Chemistry Commons^™

Exploring The Limitations Of Substrate Scope In Dimethylallyltryptophan Synthases, Evan T. Miller

Theses and Dissertations--Pharmacy

Natural products (NPs), are the largest source of bioactive compounds in Nature, and are essential to the treatment of human disease. Nearly 50% of drugs approved for use from 1981 to 2019 owe some aspect of their development to NPs, either in terms of their structure, pharmacophore, or mechanism of action. However, NPs are difficult to structurally optimize. Chemoenzymatic methods for NP derivatization have been increasingly seen as practical alternatives to traditional synthetic methods. Prenyltransferases (PTs) are involved in the primary and secondary metabolism of plants, bacteria, and fungi, and they are key enzymes in the biosynthesis of many clinically …

Multiscale Modeling Of The Thermomechanical Behavior Of Polymeric And Molecular Organic Semiconductors, Kehinde H. Fagbohungbe

University of Kentucky Doctoral Dissertations

Organic semiconductors, derived from π-conjugated polymers and molecules, enable the development of deformable, stretchable and flexible electronics due to their tunable redox, optical, electronic and mechanical properties. However, an informed understanding of how multi-scale morphological characteristics of the polymeric and molecular semiconductors influence bulk properties that contribute to electronic and optical performance, especially under operational thermal and mechanical stresses, remains incomplete. This lack of understanding poses a challenge to scalability and commercialization of organic electronics. This dissertation develops and deploys computational modeling approaches, particularly atomistic molecular dynamics (MD) simulations, to investigate the multiscale morphological behavior of these synthetic semiconducting materials …

Supramolecular Self-Assemblies Of Ru( Ii ) Phototherapeutics: Biological Activity Of Micro- And Nano-Particles Acting As Reservoirs, Jérôme Laisney, Sarah M. Kriger, Dmytro Havrylyuk, Jason M. Unrine, David K. Heidary, Edith C. Glazer

Chemistry Faculty Publications

Ruthenium( II) coordination complexes have many appealing properties as prodrugs, but can suffer from poor aqueous solubility and short circulation times, drastically decreasing efficiency in vivo. Nanoformulations using a variety of carriers, such as inclusion in polymers/lipids or adsorption on inorganic nanoparticles have been applied to overcome this limitation, but unfortunately, these approaches raise additional concerns regarding the fate of the carriers, with potential long-term toxicity and accumulation in vital organs. Here, we present an alternative delivery strategy with formation of pure and polymer-supported supramolecular self-assemblies of Ru(II) complexes acting as ‘‘reservoirs’’. A facile preparation of size-controlled particles was achieved …

Characterization And Antimicrobial Activity Of Lignin-Derived Compounds In Ground Hurd Tissue Of Cannabis Sativa L. (Hemp) Cultivars, Jourdan E. Lakes, Anjam Sadik, Robert C. Pearce, Barbara L. Knutson, Stephen E. Rankin, Bert C. Lynn, Michael D. Flythe

Chemistry Faculty Publications

Objectives: Characterize lignin-derived compounds from the hurd of 10 fiber/grain Cannabis sativa L. cultivars and investigate the antimicrobial activity of select compounds on the wasteful ruminant bacterium, Acetoanaerobium sticklandii SR.   Methods: Hurd was processed using an aqueous ethanol solvent system and analyzed via GC-MS to identify and characterize lignin derivatives. Antimicrobial activity of the hurd and three monomers was assessed using solid (hurd) and liquid medium (monomers) bioassays against SR.   Results: 27 compounds were identified, most as monomers but a few were dimers, ethylated derivatives, and organic acids. There were approximately equal G- and S-units with substantially fewer H-units. Several …

Enhanced Photostability Through Rapid Exciton Decay In Desymmetrized Cyclopentannulated Acenes With Strong Face-To-Face Pi Stacking, Chad D. Cruz, Karl J. Thorley, Zachary J. Knepp, Jared Wahlstrand, Gil M. Repa, John C. Stephenson, Sean Parkin, Lisa A. Fredin, John E. Anthony, Emily G. Bittle

Chemistry Faculty Publications

The photophysics of organic semiconductors impacts their efficiency in optoelectronic devices where exciton transitions, including singlet fission, intersystem crossing and the formation of charge transfer states influence the ability to convert between bright and dark states and to dissociate into free charges. Unfortunately, photodegradation and spurious signals often confound the results of optical studies, especially of important triplet states. Here four asymmetric cyclopentannulated acenes are synthesized and studied. This system represents an extreme in photophysics achieved via molecular design to fully quench the photoluminescence and bypass triplet formation allowing for comparative studies with other highly absorbing acenes. Rapid molecular exciton …

Utilizing Coal For Mesophase Pitch-Based Carbon Fiber Production: Precursors, Processes, And Progress, Christina M. Thompson

Theses and Dissertations--Chemistry

Graphitic materials possess unique properties due to the unique combination of layered crystalline structure and carbon’s low atomic weight. High performance carbon fiber is one such example, displaying exceptional strength-to-weight ratios, stiffness, and thermal and chemical resistance. These properties render high performance carbon fiber a critical structural reinforcement material in the manufacture of composites across various industries, such as for automotive and aerospace applications. However, balancing fiber performance with precursor and processing costs remains a challenge. As alternative carbonaceous feedstocks are explored, coal has gained interest for utilization in graphitic products as a relatively abundant and low-cost source of aromatic …

Elucidating The Impacts Of Non-Covalent Interactions In Organic Materials Through A Multiscale Computational Approach, Sashen A. Ruhunage

Theses and Dissertations--Chemistry

Noncovalent interactions (NCIs) in π-conjugated organic materials serve as tunable levers that influence molecular structure and intermolecular interactions in the condensed phase and, in turn, impact the electronic, optical, and mechanical properties of these materials. NCIs include attractive dispersion, electrostatic, and induction interactions, as well as repulsive exchange interactions. However, how to design materials with NCI considerations remains an open question across many fields. Here, we seek to provide an electronic and atomistic perspective on these interactions through multiscale simulations to aid materials design, processing, and performance optimization. In this study, we investigate NCIs and their effects across various systems …

Student Familiarity With The Periodic Table Of The Elements: Results From Cued-Recall And Eye-Tracking Assessments On Memory, Victor A. Okuo

Theses and Dissertations--Chemistry

Learning element symbol–name associations and the spatial organization of elements on the periodic table is a foundational step in learning chemistry, supporting later understanding of chemical formulas, equations, bonding, and stoichiometry. Although students often rely on memorization strategies to learn periodic table content, this task is challenging due to the large number of elements and the apparent ambiguity in matching some element symbols to their names.

This study explores students’ recall of element names when given element symbols as cues and their knowledge of element locations on the periodic table when given element names as cues. The study also examines …

Ex Vivo Single-Molecule Analysis Of Ryanodine Receptor 2 Assembly In Cardiac And Neuronal Tissue, Qianye Yin, Christopher I. Richards

Chemistry Faculty Publications

Understanding receptor assembly is critical for elucidating the mechanisms underlying their function and regulation in physiological processes. While traditional in vitro single-molecule studies rely on isolating proteins from heterologous expression systems, they often fail to capture the in vivo physiological complexity involved in the organization and assembly of cell surface proteins. This protocol employs Total Internal Reflection Fluorescence Microscopy (TIRFM) to study GFP-tagged Ryanodine Receptor 2 (RyR2) molecules encapsulated within nanoscale vesicles. These vesicles, generated from organs rapidly extracted from the animal, effectively provide a snapshot of the receptor's assembly state at the time of extraction, enabling detailed analysis of …

Valorizing Municipal Solid Waste For Sustainable Aviation Fuel And Polyhydroxyalkanoate Bioplastics: Pyrolysis And Microbial Pathways, Emon Das

Theses and Dissertations--Biosystems and Agricultural Engineering

The escalating global burden of municipal solid waste (MSW), projected to reach 3.88 billion tons annually by 2050, calls for innovative valorization strategies to mitigate environmental impacts and promote a circular bioeconomy. This thesis investigates the conversion of MSW into two high-value products: sustainable aviation fuel (SAF) and polyhydroxyalkanoate (PHA) bioplastics. Chapter one presents comprehensive physicochemical characterization and pyrolysis-GC/MS analysis of MSW feedstocks. The physicochemical results reveal that densification enhances handling and storage properties, while pyrolysis-GC/MS analysis indicates that plastic-rich MSW streams produce bio-oils with favorable hydrocarbon profiles suitable for SAF production, potentially contributing to decarbonization efforts in the aviation …

Chemoproteomic Profiling Of A Carbon-Stabilized Gold(Iii) Macrocycle Reveals Cellular Engagement With Hmox2, Sailajah Gukathasan, Chibuzor Ngozi Olelewe, Libby Ratliff, Jong H. Kim, Alyson M. Ackerman, J. Robert Mccorkle, Sean Parkin, Gunnar F. Kwakye, Jill M. Kolesar, Samuel G. Awuah

Chemistry Faculty Publications

In this work, we discovered a novel organometallic gold(III) macrocycle, Au-Mac1, that demonstrates anticancer potency in a panel of triple-negative breast cancer cells (TNBC), and based on this complex, a biotinylated-Au-Mac1 probe was designed for target identification via chemoproteomics, which uncovered the engagement of HMOX2 of the heme-energy metabolism pathway. Using orthogonal chemical biology and molecular biology approaches, including immunoblotting, flow cytometry, and cellular thermal shift assays, it was confirmed that Au-Mac1 engages HMOX2 in cells. Downstream effects of Au-Mac1 on the depletion of mitochondrial membrane proteins and bioenergetics point to the potential role of HMOX2 in cancer. Importantly, Au-Mac1 …

Electrochemical Observation And Ph Dependence Of All Three Expected Redox Couples In An Extremophilic Bifurcating Electron Transfer Flavoprotein With Fused Subunits, Debarati Das, Wassim El Housseini, Monica Brachi, Shelley D. Minteer, Anne-Frances Miller

Chemistry Faculty Publications

Bifurcating enzymes employ energy from a favorable electron transfer to drive unfavorable transfer of a second electron, thereby generating a more reactive product. They are therefore highly desirable in catalytic systems, for example, to drive challenging reactions such as nitrogen fixation. While most bifurcating enzymes contain air-sensitive metal centers, bifurcating electron transfer flavoproteins (bETFs) employ flavins. However, they have not been successfully deployed on electrodes. Herein, we demonstrate immobilization and expected thermodynamic reactivity of a bETF from a hyperthermophilic archaeon, Sulfolobus acidocaldarius (SaETF). SaETF differs from previously biochemically characterized bETFs in being a single protein, representing a …

Functional Utility Of Gold Complexes With Phosphorus Donor Ligands In Biological Systems, Adedamola S. Arojojoye, Samuel G. Awuah

Chemistry Faculty Publications

Metallo-phosphines are ubiquitous in organometallic chemistry with widespread applications as catalysts in various chemical transformations, precursors for organic electronics, and chemotherapeutic agents or chemical probes. Here, we provide a comprehensive review of the exploration of the current biological applications of Au complexes bearing phosphine donor ligands. The goal is to deepen our understanding of the synthetic utility and reactivity of Au-phosphine complexes to provide insights that could lead to the design of new molecules and enhance the cross-application or repurposing of these complexes.

Chromatographic And Electrophoretic Analysis Of Lignin-Derived Monomers And Dimers: Extraction Method Development And Evaluation Of Cyclodextrins For Recovery, Anjam Sadik

Theses and Dissertations--Chemistry

Biorefineries play a vital role in reducing dependence on fossil fuels and addressing global warming concerns. Unfortunately, investment in biorefineries remains limited due to economic sustainability concerns. One approach to enhance the economic viability of biorefineries is by fully utilizing the potential of feedstocks, particularly lignocellulosic biomass, which is commonly used in these processes. Traditional processing methods often alter the lignin portion of biomass, making it unsuitable for further utilization. However, when retained in its native form, lignin can serve as a valuable source of chemicals that contribute to the economic sustainability of biorefineries.

The lignin-first approach, which removes lignin …

Catalytic Deoxygenation Of Oleaginous Biomass To Renewable Diesel And Sustainable Aviation Fuel Via Decarboxylation/Decarbonylation, Chukwudalu Great Umenweke

Theses and Dissertations--Chemistry

Several technologies have been developed to produce hydrocarbon biofuels – renewable diesel (RD) and sustainable aviation fuel (SAF) – from fats, oils, and greases (FOG), with the hydroprocessing of esters and fatty acids (HEFA) representing one of the most mature pathways. In its current form, HEFA is mainly reliant on the hydrodeoxygenation (HDO) reaction, which has several drawbacks since HDO requires large amounts and pressures of hydrogen, feedstocks of high purity and cost, as well as problematic sulfided catalysts that risk contaminating the biofuel product with sulfur. A process based on decarboxylation/decarbonylation (deCO_x) offers an attractive alternative to …

Insights Into Factors Influencing Radical Coupling Chemistry Of Monolignols During Lignification And Induced Changes In Plant Secondary Metabolism, Rachel Poornima Sutherland

Theses and Dissertations--Chemistry

Lignin is a complex aromatic biopolymer and an important constituent in plant cell walls. The process of lignin biosynthesis, known as lignification, is poorly understood and challenging to study but has important implications in a variety of fields including sustainable energy, bioengineering, and materials science and is therefore of interest to pursue. In the final stage of lignification, H-, G-, and S-monolignols are oxidized by laccase and peroxidase enzymes to generate radical species that couple to form dimers and further oligomeric species to ultimately produce the lignin polymer. Biomimetic lignin model systems utilize in vitro oxidative coupling reactions as an …

Redox Control In A Fused Electron Transfer Flavoprotein From A Thermophilic Archaeon And Expanded Significance Of A Hydrogen Bond From A Conserved Histidine Residue That Contributes To Flavin Redox Tuning And Activation For Covalent Modification, Debarati Das

Theses and Dissertations--Chemistry

In absence of O₂ as terminal electron acceptors in anaerobic bacteria and archaea, carbohydrate metabolism is 15 times less efficient compared to aerobic energy metabolism resulting in energy deficit conditions. Despite their meager resources these anaerobes were able to generate H₂ and a chemiosmotic potential able to drive energy demanding reactions such as CO₂ or N₂ fixation. These observations raised concerns as production of high energy reductants (H₂) from mediocre fuels (NADH) defied the laws of thermodynamics.

In 2008, a known mechanism “electron bifurcation” but with flavins as redox mediators instead of quinones was …

Towards Automating The Study And Discovery Of Electroactive Π-Conjugated Molecules, Rebekah Ann Duke-Crockett

Theses and Dissertations--Chemistry

Chemistry is entering a new paradigm of automation and data-driven discovery. Automated discovery is grounded in well-curated “big data.” As generative and predictive models fueled by simulation data see growing success, emerging robotic automation enables the generation of unprecedented volumes of experimental data. Automation-powered, data-driven approaches hold tremendous potential for groundbreaking insights and innovations, particularly in the study and discovery of electroactive π-conjugated molecules. Realizing this potential, however, requires democratizing chemical data and the automation needed to generate and use it. There is a need to expand access to the tools for findable, accessible, interoperable, and reusable (FAIR) data management …

Design And Synthesis Of Novel Ligands For Bioorthogonal Catalysis, Asymmetric Synthesis, And Ferromagnetic Behavior, Alexander G. Olivelli

Theses and Dissertations--Chemistry

Small molecule metal complexes have diverse applications including usage as catalysts, single molecule magnets, photosensitizers and pharmaceuticals. The first research project in this work reports a new ligand which dimerizes upon coordination to afford a trinuclear Cu(I) complex. Due to the coordination geometry of the Cu(I) metal centers, paired with the strong nitrogen coordinating groups, the resulting complex is resistant to oxidation even in the presence of strong oxidants. The complex is shown to be efficient in the CuAAC reaction and used to tag anticancer drug candidates in vitro. The next project focuses on a series of amidine-based ligands featuring …

Machine Learning Models For Molecular-Based Functional Organic Materials, Moses Ogbaje

Theses and Dissertations--Chemistry

Organic semiconductors (OSC) are of interest for a wide range of flexible optoelectronics applications, including transistors, solar cells, and sensors, to name a few. Despite their promise, the design and optimization of OSC pose significant challenges due to the complexity of the structures of the molecular building blocks, varied packing configurations of these building blocks in the solid state, which impacts the optical and electronic response, and sensitivity of the solid-state packing to material processing conditions. Accurately predicting the solid-state properties of OSC traditionally requires high-level quantum mechanical methods. These methods, however, can be computationally demanding, particularly for large molecules …

Investigation Of D-Π-A Re (1) Complexes For The Homogenous Photocatalytic Reduction Of Co2, Ryan M. Chafin

Theses and Dissertations--Chemistry

Increasing anthropogenic emission of CO₂ into the atmosphere is a global issue that shows no signs of deceleration due to the current trends in dependencies on fossil fuels for energy demand. Although deleterious in nature, this greenhouse gas can serve as a useful feed-stock for the production of small-carbon-chain commercial chemicals if the factors owing to its inertness can be overcome. Fortuitously, CO₂’s chemically inert nature is already circumvented in nature through an elegant cascade of biochemical reactions known as photosynthesis, which nearly all plants and some families of bacteria exploit to produce simple sugars for metabolic …

Targeted Mitigation Strategies To Reduce Secondary Emissions In Co2 Capture Systems, Keemia Abad

Theses and Dissertations--Chemistry

Global CO₂ emissions from industrial, power generation and transportation sources has led to the call for increased implementation of carbon capture strategies. The most developed of these is point source carbon capture, which refers to the process of capturing CO₂ directly from large (point) source emitters, before the CO₂ is released into the atmosphere. The challenge becomes separating CO₂ from the other components of the emitted gas, mainly nitrogen. These CO₂ capture processes typically involve the use of aqueous solutions of amines to absorb (capture) CO₂ from the gas stream, where the CO₂ and the …

Exploring The Relationships Between Molecular Structure And Crystal Packing In Small-Molecule Organic Semiconductor Materials, Dean A. Windemuller

Theses and Dissertations--Chemistry

Organic semiconductor materials (OSCs) are rapidly becoming a vital part of the technological landscape. They possess unique properties that make them attractive for the electronics industry. Relatively low-temperature and low-cost processing are a large part of the promise of OSCs. Perhaps more importantly, organic materials can be modified in a relatively straightforward manner, presenting an opportunity for them to be tuned and adapted to a variety of purposes and applications. Polycyclic aromatic hydrocarbons (PAHs) form a large group within the field of OSC research. Some of the most promising high-performance materials in this category to-date are acenes and heteroacenes. This …

Effects Of A-Site Cation Structure And B-Site Metal On Optical And Electronic Properties Of 2d Ruddlesden-Popper Phase Tin-Based Hybrid Perovskites, Henry Pruett

Theses and Dissertations--Chemistry

Organic metal halide perovskites (HPs) are attractive materials for a variety of electronic applications due to their low cost, tunable band gaps, excellent charge transport properties, and high photoluminescence efficiency. As such, HPs are being investigated for use in solar cells, photodetectors, X-ray detectors, light emitting diodes, field effect transistors, lasers, resistive random-access memory, etc. Currently the most popular metal used in HPs is lead, but the use of lead comes with the potential for heavy metal exposure. Tin-based perovskites offer a less hazardous alternative, but their optoelectronic properties lag behind those of lead and less work has been done …

Physicochemical Property Effects On Immune Modulating Polymeric Nanoparticles: Potential Applications In Spinal Cord Injury, Daniel J. Kolpek, Jaechang Kim, Hisham Mohammed, John C. Gensel, Jonghyuck Park

Markey Cancer Center Faculty Publications

Nanoparticles (NPs) offer promising potential as therapeutic agents for inflammation-related diseases, owing to their capabilities in drug delivery and immune modulation. In preclinical studies focusing on spinal cord injury (SCI), polymeric NPs have demonstrated the ability to reprogram innate immune cells. This reprogramming results in redirecting immune cells away from the injury site, downregulating pro-inflammatory signaling, and promoting a regenerative environment post-injury. However, to fully understand the mechanisms driving these effects and maximize therapeutic efficacy, it is crucial to assess NP interactions with innate immune cells. This review examines how the physicochemical properties of polymeric NPs influence their modulation of …

Microfiltration Membrane Pore Functionalization With Primary And Quaternary Amines For Pfas Remediation: Capture, Regeneration, And Reuse, Sam Thompson, Angela Gutierrez, Jennifer Bukowski, Dibakar Bhattacharyya

UK CARES Faculty Publications

The widespread production and use of multi-fluorinated carbon-based substances for a variety of purposes has contributed to the contamination of the global water supply in recent decades. Conventional wastewater treatment can reduce contaminants to acceptable levels, but the concen- trated retentate stream is still a burden to the environment. A selective anion-exchange membrane capable of capture and controlled release could further concentrate necessary contaminants, mak- ing their eventual degradation or long-term storage easier. To this end, commercial microfiltration membranes were modified using pore functionalization to incorporate an anion-exchange moiety within the membrane matrix. This functionalization was performed with primary and …

Iron Oxide Nanozymes Enhanced By Ascorbic Acid For Macrophage-Based Cancer Therapy, Zhongchao Yi, Xiaoyue Yang, Ying Liang, Sheng Tong

Markey Cancer Center Faculty Publications

In recent years, using pharmacological ascorbic acid has emerged as a promising therapeutic approach in cancer treatment, owing to its capacity to induce extracellular hydrogen peroxide (H2O 2) production in solid tumors. The H2 O 2 is then converted into cytotoxic hydroxyl free radicals (HO•) by redox-active Fe2+ inside cells. However, the high dosage of ascorbic acid required for efficacy is hampered by adverse effects such as kidney stone formation. In a recent study, we demonstrated the efficient catalytic conver- sion of H2 O2 to HO• by wüstite (Fe 1−xO) nanoparticles (WNPs) through a heterogenous Fenton reaction. Here, we explore …

Response To Replication Stress And Maintenance Of Genome Stability By Wrn, The Werner Syndrome Protein, David K. Orren, Amrita Machwe

Markey Cancer Center Faculty Publications

Werner syndrome (WS) is an autosomal recessive disease caused by loss of function of WRN. WS is a segmental progeroid disease and shows early onset or increased frequency of many characteristics of normal aging. WRN possesses helicase, annealing, strand exchange, and exonuclease activities and acts on a variety of DNA substrates, even complex replication and re- combination intermediates. Here, we review the genetics, biochemistry, and probably physiological functions of the WRN protein. Although its precise role is unclear, evidence suggests WRN plays a role in pathways that respond to replication stress and maintain genome stability particularly in telomeric regions.

Inchi Isotopologue And Isotopomer Specifications, Hunter N. B. Moseley, Philippe Rocca-Serra, Reza M. Salek, Masanori Arita, Emma L. Schymanski

Markey Cancer Center Faculty Publications

This work presents a proposed extension to the International Union of Pure and Applied Chemistry (IUPAC) International Chemical Identifier (InChI) standard that allows the representation of isotopically‑resolved chemi‑ cal entities at varying levels of ambiguity in isotope location. This extension includes an improved interpretation of the current isotopic layer within the InChI standard and a new isotopologue layer specification for representing chemical intensities with ambiguous isotope localization. Both improvements support the unique isotopically‑ resolved chemical identification of features detected and measured in analytical instrumentation, specifically nuclear magnetic resonance and mass spectrometry.

Scientific contribution

This new extension to the InChI standard …

Shared Genomic Segments Analysis Identifies Mhc Class I And Class Iii Molecules As Genetic Risk Factors For Juvenile Idiopathic Arthritis, Cecile N. Avery, Nicole D. Russell, Cody J. Steely, Aimee O. Hersh, John F. Bohnsack, Sampath Prahalad, Lynn B. Jorde

Markey Cancer Center Faculty Publications

Juvenile idiopathic arthritis (JIA) is a complex rheumatic disease encompassing several clinically defined subtypes of varying severity. The etiology of JIA remains largely unknown, but genome-wide association studies (GWASs) have identified up to 22 genes associated with JIA susceptibility, including a well-established association with HLA-DRB1. Continued investigation of heritable risk factors has been hindered by disease heterogeneity and low disease prevalence. In this study, we utilized shared genomic segments (SGS) analysis on whole-genome sequencing of 40 cases from 12 multi-generational pedigrees significantly enriched for JIA. Subsets of cases are connected by a common ancestor in large extended pedigrees, increasing the …