Chemistry Commons^™

Electrochemical Study Of The Performance Of Manganese Vanadium Oxide Cathodes In Zinc Batteries, Sarat Alabidun

Graduate Research Theses & Dissertations

Zinc metal batteries are considered a promising alternative for grid energy storage due to the low redox potential (-0.76V vs SHE) and high theoretical specific capacity (850mAh/g) of zinc metal anode as well as its compatibility with aqueous electrolytes. They however face issues of poor cathode stability and rapid capacity fading. Several methods have been devised to improve the stability of the cathode materials and develop novel cathode materials with better performance including the metal ion doping of intercalation materials.This study investigated the performance of zinc metal batteries with novel manganese vanadium oxide cathodes. Organic structure directing agents have been …

Carborane-Appended Levodopa For Prostate-Specific Membrane Antigen And Boron Neutron Capture Therapy, Alejandra Macias

Graduate Research Theses & Dissertations

A multi-step organic synthetic method to attach carborane cages to biocompatible organic compounds for application in Boron Neutron Capture Therapy (BNCT) was conducted. Boron Neutron Capture Therapy is a form of radiation therapy that promises a new and effective form of cancer treatment that involves the destruction of tumor cells using an isotope of boron (10B). The effectiveness of this therapy depends on the boron content accumulated in cancerous tissue. Carboranes are boron-rich clusters that possess unique physical and chemical properties making them suitable for a wide range of applications including medicinal chemistry. Because of their high boron content, carborane-appended …

Metal Complexes Of Bis(Pyrazolyl)Methane-Based Ditopic Ligands, Pubudu Nuwan Perera Hapuarachchige

Masters Theses

No abstract provided.

Determining Material Structures And Surface Chemistry By Genetic Algorithms And Quantum Chemical Simulations, Josiah Jesse Roberts

Theses and Dissertations--Chemistry

With the advent of modern computing, the use of simulation in chemistry has become just as important as experiment. Simulations were originally only applicable to small molecules, but modern techniques, such as density functional theory (DFT) allow extension to materials science. While there are many valuable techniques for synthesis and characterization in chemistry laboratories, there are far more materials possible than can be synthesized, each with an entire host of surfaces. This wealth of chemical space to explore begs the use of computational chemistry to mimic synthesis and experimental characterization. In this work, genetic algorithms (GA), for the former, and …

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 …

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 …

Computational Insights On Medicinal Chemistry Targeting Cyp450s, Alexander D. Fenton

Theses and Dissertations--Chemistry

Modern-day medicinal chemistry has provided researchers with a wide variety of tools to not only gather greater insight from their data, but also to generate data in new ways. One such tool is the construction of computational protein models from crystallographic datasets, and their subsequent use to understand the structure-activity relationships of protein-ligand complexes. These models can be utilized for their predictive power to inform the synthesis of, and improvement of, lead compounds. It is the goal of this work to employ such models to the CYP450 enzyme system such that potent and selective inhibitors can be designed, evaluated biologically, …

Plasmon Enhanced Single Molecule Fluorescence In Zero Mode Waveguides (Zmws), Abdullah Masud

Theses and Dissertations--Chemistry

Plasmonic nanostructures are an extensive research focus due to their ability to modify the photophysical properties of nearby fluorophores. Surface plasmons (SP), defined as the collective oscillation of delocalized electrons, are the fundamental characteristic primarily responsible for altering those photophysical properties. Studying fluorophores at the single-molecule level has received significant attention since more specific information can be extracted from single molecule-based studies, which otherwise could be obscured in ensemble studies. However, single-molecule studies are inherently challenging because the signal from a single molecule is usually dim, making it difficult to detect. The situation is even worse in a crowded environment …

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 …

Flavin Modification And Redox Tuning In The Bifurcating Electron Transfer Flavoprotein From Rhodopseudomonas Palustris: Two Arginines With Different Roles, Nishya Mohamed-Raseek

Theses and Dissertations--Chemistry

Electron bifurcation is considered as a third fundamental mode of energy conservation mechanism in addition to two well-known mechanisms, substrate level phosphorylation and Oxidative phosphorylation, in electron bifurcation endergonic and exergonic redox reactions are coupled. The newly discovered flavin based electron bifurcation in electron transfer flavoproteins (ETFs) helps to reduce low potential ferredoxin, which provides electrons to drive biologically demanding reactions such as atmospheric dinitrogen fixation in diazotroph and methane production in methanogens.

Current research demonstrates the capacity for electron bifurcation in the Rhodopseudomonas palustris ETF (RpalETF) system. RpalETF contains two chemically identical but functionally different FADs: …

Elucidation Of The Structure Of Supramolecular Polymorphs In Peptide Nanofibres Using Raman Spectroscopy, Sian Sloan-Dennison, Ayala Lampel, Eileen Raßlenberg, Rein V. Ulijn, Ewen Smith, Karen Faulds, Duncan Graham

Advanced Science Research Center

Peptide fibre formation via molecular self-assembly is a key step in a range of cellular processes and increasingly considered as an approach to produce supramolecular biomaterials. We previously demonstrated the self-assembly of the tripeptide lysine-dityrosine (KYY) as a substrate for the formation of proton-conducting melanin-like materials. Point based Raman scattering is one of several techniques which were used to characterise the secondary structure of the KYY nanofibre but as is often the case with this type of fibre, the spectra are rather complex and in addition there were variations in intensity between samples making interpretation difficult. Using Raman mapping we …

Exposing The Effects Of Reaction Cavity In Solid-Phase Reaction Kinetics, Michael Carr

Master's Theses

Reactivity of molecular solids is governed by topochemical considerations, where minimizedmolecular movement dictates both product identity and kinetics. This Thesis explores the central role reaction cavity plays in the topochemical principle by using the highly varied cavities formed by the different facets of a tetracene crystal. The relative rates for ten different reaction cavities were measured via energy dispersive X-ray spectroscopy for the reaction of tetracene with vapors of maleic anhydride. Variance in cavities resulted in Diels-Alder reaction rates that differed by as much as a factor of 2.6. Effects were understood via molecular dynamic simulations which modeled the approach …

Generation, Characterization, And C-H Bond Activation Reactivity By Mononuclear High-Valent Cobalt(Iv) And Nickel(Iv) Non-Oxo Complexes, Yubin Maria Kwon

Graduate Student Theses, Dissertations, & Professional Papers

The study of terminal high-valent transition metal-oxo complexes has increased significantly over the years as it is believed that they are key reactive intermediates for a wide range of biological and industrial catalytic processes. These complexes are powerful oxidants for the activation of strong C-H bonds. The chemical and physical properties of these complexes remain elusive. It is therefore desirable to study the properties and function of these complexes through synthetic models. There have been many efforts and reports of synthetic high-valent metal-oxo complexes of early and middle transition metals (up to group 8 on the Periodic Table of Elements), …

Synthesis And Conformational Study Of Triazolylcyclohexanols And Trans-2-(Azaarylsulfanyl)-Cyclohexanols, Mulinde R. Ruyonga

University of the Pacific Theses and Dissertations

Amino-cyclohexanol derivatives have been successful models for pH-triggered conformational switches. By changing the groups on the amine nitrogen, these models provide a wide pH-range in which a switch can occur. The pH-induced switch of conformation can be monitored by 1H NMR.In this work, structurally similar trans-2-(azaarylsulfanyl)-cyclohexanol derivatives (Scheme 1) and trans-2-triazolylcyclohexanol derivatives (Scheme 2) have been explored for the first time as compounds with a potential for the analogous pH-induced conformational switch. The azaarylsulfanyl groups showed selective conformational flexibility while the triazolyl group showed a strong preference for the equatorial position. Further, conformational studies were done on a series of …

Bayesian-Derived Vancomycin Auc24h Threshold For Nephrotoxicity In Special Populations, Dan Ho

University of the Pacific Theses and Dissertations

A Bayesian-derived 24-hour area under the concentration-time curve over minimum inhibitory concentration from broth microdilution (AUC24h/MICBMD) ratio of 400 to 600 is recommended as the new monitoring parameter for vancomycin to optimize efficacy and minimize nephrotoxicity. The AUC24h threshold of 600 mg*h/L for nephrotoxicity was extrapolated from studies that assessed the general population. It is unclear if this upper threshold is consistent or varies when used in special populations such as critically ill patients, obese patients, patients with preexisting renal disease, and patients on concomitant nephrotoxins.The purpose of this study is to investigate the generalizability of the proposed vancomycin AUC24h …

Electrocatalytic Redox Neutral [3+2] Annulation Of N-Cyclopropylanilines And Alkenes, Qi Wang, Qile Wang, Yuexiang Zhang, Yasmine M. Mohamed, Carlos Pacheco, Nan Zheng, Richard N. Zare, Hao Chen

Chemistry & Biochemistry Faculty Publications and Presentations

Although synthetic organic electrochemistry (EC) has advanced significantly, net redox neutral electrosynthesis is quite rare. Two approaches have been employed to achieve this type of electrosynthesis. One relies on turnover of the product by the reactant in a chain mechanism. The other involves both oxidation on the anode and reduction on the cathode in which the radical cation or the radical anion of the product has to migrate between two electrodes. Herein, a home-built electrochemistry/mass spectrometry (EC/MS) platform was used to generate an N-cyclopropylaniline radical cation electrochemically and to monitor its reactivity toward alkenes by mass spectrometry (MS), which …

Mitochondrial Energetics With Transmembrane Electrostatically Localized Protons: Do We Have A Thermotrophic Feature?, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

Transmembrane electrostatically localized protons (TELP) theory has been recently recognized as an important addition over the classic Mitchell’s chemiosmosis; thus, the proton motive force (pmf) is largely contributed from TELP near the membrane. As an extension to this theory, a novel phenomenon of mitochondrial thermotrophic function is now characterized by biophysical analyses of pmf in relation to the TELP concentrations at the liquid-membrane interface. This leads to the conclusion that the oxidative phosphorylation also utilizes environmental heat energy associated with the thermal kinetic energy (k_BT) of TELP in mitochondria. The local pmf is now calculated to be in …

Labilization And Diversification Of Pyrogenic Dissolved Organic Matter By Microbes, Aleksandar I. Goranov, Andrew S. Wozniak, Kyle W. Bostick, Andrew R. Zimmerman, Siddhartha Mitra, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

With the increased occurrence of forest fires around the world, interest in the chemistry of pyrogenic organic matter (pyOM) and its fate in the environment has increased. Upon leaching from soils by rain events, significant amounts of dissolved pyOM (pyDOM) enter the aquatic environment and interact with microbial communities that are essential for cycling organic matter within the different biogeochemical cycles. To evaluate the bio-reactivity of pyDOM, aqueous extracts of laboratory-produced chars were incubated with soil microbes and the molecular changes to the composition of pyDOM were probed using ultrahigh resolution mass spectrometry (Fourier transform – ion cyclotron resonance – …

Fabrication, Characterization And Environmental Monitoring Of Polymer-Based Materials For Biomedical And Structural Applications, Mousumi Bose

Doctoral Dissertations

"Polymers are versatile materials utilized for variety of applications. In biomedical field, luminescence quenching based optical oxygen sensors encapsulated in polymeric substances are gaining attention for early detection of surface wounds associated with tissue oxygen. A simple and low-cost fabrication technique was developed to produce sensor arrays for continuous two-dimensional oxygen tension measurement. Sensor patch along with smart phone-based readout technique is being evaluated as a smart bandage.

The environmental concerns and limited petroleum supply demand for replacing petroleum-based polymers with renewable bio-based sources while maintaining comparable properties. A sustainable and green approach was adopted to synthesize soy polyol-derived rigid …

Relating Detonation Parameters To The Detonation Synthesis Of Nanomaterials, Martin Langenderfer

Doctoral Dissertations

“This research investigates the physical and chemical processes that contribute to the detonation synthesis of silicon carbide nanoparticles. Bulk production of SiC nanoparticles through detonation is possible due to pressures achieved over 20 GPa and temperatures over 2000 K as well as quenching rates in excess of 13 billion K/second. These conditions catalyze reaction and bottom-up molecular growth while retaining particles < 100 nm in diameter. In this work, detonation synthesis of SiC was demonstrated by incorporation of polycarbosilane, an SiC precursor material, into an RDX/TNT explosive matrix prior to detonation. Detonation Synthesis of SiC was also accomplished by reacting elemental silicon with carbon liberated by the detonation of negatively oxygen balanced TNT. Hydrodynamic simulation of a 60:40 mass ratio RDX/TNT detonation created conditions thermodynamically suitable to produce cubic silicon carbide within the first 500 nanoseconds after the passage of the detonation wave while carbon remains chemically reactive for molecular formation. Simulations and experimental tests indicated that loading configuration and impedance mismatch of the precursor additives used in detonation synthesis results in conditions in the additives that exceed the accepted detonation pressure of the explosive by greater than three times. Finally, a full factorial experimental design showed increasing silicon concentration, reducing silicon size, and reducing oxygen balance by adjusting the ratio of RDX to TNT decreased the explosives detonation pressure by 20% and increased the soot yield and concentration of SiC observed in the detonation products by 82% and 442% respectively”--Abstract, page iv.

Development Of High-Performance Hydrogels, Buddhabhushan Salunkhe

Doctoral Dissertations

Here, we present a systematic approach to design robust hydrogel compositions. The goal was to achieve excellent properties to open up new opportunities in especially two challenging applications not previously well-served by hydrogels.

The first part of this research will discuss the systematic screening of polymers for their hydrothermal stability under brine, acidic, neutral, and basic pH conditions followed by novel designs of hydrogel compositions. Certain hydrogel compositions withstand temperatures of up to 150 °C for more than 24 months in high salinity brines. This novel hydrogel composition fills a technology gap between the existing polyacrylamide-based preformed particle gels (PPGs) …

Designing Transition Metal Chalcogenides Electrocatalyst Surfaces For High-Efficiency Water Oxidation, Umanga De Silva

Doctoral Dissertations

”The rising demand for energy security and reducing fossil fuel dependence has prompted researchers to search for a clean, sustainable, and efficient energy generation system with low environmental impact. Water electrolysis has been identified as one of the most important processes satisfying the above needs to generate hydrogen as a clean fuel. Two half-cell reactions of oxygen evolution reaction (OER) at the anode and hydrogen evolution reaction (HER) at the cathode comprise the main process of water electrolysis. However, the oxygen evolution reaction is the most crucial step for efficient water splitting. Traditionally, metal oxides have been utilized as catalysts …

Development Of Intelligent Stimuli-Responsive Biomaterials And Nanodevices, Shuo Yang

Doctoral Dissertations

"Structural DNA nanotechnology utilizes DNA molecules as building blocks to fabricate ordered artificial nanostructures at the molecular level. Among all DNA-based techniques, DNA origami has been considered as one of the most powerful tools for constructing artificial nanostructures with excellent programmability and addressability. Currently, most DNA origami nanostructures are static and do not have the ability to response to environmental stimulation. The development of environmental-responsive DNA origami nanostructures is a critical step towards the realization of intelligent dynamic DNA origami-based nanodevices. This research focuses on the design and fabrication process of both static and dynamic DNA origami nanostructures and their …

Novel Synthetic Methods And Applications Of Porous Materials: Aerogel Foams, Metallic Aerogels, Amorphous And Graphitic Carbon Aerogels, Rushi Soni

Doctoral Dissertations

"We report novel methods for the synthesis of porous materials such as polymeric aerogel foams, pure metallic aerogels, amorphous and graphitic carbon aerogels, and their applications. I. Polyurethane based aerogel foams were synthesized with an aliphatic triisocyanate and ethylene glycol through a pressurized (7 bar) sol-gel method. The foam-like structure is prepared without any chemical foaming agents or templates, resulting in less expensive, more efficient, readily adaptable, and environmentally friendly process. Those materials exhibited lower thermal conductivity (by 25%) and higher oil adsorption capacity (by 36% w/w) than their corresponding aerogels. II. Monolithic, pure metallic Co(0) aerogels were synthesized from …

Identification Of New Pathways For Co Oxidation On Rh(111) & Spatial And Structural Control Of O-Induced Reconstruction Of Ag(111), Marie Turano

Dissertations

Understanding the fundamentals of oxygen surface structures under a variety of conditions is pivotal to determining reactivity of heterogeneous catalysis. Exposure of catalytically active metal surfaces to high oxygen coverages results in a myriad of surface structures. A further complication is the formation of subsurface oxygen (Osub) or oxygen present in the near subsurface region of the metal. It is known to form in transition metals yet the absorption of oxygen and resultant formation of Osub is not equivalent across all catalytically relevant metals. As a result, it is difficult to predict the stability and efficacy of the formation of …

Development Of Small Molecule Inhibitors Of Therapeutic Target Enzymes: Paths To Discover Novel Antimicrobials, Thahani Shifna Habeeb Mohammad

Dissertations

The rising antimicrobial resistance to antibiotics is a major global problem, which has been exacerbated by the inappropriate use of antibiotics. The effectiveness of frequently prescribed penicillin derivatives and β-lactamase inhibitors are compromised by the evolution of bacterial β-lactamases and antibiotic-resistant bacteria. Consequently, design and synthesis of small-molecule inhibitors of identified novel antibiotic targets is an urgent unmet medical need. We previously demonstrated that N-functionalized α-aminocyclobutanones can act as peptidomimetic enzyme inhibitors, including inhibition of a key esterase in Francisella Tularensis. The carbonyl of a cyclobutanone is electrophilic due to ring strain, therefore cyclobutanone derivatives can serve as transition state …

Synthesis And Characterization Of Redox Non-Innocent Ligand Supported Transition Metal Complexes, Adriana Marie Lugosan

Dissertations

Catalysis is an integral part of society, which is often taken for granted. Over the past few years, there has been an increased effort to develop catalysts that are more environmentally friendly, selective, and energy efficient. This work focuses on the development of novel complexes made from a carefully designed non-innocent ligand together with earth-abundant and cost-effective transition metals that can be used to understand fundamental inorganic chemistry principles and serve as model systems. The work reported within validates the utility of this novel class of redox non-innocent ligand to form metal complexes with interesting properties, such as a non-porphyrin …

The Application Of Machine Learning In Analyzing Organic Compounds From Nmr Spectral Data, Nicole Maia Powell

Senior Independent Study Theses

Nuclear magnetic resonance (NMR) is used in organic chemistry to identify unknown organic compounds. The data obtained from an NMR spectrometer are typically shown in the form of a spectrum, which is then analyzed by an analytical chemist. The action of analyzing a spectrum, especially one of a large and complex molecule, is a long and tedious process. In this project, Python is used to implement hierarchical clustering on NMR data obtained from an NMR spectrometer at the College of Wooster to explore its application in NMR analysis. MATLAB is used to build a decision tree from the same data, …

Tubular J-Aggregates Of Cyanine Dyes In The Near-Infrared, Austin Bailey, Arundhati Deshmukh, Timothy Luke Atallah, Ulugbek Barotov, Monica Pengshung

Faculty Publications

No abstract provided.

Predicting Material Properties: Applications Of Multi-Scale Multiphysics Numerical Modeling To Transport Problems In Biochemical Systems And Chemical Process Engineering, Tom Pace

Theses and Dissertations--Physics and Astronomy

Material properties are used in a wide variety of theoretical models of material behavior. Descriptive properties quantify the nature, structure, or composition of the material. Behavioral properties quantify the response of the material to an imposed condition. The central question of this work concerns the prediction of behavioral properties from previously determined descriptive properties through hierarchical multi-scale, multiphysics models implemented as numerical simulations. Applications covered focus on mass transport models, including sequential enzyme-catalyzed reactions in systems biology, and an industrial chemical process in a common reaction medium.