Chemistry Commons^™

Arylation Of Nitrogen, Oxygen And Carbon Nucleophiles By Aryl(Tmp)Iodonium Salts, Joseph Jordan Hatton

Dissertations and Theses

Substituted aromatic rings are present in industry in a plethora of organic molecules such as pharmaceuticals, agrochemicals, materials and beyond. Therefore, methods for broadly installing aryl rings into other compounds to create substituted aromatic rings are valuable to many organic chemists. Historically these transformations are achieved through methods such as nucleophilic aromatic substitution and metal catalyzed cross-coupling. Nucleophilic aromatic substitution is a user-friendly method in this space but is limited by reliance on specific electronics. Metal catalyzed cross-coupling reduced the dependence on electronics in this space, but metals are generally unattractive reagents due to high costs, toxicity and challenges with …

Iron(Ii)/Cobalt(Ii)-Mediated Silicon And Carbon Quantum Dots For Nanozyme Activity And Fluorescence Sensing Of Hydrogen Peroxide And Glucose, Kang Qin

Dissertations and Theses

Silicon quantum dots (SiQDs) and carbon quantum dots (CQDs) have been widely studied as fluorescent nanomaterials for sensing applications. In this thesis, we developed two different nanomaterials, SiQDs and CQDs, and investigated their catalytic activities and applied them for the detection of hydrogen peroxide and glucose. In the first project, Co2+-mediated SiQDs were synthesized through a hydrothermal method. The obtained nanoparticles showed obvious peroxidase-like activity toward the oxidation of tetramethylbenzidine (TMB) in the presence of H2O2 under acidic conditions. Moreover, a weak oxidation of TMB was also observed without H2O2, suggesting the existence of oxidase-like activity. To better understand the …

A Dual-Emission Polymer-Dots/Gold-Nanoclusters Nanohybrid For Ratiometric Fluorescence Detection Of Hg²⁺, Sha Wu

Dissertations and Theses

Heavy metals, such as Hg, Cd, Pb, and Cr, become a serious environmental problem because they are highly toxic, bioaccumulation, and long-term persistence, required a high sensitivity and selectivity detection method. Although laboratory testing instruments, such as inductively coupled plasma mass spectrometry, offer high sensitivity, their practical application is limited because they rely on large-scale equipment and complex sample pre-treatment processes. Single-emission fluorescence probes are simpler but can be affected by variations in probe concentration, excitation intensity, and measurement conditions. In this study, a dual-emission nanohybrid that consists of poly(9,9-di-n-hexylfluorenyl-2,7-diyl) (PDHF) and bovine serum albumin (BSA), termed as PDHF-Pdots/BSA-AuNCs nanohybrid, …

Mechanistic Rationale For Toxic Aerosol Formation From Vaping And Dabbing With A Focus On Ketene Formation From Semi-Synthetic Cannabinoids, Kaelas Ryan Munger

Dissertations and Theses

Cannabis vaping is a relatively new route of administration that is increasingly common among youth and young adults. Cannabis vaping has been associated with cases of acute lung injury, especially among youth, and most often involves the heating and aerosolization of high-potency products having cannabinoid concentrations of ~ 50 % - 98 % w/w. Proponents argue that vaping is safer than smoking due to the characteristically lower temperatures and fewer plant materials. However, the extreme cannabinoid concentrations, along with non-natural formulations having undisclosed additives, require studies of the health effects of these products. Despite the popularity of cannabis concentrate vaping, …

Investigation Into Thermodynamic And Kinetic Phenomena In Arylation Reactions With Diaryliodonium Salts, Soocheta Jha

Dissertations and Theses

Benzenoid rings are fundamental structural motifs in organic chemistry, widely recognized for their prevalence in natural products, pharmaceuticals, agrochemicals, and functional materials. Transition metal-catalyzed arylation, using catalysts such as palladium, nickel, or copper, has revolutionized C-C, C-O, and C-N bond formation, offering broad substrate scope and high efficiency. Among the reagents developed for efficient aryl group transfer, diaryliodonium salts have emerged as particularly powerful tools. Diaryliodonium salts facilitate metal-free arylations across a broad spectrum of nucleophiles, offering high reactivity, operational simplicity and environmental compatibility. The versatility of diaryliodonium salts has led to their widespread adoption as efficient arylating reagent in …

Enabling New Synthetic Platforms For Aryne Synthesis With Aryl Thianthrenium Reagents, Riley Augustus Roberts

Dissertations and Theses

The enormous importance of aromatic rings in organic molecules cannot be understated. Aromatic rings are present in the majority of pharmaceuticals, agrochemicals, and consumer products. The way in which these rings are arranged and substituted results in a molecule’s unique properties. Because of this, the current limitations of the chemical methods used to synthesize these molecules results in limited structural diversity and thus missed opportunities for the development of value-added products. To this end, this work demonstrates novel methods of aryne synthesis, aryl thianthrenium synthesis and a unique approach to structural scaffold hopping. The approaches presented herein allow for rapid …

The Role Of Homocysteine Redox Chemistry In Biomolecular Mechanisms, Megha Gupta

Dissertations and Theses

Homocysteine at elevated levels is a well-known independent risk factor for cardiovascular disease. However, it is still unclear, after large scale clinical trials, involving tens of thousands of patients, whether homocysteine is a disease mediator or marker. The disconnect between the basic science showing the association of homocysteine with cardiovascular disease and the outcomes of clinical trials based on vitamin therapy for homocysteine lowering, highlights the need for insights into the molecular mechanisms linking homocysteine to cardiovascular disease and other pathologies. For example, elevated homocysteine levels have also been associated with risk for stroke, venous thromboembolism, Alzheimer's disease, neural tube …

Photocathodes From Aerobic Oxidation Of Tellurorhodamines, Amelia Jellison

Dissertations and Theses

Growing environmental concerns have facilitated an increased need for renewable energy. Solar energy is an excellent source of renewable energy, however current dye-sensitized solar cells are not efficient enough for commercial use. This thesis attempts to create a novel dye-sensitized cathode to increase the efficiency of dye-sensitized solar cells.

Dye-sensitized cathodes could lower the energy level on the cathode and thereby increase the overall efficiency of the solar cell, however until now it has not been attempted. A tellurorhodamine dye with a mesityl ring was chosen as the dye for its ability to aerobically oxidize in the presence of light. …

Explorations Of Dna-Single-Walled Carbon Nanotube Interactions To Develop Multiplexed Molecularly Specific Biosensors For Inflammation, Amelia K. Ryan

Dissertations and Theses

Inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-12 (IL-12) are central regulators of immune signaling and key biomarkers of disease, yet existing assays for their detection remain slow, invasive, and lack multiplexing ability. This dissertation advances the development of single-walled carbon nanotube (SWCNT) optical nanosensors capable of real-time, multiplexed, and molecularly specific cytokine detection through innovative use of single-stranded DNA (ssDNA) interfaces.

First, an IL-6-specific DNA aptamer was employed as both a dispersing agent and recognition probe for SWCNT fluorescence sensing. Sequence modifications, including anchor domains, truncations, and thermally induced refolding, were systematically tested to optimize sensitivity and selectivity. The …

Hydrogen Peroxide Production From Light-Driven Water Oxidation Via Nickel Oxide-Titanium Dioxide Heteronanocrystals, Mahfuz Ahammed Swadhen

Dissertations and Theses

High dependence on fossil fuels for energy carries risks for the environment, health, energy, and geopolitical stability. One of the solutions to address this is solar energy utilization, and the use of semiconductors for photocatalytic water splitting is a tantalizing prospect. An n-type semiconductor TiO2 combined with p-type NiO producing a heteronanojunction shows effective light-driven oxidation of H2O into H2O2. We developed a synthetic method to attach NiO nanoparticles on the surface of anatase TiO2 nanorods. We characterized the materials with UV-visible spectroscopy, powder X-ray diffraction, and electron microscopy. We immobilized the HNCs on fumed silica and removed organic surfactants …

Eugenol Loaded Calcium Citrate Particle As A Ph Triggered Drug Release System And A Reducing Agent For Au (Iii), Sadia Afrin

Dissertations and Theses

The study demonstrated that eugenol affects the morphology of calcium citrate particles during their formation, as confirmed by SEM micrography and PXRD analysis. Coating of eugenol loaded calcium citrate particles (CaCit MPs) with casein improves their known pH-dependent drug release profile, as confirmed by UV absorption spectroscopy. The casein-coated eugenol-loaded CaCit MPs (CCaCit(eu) MPs) can effectively control and sustain drug release under different pH conditions, particularly at acidic pH values (4.8 and 5.5), which mimics the environment of tumor tissues. To further explore the biomedical applications of calcium citrate, a bulk nanostructured precursor to the known anti-cancer calcium citrate phosphate-based …

Synthesis And Luminescence Studies Of Europium Doped Zinc Lead Germanate Phosphors, Anika Nawar Chowdhury

Dissertations and Theses

Phosphors are luminescent materials that emit light upon excitation, which have significant uses in optoelectronics, bioimaging, sensors, security, and other fields. Inorganic luminescent materials are well known for their stability and broad applications. Among these, germanate based phosphors have recently caught attention because of their inertness, excellent chemical and thermal stability, structural flexibility, and unique properties. For optimizing the properties of the materials, impurities are added to the host intentionally, which are known as dopants. Rare earth elements are often applied as dopants because of their unique f-f transitions. Eu3+ is one of the broadly studied rare-earth dopants among these, …

Calcium Carbonate Microparticles As Acid Responsive Targeted Drug Delivery Carriers For Oral Diseases And Its Anti-Bacterial Activity, Hem Raj Joshi

Dissertations and Theses

Dental diseases are mostly caused by bacterial infections in the teeth, forming biofilms that release acids and decay the enamel of the teeth. More than half of the world's population were affected by oral diseases, including periodontitis (gum disease), dental caries (cavities), and oral cancer. Chlorhexidine (CHX) is the mostly used antimicrobial drug for dental diseases, but its overexposure to the healthy teeth causes many side effects, such as tooth staining, taste alteration, and many more. Taking advantage of the acidic environment of infected teeth, we designed a pH responsive targeted drug delivery system using calcium carbonate microparticles (CCMPs) as …

Investigating Student Expectations, Buy-In, And Engagement In Lower Division Undergraduate Chemistry Labs, Elizabeth Blanche Vaughan

Dissertations and Theses

Laboratory courses constitute an integral aspect of chemistry education at the undergraduate level. Despite their prominence, a growing number of researchers have begun to think more critically about the value of laboratory learning experiences. As pedagogical decisions should be based on evidence, it is necessary for chemistry education researchers and practitioners to investigate the claim that teaching laboratories are a valuable part of science education. Therefore, the aim of this dissertation was to address one small section of this gap in the literature by obtaining a more robust understanding of students' expectations, buy-in, and engagement in lower division, undergraduate, chemistry …

Synthesis And Computational Studies Of Α- And Δ-Substituted Macrocyclic Europium And Ytterbium Complexes, Delainey Amara Winder

Dissertations and Theses

The uses of macrocyclic lanthanide complexes are vast, with many targeted MRI contrast agents at the forefront of the field. Many of these are ParaCEST agents, which require exchangeable protons accessible on the macrocycle and the slow exchange of coordinated water molecules. The substitution at both the α- and δ-carbon on the amide pendant arm of these macrocyclic lanthanide complexes can lock bulky groups on the δ-carbon to a pseudo-axial position. When the α- and δ-carbons have the same chirality, the bulky group will be pseudo-equatorial, and when the chirality is opposed, the bulky group will be pseudo-axial. By performing …

Dft Based Modeling Of The Heavy Atom Effect In Triplet Photosensitizers: From Fundamental Mechanics To Rational Design, Bret Andrew Steinkamp

Dissertations and Theses

Photochemistry is the study of how light interacts with molecules and includes both the absorption and release of light. This document focuses on triplet photosensitizers -- molecules that utilize the excited triplet state -- for a variety of applications including photodynamic therapy and photocatalysis. There are many factors that influence the design of triplet photosensitizers; in this work, we have developed and used a methodology for the rational design of triplet photosensitizers based on an approximation of the heavy atom effect (HAE) from density functional theory calculations and the experimentally measured singlet oxygen quantum yield (Ф_Δ).

As excited …

Efficient And Chemoselective Access To Highly Functionalized Arenes By C-H Deprotonative Generation Of Aryne Intermediates, Bryan Edward Metze

Dissertations and Theses

Arenes are a ubiquitous structural motif occurring in numerous organic pharmaceuticals, agrochemicals, secondary metabolites, and functional materials. As such, studies on the characterization, functionalization, and properties of arenes have been a central pillar of organic chemistry since its inception. Early methods to synthesize complex benzenoid rings focused on ring functionalization rather than ring construction due to the high accessibility of very simple arenes and the wide range of aromatic substitution reactions discovered in the late 19th century. As the importance of arenes was recognized more methods of building complex arenes emerged. Both classical and modern approaches are still somewhat limited, …

Synthesis Of Novel 5-Aryl 2’-Deoxyuridine And 2’-Deoxycytidine Analogues, Kevin E. Persaud

Dissertations and Theses

Briefly, the following report details a synthetic route to prepare 5-phenyl-2’-deoxycytidine analogues. This multistep synthesis began with silyl protection of the 3’- and 5’-hydroxyl groups of 5-iodo-2’-deoxyuridine. Next, the installation of a phenyl ring at the C5 position of the nucleobase via a Suzuki-Miyaura cross-coupling reaction, yielding 5-phenyl-2’-deoxyuridine (5-PdU). After that, modification of the obtained 5-PdU at the C4 position was performed with benzotriazole-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate (BOP, a peptide-coupling agent) and a base (cesium carbonate) to activate the amide group of the uridine nucleobase for subsequent displacement with a variety of amines. Modification of the C4 position resulted in protected 5-phenyl-2’-deoxycytidine …

Calcium Carbonate-Based Stimuli-Responsive Microcarriers For Targeted Drug Delivery Against Oral Bacterial Infections And Development Of Glass-Free Microfluidics As An Analytical Platform, Krishantha Wijewardhane

Dissertations and Theses

Dental diseases present a significant global health challenge, affecting individuals across all age groups. This spectrum of oral health issues encompasses conditions like dental caries, periodontitis (gum disease), and oral infections. In the customer discovery interviews, dental patients have raised concerns about potential drug overexposure during and after procedures, driven by fears of adverse effects, allergies, and the increasing use of antibiotics and anesthesia. Dentists are increasingly focused on minimizing opioid and steroid-based medication doses due to potential side effects and addiction risks. This study explores an innovative approach to targeted drug delivery in the dental environment using eco-friendly and …

Change Of Metal Oxidation State At High Temperature, Impact Of Temperature And Reactive Gases, Yegor Nikitin

Dissertations and Theses

The fundamental understanding of gas-solid reactions enables a wide range of applications to be developed and improved. Specifically, the use of metal-based materials is critical to ensuring robust, safe, and long-term operations. For example, in power systems where boilers are used to generate steam for heat or electricity generation the use of stainless metal alloys is critical to allow high quality steam to be produced in a very harsh environment. Alternatively, in catalysis, the use of metal doped heterogeneous catalysts are essential in achieving selectivity and conversion performance for chemical synthesis to emissions abatement. Typically, these metal alloys must withstand …

The Impact Of Fluorination On The Volatility Of A Series Of Lanthanide Complexes, Kh Mahfuzul Alam

Dissertations and Theses

Volatile lanthanides have been proposed for applications such as chemical vapor deposition precursors and facilitating f-element separations. The latter is motivated by their broad use in technological applications. In collaboration with synthetic chemists, we studied Ln-complexes with functionalized forms of the bulky tris[(4-hydroxy-pentenylidene-2-imino)ethyl]amine (TRAC) ligand. Five ligands, labeled Yb(CH3,CH3TRAC), Yb(CH3,CF3TRAC), Yb(CF3,CF3TRAC), Yb(CF3,C3F7TRAC) and Nd(tbu,C3F7TRAC) were synthesized and volatile Ln complexes were obtained. However, the temperature at which they sublime was not sufficiently low for industrial applications. Therefore, this work examined the experimentally characterized Yb(CH3,CH3TRAC), Yb(CH3,CF3TRAC), Yb(CF3,CF3TRAC), Yb(CF3,C3F7TRAC) and Nd(tbu,C3F7TRAC) in detail. The importance of interactions between two neighboring molecules in …

Activation Of Molecular Oxygen For The Selective Oxidation Of Alkenes Catalyzed By Hollow Mn3o4 Nanoparticles, Pranab Kumar Nandy

Dissertations and Theses

This dissertation describes two distinct projects: 1) hollow Mn3O4 nanoparticles for selective oxidation of alkenes with O2, and 2) investigation of chloro[2-(mesityl(quinoline-8-yl-κN)boryl]-3,5-dimethyl-phenyl}methyl-κC)palladium(II) for activation of C-F bonds in aryl fluorides. Hollow Mn3O4 nanoparticles were synthesized from the galvanic reaction between Cu2+ and MnO nanocrystals. The hollow Mn3O4 particles were characterized with transmission electron microscopy and powder X-ray diffraction. The particles have diameter of 31 nm and a hollow cavity of 16 nm. We investigated the role of the hollow Mn3O4 nanoparticles in the selective oxidation of organic substrates with molecular oxygen. The results indicate that the hollow Mn3O4 nanoparticles catalyze …

Advancing Anti-Counterfeiting Approach Via The Development Of Functional Optical Materials, Zishen Yang

Dissertations and Theses

Counterfeiting poses a significant threat to public health and safety, necessitating robust measures to combat it. Addressing this challenge requires the development of advanced materials and techniques, coupled with a comprehensive understanding of the obstacles inherent in anti-counterfeiting endeavors. Our study delved into two approaches for crafting anti-counterfeiting technologies: plasmonic and luminescence materials. We thoroughly examined the challenges associated with each method and proposed viable solutions. Notably, we devised a streamlined process for producing inkjet printable Surface-enhanced Raman Scattering (SERS) ink, enabling the creation of low-cost covert quick response (QR) codes with a high storage capacity. Access to the encoded …

Advanced Optical Biosensing Using Ratiometric Fluorescent Polymer Dots And Nanozyme, Shuyi He

Dissertations and Theses

Biosensors have been deeply valued and widely used in fermentation technology, environmental monitoring, food engineering, clinical medicine, and the military. However, current biosensors still face many technical challenges, such as miniaturization, convenience, high precision, and low power consumption which restrict the popularization and development of biosensors. Meeting these challenges require the development of advanced materials and technologies. Optical biosensors offer distinct advantages such as high sensitivity, rapid response time, and the potential for miniaturization, making them ideal for overcoming the existing limitations. My research in this dissertation explores the development and application of advanced functional nanomaterials in optical biosensing, focusing …

Binary Phase Nio-Tio2 Heterojunction For Photocatalytic H2o2 Formation, Rashed Mia

Dissertations and Theses

The overreliance on fossil fuels contributes to geopolitical, economic, and environmental risks that adversely affect society. Photocatalytic processes in which light energy is used to drive endothermic chemical steps, such as water splitting to hydrogen and oxygen, could contribute solutions to these energy and environmental issues. Numerous substances have been developed that can effectively catalyze solar water splitting; however, their efficiency has yet to reach cost equivalence with rival technologies. The most studied materials employ semiconductors for light absorption, modified with co-catalysts to gather photogenerated charge carriers and promote electron transfer, thereby enabling endothermic redox reactions to occur. Anatase TiO2 …

Functionalization Of Pristine And Defective Monolayer Graphene To Control Biofilm Growth, Md Tusar Uddin

Dissertations and Theses

Biofilms are surface-attached microorganism communities that are embedded in extracellular matrix. They play a significant role in different infections which cause many life-threatening diseases in the world population. Many strategies have been developed to control biofilm formation and microbial adhesion on the surface such as coating by an antimicrobial agent, chemical modification of surfaces, and physical destruction of biofilm areas. However, these techniques are not sufficient to limit the widespread biofilm formation. Therefore, new antimicrobial strategies need to be developed to control these often antibiotics-resistant microorganisms. The aim of our work is to develop novel materials to maximize the capability …

Phosphorescent Carbon Dots Doped Silica Nanomaterials Via Microwave-Assisted And Modified Stöber Methods For Anti-Counterfeiting And Biosensing, Weichao Liu

Dissertations and Theses

Phosphorescent materials are essential in bioimaging, anti-counterfeiting, and other applications due to their prolonged light emission. However, current phosphorescent materials face challenges such as complex synthesis, high costs, and instability. Carbon dots (CDs), with size less than 10 nm, are a promising alternative due to their biocompatibility, tunable optical properties, and simple synthesis. This thesis explores the synthesis of CDs using ethylenediamine (EDA) and phosphoric acid via a microwave-assisted method, followed by silica encapsulation using a modified Stöber process to form CDs@SiO2, aiming to enhance their stability and optical properties. Optical characterization showed a slight blue shift in the excitation …

Recovering Relativistic Effects In Electronic Structure Calculations Of F-Element Single Molecule Magnets, Nathan Roy Loutsch

Dissertations and Theses

There has been a great interest in developing new information technologies. Single molecule magnets (SMMs) are emerging as materials for high density data storage, qubits, and molecular spintronics. SMMs containing lanthanide or actinide centers are of interest due to their potentially high magnetic anisotropy. This would enable the use of SMMs at higher temperatures. Accurately modelling the electronic structure of f-element complexes can be quite challenging. Density Functional Theory (DFT) is a popular choice for optimizing geometry and studying the electronic structure due to its relatively low cost. In certain cases, more accuracy is desired or necessary to predict experimental …

Fluorinated Thiophene Containing Aromatics And Their Polymers For Energy Storage And Semiconductor Applications, Blessing Damilola Ishola

Dissertations and Theses

The development of new fluorinated functional materials that are moisture and air-stable is crucial for the efficient production of n-type organic semiconductors. These semiconductors are integral components in electronic devices such as transistors, diodes, organic semiconductors, organic field-effect transistors, and organic light-emitting diodes. Organic materials have become increasingly popular for designing new semiconductors due to their flexibility compared to inorganic alternatives. By molecularly engineering the band gap and electron delocalization, we can improve the efficiency and performance of semiconductor devices. We design, synthesize, and characterize a new type of donor-acceptor molecule based on the structure-property relationship learned from the literature …

Designing Fluorescent Moscs For Potential Applications In Illicit Drugs Detection, Robyn Nicole Cook

Dissertations and Theses

Illicit and hazardous substances pose a serious effect on the human body which can create longer-term issues on the mental and physical health which potentially lead to fatalities. Current methods for detecting illicit substances include analytical techniques like mass spectrometry (MS) and gas/liquid chromatography (GC/LC) which are known for accuracy and sensitivity. However, these instruments are bulky, costly, time-consuming, and require highly trained personnel. An alternative approach to overcoming these limitations is to employ nanostructured molecule-based chemical sensing technologies that are user-friendly, portable, and cost-effective with the sensitivity for detecting illicit substances. One such candidate is metal-organic super-containers (MOSCs), which …