Physical Sciences and Mathematics Commons^™

Photochemical Reactions Of Optically Active Chiral And Achiral Organic Materials, Nicie Conley Murphy

Doctoral Dissertations

Sodium chlorate, NaClO₃, which crystallizes in the space group P2₁3, forms optically active crystals upon crystallization although the molecule itself is achiral. NaClO₃, has been shown to produce an asymmetric distribution of (+) and (-) crystals when crystallized from water while stirring. It has been discovered that beta or positron radiation can also induce asymmetric crystallization in NaClO₃ solutions. Like NaClO₃, achiral 4,4’-dimethylchalcone crystallizes in enantiomeric forms in the space group P2₁3. Kondepudi et al. provided evidence that stirred crystallizations of 4,4’-dimethylchalcone can induce a bimodal distribution of …

Interdisciplinary Approaches To New Chemical Analysis, David Lynn Rodman

Doctoral Dissertations

The primary focus of this dissertation is the development of new chemical analyses for inorganic, organic, and organometallic compounds. Interdisciplinary approaches combining analytical, polymer, inorganic, organic, and materials chemistry have been used to develop new analytical methods. Topics discussed in this dissertation include the development of a sol-gel based metal ion sensor, photochemical oxidation of a biomimetic Cr(III) complex, photochemical oxidation of organic ligands and other interferences in model Pd catalyst complexes, modified Fujiwara reactions for the detection of halogenated hydrocarbons, and the development of a controlled-release polymer for delivery of reagents needed for chemical sensing applications.

Structural And Spectroscopic Studies Of Transition Metal Organometallic And Coordination Complexes With Reference To Catalysis, Megan Taliaferro Bragg

Doctoral Dissertations

Inorganic chemistry encompasses a variety of topics and in many ways, these advances affect a wider sphere of chemists than purely inorganic and progress in this field is interesting to many scientists. The developments presented in this dissertation are significant as they affect three issues: catalytic reactivity, ligand fluxionality, and catalyst development. Catalysis affects industrial profit, pharmaceutical development, agrochemical synthesis, spectroscopy, enzymatic activity, and polymerization.

Progress in certain areas such as the [Cp*Rh(TsDPEN)] (TsDPEN = p-toluenesulfonyldiphenylethylenediamine) has lead to a moiety that is a powerful and efficient catalyst for the reduction of C=N bonds. The precise mechanism of the …

The Development Of Building Block Methodologies To Produce Nanostructured Heterogeneous Catalysts By Design, Jason Curtis Clark

Doctoral Dissertations

Building block methods were successfully developed to demonstrate the potential of this approach to synthesizing nanostructured heterogeneous catalysts by design. The octa(trimethyltin) cuboctameric spherosilicate, Si₈O₂₀(SnMe₃)₈, was used as the building block for the synthesis of these materials. The solid state structure of this building block was characterized and compared to other solid state structures of Si₈O₁₂ containing compounds. These studies showed that this building block is composed of rigid tetrahedral units connect through a flexible siloxy bridge. The trimethyltin functionality present on this molecular precursor will react with metal …

Synthesis Of 123-Iodine Labeled Rofecoxib Analogues: Potential Nuclear Medicine Imaging Agents, Brandy U. Belue

Masters Theses

Single photon emission computed tomography (SPECT) is a medical imaging technique which provides three-dimensional images ofliving systems after introduction ofa radiolabeled pharmaceutical. Rofecoxib (4-[ 4-methylsulphonylphenyl]-3phenylfuran-2(SH)-one) is an inhibitor of the cycloxygenase-2 enzyme, an enzyme which has been found to promote cancer cell growth. The synthesis of a no-carrier-added iodine-123 labeled rofecoxib derivative is potentially of value for the detection of cancer utilizing SPECT.

Iodine-123 labeled -(3-Iodophenyl)-4-(methanesulfonylphenyl)-SH furan-2-one, 1, and 3-(4-Iodophenyl)-4-(methanesulfonylphenyl)-5H-furan-2-one, 2, were prepared from the respective potassium organotrifluoroborate salts. The trifluoroborates were prepared from a simple six step pathway.

Studies Directed Toward The Synthesis Of Acylated Phloroglucinols, Joseph Allen Burlison

Doctoral Dissertations

The synthesis and application of α-allenyl ketones directed toward the synthesis of polycyclic polyprenylated acylphloroglucinols are described. A functionalized α-allenyl ketone was synthesized in twelve steps starting from 2-methyl-2-cyclohexenome in 24% overall yield. The α’ stereocenter in the α-allenyl ketone was stereoselectively quaternized using a Tsuji allylation, Mukaiyama adol condensation sequence to afford C-1 functionalized allenyl cyclohexanone building blocks. A survey of acetals and reaction conditions for the Mukaiyama reaction suggested that 3-tert-butyldiphenylsiloxypropanal dimethyl acetal could be used, and indeed this reagent in the presence of TiCl₄∙Ti[OCH(CH₃)₂]₄ gave the aldol product …

Factors Affecting The Phase Separation Of Liquid Crystals From Acrylate-Based Polymer Matrices, Nathan Joseph Crawford

Doctoral Dissertations

The work presented in this dissertation covers the study of phase separation of small-molecule liquid crystals (LC's) from acrylate-based polymer matrices. These materials are used in the construction of polymer dispersed liquid crystals, or PDLC's, an emerging technology with applications ranging from privacy windows to photonic materials.

The first part of this study involves the determination of the effect of increasing polymer molecular weight on the solubility of the LC 4' -octyl-4-biphenyl carbonitrile, or 8CB, in poly(methyl methacrylate), or PMMA. Optical microscopy is used to determine the equilibrium phase diagrams for blends of 8CB and PMMA with weight-average polymer molecular …

Lanthanide Separation Using Rate-Controlled Solvent Extraction, Joey Edwin Dickson

Doctoral Dissertations

Solvent extractions of many of the lanthanide ions in both single ion and mixed ion environments have been carried out. These cations were first complexed with an aqueous complexing agent and were extracted with DEHPA (di-2 ethylhexylphosphoric acid) in an organic phase (kerosene). The experiments were designed to measure the rates of extraction in the hope that separation factors might be enhanced under non-equilibrium conditions. The complexing agents tried include ethylenediaminetetraacetic acid (EDTA), tetraethylenepentamine (tetraen), nitrilotriacetic acid (NTA), and diethylenetriamine (dien). These represent a hexadentate, pentadentate, tetradentate, and tridentate agent respectively. EDTA was determined to give the best results for …

Synthesis And Applications Of Monolithic Hplc Columns, Chengdu Liang

Doctoral Dissertations

Silica and carbon monolithic columns were synthesized and modified for liquid chromatography applications. Column configurations and cladding techniques were investigated in detail. Three novel approaches have been developed for the synthesis of bimodal porous rods. Out of these three methods, gel-casting was adopted for the synthesis of silica monoliths with ordered mesopores and uniform macropores; the use of colloidal templates and dual phase separation has been successfully implemented for the synthesis of carbon monoliths with well-controlled meso- and macro- porosities. The formation of mesopores in carbon materials has been further studied in the microphase separation of block copolymers. Electrochemical modification …

Tungsten Alkyl Alkylidyne And Bis(Alkylidene) Complexes. Their Unusual Inter-Conversion And Reactions With Phosphines, Dioxygen And Water, Laurel Anne Morton

Doctoral Dissertations

This dissertation focuses on the unique chemistry of d0 alkylidyne and bis (alkylidene) complexes with β-silicon atoms. The goals of this dissertation research were to prepare and characterize these new d0 transition metal complexes, to study their reactivities including thermodynamics and kinetics of the inter-conversion between the alkylidyne and bis(alkylidene) complexes, and to explore the mechanism of the reactions of O2 or water with d0 alkylidyne complexes.

A summary of the research in this dissertation is provided in Chapter 1.Chapter 2 reports the study of an unusual exchange between new alkyl alkylidyne and bis(alkylidene) complexes …

Synthesis Of A C-Linked Methyl Β-Disaccharide As A Building Block Of Hyaluronic Acid Oligosaccharide Mimetics, Kpakpo Ambroise Akue

Doctoral Dissertations

Hyaluronic acid is a viscous high MW polysaccharide that is synthesized in the plasma membrane. It is found in the connective tissue space, in the synovial fluid of movable joints and in the vitreous humor of the eye. Its chemical structure is composed of a repeating disaccharide unit in which D-glucuronic acid is linked to the 3-position of N-acetyl-D-glucosamine. It appears to play an important role in the metastasis of cancer cells since cancer cell’s CD44 receptors adhere to it and migrate to host cells. Our goal was to synthesize small HA-oligosaccharides that would behave as CD44 metastasis receptor antagonists. …

Understanding And Controlling The Molecular Level Processes Involved In The Development Of Latent Fingerprints Using The Cyanoacrylate Fuming Method, Stephen Paul Wargacki

Doctoral Dissertations

The cyanoacrylate fuming method (CFM) is the standard method for forensic investigators to develop latent fingerprints from nonporous substrates. Variations in the effectiveness of the technique and the quality of the ethylcyanoacrylate (ECA) polymer impression formed during the development process have lead researchers to investigate the fundamental reactions between the print residue and the developing vapor. Identification of the active initiating species in the residue is an essential first step to understanding the development process. The fingerprint residue is composed primarily of water and eccrine salts, of which, water is generally accepted as the active initiator. However, initiation by water …

Improvement Of Long Range Order In Diblock Copolymer Templates For Nanostructure Deposition, Scott Michael Fontana

Doctoral Dissertations

This dissertation presents work that examines the use of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer thin films as nanoporous templates. Diblock copolymer thin films are able to microphase separate to produce microdomains on the nanometer length scale. Cylindrical domains can be perpendicularly oriented when cast as a thin film on a neutral surface. From the perpendicularly oriented cylindrical microdomains, nanoporous templates can be created.

Cylindrical domain block copolymer templates can lead to the production of nanostructures, but the lack of long range ordering prevents the use of diblock copolymer template for some industrial applications. Graphoepitaxy utilizes a …

Atomistic Investigation Of Anomalous Diffusion On Surfaces: A Deterministic Approach, James Wesley Mancillas

Doctoral Dissertations

The observation of anomalous diffusion rates on surfaces by recent experiments has renewed interest in diffusion mechanics. In order to provide a better understanding of the atomistic motions resulting in anomalous diffusion, we have investigated the diffusion dynamics of sodium on a copper surface using conservative molecular dynamics. The properties of diffusing adatoms transitioning between normal diffusive motion and anomalous motion have then been examined. Utilizing short time approximation Lyapunov exponents, stable cantori within chaotic manifolds are identified. At the periphery of these stable cantori from which anomalous diffusion originates, we have examined the transition properties of diffusive motions with …

Overcoming Statistical Error And Bias In Quantum Monte Carlo: Application To Metal-Doped Helium Clusters, Gary Lee Warren Jr.

Doctoral Dissertations

Quantum Monte Carlo (QMC) methods are a class of powerful computer simulation techniques for solving the many-body Schrӧdinger equation. These techniques deliver essentially exact results and boast favorable computational scaling with system size. Calculations provide a full quantum mechanical treatment and may be carried to arbitrary precision. These characteristics make QMC a promising choice for the investigation of doped helium clusters, where quantum effects are substantial.

Stochastic in nature, QMC methods are susceptible to statistical bias and error, which must be carefully controlled. Moreover, the relationship between the finite sampling error and the statistical uncertainty in observables has never been …

Experimental Studies Of Intra- And Intermolecular Chemical Structure, Cara Lynn Nygren

Doctoral Dissertations

The purpose of this study was two fold. The determination of hydrogen atom positions by X-ray diffraction methods is widely underused. With advances in instrument and computing technology, the use of X-ray diffraction experiments to accurately image the electron density associated with a hydrogen bond has become feasible. Secondly, general crystallographic computing programs analyze diffraction data by employing a spherical atom model. However, no such atom can be defined solely by a sphere when bound in a molecule. The use of spherical harmonics to model diffraction data enables a more complete description of the electron density in a molecular system. …

Syntheses, Structures, And Reactivities Of Early-Transition-Metal Silyl, Amide, And Imide Complexes, Xianghua Yu

Doctoral Dissertations

This dissertation describes syntheses, characterization, and reactivities of Groups 4 and 5 metal amide silyl complexes free of anionic π-ligands such as cyclopentadienyl (Cp).

A summary of the research in this dissertation is provided in Chapter 1. Chapter 2 reports unusual equilibria involving zirconium amides, silyl anions, and zirconium silyl complexes through amide-silyl ligand exchange reactions. Silyl anion SiBu^{tPh_{2− (}}2) was found to substitute an amide ligand in Zr(NMe2)4 (3) to give (Me2N)3Zr(SiButPh2)2− (1a) and Zr(NMe2)5− (1b) in THF. Silyl anion 2 also selectively attacks the –N(SiMe3)2 ligand in (Me2N)3Zr[N(SiMe3)2] …

Development Of Novel Synthetic Methods Utilizing Group Iii And Iv Reagents, Gang Dong

Doctoral Dissertations

This dissertation summarizes the development of novel synthetic methods involving Group III & IV reagents. These newly discovered reactions include the rhodium-catalyzed direct cross-coupling of allylic alcohols with aryl- and vinylboronic acids; palladium-catalyzed coupling reaction of Baylis-Hillman acetate adducts with both potassium organotrifluoroborate reagents and organosiloxanes; efficient syntheses of functionalized allylmetals such as allylboranes, allylsilanes, and allylgermanes; application of allylboranes to the synthesis of homoallylic alcohols; syntheses of 4-(1-alkynyl)-2(5H)-furanones and coumarins; utilization of potassium alkynyltrifluoroborates in the synthesis of conjugated enediynes; and application of potassium alkynyltrifluoroborates as reagents in the Petasis reaction.

The new synthetic methodologies involving Group III & …

Approaches To Uniform-Morphology: Polymer-Based Sers Substrates, Kathleen Sue Giesfeldt

Doctoral Dissertations

Polymer-nano-metallic-particle composites have demonstrated technological potential due to their unique optical and electrical properties. We report on composites prepared via physical vapor deposition of silver and gold onto pliable polydimethlysiloxane (PDMS) polymer. Rapid metal diffusion and nano-metallic-particle formation in a phase-separated surface layer of the PDMS creates unique sub-surface-based composites that vary in properties based on rate of deposition and average metal thickness. In addition, nano-metallicparticle spacing can be altered with fair reproducibility and reversibility by physically manipulating the composite. A practical technological characteristic of these composite materials arises from their potential to be molded into functional devices. Surface enhanced …

Studies Of Alkaline Phosphatase Inhibition By Metal Chelators Using Capillary Electrophoresis, Courtney A. Neel

Masters Theses

Alkaline phosphatase inhibition by metal chelators has been studied using capillary electrophoresis. The enzyme-inhibition assays were performed by electrophoretically mixing enzyme and inhibitor zones in a substrate filled capillary. Enzyme inhibition could be seen as a decrease in product formation as detected using laser-induced fluorescence. The enzyme-inhibition assays were adapted so they could be performed using a commercial CE system. Use of a commercial system is desirable for these assays due to ease of use and system features such as autosamplers and capillary and sample cooling. This technique could prove useful for pharmaceutical industries as a screening tool for new …

Thermodynamic Contributions Of Various Metal-Nucleotide Complexes Binding To Yeast Phosphoglycerate Kinase, Randall Allen Holzberger

Masters Theses

The purpose of this study was to determine the thermodynamic parameters of various enzyme-substrate complexes of Yeast Phosphoglycerate Kinase by using Isothermal Titration Calorimetry (ITC). The addition of metal-nucleotide substrate to a PGK solution elicited an exothermic response ranging from 0.5 kilocalories to 2.8 kilocalories. Titrations of MgATP and MgADP into PGK yielding binary complexes generated a greater amount of heat than titrations of MgADP into PGA-PGK and MgAMP-PCP into PGA-PGK yielding ternary complexes. The entropic contribution of the ternary complex formations was significantly greater than binary complex formations. Although entropic and enthalpic contributions varied, the Gibbs free energy remained …