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Understanding Of Processing Additives Influence In Tin Halide Perovskites: Chemistry, Defect, And Photovoltaic Performance, Syed Rahmath Ullah Joy

Theses and Dissertations--Chemistry

Metal halide perovskite semiconductors have attracted much interest for various applications, such as solar cells, light emitting diodes, photodetectors, and lasers, due to their excellent optoelectronic properties. Photovoltaic cell development is centered on Pb-based perovskites, which have equal photovoltaic performance compared to the traditional silicon photovoltaic. But concerns arising from the usage of toxic lead metal have motivated the research community to seek an alternative derivative. Among those, tin halide perovskites show much promise as an alternative to Pb-counterparts due to their ideal bandgap for single junction photovoltaics and similar optoelectronic properties to Pb perovskites. Nevertheless, tin perovskites suffer from …

Translating Chemistry, Structure, And Processing To The Solid-State Morphology And Function Of Organic Semiconductors Through Computational Modeling And Simulations, Chamikara D. Karunasena

Theses and Dissertations--Chemistry

The immense synthetic design space and material versatility have driven the exploration and development of organic semiconductors (OSC) over several decades. While many OSC designs focus on the chemistries of the molecular or polymer building blocks, a priori, multiscale control over the solid-state morphology is required for effective application of the active layer in a given technology. However, molecular assembly during solid-state formation is a complex function interconnecting the building block chemistry and the processing environment. Insufficient knowledge as to how these aspects engage, especially at the atomistic and molecular scales, has so far limited the ability to predict …

Surface Modification Of Carbon-Based Electrodes For Electrochemical Conversion Processes: Oxygen Reduction Reaction And Bicarbonate Conversion, Udari Shyamika Kodithuwakku Arachchige

Theses and Dissertations--Chemistry

Oxygen reduction reaction (ORR) and conversion of bicarbonate into value-added chemicals are two significant electrochemical processes for energy storage and conversion. ORR is an important electrochemical reaction in fuel cells and metal-air batteries that provide power conversion and storage capacity, respectively, for portable electronics, and electric vehicles. However, the performance of catalysts (e.g., platinum-based) is critically limited by slow kinetics, inefficient four-electron pathway, and surface deactivation. This limited performance of platinum-based catalysts, the scarcity of platinum, and vulnerable supply chains for critical minerals require the development of alternative electrocatalysts now more than ever. Carbon-based materials possess several key properties that …

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 …

Exploring The Role Of Ring Annulation In Polycyclic Aromatic Hydrocarbons For Organic Electronic Applications, Tanner Smith

Theses and Dissertations--Chemistry

Organic materials offer promising potential for the next generation of electronic devices, as their tunability, processability, and low-temperature manufacturing make them a cheap and versatile alternative to traditional silicon-based electronics. The ability to systematically alter the electronic properties of organic materials is vital for their incorporation into device applications. Polycyclic aromatic hydrocarbons (PAHs) are of significant interest for organic electronic applications, as relevant properties are highly dependent on their size, structure, and functionalities, and thus can be tuned to fit a wide variety of applications. Due to the enormous number of structural isomers available in larger PAHs, the development of …

Developing And Deploying Data-Driven Tools For Accelerated Design Of Organic Semiconductors, Vinayak Bhat

Theses and Dissertations--Chemistry

Organic semiconductors have gained widespread attention due to their potential applications in flexible, low-cost, lightweight electronics, energy storage and generation technologies, and sensing applications. However, developing new organic semiconductors with improved performance remains a significant challenge due to the vast chemical space of possible molecular and materials structures. Furthermore, the high cost and time-consuming nature of experimental synthesis and characterization hinder the rapid discovery of new materials. To overcome these challenges, this dissertation presents a data-driven approach to organic semiconductor discovery. The primary focus of this work is the development of data-driven tools, namely machine learning models, to predict critical …

Development And Biological Evaluation Of Selective Small-Molecule Inhibitors Of The Human Cytochrome P450 1b1, Austin Hachey

Theses and Dissertations--Chemistry

The human cytochrome P450 1B1 (CYP1B1) is an emerging target for small- molecule therapeutics. Several solid tumors overexpress CYP1B1 to the degree that it has been referred to as a universal tumor antigen. Conversely, its expression is low in healthy tissues. CYP1B1 may drive tumorigenesis through promoting the formation of reactive toxins from environmental pollutants or from endogenous hormone substrates. Additionally, the expression of CYP1B1 in tumors is associated with resistance to several common chemotherapies and with poor prognoses in cancer patients. However, inhibiting CYP1B1 with small molecules has been demonstrated in cellular and murine model systems to reverse this …

Application Of Mass Spectrometry For The Characterization Of Synthetic Oligomers And Natural Lignin, Poorya Kamali

Theses and Dissertations--Chemistry

As part of the ongoing effort to substitute finite fuel and chemical resources with renewable ones, biomass is emerging as one of the most promising sources. Biomass consists of three main components of cellulose, hemicellulose, and lignin. Traditionally, cellulose has been used extensively in pulping industry, while lignin has been considered waste and is burned to generate heat. Lignin, a complex aromatic polymer component of biomass, has the potential to be used as a source of aromatic chemicals and pharmaceutical synthons. The recalcitrant nature of lignin, the lack of effective lignin breakdown methods and analytical techniques to analyze it are …

First Principles Calculations To Investigate Surface And Catalytic Properties Of Materials For Green Energy Generation, Keerthan Raghavendra Rao

Theses and Dissertations--Chemistry

Climate change due to greenhouse gas build up in the earth’s atmosphere is an existential threat to humanity. To mitigate climate change, a significant shift from fossil fuels is necessary. Over the years, several renewable energy sources like solar, wind, geothermal etc. have been explored with the aim providing carbon-free energy. In this work, we focus on using density functional theory (DFT) methods to investigate key functional properties of materials of interest for applications in solar cells and catalytic conversion for energy generation. We show geometric effects of carboxylic acid binding on a transition metal surface to impact the deoxygenation …

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 …

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 …

Succinylated Polyethylenimine Gene Delivery Agents For Enhanced Transfection Efficacy, Md. Nasir Uddin

Theses and Dissertations--Chemistry

Gene therapy aims to treat patients by altering or controlling gene expression. Today, most clinical approaches are viral-based due to their inherent gene delivery activity. However, there is still a significant interest in nonviral alternatives for gene delivery, particularly synthetic lipids and polymers, that do not suffer the immunogenicity, high cost, or mutagenesis concerns of viral vectors. Polymeric vectors are of particular interest due to the ability to further tune the polymer properties through the incorporation of additional functional units such as targeting ligands or shielding domains. Polyethylenimine (PEI), a highly cationic polymer, is often considered a benchmark for polymer-based …

Structural Basis Of Bacterial Flagellin For Naip5 Binding And Nlrc4 Inflammasome Activation And The Mechanism Of Flagellin Induced Release Of Cytokines In Vivo, Jian Cui

Theses and Dissertations--Chemistry

The bacterial flagellum is a whip-like structure that protrudes from the cell membrane and is one of the most complex and dynamic biological molecular machines that propels bacteria to swim toward beneficial environments and the sites of infection. It is composed of a basal body, a hook, and a long filament. The flagellar filament contains thousands of copies of the protein flagellin (FliC) monomer arranged helically and ending with a filament cap composed of oligomer protein FliD. The overall structure of the filament core is preserved across bacterial species, while the outer domains exhibit high variability, and in some cases …

Antibiotic Permeation In Gram-Negative Bacteria And Contribution Of Inflammasome Activation And Pyroptosis In Pathogenesis Of Salmonella Systemic Infection, Ankit Pandeya

Theses and Dissertations--Chemistry

Antibiotic resistance is one of the major global issues in the field of public health and medicine. Good antibiotic candidates need to be selectively toxic, inhibit cellular target, and effectively penetrate and accumulate in bacterial cells. The last factor is a formidable barrier in the development of antimicrobials effective in Gram-negative bacteria, due to the presence of two layers of cell envelope. The first half of my thesis focuses on understanding the permeation of small molecules through this formidable cell envelope, distribution inside the cell of Gram-negative bacteria, and design of novel methods to make small molecules effectively cross the …

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, …

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 …

Nicotine And Cotinine: Microbial Modulators Of The Immune Response, Jourdan Lakes

Theses and Dissertations--Chemistry

The consumption of tobacco products is a known contributor to a variety of health conditions and disease pathologies including cardiovascular and lung diseases. In addition to these well-known pathological effects of tobacco use, it has been established recently that tobacco consumption as well as nicotine consumption alone results in distinct, dysbiotic perturbations to the enteric microflora of the gastrointestinal tract. Previous research into the intestinal microbiome has demonstrated that these microbes are active contributors to the maintenance of a homeostatic and tolerogenic environment within the host. In fact, the presence of our enteric microflora is necessary for the proper development …

Cell-Engineered Vesicles For Therapeutic Delivery And Immunomodulatory Applications, Khaga Neupane

Theses and Dissertations--Chemistry

Development of a new kind of drug delivery system (DDS) that could efficiently deliver therapeutics to the cell of interest would allow us to accomplish cell-specific drug delivery while eliminating systemic toxicity. Although nanocarriers including endogenously released extracellular vesicles (EEVs), liposomes, and small molecules seem to be promising drug delivery systems, biological challenges persist for their use in clinical applications. Here, we demonstrate nanovesicles engineered by fragmenting cellular membranes can be exploited as versatile DDSs for therapeutics delivery as well as immunomodulatory functions. Cell-engineered vesicles were produced by cavitating cells using nitrogen gas at high pressure followed by serial centrifugation. …

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: …

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 …

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 …

Mechanism Of Antibiotic Permeability Through The Gram-Negative Bacterial Envelope, Olaniyi Alegun

Theses and Dissertations--Chemistry

The outer membrane of Gram-negative bacteria (GN) makes them distinct among superbugs that are associated with the development of antibiotic resistance. The outer membrane, and inner membrane, separated by the periplasm, form a double-membrane barrier to the entry of antibiotics into the cell. Several studies have been conducted to examine the role of outer membrane modifications such as porins, lipopolysaccharides, and efflux pumps on antibiotic resistance. However, there is a paucity of knowledge on how antibiotics behave in the periplasm, to gain access into their target region. My thesis focuses on understanding the mechanism of antibiotic permeability through the cellular …

Developments In Gold(Iii) Scaffolds For Protein Bioconjugation And Enhanced Anticancer Activity, Sailajah Gukathasan

Theses and Dissertations--Chemistry

Site-selective modifications of target proteins using specially designed small molecules is a powerful tool that has been extensively utilized in biomedicine. Small molecules can modify proteins either covalently or non-covalently depending on their structures and intrinsic chemical reactivity. Covalent chemical modification presents a more stable and often irreversible interaction with target proteins; unlike non-covalent binders, which form weak, reversible interactions with protein. Therefore, covalent modifiers represent an effective class of therapeutics due to their stability and irreversibility once bound to target proteins of interest. I hypothesized that tuning biocompatible, high-valent gold(III) complexes toward nucleophile-induced reductive elimination will lead to covalent …

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 …

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 …

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 …

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 …

Synthesis, Crystal Engineering, And Material Properties Of Small-Molecule Organic Semiconductors, Emma Holland

Theses and Dissertations--Chemistry

Small-molecule organic materials are of increasing interest for electronic and photonic devices due to their solution processability and tunability, allowing devices to be fabricated at low temperature on flexible substrates and offering utility in specialized applications. This tunability is the result of functionalization through careful synthetic strategy to influence both material properties and solid-state arrangement, both crucial variables in device applications. Functionalization of a core molecule with various substituents allows the fine-tuning of optical and electronic properties, and functionalization with solubilizing groups allows some degree of control over the solid- state order, or crystal packing. These combinations of core chromophores …

Mass Spectrometry Method Development For The Discovery And Characterization Of Secondary Metabolites, Zachary Kelley

Theses and Dissertations--Chemistry

Secondary metabolites are organic compounds produced by an organism for reasons other than growth and development. In plants, secondary metabolites generally act as defense agents produced to deter predators and inhibit other competitive species. For humans, these compounds can often have a beneficial effect and are pursued and utilized as natural pharmaceuticals. The development of sensitive, high-throughput analytical screening methods for plant derived metabolites is crucial for natural pharmaceutical product discovery and plant metabolomic profiling. Here, metabolomic profiling methods were developed using a microfluidic capillary zone electrophoresis device and evaluated against traditional separation approaches. An alkaloid screening assay was constructed …

Understanding The Role Of Charge On Particle Transport Within Semidilute And Concentrated Biopolymer Solutions And Tau Protein Condensates, Kanthi Nuti

Theses and Dissertations--Chemistry

Biological polymer networks such as mucus, extracellular matrix, nuclear pore complex, and bacterial biofilms, play a critical role in governing the transport of nutrients, biomolecules and particles within cells and tissues. The interactions between particle and polymer chains are responsible for effective selective filtering of particles within these macromolecular networks. This selective filtering is not dictated by steric alone but must use additional interactions such electrostatics, hydrophobic and hydrodynamic effects to control particle transport within biogels. Depending on chemical composition and desired function, biogels use selective filtering to allow some particles to permeate while preventing others from penetrating the biogel. …