman spectrometer as one of the major instruments for its new Mars lander mission, Mars 2020, in the search for biomarkers that would be the indicators of past or present life. Raman scattering is strongest at UV wavelengths because of the inherent increase in the Raman cross section at shorter wavelengths and because …

Ligand-Induced Magnetic Changes In Metal Thin Films, Fiona Senta Oberbeck-Oxsher

Theses and Dissertations

The investigation of magnetic properties of thin films whose surfaces were modified by organic molecules shows that the addition of any functional group to the surface measurably changes the magnetic properties. The effect often scales with ligand strength and is not limited to surfaces with ferromagnetic properties. Improving upon the technique developed by Knaus et al. [1], a stable and sensitive device was developed to measure this magnetic effect using the planar Hall effect (PHE) in order to shed light onto controversial questions of purported paramagnetism of thiolated gold. There is a measureable non-diamagnetic response of thin gold layers when …

Structural And Functional Studies Of Nicotinamide Adenine Dinucleotide And Streptolysin S Biosynthesis Proteins From Streptococcus Pyogenes, William T. Booth

Theses and Dissertations

Invasive infections caused by Streptococcus pyogenes, also known as Group A Strep (GAS), results in approximately 600,000 deaths annually. With evidence of antibiotic-resistant strains of this bacterium on the rise, there is a need for the identification of new drug targets to control these infections. In our approach we target the quinolinate-salvage pathway (QSP) and the streptolysin S (SLS) biosynthesis pathway. The QSP provides a secondary pathway for NAD+ biosynthesis within this organism; the SLS pathway leads to the formation of a quorum sensing molecule (SLS). We hypothesize that inhibition of the pathways will lead to GAS cell death or …

The Chemistry Of Photography, Nichole Marie Witten

Senior Theses

People nowadays are used to instant gratification when it comes to taking photographs. They look at a digital display, click a button, and get a perfectly focused and lighted picture that they can see right away. New technologies enable people to have pocket-sized digital cameras, their smart phones, with them at all times, and they’re easy convenient, and fast. Behind a single lens reflex (SLR) film camera, the scenario is much different. More time is needed in framing the image and adjusting the aperture and shutter speed to get the correct exposure, and the film must be processed darkroom before …

From The Sewing Room To The Ballroom, The Evolution Of Ballroom Dance Costumes, Jessica Marie Russell

Senior Theses

Although I have danced all my life, I only began to ballroom dance and dance socially after starting college at the University of South Carolina. While dancing with the Carolina Ballroom Club, I learned some of the history of ballroom dance from our instructors, but I never quite understood how we went from having very conservative court dances to the wide variety of ballroom dances where dancers wear extravagant costumes. I also have been sewing since I was a child; I helped do minor repairs in the costume room for ballet productions, and recently began making clothing for myself. I …

Xenoestrogens From Household Plastics Bind Estrogen Receptors And Affect Cell Proliferation, Susan G. Hurley, Brett R. Lackey, Patricia L. Tate, Sandra L. Gray

Journal of the South Carolina Academy of Science

Xenoestrogens are “foreign” chemicals or compounds that interact with estrogen receptors as either agonists or antagonists to interfere with endocrine system function. Xenoestrogens include phytoestrogens, pesticides, industrial by- products and synthetic estrogens. In this study, consumer plasticware, including baby bottles and food storage containers, were found to release xenoestrogenic compounds that bound to ERα and ERβ and affected cell proliferation.