Chemistry Commons^™

Gas Phase C-H And C-C Bond Activation By Ternary Metal Complexes, Kevin Parker

Graduate Research Theses & Dissertations

The activation of relatively inert C-H bonds has remained a challenge in organic chemistry for over a century. Metal catalysts have been deployed to overcome the labile reactivity of these bonds and through gas-phase studies, detailed mechanisms can be elucidated for this important class of chemistry. The powerful combination of ion-molecule reactions, collisional activation of ions, and density functional theory calculations allows for structural elucidation, intermediate determination, and as shown throughout this work, a complete picture of catalytic processes. Modified linear ion-trap mass spectrometers were used to trap and generate reactive intermediates of the form [(L)(M)(X)]+ (L= auxiliary ligand; M= …

Novel Modes Of Synchronization And Extreme Events In Coupled Chemical Oscillators, David Allen Mersing

Graduate Theses, Dissertations, and Problem Reports (ETD)

We experimentally and computationally investigate dynamical behaviors in coupled chemical oscillators. These networks of chemical oscillators are created using catalytic Ru(bpy)₃²⁺ loaded cation exchange beads submerged in catalyst-free Belousov-Zhabotinsky (BZ) solutions. Various network structures are created by utilizing the photosensitive nature of the Ru(bpy) ₃²⁺ catalyst. The response of the oscillators due to light stimuli can be characterized by constructing a phase response curve (PRC). The PRC quantifies the excitatory and inhibitory responses of BZ oscillators due to applied light perturbations as a function of the oscillators' phase. Different initial concentrations of reactants in the BZ reaction …

Study Of Resonantly Stabilized Radicals In Combustion Environments, James H. Lee

Graduate Theses, Dissertations, and Problem Reports (ETD)

Resonantly stabilized radicals (RSRs) play an important role in combustion environments due to their high stability resulting from resonance. Many RSRs such as the propargyl, allyl, or benzyl radicals are precursors to the formation of polycyclic aromatic hydrocarbons (PAHs), which can aggregate to form soot. Due to their stability, these RSRs can accumulate in combustion environments in significant quantities. The primary way these radical species are consumed in flames or by reactions with other abundant radicals, by self-recombination of propargyl to form benzene, or in the form of other abundant radicals such as the hydroxyl radical. Experimentally determining the pathways …

Identifying And Minimizing Sources Of Variability Within Modern Spectroscopic Techniques For The Forensic Analysis Of Glass, Oriana Christy Ovide

Graduate Theses, Dissertations, and Problem Reports (ETD)

Broken glass is a trace material frequently found at crime scenes such as hit-and-runs, burglaries, assaults, and homicides. Existing research encompassing the forensic analysis of glass evidence is vast. Published studies cover the analysis and interpretation of various types of glass. However, organizations such as the National Institute of Justice (NIJ), National Institute of Standards and Technology Organization of Scientific Area Committees (NIST-OSAC), and American Society of Trace Evidence Examiners (ASTEE) continue to identify glass-specific research needs to strengthen the scientific foundations of the field. Current gaps within the forensic glass community involve understanding modern glass formulations, re-evaluating the performance …

Analysis Of Forensically Relevant Evidence Using Electrochemistry, Spectroscopy, And Mass Spectrometry Tools, Colby Edward Ott

Graduate Theses, Dissertations, and Problem Reports (ETD)

Forensic science relies on the use of multiple techniques in the assessment of evidence to increase the accuracy and reliability of the results. However, with the rapidly changing drug landscape due to the introduction of novel psychoactive substances, many traditional screening methods are no longer sensitive or selective enough for use. Additionally, many screening methods such as chemical color tests are prone to false positive and negative results and are subjective. Therefore, the goal of this dissertation was to develop a novel analytical scheme that can provide a more efficient, rapid, and sensitive method that will facilitate adoption in the …

Photocatalytic Degradation Of Lignin By Supported Silver Nanoparticles, Ning Wei

Theses and Dissertations--Chemical and Materials Engineering

Lignin is the second most abundant form of biomass on earth. The phenolic structure and high carbon to oxygen ratio make lignin an attractive renewable source of fuel and chemicals. However, its recalcitrance and heterogeneous nature prove difficult for decomposing lignin’s polymer structure and separation of the products. This work has focused on the use of low-energy catalytic approaches to overcome these barriers. A mimic of the lignin degrading enzyme laccase, consisting of a copper cluster Cu4Py4I4 modified with AgNO3, was developed to function similarly to the laccase active site. The prepared copper complex solution was found to be active …

Efficient Removal Of Lead Ions From Aqueous Media Using Sustainable Sources On Marine Algae, Hannah Namkoong, Erik Biehler, Gon Namkoong, Tarek M. Abdel-Fattah

Electrical & Computer Engineering Faculty Publications

The goal of this project is to explore a new method to efficiently remove Pb(II) ions from water by processing Undaria pinnatifida into immobilized beads using sodium alginate and calcium chloride. The resulting biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Using immobilized U. pinnatifida, we investigated the effect of various factors on Pb(II) ion removal efficiency such as temperature, pH, ionic strength, time, and underlying biosorption mechanisms. For Pb(II) ion biosorption studies, Pb(II) ion biosorption data were obtained and analyzed using Langmuir and Freundlich adsorption models. It …

Hybridization From Guest-Host Interactions Reduces The Thermal Conductivity Of Metal-Organic Frameworks, Mallory E. Decoster, Hasan Babaei, Sangeun S. Jung, Zeinab M. Hassan, John T. Gaskins, Ashutosh Giri, Emma M. Tiernan, John A. Tomko, Helmut Baumgart, Pamela M. Norris, Alan J.H. Mcgaughey, Christopher E. Wilmer, Engelbert Redel, Gaurav Giri, Patrick E. Hopkins

Electrical & Computer Engineering Faculty Publications

We experimentally and theoretically investigate the thermal conductivity and mechanical properties of polycrystalline HKUST-1 metal–organic frameworks (MOFs) infiltrated with three guest molecules: tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), and (cyclohexane-1,4-diylidene)dimalononitrile (H4-TCNQ). This allows for modification of the interaction strength between the guest and host, presenting an opportunity to study the fundamental atomic scale mechanisms of how guest molecules impact the thermal conductivity of large unit cell porous crystals. The thermal conductivities of the guest@MOF systems decrease significantly, by on average a factor of 4, for all infiltrated samples as compared to the uninfiltrated, pristine HKUST-1. This reduction in thermal conductivity goes in …

Oxidative Damage To Brain Cells Underlies: (I) Resistance To Radiation And Increased Tumor Cell Growth In Glioblastoma; (Ii) Apoe Allele Status And Pentose Phosphate Pathway Proteins In Alzheimer Disease Mouse Models, Nicole Rummel

Theses and Dissertations--Chemistry

Oxidative phosphorylation occurs within the inner mitochondrial membrane producing ATP for the cell’s energy needs. The Electron Transport Chain carries out the transfer of electrons from electron carriers through a series of proteins to form a proton gradient across the inner mitochondrial membrane. This gradient acts as the energy source needed to put a phosphate onto ADP and form ATP. With the large amounts of free electrons and oxygen within the mitochondria, an inevitable by-product of free radicals in the form of superoxide are produced. Superoxide (O^-̇₂) is a reactive radical that can react further to …

Synthesis Of 6,6- And 7,7-Difluoro-1-Acetamidopyrrolizidines And Their Oxidation Catalyzed By The Nonheme Fe Oxygenase Lolo, Nabin Panth

Theses and Dissertations--Chemistry

One of the remarkable steps in loline alkaloid biosynthesis is the installation of an ether bridge between two unactivated C atoms in 1-exo-acetamidopyrrolizidine (AcAP). LolO, a 2-oxoglutarate-dependent nonheme Fe oxygenase, catalyzes both the hydroxylation of AcAP and the resulting alcohol's cycloetherification to give N-acetylnornoline (NANL). The mechanism of hydroxylation is well understood, but the mechanism of the oxacyclization is not. I synthesized difluorinated analogs of AcAP in an attempt to further understand the mechanism of the unusual cycloetherification step.

I prepared 6,6-F₂-AcAP in eight steps from N,O-protected 4-oxoproline. The key step was a Dieckmann …

Crystal Engineering Of Asymmetric And Pyrene Fused Annulenes For Use In Organic Electronic Materials, Garrett Fregoso

Theses and Dissertations--Chemistry

Since the development of TiPS Pentacene, the use of trialkylsilylethynyl groups has become a commonly utilized moiety for stabilizing, solubilizing, and directing crystal packing of acenes and acene-like compounds, leading to the development of a well-defined series of trends that aid in the prediction of crystal packing for the development of organic semiconducting materials. While these trends have been extensively studied in mainly symmetric linear systems, it is important to determine how, if at all, asymmetry of the aromatic core affects these well-defined trends. This constitutes the basis of Chapter 2, which explores the crystal engineering and physical properties of …

Mass Spectrometric Analysis Of Lignin Model Compounds: Fundamental Investigations Of Ionization And Supramolecular Interactions For Lignocellulosic Biomass Applications, Kimberly Dean

Theses and Dissertations--Chemistry

Lignocellulosic biomass is pivotal for the development of renewable energy sources and materials essential to mitigate the exploitation of fossil fuels causing climate change and environmental pollution issues. The conversion of biomass into fuel requires the hydrolysis of cellulose and a biproduct of this process is the isolation of millions of tons of lignin as biorefinery waste. Lignin is a complex high molecular weight polymer whose structure remains undefined and critically limits potential industrial applications of lignocellulosic biomass. The advancement of analytical methods for structural elucidation of lignin and its ensemble of phenolic compounds is therefore essential to advance this …

The Role Of Charge On Dna Packaging And Integrity Within Reconstituted Peptide-Dna Assemblies, Ehigbai Oikeh

Theses and Dissertations--Chemistry

In nature, DNA exists primarily in a highly compacted form. The compaction of DNA in vivo is mediated by cationic proteins; histone in somatic nuclei and arginine-rich peptides called protamines in sperm chromatin. The packaging in the sperm nucleus is significantly higher than somatic nuclei resulting in a final volume roughly 1/20^th that of a somatic nucleus. This tight packaging results in a near crystalline packaging of the DNA helices. While the dense packaging of DNA in sperm nuclei is considered essential for both efficient genetic delivery as well as DNA protection against damage by mutagens and oxidative species, …

Development Of Fluorescence Based Approaches To Understand Astrocyte Biology In The Context Of Nicotine And Nicotinic Receptor Activity, Surya P. Aryal

Theses and Dissertations--Chemistry

Smoking and tobacco use (STU) is a major global health problem and worldwide more than six million people die due to tobacco related diseases each year. Although majority of smokers try to quit smoking several times in their life, traditional therapeutic approaches, which focus only on neuronal cells, have a very low success rate. Understanding the effect of nicotine on glial cells, synaptic communication and blood vasculature in the brain can provide further insights on the neurobiology of substance abuse and can potentially help to design better therapeutic approaches. Glial cells are non-excitable cells in the brain which do not …

Application Of Mass Spectrometry For Characterization Of Plant-Based Phenolics And Alkaloids, Masoumeh Dorrani

Theses and Dissertations--Chemistry

Plant-derived compounds have the potential to produce value-added compounds with a variety of applications. For example, the lignin part of the lignocellulosic biomass, produced in large quantities as waste from the paper and pulp industries, is a rich source of phenolics with potential applications in the renewable energy sector, pharmaceutical, and chemical industries. On the other hand, plant alkaloids are the primary source for developing plant-derived therapeutics. Unfortunately, the recalcitrant nature of plant cell walls, low extraction yields of small secondary metabolites, and the lack of effective analytical methods for a rapid and accurate identification of plant-based compounds and plant’s …

Nanomaterial Synthesis And Real Time Investigation Of Thermal Effects On Nanomaterial And Nano-Interfaces For Real World Applications, Rose H. Pham

Theses and Dissertations--Chemistry

As interest in nanomaterials and nanotechnology continues to grow, so does the need for more efficient and economical synthesis methods to keep up with the demand. The applications for nanomaterials are seemingly endless as they have functions in energy, biomedical, environmental, and many more. Working to develop different morphologies and sizes of nanomaterials will further help expand its utility. With the use of advanced characterization techniques such as in situ transmission electron microscopy (TEM), real time studies on the effects of external forces on nanomaterials are possible under controlled environments. This will give insight on how nanomaterials will perform in …

Development Of Ph-Sensitive And Amine-Reactive Lifters For The Detection Of Latent Fingermarks, Andrei Gregory Mlakar

Graduate Research Theses & Dissertations

Latent fingermarks are among the most common forms of physical evidence left at crime scenes. Being composed largely of eccrine and sebaceous secretions, they are typically invisible unless they are treated with, e.g., powders or cyanoacrylate fumes. Drawbacks to these and other commonly used methods, however, may include limited substrate compatibility, safety hazards, inability to detect older marks, and the need for expensive instrumentation and expert practitioners. Fingermarks on curved, reflective, patterned, or luminescent substrates are particularly challenging to image with most common techniques. After treatment, fingermarks on such difficult substrates may be transferred to, or “lifted” by, flexible adhesives, …

Interfacial Electrochemistry In Metallic Film Fabrication, Eric S. Tuala

Masters Theses

An experimental determination of RC constant at the edge and the center of a disk electrode was done using in situ reflectance spectroscopy on a Au electrode immersed in HClO₄ as electrolyte. The RC constant at the edge of the disk electrode was found much smaller than that at the center. Such differences contribute to the selective removal of the deposited Cu on an Au disk electrode.

Furthermore, the electrochemical corrosion of Cu²⁺ towards Co electrode (called cementation reaction) was investigated using a Co/Pt rotating disk electrode. The Open Circuit Potential of Co electrode in CuSO₄ electrolyte …

A Study Of Π – Π Stacking Interactions In Rhenium Carbonyl Complexes Based On Backbone Functionalized Bis(Pyrazolyl)Methane Ligands, Balamani Guduru

Masters Theses

π – π Stacking interactions are one of the most important non-covalent inter-molecular forces, which play an important role in the architecture of 1D and 2D networks of supramolecular chemistry. This associative contact involves the attractive interactions of aromatic molecules with each other. To describe and study the strength of the π – π stacking interactions, four new bis(pyrazolyl)ethanamine ligands having different aromatic groups (1-pyrenyl, 1-naphthyl, 2-naphthyl, and 9-anthracenyl) known for their propensity to be involved in π – π stacking interactions were prepared by the reaction of one equivalent of bis(pyrazolyl)ethanamine with one equivalent of the corresponding aromatic aldehyde. …

Synthesis And In Situ Characterization Of Intercalated Transition Metal Oxide Nanomaterials Investigated For Novel Cathode Applications, Ahamed Ullah

Theses and Dissertations--Chemistry

To develop an effective battery cathode material that can be useful for future batteries, the thermal stability and ion diffusion dynamics need to be well understood. In situ transmission electron microscopy (TEM) is a popular and proven technique to study the evolution of local structures during the dynamic processes in the cathode materials. This dissertation will demonstrate the application of high-resolution imaging and in situ heating and biasing in the TEM to study the structure and composition, morphology change, and ion diffusion in the cathode materials.

The three chapters in this dissertation will be focused on the two cathode materials: …

Fundamental Study Of Dopant Effect And Toxicity In Perovskite Materials, Xun Li

Graduate Research Theses & Dissertations

This dissertation comprehensively studies the research on organic-inorganic hybrid perovskite to solve the toxicity issue of perovskite-based solar cells under practical conditions, understand the doping effect on hybrid perovskite materials in optoelectronic applications, and improve the photovoltaic performance of perovskite-based solar cells by composition tailoring. Specifically, an innovative and simple chemical approach was invented for on-device sequestration of toxic Pb leakage caused by severe device damage. To mimic the practical conditions, the sequestration of lead leakage was conducted under cold water, warm water, acid water, dripping water, and water with competitive ions. Crucially, it was found that at least 96% …

The Design And Synthesis Of New Organic Dithiols For Environmental Applications, Shashika Nadishani Bandara

Theses and Dissertations--Chemistry

A thiol molecule, 2,6-pyridinediamidoethanethiol (PB9), was synthesized based on the pyridine-2,6-dicarboxamide scaffold with appended cysteamine groups. PB9 acts as an effective chelator for Pb(II) due to multiple binding sites (N₃S₂) through irreversible binding precipitating Pb(II). Removal of aqueous Pb(II) from solution was demonstrated by exploring the effects of time, initial PB9:Pb(II) ratios, pH, exposure time, and solution temperature. After 15 min the Pb(II) concentrations were reduced from 50.00 ppm to 0.30 ppm (99.4%) and 0.25 ppm (99.5%) for PB9:Pb ratios of 1:1 and 2:1, respectively. Removal of > 93% Pb(II) was observed over multiple pH values with …

1,2-Diamination Of Alkenes Via Reduction Of 1,2,3-Triazolinium Ions, Setareh Saryazdi

Theses and Dissertations--Chemistry

1,2-Diamine substructures are prevalent functional motifs in natural products, pharmaceutical compounds, and ligands. The interesting functionalities of 1,2-diamines have inspired many synthetic chemists to design various methodologies for preparing these structures from simple precursors such as alkenes. In this work, we described two different but related methods using simple and easily accessible reagents for 1,2-diamination of alkenes. In the first method, an alkene undergoes 1,3-dipolar cycloaddition with an organic azide to form a 1,2,3-triazoline. Subsequent N-alkylation of the generated 1,2,3-triazoline gives the 1,2,3-triazolinium ion, which is then hydrogenated over Raney Ni with a balloon of H₂ to produce …

Assembly Mechanism Of Early Hsp90-Cdc37-Kinase Complexes, Dimitra Keramisanou, M.V. Vasantha Kumar, Nicole Boose, Rinat R. Abzalimov, Ioannis Gelis

Advanced Science Research Center

Molecular chaperones have an essential role for the maintenance of a balanced protein homeostasis. Here, we investigate how protein kinases are recruited and loaded to the Hsp90-Cdc37 complex, the first step during Hsp90-mediated chaperoning that leads to enhanced client kinase stability and activation. We show that conformational dynamics of all partners is a critical feature of the underlying loading mechanism. The kinome co-chaperone Cdc37 exists primarily in a dynamic extended conformation but samples a low-populated, well-defined compact structure. Exchange between these two states is maintained in an assembled Hsp90-Cdc37 complex and is necessary for substrate loading. Breathing motions at the …

Genomic Analysis Of Pollen Grains For Forensic Applications, Luz Kelley

Electronic Theses and Dissertations, 2020-2023

With over 300,000 plant species on the planet and more than 90% of them relying on pollen for reproduction, palynology, the study of pollen grains plays a vital role in many research fields. One of them is forensic palynology, which uses pollen as a proxy to link individuals or objects to a location or instance. It relies on the fact that (1) pollen is an ever-present feature of the environment; (2) different locations have different pollen signatures, allowing for inference related to spatial tracking; (3) plants bloom at different times, allowing for temporal inference; and (4) pollen is exceptionally durable …

Density Functional Theory Of Samarium(Ii) Reactivity In Thf And Water, Parisa Fasihianifard

Dissertations and Theses

Sm(II) diiodide is widely used in organic synthesis for the reduction of functional groups such as esters, anhydrides, amides, carbonyls, and arenes. Moreover, in aqueous systems and in mixtures of water and THF, the addition of Sm(II) diiodide can reduce water directly resulting in the formation of hydrogen gas. However, the mechanism of these reactions is not completely understood, making it difficult to improve experimental design. The reaction can proceed either through subsequent electron-transfer proton-transfer (ET-PT), subsequent proton transfer electron-transfer (PT-ET), or via proton coupled electron transfer (PCET). Density functional theory (DFT) calculations were performed to understand the speciation of …

Computational Study On The Nucleation Of Polyoxovanadate-Alkoxide Clusters, S M Gulam Rabbani

Dissertations and Theses

Polyoxovanadate-alkoxide (POV-alkoxide) clusters are a new class of electroactive species with potential electrochemical applications in redox catalysis, energy storage, and optoelectronics. These clusters' redox properties can be tuned by the functionalization via heterometallic installation and changing alkoxide ligands. However, the formation mechanism of these POV-alkoxides in the solvothermal process is unknown, limiting the rational design to improve their electronic properties. This dissertation reports the speciation study of POV-alkoxide clusters, which is fundamental to controlling and manipulating the evolution of transient species during their nucleation and tuning the final product's properties. Chapter 2 and chapter 3 describe our computational study of …

Semiconducting Polymer Dots-Based Ratiometric Fluorescent Probes For Detection Of Biomarkers, Shuyi He

Dissertations and Theses

Biomarkers serve a key role in illness diagnosis and treatment. Importantly, early detection can boost the therapy success rate greatly. However, traditional approaches to detect biomarkers based on fluorescence intensity changes of individual fluorophores did not completely realize the potential due to several technical problems such as low sensitivity. Ratiometric fluorescent methods use changes in the intensity of two or more emission bands (caused by the analyte) to create an internal reference that improves detection sensitivity. Due to their unique photophysical properties, such as high fluorescence intensity, high quantum yield, and low toxicity, semiconductor quantum dots (Pdots) are an ideal …

Synthesis And Characterization Of Ruthenium Complexes And Their Potential And Photosensitizers For Photodynamic Therapy, Keit Dine

Master's Theses

Cancer is one of the leading causes of death in the world with over 10 million people dying of the disease every year. Inorganic complexes supported by platinum metal centers are often used in cancer treatment. However, these complexes lack selectivity for tumor cells. As such, other alternatives to platinum have been explored. Ruthenium (Ru) complexes are one of the most promising candidates due to their ability to be used as photosensitizing drugs in photodynamic therapy. Herein, we report the design, synthesis, and characterization of two novel ruthenium-based complexes. One compound is a Ru(II) homoleptic complex, while the other is …

Gas-Phase Acid-Base Properties And Conformations Of Oligopeptides Through Mass Spectrometry And Computational Studies, Yuntao Zhang

University of the Pacific Theses and Dissertations

This dissertation presents a comprehensive study of the peptides of interest to deeper understand the gas-phase acid-base properties in relation to their conformations and chirality. In the first part of the study, two pairs of alanine (A)-based isomeric peptides consisting of a basic probe, lysine (Lys) or 2,3-diaminopropionic acid (Dap), were investigated to understand the nature of the enhanced basicity when the basic probe was moved from the N-terminus to the C-terminus. In the second part of the study, alanine-based peptides containing a cysteine (C) as the acidic probe were investigated to understand the chirality effects on the gas-phase acidity …