Physical Sciences and Mathematics Commons^™

Water-Soluble Palladium, Copper, And Nickel Catalysts And Their Formation In Ligand-Free Suzuki-Miyaura Cross-Coupling Reactions, Priya Karna

Theses and Dissertations--Chemistry

Transition-metal catalyzed Suzuki-Miyaura (SM) cross coupling is a powerful synthetic method for constructing carbon-carbon and carbon-heteroatom bonds in designing organic compounds, agrochemicals, pharmaceuticals, and precursors for materials. However, the nature of catalysis and identity of the transition metal catalysts used in these reactions remain under debate or unknown. This dissertation reports the studies of three metals: Pd, Cu, and Ni. Pd-nanocluster catalysts and their formation in ligand-free SM reactions with Pd(II) nitrate as a precatalyst was investigated. The catalysts are water-soluble neutral Pd tetramer and trimer in their singlet electronic states as identified by UV-Vis absorption spectroscopy and are formed …

Design, Synthesis, And Anticancer Properties Of Ru(Ii) Complexes With Organometallic, “Expanded” Bipyridine, And O,O’-Chelating Ligands, Raphael Ryan

Theses and Dissertations--Chemistry

Cancer is a worldwide public health crisis that requires new and improved drugs to be developed to extend survival rates and improve quality of life for the patient. Platinum-based drugs are used in approximately 50% of cancer treatment regimens. These drugs are highly effective in many kinds of cancer; however, cancers can develop platinum resistance and these drugs have troubling side effects that reduced their use and efficacy. To overcome these disadvantages, many other metals have been studied for their anticancer properties. Notably, the anticancer properties of ruthenium-based agents have drawn considerable attention with multiple ruthenium complexes entering clinical trials. …

Developing Synthetic Strategies For Multifaceted Applications Of Stable Gold-Based Complexes, Randall Tyler Mertens

Theses and Dissertations--Chemistry

Development of stable gold-based complexes has been a rapidly advancing field due to the popularity of gold complexes, particularly for use in biomedical research and catalytic transformations. Given that auranofin, a gold(I) complex with FDA approval for the treatment of rheumatoid arthritis is used in the clinic, the development of stable gold-based molecules of clinical relevance is urgently needed. Herein are reported, synthetic strategies used for the development of new classes of gold(I) and gold(III) complexes for advancement in mitochondrial modulation for use as chemotherapeutics as well as application to gold catalysis due to the unique geometry of complexes presented …

Uncovering Structure-Property Relationships Of Inorganic Nanomaterials Via Transmission Electron Microscopy, Melonie Thomas

Theses and Dissertations--Chemistry

The rapid increase of research in nanoscale devices and nanotechnology in the past few decades has revealed that nanomaterials may possess exceptional properties that are significantly different from the bulk counterpart, due to local rearrangements of the atoms at surfaces and defects. Transmission electron microscopy (TEM) is an indispensable tool when it comes to the characterization of nanomaterials, primarily due to its ability to resolve the local-structure of materials at the atomic-scale. To study dynamic processes, however, regular TEM experiments are inadequate, as they provide only before and after information rather than the real-time data essential to understanding a reaction …

Designing Metal-Halide Perovskites With Enhanced Optical Properties And Stability Using Surface Ligands, Md Aslam Uddin

Theses and Dissertations--Chemistry

Metal-halide perovskites (MHPs), with formula ABX₃ (A = methylammonium, formamidinium, or Cs⁺; B = Sn²⁺ or Pb²⁺; and X = Cl^-, Br^-, or I^-) are versatile and attractive materials because of their tunable optical and electronic properties. These optical and electronic properties include tunable direct band gaps, high absorption coefficients, low exciton binding energies, relatively high electron and hole mobilities, narrow emission line-widths, and high photoluminescence (PL) quantum yields (Φ_PL). Much of the initial excitement around organic metal-halide perovskites focused on their application in photovoltaics (PVs) …

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle

Theses and Dissertations--Chemistry

This project was motivated by an in situ heating experiment in the transmission electron microscope (TEM) in which gold (Au) nanoparticles were observed to dissolve tin dioxide (SnO2) nanowires (NWs) under vacuum. The explanation for this observation was that the high-temperature and low-pressure environment of the TEM caused the reverse reaction of the well-known vapor-liquid-solid (VLS) method commonly used to grow NWs. In the VLS process, a metal catalyst absorbs reactant vapor until it becomes supersaturated. The precipitation of the NW occurs at the liquid-solid interface, which ceases when there is no longer reactant vapor, and the diameter of the …

Identification Of Adsorbate Ft-Ir Bands Using In-Situ Techniques: Pd Speciation And Adsorption Chemistry Of Pd-Zeolites For Passive Nox Adsorption, Robert Bruce Pace Iii

Theses and Dissertations--Chemistry

To meet increasingly stringent automotive emissions standards, further improvements in catalytic converter design are necessary. Current automotive catalyst systems are effective at eliminating emission of nitrogen oxides (NO_x) once the catalyst reaches operational temperature (~200 °C). NO_x emitted at lower catalyst temperatures now comprises most of the NO_x released during a typical test cycle. Referred to as “the cold start problem” this issue has come to the forefront of automotive catalyst development, as mitigating these emissions is necessary to further reduce automotive emissions. Passive NO_x adsorbers present an appealing solution to the cold start problem, …

Oxidative Depolymerization Of Lignin To Low Molecular Weight Aromatics, Yang Song

Theses and Dissertations--Chemistry

To date, most lignocellulosic biorefinery strategies have focused on optimizing conversion of cellulose to ethanol, leaving lignin as an underutilized biomass constituent. Lignin is engineered by nature with the intent to protect plants from chemical and biological attack; this leaves lignin with high structural irregularity and recalcitrance, rendering conversion of the lignin macromolecule to valuable products particularly challenging. Nevertheless, given that the economics of cellulosic ethanol production are strongly dependent on the value that can be obtained for the lignin co-product, the successful valorization of lignin is a crucial step in the transition towards a bio-based economy.

This thesis focuses …

Catalytic Conversion Of Monosaccharides Into 5-(Hydroxymethyl)Furfural In Ionic Liquids Using Aluminum Complexes Bearing Bidentate (Aminomethyl)Phenolate Ligands, Daudi Sayialel Saang'onyo

Theses and Dissertations--Chemistry

Currently, the major sources of fuel, energy, and chemicals are nonrenewable fossil resources such as petroleum, natural gas, and coal. Additionally, petroleum is used for the production of most transportation fuels and for the production of about 95% of organic chemicals. However, the production and use of non-renewable fossil fuels are unsustainable. For economic and environmental sustainability, there is a need to search for new and/or renewable resources and technologies for energy, fuels, and chemicals production that have the potential of effectively substituting fossil resources. In this context, lignocellulosic biomass is one of the candidates that meet these requirements due …

New Approaches To Cyclopentadienyl-Fused Thiophene Complexes Of Iron And Synthesis And Characterization Of Carbonic Anhydrase Active-Site Mimics For Co2 Hydration, Deepshikha Gupta

Theses and Dissertations--Chemistry

Polyheterocycles such as polythiophene and its derivatives comprise an important class of conducting polymers used for electronic applications. They have been of great interest for use in electronic materials due to their increased environmental stability as well as novel electronic properties in their polymer states. We have been interested in exploring the electronic properties of organometallic analogues of the low-band-gap polymer poly(benzo[3,4-c]thiophene) (polyisothianaphthene) that incorporates η⁵-cyclopenta[c]thienyl monomers such as ferroceno[c]thiophene. First chapter of this dissertation involved synthetic attempts to ferroceno[c]thiophene. Exploring a shorter synthetic route to starting material, 1,2-di(hydroxymethyl)ferrocene was …

Heterogeneous Catalytic Deoxygenation Of Lipids To Fuel-Like Hydrocarbons Over Improved Bimetallic Nickel Catalysts, Ryan Andrew Loe

Theses and Dissertations--Chemistry

Diminishing petroleum reserves and environmental considerations have strengthened the demand for developing renewable fuel technologies. One alternative is deoxygenating plant oils, animal fats, and waste lipid streams to fuel-like hydrocarbons. These fuels offer a drop-in replacement to petroleum products while potentially becoming carbon neutral, satisfying both fuel and environmental concerns. This fuel is obtained through catalytic deoxygenation via either hydrodeoxygenation (HDO) or decarboxylation/ decarbonylation (deCO_x). HDO requires problematic sulfided catalysts and extreme hydrogen pressures to convert lipids to fuel-like hydrocarbons. Therefore, this work focuses on the deCO_x pathway, where hydrogen is not required for deoxygenation to take …

Exploring The Structure And Properties Of Nanomaterials Using Advanced Electron Microscopy Techniques, Yao-Jen Chang

Theses and Dissertations--Chemistry

Nowadays people are relying on all kinds of electronic devices in their daily life. All these devices are getting smaller and lighter with longer battery life due to the improvement of nanotechnology and materials sciences. Electron microscopy (EM) plays a vital role in the evolution of materials characterization which shapes the technology in today’s life. In electron microscopy, electron beam is used as the illumination source instead of visible light used in traditional optical microscopy, the wavelength of an electron is about 10⁵ times shorter than visible light. By taking this advantage, the resolving power and magnification are greatly …

Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu

Theses and Dissertations--Chemistry

Metal oxides are of interest not only because of their huge abundance but also for their many applications such as for electrocatalysts, gas sensors, diodes, solar cells and lithium ion batteries (LIBs). Nano-sized metal oxides are especially desirable since they have larger surface-to-volume ratios advantageous for catalytic properties, and can display size and shape confinement properties such as magnetism. Thus, it is very important to explore the synthetic methods for these materials. It is essential, therefore, to understand the reaction mechanisms to create these materials, both on the nanoscale, and in real-time, to have design control of materials with desired …

Heterogeneous Base Metal Catalyzed Oxidative Depolymerization Of Lignin And Lignin Model Compounds, John Adam Jennings

Theses and Dissertations--Chemistry

With the dwindling availability of petroleum, focus has shifted to renewable energy sources such as lignocellulosic biomass. Lignocellulosic biomass is composed of three main constituents, lignin, cellulose and hemicellulose. Due to the low value of cellulosic ethanol, utilization of the lignin component is necessary for the realization of an economically sustainable biorefinery model. Once depolymerized, lignin has the potential to replace petroleum-derived molecules used as bulk and specialty aromatic chemicals. Numerous lignin depolymerization strategies focus on cleavage of β-aryl ether linkages, usually at high temperatures and under reductive conditions.

Alternatively, selective benzylic oxidation strategies have recently been explored for …

Arsenic Removal With A Dithiol Ligand Supported On Magnetic Nanoparticles, John Hamilton Walrod Ii

Theses and Dissertations--Chemistry

Exposure to arsenic (As) in water, the ubiquitous toxin that poses adverse health risks to tens of millions, is the result of both anthropogenic and geochemical mobilization. Despite recent publicity and an increased public awareness, the dangers associated with arsenic exposure rank among the top priorities of public health agencies globally. Existing sequestration applications mainly include reductions and adsorption with zero-valent metals and their oxides. The performance of adsorption media is known to preferentially favor aqueous As(V) over As(III) due to the charge of the dissolved oxyanion. Magnetic nanoparticles (MNP) have been the focus of multidisciplinary research efforts for the …

Interactions Of Compounds Containing Group 12 And 16 Elements, Daniel Burriss

Theses and Dissertations--Chemistry

The focus of this dissertation is on the interactions of compounds containing group 12 and 16 elements. This work is presented in three major parts. First, the interaction of the synthetic dithiol N,N’-bis(2-mercaptoethyl)isophthalamide), abbreviated BDTH₂, with selenite. Second, the interaction of cysteine with Cd(II) and the biologically relevant Cd-Cysteine crystal structure. Third, the green synthesis of CdSe quantum dots (QDs).

The interaction of BDTH₂ with selenite is different from the interactions with other metals and metalloids previously studied. Under ambient conditions, BDTH₂ is oxidized to the disulfide, BDT(S-S), while selenite is reduced to elemental selenium. However, …

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 …

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, …

Ceria Based Catalysts For Low Temperature NoX Storage And Release, Samantha Jones

Theses and Dissertations--Chemistry

Model ceria catalysts were evaluated for NOx storage and desorption performance under lean conditions. Three different storage temperatures (80 °C, 120 °C, and 160 °C) were utilized to evaluate NO_x storage. Higher temperatures resulted in higher NO_x storage. It was observed that storage of platinum promoted ceria resulted in higher NO_x storage compared to promotion with palladium. NO_x desorption behavior of platinum promoted ceria indicated that the majority of NO_x is released at high temperatures (> 350 °C), comparatively palladium promotion released more of the stored NO_x at lower temperatures. Diffuse Reflectance Infrared Fourier …

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 …

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, …

Investigation Into The Competitive Partitioning Of Dissociated H2 And D2 On Activated Fischer-Tropsch Catalysts, Wilson D. Shafer

Theses and Dissertations--Chemistry

The Fischer-Tropsch process, discovered in the early to mid-1920s, still has researchers disputing the C₁ monomer, and the rate-determining step. A tremendous amount of work, over the years, has focused on how hydrogen plays a role in the pseudo-polymerization of chain initiation and propagation, in an attempt to reveal the mechanism. These investigations attempted to elucidate the debated issues through studying the kinetic isotopic effect (KIE) for CO hydrogenation by switching the syngas from CO/H₂ to CO/D₂ during a steady-state period. Applying this switching step could result in a deviation in the rate of CO hydrogenation, indicating …

Ferrocene-Fused Derivatives Of Acenes, Tropones And Thiepins, Bidhya L. Maharjan

Theses and Dissertations--Chemistry

This research project is concentrated on tuning the properties of small organic molecules, namely polyacenes, tropones and thiepins, by incorporating redox-active transition metal centers π-bonded to terminal cyclopentadienyl ligands. Organometallic-fused acenequinones, tropones, thiepins and cyclopentadiene-capped polyacenes were synthesized and characterized. This work was divided into three parts: first, the synthesis of ferrocene-fused acenequinones, cyclopentadiene-capped acenequinones and their subsequent aromatization to polyacenes; second, the synthesis of ferrocene-fused tropones, thiotropones and tropone oxime; and third, the synthesis of ferrocene-fused thiepins. Ferrocene-fused quinones are the precursors to our target complexes. Our synthetic route to ferrocenequinones involved two-fold aldol condensation between 1,2-diformylferrocene and naphthalene-1,4-diol …

Salen Aluminum Compounds In The Dealkylation And Detection Of Organophosphates, Rahul R. Butala

Theses and Dissertations--Chemistry

The focus of this dissertation is the use of aluminum Schiff base compounds, Salen(^tBu)AlBr (SAB), in the dealkylation and detection of organophosphates (OPs). Three SAB compounds, Salen(^tBu)AlBr (1), Salpen(^tBu)AlBr (2), and Salophen(^tBu)AlBr (3) were used to dealkylate a variety of trialkyl OPs. These reactions lead to unique organic-soluble aluminum phosphate compounds containing six-coordinate aluminum. Examples include [salen(^tBu)AlOP(O)(OCH₃)₂]_n (4), [salen(^tBu)AlOP(O)(OCH₂CH₃)₂]_n (5), [salen(^tBu)AlOP(O)(OPh)₂]_{n …}

Electron And Ion Spectroscopy Of Metal Hydrocarbon Complexes, Sudesh Kumari

Theses and Dissertations--Chemistry

Metal-hydrocarbon complexes were prepared in a laser-vaporization molecular beam source and studied by single-photon zero electron kinetic energy (ZEKE) and mass-analyzed threshold ionization (MATI) spectroscopy. The ionization energies and vibrational frequencies of the metal complexes were measured from the ZEKE and MATI spectra. Metal-ligand bonding and low-lying electronic states of the neutral and ionized complexes were analyzed by combining the spectroscopic measurements with quantum chemical calculations and spectral simulations.

In this dissertation, the metal complexes of mesitylene, aniline, cyclooctatetraene, benzene, ethene, and propene were studied. For each complex, different effects from metal coordination have been identified. Although metal-bis(mesitylene) sandwich complexes …

Hydrogenation And Hydrogenolysis Of Furan Derivatives Using Bipyridine-Based Electrophilic Ruthenium(Ii) Catalysts, Anitha Shankaralinge Gowda

Theses and Dissertations--Chemistry

The catalytic activity of ruthenium(II) bis(diimine) complexes cis-[Ru(6,6′-Cl₂bpy)₂(OH₂)₂](Z)₂ (2, Z = CF₃SO₃; 3, Z = (3,5-(CF₃)₂C₆H₃)₄B ,i.e. BArF), cis-[Ru(4,4′-Cl₂bpy)₂(OH₂)₂](Z)₂ (4, Z = CF₃SO₃; 5, Z = BArF) and cis-[Ru(bpy)₂(PR₃)(OH₂)](CF₃SO₃)₂ (7, bpy = 2,2’-bipyridine, PR₃ = P(C₆H₄F)_{3 …}

Preparation, Characterization And Applications Of Functionalized Carbon Nano-Onions, Mahendra K. Sreeramoju

Theses and Dissertations--Chemistry

Carbon nano-onions (CNOs) discovered by Ugarte in 1992 are multi-layered fullerenes that are spherical analogs of multi-walled carbon nanotubes with diameters varying from 6 nm to 30 nm. Among the various methods of synthesis, CNOs prepared by graphitization of nanodiamonds (N-CNOs) and underwater electric arc of graphite rods (A-CNOs) are the subject of our research. N-CNOs are considered as more reactive than A-CNOs due to their smaller size, high curvature and surface defects.

This dissertation focuses on structural analysis and surface functionalization of N- CNOs with diameters ranging from 6—10 nm. Synthetic approaches such as oleum- assisted oxidation, Freidel-Crafts acylation …

Physicochemical Modifications And Applications Of Carbon Nano-Onions For Electrochemical Energy Storage, Rituraj Borgohain

Theses and Dissertations--Chemistry

Carbon nano-onions (CNOs), concentrically multilayered fullerenes, are prepared by several different methods. We are studying the properties of two specific CNOs: A-CNOs and N-CNOs. A-CNOs are synthesized by underwater arc discharge, and N-CNOs are synthesized by high-temperature graphitization of commercial nanodiamond. In this study the synthesis of A-CNOs are optimized by designing an arc discharge aparatus to control the arc plasma. Moreover other synthesis parameters such as arc power, duty cycles, temperature, graphitic and metal impurities are controlled for optimum production of A-CNOs. Also, a very efficient purification method is developed to screen out A-CNOs from carboneseous and metal impurities. …