Chemistry Commons^™

Metals On Titania/Hopg As Models For Heterogeneous Catalysts, Randima Piyumalie Galhenage

Theses and Dissertations

The work done in this thesis is mainly focused on understanding the nanoscale morphology and activity of model heterogeneous catalysts. In order to do this we design and prepare model catalytic surfaces in ultrahigh vacuum (UHV) and study these surfaces using electron and ion based microscopies and spectroscopies. The nucleation, growth and chemical activity of mono and bimetallic clusters on TiO₂(110) were investigated in order to understand how activity is influenced by cluster sizes, interactions with the oxide support and surface compositions of the bimetallic clusters. For example, Au-based and Pt-based bimetallic clusters such as Co-Au, Co-Pt, and …

Facile Method For Large Scale Alignment Of One Dimensional Nanoparticles And Its Biomedical Application, Sheng Feng

Theses and Dissertations

Topographical cues can profoundly affect cellular behaviors. This thesis investigate how to utilize the topographical cues generated by two techniques, flow assembly and electrospinning, to regulate cellular behaviors.

First of all, a facile and robust method to align one-dimensional (1D) nanoparticles (NPs) in large scale has been developed. Using flow assembly, representative rod-like nanoparticles, including tobacco mosaic virus (TMV), gold nanorods and bacteriophage M13, have been aligned inside capillaries by controlling flow rate and substrate surface properties. The properties of 1D NPs, such as stiffness and aspect ratio, play a critical role in the alignment. Furthermore, these hierarchically organized structures …

Synthesis And Characterization Of Carbonized Poly (Divinylbenzene) Microspheres For Carbon/Nanodiamond/Polymer-Based Core-Shell Materials And Applications Of This Mixed-Mode Phase To High-Performance Liquid Chromatography, Chuan-Hsi Hung

Theses and Dissertations

This work focuses on improving the quality of carbon-based core-shell materials for high performance liquid chromatography (HPLC) via the characterization of the core materials, and also the development of chromatographic methods (separations) for them. In the early part of this work, I applied organic synthesis to make uniform, spherical poly(divinylbenzene) (PDVB) microspheres, and then carbonized them to prepare carbon core materials for core-shell particle synthesis. Here, I studied in detail the surface and material properties of these particles with multiple instruments, which allowed me to describe the physical and chemical changes that took place during each treatment. The uniform, spherical …

Immunoassays Of Potential Cancer Biomarkers In Microfluidic Devices, Jayson Virola Pagaduan

Theses and Dissertations

Laboratory test results are important in making decisions regarding a patient's diagnosis and response to treatment. These tests often measure the biomarkers found in biological fluids such blood, urine, and saliva. Immunoassay is one type of laboratory test used to measure the level of biomarkers using specific antibodies. Microfluidics offer several advantages such as speed, small sample volume requirement, portability, integration, and automation. These advantages are motivating to develop microfluidic platforms of conventional laboratory tests. I have fabricated polymer microfluidic devices and developed immunoassays on-chip for potential cancer markers. Silicon template devices were fabricated using standard photolithographic techniques. The template …

Optimization Of Nonadsorptive Polymerized Polyethylene Glycol Diacrylate As A Material For Microfluidics And Sensor Integration, Chad Rogers

Theses and Dissertations

Microfluidics is a continually growing field covering a wide range of applications, such as cellular analysis, biomarker quantification, and drug discovery; but in spite of this, the field of microfluidics remains predominately academic. New materials are pivotal in providing tailored properties to improve device integration and decrease prototype turnaround times. In biosensing, nonspecific adsorption in microfluidic systems can deplete target molecules in solution and prevent analytes, especially those at low concentrations, from reaching the detector. Polyethylene glycol diacrylate (PEGDA) mixed with photoinitiator forms, on exposure to ultraviolet (UV) radiation, a polymer with inherent resistance to nonspecific adsorption. Optimization of the …

Functional Expression And Characterization Of A Truncated Candida Antarctica Lipase B In Yeast, Samantha Robinson

Theses and Dissertations

Candida antarctica lipase B is an enzyme capable of hydrolyzing ester bonds in a lipid-water interface with potential to become a useful biocatalyst for production of biodiesel fuel. Enzymatically catalyzing the transesterification of triacylglycerides to produce fatty acid alkyl esters (biodiesel) is an environmentally cleaner alternative to the current process which utilizes chemical reagents as catalysts. Optimization and development of strains to express highly active, stable, large quantities of these biocatalysts is essential for inexpensive production of biodiesel. Additionally, lipase enzymes can be immobilized onto a resin, eliminating the need to recover the catalyst from the product and allowing multiple …

Comparing Three Methods For Estimating Ozone Depleting Substance Substitute Greenhouse Gases: Case Study Of The New York City Region, Wallace A. Murray Iii

Theses and Dissertations

This thesis evaluates the United States Environmental Protection Agency (EPA) method for estimating emissions from one source, Ozone Depleting Substances Substitutes (ODS substitutes) by comparing results for the New York City Metropolitan Statistical Area (NYC-MSA) with results from two other methodologies. The EPA’s method utilizes population data and GDP data to estimate and geographically allocate emissions, with little regard for the geographies of industrial activity. The two alternative methods use data for industrial employment and activity to provide results for comparison and perhaps a more accurate accounting and allocation of emissions throughout the NYC-MSA.

Novel Sustainable Polymers Derived From Renewable Rosin And Fatty Acids, Perry Wilbon

Theses and Dissertations

In the work of this dissertation, polymers derived from renewable bio-based resources prepared by various polymerization techniques were investigated. The properties of these polymeric materials were characterized and discussed. Rosin was first converted into acrylate or methacrylate monomers for atom transfer radical polymerization (ATRP). Second, rosin was combined with vegetable oil to produce completely renewable novel polyesters by acyclic diene metathesis (ADMET) polymerization. Third, degradable block copolymers were synthesized composed of polycaprolactone and rosin grafted polycaprolactone with the aid of ring-opening polymerization (ROP). Finally, degradable polyesters were produced using vegetable oil derivatives as starting materials. These new rosin and fatty …

A Convergent Approach To The Continuous Synthesis Of Telmisartan Via A Suzuki Reaction Between Two Functionalized Benzimidazoles, Alex D. Martin

Theses and Dissertations

A direct and highly efficient synthesis has been developed for telmisartan, the active ingredient in the widely prescribed antihypertensive drug Micardis®. This approach brings together two functionalized benzimidazoles using a high-yielding Suzuki reaction that can be catalyzed by a homogeneous palladium source or palladium on a solid support.

The ability to perform the cross-coupling reaction was facilitated by the regio-controlled preparation of a 2-bromo-1-methylbenzimidazole precursor. The method developed is the first reported selective bromination at the 2-position of a benzimidazole and produces the first major precursor in high yield (93%). The second precursor, potassium (4-methyl-2-propylbenzimidazol-6-yl) trifluoroborate, was prepared from commercially …

Analytical Method Development For The Detection And Analysis Of Protein Carbonyls, Chelsea M. Coffey

Theses and Dissertations

Oxidative stress can result in changes to many biomolecules and also affect their activities. We are interested in protein carbonylation, a type of unnatural oxidation which has been associated with numerous degenerative disease states and is also a consequence of the natural aging process. Protein carbonyls are stable species, but countless analytical barriers exist in terms of their identification. Thus, the main goal of this work was to develop and optimize analytical methods that could be used to help us better understand which, where, and how proteins are being carbonylated.

Initial studies involved method validation for carbonylating, tagging, and enriching …

Development Of Non-Traditional Platinum Anticancer Agents: Trans-Platinum Planar Amine Compounds And Polynuclear Platinum Compounds, Daniel E. Lee

Theses and Dissertations

Development of Non-Traditional Platinum Anticancer Agents: trans-Platinum Planar Amine Compounds and Polynuclear Platinum Compounds

By Daniel E. Lee, Ph.D.

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Virginia Commonwealth University, 2015

Major Director: Nicholas P Farrell, Ph.D., Professor, Department of Chemistry

Platinum anticancer compounds with cis geometry, similar to cisplatin, have been explored to circumvent the cisplatin resistance; however, they were not considered broadly active in cisplatin cells due to exhibiting similar or same cell death mechanism as cisplatin. Platinum compounds with trans geometry were less studied …

Iridium – Bismuth Carbonyl Cluster Complexes: New Directions For Chemistry And Selective Oxidation Catalysis, Gaya R. Elpitiya

Theses and Dissertations

CHAPTER 2 The reaction of Ir3(CO)9(μ3-Bi), 2.1, with BiPh3 has yielded a iridium−bismuth cluster complex Ir5(CO)10(μ3-Bi)2(μ4-Bi), 2.2. The first examples of bimetallic iridium−bismuth nanoparticles have been subsequently synthesized from 2.1 and 2.2, and these have been securely anchored onto the inner walls of mesoporous silica. These isolated, bimetallic iridium−bismuth nanoparticles display a superior catalytic performance, when compared to their analogous monometallic counterparts and equivalent physical mixtures, in the C−H activation of 3-picoline to yield niacin.

CHAPTER 3 The reaction of Ir3(CO)9(μ3-Bi) with Ph3GeH yielded the compound Ir3(CO)6(GePh3)3(μ3-Bi)(μ-H)3 3.1 When 3.1 was heated to reflux in hexane, it was transformed into …

Biginelli Synthesis And Characterization Of Potentially Anti-Proliferative Dihydropyrimidinone Thione Analogs, Timothy K. Summers

Theses and Dissertations

No abstract provided.

Fluorescence Imaging Of Analyte Profiles In An Inductively Coupled Plasma With Laser Ablation As A Sample Introduction Source, Lance Moses

Theses and Dissertations

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has risen to among the top tier techniques for the direct analysis of solid samples. However, significant problems remain that must be solved to achieve the full analytical potential of LA-ICP-MS. Inefficient conversion of aerosol to ions within the ICP or transmission through the MS interface may decrease precision, sensitivity, and/or accuracy. Although fundamental mechanisms that govern ion production and transmission have been studied extensively in solution-nebulization (SN) ICP-MS instruments, significant gaps in our understanding remain. Furthermore, it is unclear to what extent differences between the aerosols generated during SN and LA …

A Silylation-Based Kinetic Resolution Of Hydroxy Lactones And Lactams With Subsequent Mechanistic Investigations, Robert W. Clark

Theses and Dissertations

The work contained herein focuses on the methodology and design of new reactions for the production of stereoenriched compounds. The primary focus of research discussed is kinetic resolution, a classic and powerful methodology for the separation of a single enantiomer from a racemic mixture. In 2011, a silylation-based resolution catalyzed by a chiral isothiourea produced synthetically useful selectivity factors for mono-functional secondary alcohols. In chapter 2, this methodology was subsequently expanded to include α-hydroxy lactones with selectivity factors up to 100. This study resulted in the most selective reaction reported to date for the aforementioned silylation-based resolution. In addition to …

Synthesis, Surface Functionalization, And Biological Testing Of Iron Oxide Nanoparticles For Development As A Cancer Therapeutic, Stanley E. Gilliland Iii

Theses and Dissertations

Iron oxide nanoparticles are highly researched for their use in biomedical applications such as drug delivery, diagnosis, and therapy. The inherent biodegradable and biocompatible nanoparticle properties make them highly advantageous in nanomedicine. The magnetic properties of iron oxide nanoparticles make them promising candidates for magnetic fluid hyperthermia applications. Designing an efficient iron oxide nanoparticle for hyperthermia requires synthetic, surface functionalization, stability, and biological investigations. This research focused on the following three areas: optimizing synthesis conditions for maximum radiofrequency induced magnetic hyperthermia, designing a simple and modifiable surface functionalization method for specific or broad biological stability, and in vitro and in …

Quartz Crystal Microbalance Studies On Friction Modifiers For Lubricant Applications, Carey Lehner

Theses and Dissertations

Lubricants are used in numerous applications to control friction and protect moving parts from fatigue. These fluids consist of a variety of surface active chemistries competing for the surface to provide performance. In order to develop fluids that meet the ever-increasing requirements (from legislation and manufacturers), techniques that can provide insight into surface adsorption, in real time, and relate it back to performance are critical.

The objective of this work is to determine if Quartz Crystal Microbalance with Dissipation (QCM-D) is an effective technique to investigate surfactant adsorption in regimes that are common to the transportation lubricant industry. QCM-D is …

Assessing The Magnitude And Impact Of Seawater/Pore Water Exchange In Salt Marsh Systems, Carrie Lee Milliken

Theses and Dissertations

Submarine groundwater discharge is a hydrological process that is important to study and understand as it impacts biogeochemical processes and hydrological cycles. Particularly in coastal salt marsh systems, it is an important process to analyze as these systems serve as crucial interfaces between terrestrial and marine waters and particulates. There is evidence that these systems, typically thought to have little exchange across the interface due to impermeable sediments, could actually allow for significant flow of water and particulates at shallow depths. In order to measure and quantify this flow, a method using 224Ra as a tracer has been tested. The …

The Development Of Efficient Geminal-Based Methods For Quantum Chemical Calculations, Brett Allen Cagg

Theses and Dissertations

Incorporation of electron correlation to improve the accuracy of computations remains a driving force in quantum chemical method development. Traditionally, electron correlation effects are divided into static and dynamic correlation parts, and the inclusion of both results in methods that are impractical for large chemical systems. The goal of this doctoral research is to develop a method that efficiently accounts for both components of electron correlation in a separate but balanced manner. The approach focuses on combining a geminal method, called the antisymmetrized product of singlet-type, strongly orthogonal geminals (SSG), with dynamic correlation by either density functionals or a recently …

Chemical Processes Governing The Equilibrium Between Organic And Inorganic Carbon: Probing The Mechanisms Of Iron Catalyzed Reactive Oxygen Species Production, Joy Kelechi Ihekweazu

Theses and Dissertations

This study examines the oxidation of organic carbon that occurs concurrently with the autoxidation of Fe(II) to determine the role that geochemical constituents have on both the autoxidation of Fe(II) and subsequent ROS production. The reaction between reduced carbon and oxygen is thermodynamically favorable, but kinetically proceeds slowly. Fe(II) facilitates the equilibration of reduced carbon and oxygen. This equilibration occurs naturally in saline estuaries, where oxygen rich seawater mixes with anoxic groundwater. We characterized a saline estuary at the Baruch Institute and used those characterizations to recreate natural water conditions in the lab. Using simulated natural water we then examined …

The Role Of Intermembrane Space Redox Factors In Glutathione Metabolism And Intracellular Redox Equilibrium, Hatice Kubra Ozer

Theses and Dissertations

The mitochondrial intermembrane space (IMS) is a unique subcellular compartment that houses key thiol-dependent redox pathways such as protein transport, mitochondrial respiration, and detoxification of ROS (reactive oxygen species). These pathways are all dependent on cysteine-rich proteins, thus maintaining thiol-disulfide balance in this organelle is crucial for cellular functions. An IMS protein import pathway called the Mia40-Erv1 disulfide relay system uses disulfide bond formation for the import and retention of substrate proteins in the IMS. Erv1 is also suggested to be involved in maturation of cytosolic Fe-S cluster proteins and regulation of iron homeostasis in S. cerevisiae. However, these studies …

Illuminating The Interactions And Functions Of Glutaredoxins, Bola Proteins, And Erv1 In Iron Homeostasis, Adrian Colleen Dlouhy

Theses and Dissertations

Iron is a redox-active protein cofactor required for essential cellular functions such as respiration, however excess intracellular iron can generate damaging reactive oxygen species. Understanding how cells regulate iron levels is critical for treatment of human diseases that span from anemia to iron overload disorders. Glutaredoxins (Grxs) with a CGFS active site are highly conserved proteins shown to have roles in iron homeostasis and iron-sulfur cluster assembly, thus earning them the title “the Iron Whores”. They can exist either as a [2Fe-2S] cluster-bound dimer or an apo monomer, suggesting conservation of structure and function. In addition, Grxs interact with the …

Light Controlled Drug Activation And Release, Jonathon Sheldon

Theses and Dissertations

Cancer constitutes a terrible burden on modern society. In the United States there are an estimated 1,658,370 new cancer diagnoses resulting in 589,430 deaths in 2015 alone.^[1] An estimated 41,170 of these cases will be diagnosed right here in Virginia. With new cancer patients comes the expanding demand for new treatments. As we all know, many modern chemotherapeutics cause adverse reactions to patients. This is because the toxic nature of these therapies often affects normal tissue alongside the tumors that are infesting the body. Therefore, researching novel ways to make chemotherapeutics selective for cancer, while leaving healthy tissue unscathed, …

Dispersant Effects On Zinc Dialkyldithiophosphate (Zddp) Tribofilm Structure And Composition, Makaye Tabibi

Theses and Dissertations

For decades, global regulations and government mandates have driven technological developments to improve vehicle fuel economy. Tribological components found in all automotive engines contain metal-on-metal contact zones that may result in increased friction and wear, reducing overall engine efficiency. Lubricant additives such as antiwear and friction modifying components are added to motor oils to prevent some of the damages that may occur at contact zones and improve friction. The effects of other additive components, such as dispersants, that are prevalent in a lubricant additive package on the anti-wear layer remain relatively unknown. Polyisobutenyl Succinimide (PIBSI) dispersants were evaluated for their …

Heteroatom-Doped Nanoporous Carbons: Synthesis, Characterization And Application To Gas Storage And Separation, Babak Ashourirad

Theses and Dissertations

Activated carbons as emerging classes of porous materials have gained tremendous attention because of their versatile applications such as gas storage/separations sorbents, oxygen reduction reaction (ORR) catalysts and supercapacitor electrodes. This diversity originates from fascinating features such as low-cost, lightweight, thermal, chemical and physical stability as well as adjustable textural properties. More interestingly, sole heteroatom or combinations of various elements can be doped into their framework to modify the surface chemistry. Among all dopants, nitrogen as the most frequently used element, induces basicity and charge delocalization into the carbon network and enhances selective adsorption of CO₂. Transformation of …

Physicochemical And Structural Analysis Of Polymers As Putative Drugs, Meghan L. Thompson

Theses and Dissertations

Sulfated low molecular weight lignins (LMWLs) have shown good activity as anticoagulants by allosterically inhibiting thrombin, as well as promising agents for treating emphysema through inhibition of elastolysis, oxidation, and inflammation. Sulfated LMWLs are chemo-enzymatically synthesized from starting monomers caffeic, ferulic, and sinapic acid into sulfated dehydropolymers known as CDS, FDS, and SDS. To further the LMWLs’ development as drugs, their structural composition and physicochemical characteristics were defined in this work. The molecular weight distribution profile of the sulfated LMWLs from size exclusion chromatography performed on a high pressure liquid chromatography system (SEC-HPLC) changed from bimodal when no surfactant is …

Gas-Phase Reactions And Mechanistic Details Of Gold, Silver, And Iridium Complexes, Christopher Swift

Theses and Dissertations

The ever increasing demand for more efficient and environmentally benign routes for synthesizing target compounds, has led to the use of organometallic catalysts. This demand has created the need to understand the mechanistic details that are at work in these organometallic catalytic cycles. Along with this, there is a demand for new organometallic catalysts that are tailored for specific transformations. This presents a myriad of challenges for organometallic chemists. Unfortunately, it is often difficult to gain an understanding of the reaction mechanisms at work when the intermediates are too short lived to be observed in the condensed phase. It is …

Electronic Principles Governing The Stability And Reactivity Of Ligated Metal And Silicon Encapsulated Transition Metal Clusters, Marissa B. Abreu

Theses and Dissertations

A thorough understanding of the underlying electronic principles guiding the stability and reactivity of clusters has direct implications for the identification of stable clusters for incorporation into clusters-assembled materials with tunable properties. This work explores the electronic principles governing the stability and reactivity of two types of clusters: ligated metal clusters and silicon encapsulated transition metal clusters. In the first case, the reactivity of iodine-protected aluminum clusters, Al₁₃I_x^- (x=0-4) and Al₁₄I_y^- (y-0-5), with the protic species methanol was studied. The symmetrical ground states of Al₁₃I_x^- showed no reactivity …

Synthesis Of Unnatural Amino Acids For Genetic Encoding By The Pyrrolysyl-Trna/Rna Synthetase System, William A. Knight

Theses and Dissertations

The complexity of all biomolecules in existence today can be attributed to the variation of the amino acid repertoire. In nature, 20 canonical amino acids are translated to form these biomolecules, however, many of these amino acids have revealed posttranslational modifications (i.e. acetylation, methylation) after incorporation. Amino acids that exhibit PTM are known for their involvement in cellular processes such as DNA repair and DNA replication; these PTMs are commonly found on histones within the chromatin complex. Utilization of in vivo site-specific incorporation has recently reported functionality of post-translationally modified amino acids.1 xii Here we report the synthesis and in …

A Continuous Process Towards The Synthesis Of Quinolones, Stevara N. Clinton

Theses and Dissertations

Abstract

The development of quinolones is described from the first quinolone to the latest fluoroquinolones. Quinolones have generated considerable interest since their discovery because of their antibacterial capabilities. Analogs incorporating the 4-quinolone ring system comprise a largely expanding group of synthetic compounds. The development of antibacterial resistance has created the need for an efficient synthesis of quinolones that can be easily adapted toward the assembly of quinolone based antibacterial drugs.

There are several reported approaches to the 4-quinolone ring system. Many of these methods use expensive starting materials, require the removal of high boiling solvents, or use high temperature conditions …