Chemistry Commons^™

The Optimization Of The Synthesis And Characterization Of Vapor-Liquid-Solid Grown Zno Nanowires, Silas R. Fiefhaus

Theses and Dissertations--Chemistry

ZnO nanowires are a promising material with great semiconductor properties. ZnO nanowires were prepared by carbothermal reduction and vapor-liquid-solid growth mechanism. Altering a variety of parameters ranging from mole to mole ratio of ZnO to C all the way to gas flow rate was examined. The nanowires were then characterized and their morphology examined under a SEM to observe what effect the parameter had on the morphology of the nanowires. From the experiments and the parameters tested it was observed that in order to produce the highest quality straight nanowires one should use a mole to mole ratio of ZnO …

Towards An Understanding Of The Role Of Cation Packaging On Dna Protection From Oxidative Damage, Cody E. Gay

Theses and Dissertations--Chemistry

In sperm chromatin, DNA exists in a highly condensed state reaching a final volume roughly twenty times that of a somatic nucleus. For the vast majority (>90%) of sperm DNA in mammals, somatic-like histones are first replaced by transition proteins which in turn are replaced by arginine-rich protamines. This near crystalline organization of the DNA in mature sperm is thought crucial for both the transport and protection of genetic information since all DNA repair mechanisms are shut down. Recent studies show that increased DNA damage is linked to dysfunctions in replacing histones with protamines resulting in mispackaged DNA. This …

Towards An Understanding Of Pharmacologically Induced Intracellular Changes In Nicotinic Acetylcholine Receptors: A Fluorescence Microscopy Approach, Ashley M. Loe

Theses and Dissertations--Chemistry

Upregulation of nicotinic acetylcholine receptors (nAChRs) is a well-documented response to chronic nicotine exposure. Nicotinic acetylcholine receptors are pentameric ligand-gated ion channels consisting of alpha (α2-10) and beta (β2-4) subunits. Nicotine, an agonist of nAChRs, alters trafficking and assembly of some subtypes of nAChRs, leading to an increase in expression of high sensitivity receptors on the plasma membrane. These physiological changes in nAChRs are believed to contribute to nicotine addiction, although the mechanism of these processes has not been resolved. Recently, many studies have converged on the idea that nicotine induces upregulation by an intracellular mechanism. In this dissertation, expression …

Organometallic Materials: Ferroceno[C]Thiophenes And 1,2-Bisthienylmetallocenes, Surya R. Banks

Theses and Dissertations--Chemistry

Development of synthetic routes toward two general organometallic frameworks was undertaken. The first project involved synthetic attempts of substituted and unsubstituted ferroceno[c]thiophene while the second one was the synthesis of 1,2-dithienylmetallocenes. The long-term goal of this work is to lay the foundations for study of electronic, electrochromic, redox, and optical properties of thiophene-based materials integrated with organometallic systems such as ferrocene, ruthenocene and cymantrene. The synthetic pathway for the target molecule in the first project involved converting 1,2-bis(hydroxymethyl)ferrocene to 1,2-bis(thiouroniummethyl)ferrocene with thiourea under acidic conditions. Refluxing the salt in base followed by acidification resulted in 1,2-bis(mercaptomethyl)ferrocene, which is …

Understanding Electrical Conduction In Lithium Ion Batteries Through Multi-Scale Modeling, Jie Pan

Theses and Dissertations--Chemical and Materials Engineering

Silicon (Si) has been considered as a promising negative electrode material for lithium ion batteries (LIBs) because of its high theoretical capacity, low discharge voltage, and low cost. However, the utilization of Si electrode has been hampered by problems such as slow ionic transport, large stress/strain generation, and unstable solid electrolyte interphase (SEI). These problems severely influence the performance and cycle life of Si electrodes. In general, ionic conduction determines the rate performance of the electrode, while electron leakage through the SEI causes electrolyte decomposition and, thus, causes capacity loss. The goal of this thesis research is to design Si …

Design, Synthesis And Physicochemical Analysis Of Ruthenium(Ii) Polypyridyl Complexes For Application In Phototherapy And Nucleic Acid Sensing, Erin Melissa Wachter

Theses and Dissertations--Chemistry

Current chemotherapeutics exhibit debilitating side effects as a result of their toxicity to healthy tissues. Reducing these side effects by developing chemotherapeutics with selectivity for cancer cells is an active area of research. Phototherapy is one promising modality for selective treatment, where drug molecules are “turned on” when irradiated with light, reducing damage to healthy tissues by spatially restricting the areas exposed to irradiation. A second approach to improve selectivity is to exploit the differences in cancerous versus healthy cells, such as increased metabolism and/or upregulation of cell surface receptors. Ruthenium(II) polypyridyl complexes are candidates for phototherapy due to their …

Towards Catalytic Oxidative Depolymerization Of Lignin, Justin K. Mobley

Theses and Dissertations--Chemistry

Lignin is one of the most abundant and underutilized biopolymers on earth. Primarily composed on three monolignol units (sinapyl, coniferyl, and p-coumaryl alcohol), lignin is formed through a radical pathway resulting in an assortment of linkages, of which the β-O-4 linkage is the most prevalent (up to 60% in some hardwood species). In planta, lignin plays an important role in water transport and in protecting plants from chemical and biological attack. Traditional attempts to depolymerize lignin have focused on the cleavage of β-O-4 linkages via thermal or reductive routes. However these pathways lead to low-value, unstable product mixtures. Moreover, …

The Development Of Colorimetric Assays To Determine The Identity And Frequency Of Specific Nucleobases In Dna Oligomers, Elizabeth Marie Thomas

Theses and Dissertations--Chemistry

Colorimetric methods combined with color-changing chemical probes are widely used as simple yet effective tools for identifying and quantifying a wide variety of molecules in solution. For nucleic acids (DNA and RNA), perhaps the most commonly used colorimetric probe is potassium permanganate, which can be used to identify single-stranded pyrimidines (thymine and cytosine) in polymers. Unfortunately, permanganate is not an effective probe for identifying purines (adenine and guanine), especially in the presence of the more reactive pyrimidines. Therefore, robust methods for discriminating between the purines remain elusive, thereby creating a barrier toward developing more complex colorimetric applications. In this dissertation, …

Using Conventional And In Situ Transmission Electron Microscopy Techniques To Understand Nanoscale Crystallography, Bethany M. Hudak

Theses and Dissertations--Chemistry

Transmission electron microscopy (TEM) is a powerful tool for studying solidstate crystalline systems. With the advances in aberration correction, monochromation, and in situ capabilities, these microscopes are now more useful for addressing fundamental materials chemistry problems than ever before. This dissertation will illustrate the ways in which I have been using high-resolution imaging and in situ heating in the TEM during my Ph.D. research to investigate unique solid state chemistry questions.

This dissertation will focus on four unique crystal systems: thermoelectric skutterudite crystals, vapor-liquid-solid (VLS) grown nanowires, and hafnium dioxide nanorods. Although these systems are very different from one another, …

Rhenium-Pyridyl-Nhcs For Photocatalytic Co2 Reduction, Emily Anne Sharpe

Honors Theses

The ability to transform CO2 into a useable fuel source would have a remarkably positive impact on the environment by taking the vast amounts of previous unusable CO2 from the atmosphere and reducing it to CO, which can then be turned into fuel. This project involves the synthesis and testing of air and water stable Re (I) pyridyl N- heterocyclic carbene (NHC) compounds for photocatalytic reduction of CO2 into CO using a simulated solar spectrum. Previous research in this area focused on the use of Re(bpy)CO3X, which quickly became the benchmark of homogeneous CO2 reduction photocatalysts. The Re (I) pyridyl …

The Synthesis Of Substituted Pentadentate Ligand Scaffolds And Their Future Application In Ruthenium-Catalyzed Water Oxidation, Manpreet Singh

Honors Theses

Rising global energy demands coupled with depleting natural resources have led to a strong emphasis on finding new sources of energy that are renewable and which limit the negative impact on the environment. One of the strongest candidates is utilizing solar energy to drive water oxidation to produce hydrogen as a fuel source. In order to do this, a better understanding of the mechanism involved in this process must be revealed. Homogenous molecular catalysts allow mechanistic studies and can be also used in Photoelectrochemical Cells (PECs) and other systems to produce chemical fuels. In this work, the new syntheses of …

The Evolution Of The Sugarcoated American Food Market And The Paradox Of Artificial Sweeteners, Mary Moses Hitt

Honors Theses

Living in present-day America makes it hard to imagine an era when sugar was not as inexpensive and readily available as it is now. It is in little colorful packets on restaurant tables, filled to the brim in jars at coffee shops, or mixed into candy products located at the beginning of every cash register. Today, sugar is one of, if not, the most widely consumed food products in the world, but our love for sugar is nothing new. Humans have been experiencing the bliss triggered by sweet-tasting foods since their earliest diets, which included fruits and honey. Our diets …

Nucleophile Promoted Gold Redox Catalysis With Diazonium: Cbr, C-S And C-P Bond Formation Through Catalytic Sandmeyer Coupling, Haihui Peng, Rong Cai, Chang Xu, Hao Chen, Xiaodong Shi

Faculty & Staff Scholarship

Gold-catalyzed C-heteroatom (C-X) coupling reactions are evaluated without using sacrificial oxidants. Vital to the success of this methodology is the nucleophile-assisted activation of aryldiazonium salts, which could be an effective oxidant to convert Au(I) to Au(III) even without the addition of assisting ligand or photocatalyst. By accelerating reaction kinetics to outcompete C-C homo-coupling or diazonium dediazoniation, gold-catalyzed Sandmeyer reactions were achieved with different nucleophiles, forming C-Br, C-S and C-P bonds in high yields and selectivity.

Study Of An Active-State Cb1 Receptor Model And Jwh Compound Interactions To Predict New Emerging Synthetic Cannabinoids, Kelsey Leigh Pettus

Honors Theses

In recent years, a new class of compounds, called synthetic cannabinoids, have made their appearance in the market as a substitute for illegal marijuana or its constituent natural cannabinoids. These compounds, which are active at the same G- protein coupled receptors (GPCRS) as cannabinoids, are continuing to gain popularity because of the same cannabinoid-like effects they create. Though two cannabinoid receptors have been identified in humans, known as CB1 and CB2, synthetic cannabinoid activity at the CB1 receptor has been the focus of much research regarding synthetic cannabinoid ligand binding. In this study, the structure of the CB1 receptor is …

Paleolithic Protection In A Western World: A Look Into Preagricultural Nutrition As A Remedy For The Diseases Of Civilization, Emilie R. Caron

Honors Theses

The aim of this investigation is to discover the associations of the Western diet to noncommunicable diseases and to determine if a reversion to a Paleolithic diet will provide treatment and prevention of these diseases. Noncommunicable diseases, otherwise known as Diseases of Civilization, are lifestyle influenced diseases and encompass obesity, diabetes mellitus, cardiovascular disease, and associated cancers. Incidences of these diseases have skyrocketed in the past century and show no signs of decline. Since 1900, the death rates due to heart disease and cancer have risen to account for 47% of total deaths in the United States in 2010. (Tippett, …

Two-Photon Excitation Based Photochemistry And Neural Imaging, Kevin Andrew Hatch

Open Access Theses & Dissertations

Two-photon microscopy is a fluorescence imaging technique which provides distinct advantages in three-dimensional cellular and molecular imaging. The benefits of this technology may extend beyond imaging capabilities through exploitation of the quantum processes responsible for fluorescent events. This study utilized a two-photon microscope to investigate a synthetic photoreactive collagen peptidomimetic, which may serve as a potential material for tissue engineering using the techniques of two-photon photolysis and two-photon polymerization. The combination of these techniques could potentially be used to produce a scaffold for the vascularization of engineered three-dimensional tissues in vitro to address the current limitations of tissue engineering. Additionally, …

Synthesis Of Neoglycoproteins/Neoglycopeptides And Their Immunological Evaluation In The Context Of Chagas Disease, Nathaniel Scott Schocker

Open Access Theses & Dissertations

The protozoan parasite, Trypanosoma cruzi, the etiologic agent of Chagas disease (ChD), has a cell surface covered by immunogenic glycoconjugates. A synthetic glycoarray containing non-reducing α-galactopyranosyl moieties related to mucin O-glycans of the parasite T. cruzi was evaluated by a chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) with sera from patients with chronic ChD, revealing the disaccharide Galα(1,3)Galβ as the immunodominant glycotope (Chapter 2). This disaccharide comprises the two terminal sugars of the known immunodominant glycotope Galα(1,3)Galβ(1,4)GlcNAcα, which is expressed on glycosylphosphatidylinositol-anchored mucins of the infective trypomastigote stage of T. cruzi and triggers high levels of protective anti-α-Gal antibodies (Abs) in infected …

Modulation Of The Physiological And Biochemical Effects Of Copper Nanoparticles In Kidney Beans (Phaseouls Vulgaris) Treated By Kinetin, Suzanne Annette Apodaca

Open Access Theses & Dissertations

It is imperative to not only understand the impact of engineered nanomaterials (ENMs) in edible plants, but also the interactions they have with various additives used in agriculture. In this study, kidney bean plants were grown in potting soil treated with nano copper (nCu), bulk copper (bCu), and copper chloride (CuCl2) at concentrations of 0, 50, and 100 mg/kg for 55 and 90 days. At 15 days of growth, 0, 10, and 100 μm of kinetin (KN) were applied to plants. Plant tissue samples were harvested at 55 days and seeds were reaped at 90 days. Physiological and biochemical parameters …

The Characterization Of A Recombinant Virophage Integrase, Martin Christopher Chacon

Open Access Theses & Dissertations

Virophages are satellite-like dsDNA viruses that parasitize giant viruses of the family Mimiviridae. Mavirus is the second virophage discovered that associates with its host virus Cafeteria roenbergensis Virus (CroV). When co-infecting their common host cell Cafeteria roenbergensis, a marine zooplankton that is widely spread throughout the oceans, mavirus will inhibit CroV's replication. In addition, mavirus was shown to share high similarities to the Maverick/Polinton eukaryotic DNA transposons. A coding sequence in mavirus genome (MV02) reveals high homology to retroviral integrases such as those found in HIVs. The putative integrase MV02 is predicted to integrate mavirus DNA into the host genome. …

Atomic Oxygen Adsorption And Absorption On Rh(111) And Ag(111), Jonathan Derouin

Dissertations

A central question in the field of heterogeneous catalysis is how surface structure and subsurface species influence catalytic behavior. One key to answering that question is determining which surface structures and subsurface species are present under catalytically relevant conditions. This dissertation presents results of Auger electron spectroscopy, low energy electron diffraction, temperature programmed desorption, and scanning tunneling microscopy experiments on oxidized Rh(111) and Ag(111) crystals. Exposing Rh(111) to O2 produced a predominately (2 × 1) adlayer, but even after extended dosing, (2 × 2) domains were also present. Exposing Rh(111) to atomic oxygen yielded O coverages greater than 0.5 ML …

Development Of Folate Directed, Protein Based Photodynamic Therapy Agents, Rojenia Jones

Dissertations

To attack cancer cells in a specific manner, we have developed a folate-targeted, photodynamic therapy (PDT) agent. The folate (FA) and the chlorin e6 (Ce6) photosensitizer were attached to bovine serum albumin (BSA) using carbodiimide chemistry. Since over 50% of cancers overexpress folate receptors, FA-BSA-Ce6 can be taken up by them and is an effective PDT agent. Hela cells exposed to FA-BSA-Ce6 in the dark showed no cytotoxicity. Upon exposure to light, the conjugate was dose (time and concentration) dependent. Concentrations less than or equal to 2 µM were not effective at killing Hela cells but concentrations of at 5 …

Exploring Conditions For The Enhancement Of Acene Semiconductors Through The Use Of The Diels-Alder Reaction, Brittni Qualizza Qualizza

Dissertations

This dissertation demonstrates the application of SAMs to the surface of acene crystals, specifically of tetracene and rubrene, using the Diels-Alder reaction. The second chapter details preliminary reaction results and two analytical methods which were employed to confirm adsorption of the dienophile on the surface of single crystals, tetracene and rubrene. These were mass spectrometry and X-ray photoelectron spectroscopy (XPS). Mass spectrometry experiments distinguish the chemical identity of adduct on the crystals and also it discerned chemi- and physisorbed molecules from one another. XPS was used to prove face selectivity of the reaction by the detection of dichloromaleic anhydride. From …

Molecularly Imprinted Polymers For Enantiomer Separations And Biomolecular Sensors, Britney Lyn Hebert

LSU Doctoral Dissertations

Molecularly Imprinted Polymers (MIPs) encompass a wide range of applications by changing the different components, e.g. the template, crosslinker or functional monomers. Of interest among these different applications are separations and sensors. Separations by MIPs traditionally use a chiral pure template but in some cases that chiral pure template may not be available for imprinting. Using chiral (N-α-bismethacyloyl-L-alanine) and achiral (N,O-bisacrylamide ethanolamine) crosslinkers we investigated imprinting of scalemic and racemic template mixtures of Boc-tyrosine enantiomers. The achiral and chiral crosslinkers yielded similar results for the partial separation of enantiomers by scalemic imprinted polymers because separation and recognition are not dependent …

Synthesis And Characterization Of Polyhalogenated Boron Dipyrromethenes And Carboranylbisthiophene Oligomers, Ning Zhao

LSU Doctoral Dissertations

Chapter 1 of this dissertation shows a brief overview of fundamental concepts and classic synthetic routes of BODIPY dyes. The synthetic strategies and various application (e.g. PDT sensitizers and fluorescent indicators) of halogenated BODIPYs are also presented in this chapter. Chapters 2-4 describe the synthesis of three new polyhalogenated BODIPY platforms and their regioselective functionalization. Such new platforms provide new methodologies for producing both symmetric and asymmetric BODIPYs. Pd(0)-catalyzed cross-couplings and aromatic substitution reactions were applied to investigate the reactivity and regioselectivity of different halogen groups on the BODIPY platforms. The studies showed that the reactivity order of the halogens …

Design, Synthesis And Biological Applications Of Polypeptoids And Boron Dipyrromethenes, Sunting Xuan

LSU Doctoral Dissertations

The dissertation is about the design, synthesis and biological applications of polypeptoids and boron dipyrromethenes (BODIPYs). The dissertation is divided into seven chapters reporting various aspects of the background to my field of study and the results obtained during my PhD program. Chapter 1 is a concise overview of the fundamental concepts of polypeptoids and hydrogels, as well as their recent developments on synthetic strategies, property investigations, and biological applications in different fields. Chapter 2 presents the design, synthesis and potential application as tissue engineering scaffold of thermoreversible ABC polypeptoid hydrogels. A series of ABC copolypeptoids were synthesized and their …

Scanning Probe Investigations Of Multidentate Thiol And Spatially Confined Porphyrin Nanoassemblies Using Nanoscale Lithography, Xianglin Zhai Zhai

LSU Doctoral Dissertations

Approaches to prepare spatially selective surfaces were developed in this dissertation for constructing nanopatterns of organic thin film materials. Nanoscale surface patterns were prepared using immersion particle lithography and scanning probe lithography combined with organothiol chemistry. Organic thin films and nanomaterials can be patterned with tunable periodicities and designed shapes by selecting the diameter of mesospheres used as surface masks or scanning probe lithography, respectively. The surface platforms of well-defined nanopatterns are ideal for high resolution investigations using scanning probe microscopy (SPM). Local measurements of surface properties and conductive properties combined with nanolithography were accomplished at the molecular level. Sample …

Tip-Enhanced Laser Ablation Sample Transfer For Mass Spectrometry, Chinthaka Aravinda Seneviratne

LSU Doctoral Dissertations

In this research, atomic force microscope tip-enhanced laser ablation mass spectrometry (AFM TELA-MS), an ambient sub-micrometer scale sampling method for offline MS was developed. AFM TELA was used to transfer molecules from thin films to a suspended silver wire for off-line mass spectrometry using laser desorption ionization (LDI) and matrix-assisted laser desorption ionization (MALDI). An AFM with a 30 nm radius gold-coated silicon tip was used to image the sample and to hold the tip 15 nm from the surface for material removal using a pulsed Nd:YAG laser, which provides output at wavelengths of 532 nm in the visible, 1064 …

Optimizing Solvent Blends For A Quinary System, Thomas L. Hoy

Williams Honors College, Honors Research Projects

The Department of Polymer Engineering had received a grant from the Keck foundation to produce a process in which hundreds of copolymers can be formulated, synthesized, analyzed and then extrapolated to produce the optimal polymer for the desired material property. This process involves synthesizing approximately fifty polymers in a custom apparatus, none of which necessarily have the same monomer components. This leads to issue of which solvent or blend of solvents to use that would sufficiently dissolve both monomers and the resulting copolymer. If the monomers are not completely dissolved, a homogenous reaction will be impossible and if the copolymer …

Reactivity Of (3-Methylpentadienyl)Iron(1+) Cation: Late-Stage Introduction Of A (3-Methyl-2z,4-Pentadien-1-Yl) Side Chain, Subhabrata Chaudhury, Shukun Li, William A. Donaldson

Chemistry Faculty Research and Publications

The 3-methyl-2Z,4-pentadien-1-yl sidechain is found in various sesquiterpenes and diterpenes. A route for the late stage introduction of this functionality was developed which relies on nucleophilic attack on the (3-methylpentadienyl)iron(1+) cation, followed by oxidative decomplexation. This methodology was applied to the synthesis of the proposed structure of heteroscyphic acid A methyl ester. Realization of this synthesis led to a correction of the proposed structure.

A Full-Dimensional Model Of Ozone Forming Reaction: The Absolute Value Of The Recombination Rate Coefficient, Its Pressure And Temperature Dependencies, Alexander Teplukhin, Dmitri Babikov

Chemistry Faculty Research and Publications

Rigorous calculations of scattering resonances in ozone are carried out for a broad range of rotational excitations. The accurate potential energy surface of Dawes is adopted, and a new efficient method for calculations of ro–vibrational energies, wave functions and resonance lifetimes is employed (which uses hyper-spherical coordinates, the sequential diagonalization/truncation approach, grid optimization and complex absorbing potential). A detailed analysis is carried out to characterize distributions of resonance energies and lifetimes, their rotational/vibrational content and their positions with respect to the centrifugal barrier. Emphasis is on the contribution of these resonances to the recombination process that forms ozone. It is …