Physical Sciences and Mathematics Commons^™

Exploration Of Sulfonamides And Benzothiazoles As Peptide-Based Cleavable Linkers, Abigail Dalton

Honors Theses

Cleavable linkers have demonstrated great potential in various applications of medicinal organic chemistry, such as in modern therapeutic development. Linkers are stable compounds that cleave in specific conditions to release molecular cargo. We have developed cleavable linkers based on nucleophilic aromatic substitution reactions on sulfonamide and benzothiazole substrates in small molecule and in peptide studies. Sulfonamides, commonly with an electron-withdrawing group, reacted in high conversion of starting material to the sulfide product in small molecule studies, but was unable to successfully cleave the sulfonamide linker on peptide in mild conditions. Next, a benzothiazole sulfone substrate was analyzed and optimized in …

Covalent Inhibition Of Enzyme Sortase A As A New Pathway Against Bacterial Resistance Of Staphylococcus Aureus, Umyeena Bashir

Master's Theses

The continued rise of antibiotic-resistant bacteria, such as MRSA (methicillin-resistant Staphylococcus aureus), has made the discovery of novel antibiotics critical. While bacteriostatic and bactericidal antibiotics inevitably exert evolutionary pressure on bacteria to develop resistance, small molecules that target mechanisms of bacterial virulence present a promising alternative for treatment. Sortase A (Srt A), a cysteine protease of S. aureus, promotes bacterial virulence by covalently attaching proteins such as pilin to the bacterial surface, enabling bacterial adhesion to mammalian cells. Inhibitory studies of this enzyme have gained prominent interest as a new pathway for drug development since blocking this enzyme's ability to …

The Effects Of Prior Calculus Classes On Success In Organic Chemistry, Tori Williamson

Theses/Capstones/Creative Projects

Within University of Nebraska – Omaha (UNO) chemistry-based degree programs, organic chemistry along with at least two semesters of calculus are required courses. There is, however, no requirement for the order in which these courses should be taken. This is mainly due to the notion that for chemistry courses, organic chemistry is detached from the typical quantitative concepts studied in other chemistry-based courses. This is untrue, however, as many organic chemistry concepts rely on three-dimensional spatial visualizations and manipulations. Spatial awareness skills are strengthened within higher-level calculus classes. A survey was administered to organic chemistry students enrolled in 2022-2023. The …

Asymmetric Cuh-Catalyzed Reductive Coupling Of Allenamides With Carbonyl Electrophiles & Development Of Nanocatalysts For Heterogeneously Catalyzed Buchwald-Hartwig Amination, Raphael K. Klake

Theses and Dissertations

Many drugs and natural products contain multiple stereogenic carbons bearing heteroatoms throughout their carbon framework. Therefore, methods that can efficiently install multiple heteroatoms on a molecule are valuable. Reductive coupling reactions have been extensively studied, and the allylation of carbonyls via the reductive coupling approach has been a key method for generating chiral tertiary and secondary allylic alcohols. This work utilizes inexpensive Cu for the asymmetric reductive coupling of allenamides with carbonyls to simultaneously install two heteroatoms (oxygen and nitrogen) on the product. These molecules have a polarity profile that make them difficult to make using traditional methods. Herein, we …

New Synthetic Methods Based On Silicon-Tethered Nucleophilic Addition Reactions, Alexie W. Clover

WWU Graduate School Collection

With the recent discovery of an iodine mediated rearrangement of diallylsilanes, we set out to investigate a similar fluorine mediated rearrangement, aimed at introducing a new method for synthesizing organofluorine compounds. Interest in incorporating fluorine into organic molecules has grown significantly in recent years, primarily for medicinal applications. Since certain fluorination methods require the use of mCPBA, a common epoxidizing reagent, control experiments were performed on the reaction of several diallylsilanes with mCPBA, anticipating that a competing epoxidation of the diallylsilanes might occur. It was found that the formation of the hydroxy ester occurred through a regioselective epoxide opening from …

Synthesis, Characterization And Cell Viability Of Novel Tripodal Amines, Kinsley Lupton

Honors College Theses

Cancer, over the years, has become a much more prevalent focus for the scientific community. Organizations and laboratories all over the world have spent countless hours searching for a cure, trying to learn more about what makes cancer so powerful and what is the best way to stop its growth. Iron-chelation drugs were already on the market, and it was shown that they did have the ability to act as both iron-chelators and anticancer drugs. Most of these iron-chelating drugs are not as effective at killing cancer cells as the medical field desires. Novel iron-chelating tris-indolyl derivatives, GSO2, GSO4 and …

Pyridyl Bis-Urea Macrocycles As Supramolecular Synthons And The Design And Synthesis Of Small Molecule Pharmaceuticals Targeting Ly6k, Devan D. Buchanan

Theses and Dissertations

Assembled pyridyl bis-urea macrocycles have been utilized as 1D supramolecular synthons to construct hierarchical assemblies. These macrocycles have both urea and pyridyl functional groups and can form non-covalent interactions with hydrogen or halogen bond donors through symmetric, ditopic acceptor motifs. Bis-urea macrocycles offer interesting capabilities as synthons to organize donors into well-defined crystal structures. In part, this is due to the urea motifs’ propensity to assemble through hydrogen bonding. New, asymmetric pyridyl macrocycles were synthesized, crystallized, and experimentally probed to determine how symmetry affects their assembly and utility as supramolecular synthons.

The Uphadhyay group identified small molecules, including NSC11150, …

Gene Vectors With Fluorescence Tracking Capabilities, Sophia Despina Angelopoulos

Browse all Theses and Dissertations

This project focuses on the optimization of benzothiazole-based chromophores to utilize them as fluorescent tags functionalized onto stimuli-responsive, or “smart,” polymers as non-viral gene delivery vectors for gene therapy applications. Blue-fluorescent emissive chromophores will allow tracking capabilities for the transfection pathway of the vector to be monitored as it delivers the DNA payload within intercellular space. The most appropriate chromophore must be covalently bound to a free amine within the vector, which is accomplished through NAS chemistry from fluorophenyl-benzothiazoles (F-BTZ-CBz) derivatives to amidated hyperbranched poly(ethyleneimine)(HPEI-IBAm0.61). HPEI is considered to be a synthetic polycation, which promotes tunable solubility through characteristics of …

Covalent Attachment Of Tadf Chromophores To Thermally Stable Poly(Arylene Ether)S, Samuel Farrar

Browse all Theses and Dissertations

The covalent attachment of a blue emitting, benzothiazole based TADF chromophore into poly(arylene ether) backbone polymers was explored. A benzothiazole derivative, 2-(2,4-difluorophenyl)-benzothiazole (2,4-diF-BTZ), was synthesized to form the electrophilic component of the host polymer. Two polymers were synthesized to have chromophore incorporated, using 2,4-diFBTZ and 4,4-dihydroxydiphenyl ether (DPE) or 4,4’-biphenol (BP). The chromophore was covalently incorporated at a 10% molar ratio into the polymer backbone by copolymerization with 2,4-diF-BTZ and BP, utilizing nucleophilic aromatic substitution (NAS). Structural characterization was provided via NMR spectroscopy and GC/MS analysis. The polymer syntheses provided high molecular weight materials that were able to be cast …

One-Pot Synthesis Of Disubstituted Primary Amines From Nitriles Via Grignard Addition And Metal-Alcohol Reduction, Joshua Peltan

Honors Theses

The process of developing a working base case procedure for a novel one-pot-two-step synthesis of primary amines from Grignard reagents, nitriles, sodium metal or alkali metal loaded silica gel, and alcohol is described. Initial steps towards applying the process broadly are detailed. The process has the potential to be an affordable, convenient, safer, greener, and more accessible alternative to exiting methods of accomplishing the same transformation. The reaction scheme has been proven to provide yields and purity comparable to existing methods for certain pairs of substrates; however, its utility as a general-purpose method for transforming arbitrary pairs of Grignard reagent …

Renewable Energy Conversion: Organic Redox Flow Batteries And Electrocatalytic Carbon Dioxide Reduction, Camden R. Debruler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Steadily increasing global energy demands have pushed the industry to investigate renewable energy sources like solar and wind to help alleviate the strain on fossil fuel based non-renewable energy sources while also reducing carbon emissions. However, the energy producing power of these renewable technologies is limited by factors such as weather and the day-night cycle. Additional energy storage technologies are needed which are capable of storing excess energy during periods of high productivity, and delivering it when production rates fluctuate.

Batteries represent one possible energy storage device to meet this need. Specifically, redox flow batteries (RFBs) offer advantages in terms …

Effect Of Precise Control Of Crosslink Density On The Thermal, Mechanical, And Conductive Properties Of Covalently Crosslinked Ionene Networks, Alexander Thome

Honors College Theses

Ionic liquids (ILs), besides being well known as environmentally friendly solvents, have attracted attention for a wide variety of other applications, including gas separation, 3D-printing and electrochemical actuators. However, for many such applications, incorporation of the IL moiety into a polymeric material eliminates the use of mechanically unstable free ILs while maintaining many of their electrochemical benefits. Such polymers can take two basic forms: poly(ionic liquid)s are ion-containing polymers in which the IL group is attached pendant to the polymeric backbone, while ionenes are ion-containing polymers in which the IL group is anchored directly into the backbone of the repeating …

The Development Of Fluorine-18 Imaging Agents Targeting The Ghsr, Marina D. Childs

Electronic Thesis and Dissertation Repository

Molecular imaging is an interdisciplinary field of study that allows for real-time visualization of biological processes in both healthy and disease states. Fluorine-18 positron emission tomography (PET) imaging is a highly sensitive technique where molecular probes containing fluorine-18 serve to specifically locate and visualize the expression of relevant disease biomarkers. The growth hormone secretagogue receptor 1a (GHSR) is differentially expressed in cancer and cardiac pathology, making it a biomarker of interest for imaging such diseases. This thesis discusses the development and optimization of GHSR-targeting ¹⁸F-PET imaging probes as well as proposes a new imaging agent discovery technique.

Chapter 2 …

Using Quantitative Methods To Investigate Student Attitudes Toward Chemistry: Women Of Color Deserve The Spotlight, Guizella A. Rocabado Delgadillo

USF Tampa Graduate Theses and Dissertations

The field of Chemistry Education Research (CER) has been interested in understanding the reasons why students struggle in organic chemistry courses. Reports show that students perceive the material as difficult and have trouble keeping pace with the volume of content taught within the course. Beyond these and other explanations of why students struggle in organic chemistry are affective factors, such as attitude toward chemistry, that influence students’ success and retention in this course. Studies have shown that in many instances, underrepresented groups of students report less positive attitudes than their peers. Of greater concern are the students representing multiple marginalized …

Engineering Stimuli-Responsive Polymeric Nanoassemblies: Rational Designs For Intracellular Delivery Of Biologics, Kingshuk Dutta

Doctoral Dissertations

Biologic drugs have gained enormous research attention in recent years as reflected by the development of multiple candidates to the clinical pipelines and an increased percentage of FDA approval. This is reasoned by the fact that biologics have been proven to deliver more predictive and promising benefits for many hard-to-cure diseases by ‘drugging the undruggable’ targets. However, the challenges associated with biologic drug development are multi-fold, viz, poor encapsulation efficacy, systemic instability, low cellular internalization and endosomal escape capability. Thus, it is essential to develop new molecular strategies that can not only address the associated drug delivery challenges, but also …

Synthesis And Biological Evaluation Of Azide- Tagged Biomimetic Probes For Global Labeling Of The Saccharomyces Cerevisiae Glycerolipidome, Matthew R. Johnson

Masters Theses

Lipid metabolism is an extremely complex, interconnected process that, when dysregulated, is strongly linked to cellular disease states including cancer. Study of these metabolic processes is complicated by the characteristic intricacy of these systems; nonetheless, it is achievable through metabolic labeling. Visualization of biosynthesis is an advantage offered by metabolic labeling through the incorporation of fluorescent tags. In this technique, synthetic probes bearing a clickable tag such as azide are fed into live cells where they are directly incorporated using the native enzymatic and cellular processes to metabolically label lipid products. These labeled lipid products are capable of being studied …

Synthesis Of Biologically Active Phosphorus Heterocycles, Giri Gnawali

Dissertations

This dissertation work is divided into two parts. The first part is focused in the development of methodology for the synthesis of phostones and phosphonosugars and advancement thereof. The second part is focused in the development of affinity probes based on analogs of natural products cyclophostin and the cyclipostins.

Phostone (3) and phosphonosugars are cyclic phosphonates. The anomeric carbon of sugar is replaced by a phosphorus atom. The synthesis of phostones has been achieved starting form the key intermediate, γ,δ-epoxy vinyl phosphonate (1). The palladium catalyzed ring opening of γ,δ-epoxy vinyl phosphonates by a nucleophile results …

Elucidation Of Radical Cation Trapping Chemistry: Using Electrochemical And Photochemical Techniques To Qualitatively Assess The Kinetics Behind Anodic Oxidative Cyclizations, Luisalberto Gonzalez

Arts & Sciences Electronic Theses and Dissertations

While the field of organic chemistry has grown throughout the decades, its primary concern has always been on the generation, conversion, and study of molecular structures. Within that philosophy, the development of new reactions affords chemists the ability to overcome previous synthetic barriers or develop more elegant and simple synthetic routes to difficult-to-construct molecules. Within that realm, electrochemistry is seeing increased attention due its ability to generate highly reactive intermediates, recycle chemical reagents, and reverse the polarity of known functional groups. One example of such an application is the use of electrochemistry to form radical cations. While radical cations have …

New Catalytic Reactions In Carbohydrate Chemistry, Scott Geringer

Dissertations

Carbohydrates or sugars are some of the most diverse and abundant biological molecules. They are involved in a multitude of processes in the body such as fertilization, cell-cell communication, and cancer metathesis. Because of these vital functions, the study of sugars is rapidly growing field. The field however is limited due to the complex nature of sugars which results in difficulties in obtaining large quantities for study.

Protecting group manipulation is a large emphasis area in carbohydrate chemistry due to the need to selectively protect different functional groups of each molecule during synthesis. Catalytic and selective cleavage of protecting groups …

N,N’-Dimethyimidazolium-2-Carboxylate As A Ligand Precursor For The Accession Of A Constrained Olefin Dimerization Catalyst, Michael Harris

Honors Projects

A significant market share of modern plastics is held by long-chain hydrocarbon polymers, such as polyethylene and polypropylene, properties of which can be dramatically changed by addition of linear α-olefins. Production of linear α-olefins involves the creation of many unwanted byproducts, representing significant quantities of both economic and ecological waste. While catalysts have been designed to selectively produce industrially useful olefins, these catalysts often encounter challenges such as synthesis of other unwanted byproducts, slow reaction times, and difficulty of synthesis. Based on one such prior catalyst, we report here synthetic work towards a cobalt catalyst with a constrained N-heterocyclic carbene …

Exploration Of Cis-1,2-Diaminocyclohexane-Based Conformationally Locked Chiral Ligands In Asymmetric Synthesis, Carim Van Beek

University of the Pacific Theses and Dissertations

Natural products have been demonstrated to be of great significance to the pharmaceutical industry in the development of new drugs and medicine. Unfortunately, synthetic approaches to obtain these natural products often prove increasingly challenging due to the complexity of synthesizing the target drug in the proper stereochemistry. The availability of enantioselective reactions can play a pivotal role in overcoming this challenge, yielding access to optically pure intermediates and products. Chiral ligands based on a trans-1,2-diaminocyclohexane motif are often employed for this purpose and their complexes with transition metals have been demonstrated to act as efficient chiral catalysts in asymmetric reactions. …

Quantum Chemical Pka Estimation Of Carbon Acids, Saturated Alcohols, And Ketones Via Quantitative Structure-Activity Relationships, Corey Adam Baldasare

Browse all Theses and Dissertations

Acid dissociation constants, often expressed as pKa values, afford vital information with regards to molecular behavior in various environments and are of significance in fields of organic, inorganic, and medicinal chemistry. Several quantitative structure-activity relationships (QSARs) were developed that correlate experimental pKas for a given class of compounds with a descriptor(s) calculated using density functional theory at the B3LYP/6-31+G** level utilizing the CPCM solvent model. A set of carbon acids provided a good final QSAR model of experimental aqueous pKas versus ΔEH2O (R2 = 0.9647) upon removal of three aldehydes as outliers. A study of saturated alcohols offered a final …

Development Of Ni-Catalyzed Alkene Dicarbofunctionalization Reactions, Shekhar Kc

Chemistry and Chemical Biology ETDs

Alkenes serve as one of the most important feedstocks for organic synthesis, having two vicinal sites for bond formation. In alkenes, both vicinal sites can be functionalized with two reagents in a process commonly known as alkene difunctionalization, which results in the formation of two new bonds. A number of alkenes difunctionalization reactions, such as diamination, dioxygenation, carboamination and carbooxygenation, are known. However, difunctionalization of alkenes with two carbon-based entities, termed alkene dicarbofunctionalization, is relatively less common. Development of such a process could provide a powerful method to introduce two different carbon fragments across an alkene in a regioselective manner, …

Chemical And Physical Studies Of Charge Transfer Excited States Of Ruthenium Complexes With Aromatic Ligands, Marim Khalifa Alnaed

Wayne State University Dissertations

The 3MLCT excited states generated from tris-bipyridineruthenium(II), [Ru(bpy)3]2+ and related complexes was ionized by 405 nm irradiation in ambient, acidic aqueous solutions. The photoionization product was Ru(bpy)3]3+ and an electron with a quantum yield of about 0.040.02 in 0.5 M acid. However, 532 nm radiation does not induce photoionization, and it generates the 3MLCT excited state that can be photoionized by 405 nm irradiation. The proton is a very good electron scavenger, and the rate of phoionization of the 3MLCT excited state was determined to be acid dependent and it increased about ten-fold for acid concentrations beween 0.001 and 4 …

The Synthesis Of Highly Substituted Aromatics And The Reaction Of Alkene Pi Systems With Vinyl Cations, Nicholas Jarrod Dodge

Graduate College Dissertations and Theses

Aldol cyclotrimerizations have been used to achieve the rational chemical synthesis of both fullerenes and fullerene fragments in the past. Under certain conditions this reaction produces the corresponding cyclotetramer which has sometimes been regarded as an undesired byproduct. This work details efforts to synthesize and use these cyclotetramers toward a synthesis of a C240 fullerene fragment. One principal focus in this work is tridecacyclene, a cyclic tetramer of acenaphthylene given its name by our group for its thirteen rings. Relatively low yields for the synthesis of tridecacyclene and its derivatives drove us to investigate the mechanism of its formation and …

Synthesis Of 5-Methyl-3-Phenyl-1,3,4-Oxadiazol-2(3h)-One Derivatives By Electrophilic Aromatic Substitution, Amanda Solis Conde

Browse all Theses and Dissertations

An important research element in the Turnbull laboratory has been the one-pot synthesis of 5-methyl-3-phenyl-1,3,4-oxadiazol-2(3H)-one from sydnone. The present study reexamined the reaction of 5-methyl-3-phenyl-1,3,4-oxadiazol-2(3H)-one with electrophiles and optimized methods for synthesis of oxadiazolinone derivatives. Further the oxadiazolinone derivatives were reacted with electrophiles to better comprehend the donating ability of the oxadiazolinone ring system in general with the expectation that the oxadiazolinone ring system is a slightly donating system. Additionally, when the structure assignment of the oxadiazolinone derivative was ambiguous, the corresponding oxadiazolinone or it’s isomer was synthesized from the appropriate sydnone to validate or refute the suggested structure. The …

Design And Synthesis Of Analogs Of Myo-Inositol, Serine, And Cysteine To Enable Chemical Biology Studies, Tanei J. Ricks

Doctoral Dissertations

Phosphorylated myo-inositol compounds including inositol phosphates (InsPs) as well as the phosphatidylinositol polyphosphate lipids (PIP_ns) are critical biomolecules that regulate many of the most important biological processes and pathways. They are aberrant in many disease states due to their regulatory function. The same is true of the phospholipid phosphatidylserine (PS) which can serve as a marker to begin apoptosis. However, the full scope of activities of these structures is not clear, particularly since techniques that enable global detection and analysis of the production of these compounds spatially and temporally are lacking. With all of these obstacles in …

Iodine-Initiated Hydration Of Internal Alkynes, Nicholas J. Shuber, Karelle Aiken

Honors College Theses

The iodine-initiated hydration of internal alkynes is a novel, green, and inexpensive synthetic pathway in comparison with the commonly used transition metal catalyzed reactions. This can be a useful alternative in many fields, academic or industrial. This experimental design has been used successfully on terminal alkynes and is now being extended to internal alkynes. Through systematic probing of the reaction conditions, we have gleaned sufficient information to determine a strong mechanistic hypothesis based on neighboring group participation. Here in, we will report our result with a series of internal, keto alkynes reacted under ambient conditions with iodine in “wet” solvent. …

Synthesis Of Alkyl Substituted Phenylated Poly(Ether Ether Ketone Ketone)S, Matthew Cerone

Browse all Theses and Dissertations

A phenylated bis(fluorobenzoyl) monomer, 5-hexyl-2,3-diphenyl-1,4-bis(fluorobenzoyl)benzene, was synthesized via a four-step process. The first three compounds synthesized were diethyl 5-hexyl-2,3-diphenyl-1,4-benzenedicarboxylate, 5-hexyl-1,4-bis(hydroxymethyl)-2,3-diphenylbenzene and 5-hexyl-2,3-diphenyl-1,4-benzenedicarboxaldehyde. The final step involved the reaction of the Grignard formed from p-bromofluorobenzene with the dialdehyde to yield a diol intermediate which was oxidized to the bis(fluorobenzoyl) monomer by use of a Jones oxidation. The monomer was polymerized by nucleophilic aromatic substitution (NAS) with bisphenol-A, resorcinol, and hydroquinone in N-methyl-pyrrolidone (NMP) to yield novel, phenylated PEEKKs. The number-average molecular weights (Mn) for the polymers were found to be 35,700 g/mol, 34,800 g/mol and 28,000 g/mol, respectively and the weight-average …

Strategic Molecular Design To Engineer The Electron Affinity Of Self-Assembling Organic Semiconductors, Kelly Nicole Zaugg

UNLV Theses, Dissertations, Professional Papers, and Capstones

Development of electron-accepting (n-type) semiconductors used in organic photovoltaic cells and field effect transistors has been an area of research with less advancement compared to their electron-donating (p-type) counterparts. Currently, the highest performing n-type semiconductor is a fullerene-based derivative (PCBM) with a favorable ELUMO of -4.08 eV. However, PCBM has limited absorption in the visible region and fixed electron affinity. This work focuses on the development of self-assembling n-type materials with controllable electronic properties by strategically lowering ELUMO to a level comparable to PCBM. Molecular design follows an acceptor-acceptor'-acceptor (A-A'-A) configuration; with A being two 2,3-dioctyloxyphenazine substituents connected to A’ …