Chemistry Commons^™

Metalloglycomics: Investigating The Interactions Of Metal Complexes With Heparan Mimetics, Wyatt Johnson

Theses and Dissertations

Proteoglycans containing Heparan Sulfate (HS), a sulfated glycosaminoglycan (GAG), play a major role in the cell signaling process, interacting with many different proteins. HS is over expressed on the surface of many cancer cells. Enzymatic cleavage of HS-GAGs by heparanase causes release of angiogenic growth factors leading to tumor cell migration. Heparanase is also over-expressed in tumors with significant correlation between metastatic potential and heparanase activity. Proteoglycans and their associated enzymes are thus significant drug targets of high biological relevance.

A functional consequence of strong PPC-HS binding has been shown in proof-of-concept studies confirming inhibition of the model pentasaccharide, Fondaparinux, …

Fabrication And Application Of Functional Polymer-Protein Coreshell Nanoparticles, Lin Lu

Theses and Dissertations

The study of polymer-protein nanoparticles is of increasing interest due to their various potential applications in biosensing, imaging, bioseparations, gene and drug delivery, etc. Synthetic polymers can be tailored with different functional groups and properties, therefore, they can serve as platforms to impart proteins with additional features and assist proteins to better perform biological functions. In this dissertation work, we were mainly focusing on the preparation of polymer-protein core-shell nanoparticles by synthesizing new functional polymers and assembling them with proteins for different applications. In chapter 1, a pyridine grafted diblock copolymer P(CL-g-Py)-b-PCL was prepared through ROP and CuAAC reactions. …

Structural Transformations Of Multimetallic Nanoparticles, Guangfang Li

Theses and Dissertations

Atomic-level understanding of the structural transformations of multimetallic nanoparticles (NPs) triggered by external stimuli is of vital importance to the enhancement of our capabilities to precisely fine-tailor the key structural parameters and thereby to fine-tune the catalytic properties of the NPs. In this work, I firstly show that Au-Cu bimetallic NPs demonstrate stoichiometry-dependent architectural evolutions during chemical dealloying processes and nanoporosity-evolving percolation dealloying only occurs for Au-Cu alloy NPs with Cu atomic fractions above the parting limit. The electrochemically active surface area and the specific activity of the dealloyed nanoframes can be systematically tuned to achieve the optimal electrocatalytic activity. …

Probing Solvent Effects In Aromatic Interactions Using Molecular Balances, Josef M. Maier

Theses and Dissertations

Aromatic interactions play a key role in many important processes, such as the formation and stability of biological and synthetic assemblies, facilitation of molecular recognition processes, and catalysis of chemical reactions. One of the key factors determining the strength of aromatic interaction is the solvent environment. Therefore, developing model systems that can accurately measure the influence or effects of solvents on non-polar interaction strengths is a task of great importance. Over the years, we have been approaching this challenge via designing and analyzing molecular devices that can quantitatively report aromatic interaction energies under various solvent and chemical environments. With this …

Synthesis Of Small-Molecule Fluorescent Probe And Polymers For Bioapplication: Bioimaging And Enzyme Stabilization, Yanmei Xu

Theses and Dissertations

In chapter one, we designed, synthesized and characterized two cysteine sensors CCPAP and CCPAN, with improved water solubility, cell penetration ability, and potential targeting selectivity. Two types of positive charged groups, i.e. triphenylphosphonium and pyridinium were introduced respectively to the frame structure CCP by coupling carboxylic acid with amine to improve the cell permeability and cysteine selectivity. ESI-MS, NMR and IR were employed to characterize the molecular structures of the two novel probes. These probes have better water solubility than the parent molecule DCP, and better cell penetration capability than CEP, which could further distinguish the cysteine concentration differences in …

Mechanisms Of Decarboxylation In The Cyp152 Family Of Cytochrome P450s, José Armando Amaya

Theses and Dissertations

Intense interest has focused on the development of enzymes as next-generation catalysts for the production of molecules with biotechnological potential. OleTJE, a member of the cytochrome P450 CYP152 family is an excellent candidate for the generation of advanced biofuels. OleTJE catalyzes the hydrogen peroxide-dependent decarboxylation of Cn fatty acids to produce Cn-1 terminal alkenes. Despite the ability of this enzyme to yield long chain alkenes with nearly exclusive chemoselectivity, its reactivity towards shorter chain length substrates results in undesired levels of hydroxylated side-products, limiting its industrial potential. Previous transient kinetic studies have demonstrated that, despite its unusual chemistry, the reaction …

Instrumentation For, And Application Of, Novel Electrochemical Tools For In Vivo Analysis Of Neurotransmitters In The Context Of Psychiatric Disease, Rhiannon Robke

Theses and Dissertations

ABSTRACTSerotonin’s involvement in many physiological processes including anxiety, stress, compulsivity, and mood has been speculated for decades. Insufficient progress in our understanding of serotonin chemistry is due to the lack of effective tools to selectively measure this neurotransmitter on a neurotransmission-relevant time scale in vivo. An analytical technique for serotonin measurements, fast-scan cyclic voltammetry (FSCV), was pioneered in the last decade in anesthetized rodents and is beginning to shed light on the complexity of serotonergic activity on a sub-second timescale. Complementary, more recent technological innovations have enabled ambient neurotransmitter levels to be determined every few seconds using a method called …

Understanding The Adsorption And Nucleation Of Transition Metals On A Model Carbon Support, Grant S. Seuser

Theses and Dissertations

Heterogeneous catalysis plays a vital role in the commercial production of chemicals. However, much is still unknown about the fundamental surface chemistry involved in catalyst preparation and the surface chemistry of the catalysts themselves. In the first part of this work, a surface science approach was employed to develop a fundamental understanding of the surface chemistry of strong electrostatic adsorption (SEA) of metal precursors on a model carbon support, highly oriented pyrolytic graphite (HOPG). SEA is a wet impregnation method in which anionic/cationic metal precursors are adsorbed onto positively/negatively charged functional groups by adjusting the pH of the solution above …

Studies Of The Activation Of Carbon-Gold And Carbon-Hydrogen Bonds By The Pentaruthenium Carbonyl Cluster Ru5(Μ5-C)(Co)15, Jonathan Darrell Tedder

Theses and Dissertations

The current practical uses of hydrocarbons by industry are discussed in Chapter 1. Carbon-hydrogen (C-H) bond activation and selective functionalization by transition metal complexes is presented as a possible alternative for the upgrading of hydrocarbons. The comparison of carbon-gold (C-Au) bond activation to C-H bond activation based on isolobal principles by transition metal complexes is presented. The high nuclearity ruthenium cluster complexes Ru6C and Ru5C are presented and their early chemistry is discussed.

The reactions of high nuclearity carbido cluster complexes, Ru6C(CO)17 and Ru5C(CO)15, with PhAuNHC are presented in Chapter 2. The reaction of Ru6C(CO)17 with PhAuNHC yields the π-arene …

Multiple C-H Bond Activations Of Aromatic Compounds By Unsaturated Dirhenium Carbonyl Complexes, Poonam Dhull

Theses and Dissertations

The background and importance of aromatic C-H bond activation by metal complexes are discussed in Chapter 1 with the help of various examples from the literature. Synthesis of the dirhenium complex Re2(CO)8(-C6H5)(-H) 1.1 is also discussed in detail. It also includes work done on C-H activation on arenes and heteroarenes by previous members of Dr. Adams’ group. The reactions of Re2(CO)8(-C6H5)(-H) with naphthalene and anthracene yielding the first multiply-CH activated arene products by the multiple oxidative-addition processes are presented in Chapter 2. The reaction of Re2(CO)8(-C6H5)(-H) with itself yielded the doubly-Re2-metalated C6H4 bridged compound Re2(CO)8(µ-H)(µ-1,µ-3- C6H4)Re2(CO)8(µ-H), 2.3. The reaction of …

Inorganic Nanocrystals And Their Applications In Hybrid 0d:2d Material Optoelectronics, Mathew Kelley

Theses and Dissertations

Functional nanomaterials have garnered great interest as candidates for use in next-generational optoelectronics such as solar photovoltaics, light-emitting diodes, and photodetectors. Among these low-dimensional materials, hybrid devices employing both 0D and 2D materials are of interest due to exploitation of the favorable characteristics of each component, and performances superior to standalone counterparts are achievable. This thesis is divided into two parts, as follows. The first two chapters will introduce lowdimensional materials and their favorable characteristics; our work on the formation of ligand-exchanged nanocrystal thin films purified by gel-permeation chromatography will also be discussed. In the second component, the formation and …

Hierarchical Corannulene-Based Materials, Allison M. Rice

Theses and Dissertations

Merging the intrinsic properties of fullerene (buckyball) and corannulene (buckybowl) derivatives with the inherent properties of crystalline metal- and covalentorganic frameworks (MOFs and COFs), including their modularity, porosity, versatility, high surface area, and structural tunability, opens a pathway to unlock a novel class of fulleretic materials. Despite the great interest in MOFs and COFs, as well as fullerene derivatives, this dissertation is focused on crystalline fullerene- and corannulenecontaining frameworks, highlighting their potential contributions in the fields of optoelectronic devices, electrodes, and photosensitizers. We have revealed a dual role of fullerene- and corannulene-containing building blocks showing their versatility to act as …

Sustainable Soybean Oil And Lignin Derived Monomers And Polymers For Potential Use In Polymeric Materials, Ryan Miskin

Theses and Dissertations

In this thesis project, high oleic soybean oil and lignin derived monomers and polymers are investigated. The properties of these monomers and polymers are characterized and discussed.

Chapter 1 details the potential impact of bio-based resources, monomers, and polymers on the environment. An introduction on polymerization techniques is given, and the overall objectives of my research are discussed.

In Chapter 2, attempts are made at modifying a soybean oil derived thermoplastic polymer into a vitrimer. The synthesis of thermoplastics is reviewed and the vitrimer trials outlined. Different scenarios that arose are examined and discussed.

Chapter 3 outlines the preparation of …

Cationic Metallocene-Containing Biomaterials For Antimicrobial Applications, Parasmani Pageni

Theses and Dissertations

Metal-containing polymers or metallopolymers, are one of the major classes of polymers which stand out independently because of a unique combination of organic and inorganic components in one macromolecular system. Among the variety of metallopolymers, metallocene-containing polymers have been widely utilized for applications ranging from electrochemical sensors to templates for advanced inorganic catalysts to battery materials, due to their unique physicochemical properties. This dissertation is focused on the synthesis, characterization, and application of cationic metallocene-containing polymeric materials. Cationic-cobaltocenium was grafted in various inorganic nanoparticles using polymerization techniques such as reversible addition-fragmentation chain transfer polymerization.

In Chapter 1, the overall background …

Construction Of Supramolecular And Coordination Compounds From Pyridyl Bis-Urea Macrocycles, Bozumeh Som

Theses and Dissertations

The self-assembly of macrocyclic molecules in solution and in the solid state modulates and in many cases enhances their properties for applications in sensing, catalysis and optoelectronics. The self-assembled structures are typically organized by non-covalent interactions such as hydrogen bonding, π-π stacking and dipole-dipole interactions. Our group has focused on the design and synthesis of bis-urea macrocycles that can self-assemble into solid cylinders or tubular structures affording crystalline materials. These macrocycles consist of two urea groups and two rigid C-shaped spacers. Easy functionalization of this system enables access to bis-urea macrocycle structures that could serve as molecular reactors, coordinating ligands …

Design, Synthesis, Characterization, And Applications Of Matrix Free Polymer Nanocomposites, Yucheng Huang

Theses and Dissertations

This dissertation focuses on the design, synthesis, characterization and application of matrix free polymer nanocomposites. Reversible addition-fragmentation chain transfer (RAFT) polymerization was used to synthesize block copolymers and polymer grafted silica nanoparticles with precise control over architectures.

In the first chapter, thermoplastic elastomer (TPE) grafted nanoparticles were prepared by grafting block copolymer poly(styrene-block-(n-butyl acrylate)) onto silica nanoparticles (NPs) (~15nm) via surface initiated RAFT polymerization. The effects of polymer chain length and graft density on the mechanical properties were investigated using films made solely from the grafted NPs. The ultimate tensile stress and elastic modulus increased with the increase of PS …

Synthesis And Reactivity Of Carborane Backbone Pincer Complexes, Bennett J. Eleazer

Theses and Dissertations

In organometallic chemistry, boron-centered ligand systems represent a powerful synthetic strategy for the promotion of a variety of catalytic transformations. These ligands offer a versatile array of bonding motifs, which can function as borane, boratrane, boryl, borate, or borylenes type ligands, and are likely the strongest σ-donors in the anionic series of ligands based on boron, carbon, nitrogen, and oxygen. Carboranes, which are icosahedral boron clusters of the type C2B10H12, offer unique potential as metal ligands, such as their bonding to exohedral metal centers being dominated by two-center-two-electron σ-bond interactions, their three-dimensional cluster structure providing considerable steric shielding to a …

Designed Polymer Brush Interfaces For Plutonium Separations And Polyethylene Nanocomposites, Julia G. Pribyl

Theses and Dissertations

Modification of surfaces with polymer brushes has become an important area of research for developing materials with a variety of advanced properties. Flat or continuous surfaces modified with polymer brushes can serve as surfaces where chemical reactions or separations take place, and discrete nanoparticles covered in a polymer brush can disperse within a miscible surrounding polymer, generating a composite which retains the processability of the polymer but becomes endowed with the properties of the filler as well. Presented herein are new synthetic approaches to modify both continuous surfaces as well as discrete particles with polymer brushes for complex applications. In …

Synthesis And Characterization Of Polydiene-Grafted Nanoparticles, Zaid Mohammed Abbas Alajeeli

Theses and Dissertations

This dissertation presents the design, synthesis, and characterization of polydiene grafted nanoparticles as a way to tailor nanocomposite interfaces and properties via interface design. The polymerization of dienes was done via reversible addition fragmentation chain transfer (RAFT) polymerization. The grafting of polymer chains on the surface of silica nanoparticles can be controlled through the molecular design of the RAFT agents attached to the nanoparticles surface. The properties of the nanocomposites largely depended on the interface between the particles and the polymer matrix. In the first part of this work, the polymerization of diene monomers was done on 15 nm diameter …

Development Of A High-Resolution Spatial Heterodyne Libs Spectrometer, Kevin A. Dudley

Theses and Dissertations

Laser-Induced Breakdown Spectroscopy (LIBS) is an atomic emission technique that uses a pulse laser to ablate a sample and form a plasma. Atomic emissions from the plasma provide unique elemental characteristics regarding the composition of the sample. The technique produces valuable qualitative results, but the accuracy of quantitative analyses is hindered by spectral line broadening mechanisms and laser pulse reproducibility, among other factors. The Spatial Heterodyne Spectrometer (SHS) is a high-resolution spectrometer with very high light throughput, and its use to LIBS is currently limited to two peer-reviewed publications. In the following work a high resolution SHS is developed and …

Use Of Surface Enhanced Raman Spectroscopy For The Detection Of Bioactive Lipids, Christopher M. Ohlhaver

Theses and Dissertations

The detection and analysis of lipids in biological matrices for clinical applications poses many challenges, but rapid and reliable detection will prove invaluable for clinical diagnosis. Herein, we report the application of drop-casted Ag nanoplatelets as surface enhanced Raman scattering (SERS) substrates for qualitative detection of 20-hydroxyeicosatetraenoic acid (20-HETE), which is a potential biomarker for diagnosis of hypertensive disorders. Biomarker peaks of 20-HETE can be reliably detected and differentiated from those of the structurally similar lipids (arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid) commonly found in human blood, even 1 pM concentrations. Additionally, one study mixed 20-HETE with three structurally …

Colloidal Synthesis And Photophysical Characterization Of Group Iv Alloy And Group Iv-V Semiconductors: Ge1-Xsnx And Sn-P Quantum Dots, Venkatesham Tallapally

Theses and Dissertations

Nanomaterials, typically less than 100 nm size in any direction have gained noteworthy interest from scientific community owing to their significantly different and often improved physical properties compared to their bulk counterparts. Semiconductor nanoparticles (NPs) are of great interest to study their tunable optical properties, primarily as a function of size and shape. Accordingly, there has been a lot of attention paid to synthesize discrete semiconducting nanoparticles, of where Group III-V and II-VI materials have been studied extensively. In contrast, Group IV and Group IV-V based nanocrystals as earth abundant and less-non-toxic semiconductors have not been studied thoroughly. From the …

Metal-Organic Frameworks And Graphene-Based Support Materials For Heterogeneous Catalysis, Andrew Lin

Theses and Dissertations

Nanoparticles are involved in a broad range of applications, including heterogeneous catalysis. Nanoparticles tend to quickly lose their well-defined shapes and facets due to aggregation under duress such as heat.

A series of highly studied materials are explored as support materials for nanoparticle supports. These supports include metal-organic frameworks (MOF), graphene oxide (GO), and a MOF-PRGO (partially reduced graphene oxide) hybrid. The inclusion of a support with the palladium increased lifespan of the catalyst by separation of nanoparticles. The choice of support material not only allowed for supporting of palladium nanoparticles, but allowed for rational catalyst synthesis in order to …

Heteroatom Doped Porous Carbon For Alternative Energy Conversion And Storage Systems, Fatema A. Choudhury

Theses and Dissertations

Abstract

The electrocatalysis of oxygen plays a significant role in several electrochemical energy storage and conversion systems including metal−air batteries, fuel cells, electrocatalytic and photocatalytic water splitting. The sluggish kinetics and complex reaction mechanism of this cathodic oxygen reduction reaction (ORR) affect the performance and practical application of such renewable energy technologies. To address this limiting factor, a suitable electrocatalyst is required for ORR. In general, platinum or highly dispersed Pt-based nanoparticles on carbon black are considered as the best ORR catalyst. But platinum being very scarce and expensive tends to increase the cost. Moreover, platinum-based catalysts are prone to …

Water Dynamics And The Effect Of Static And Alternating Electric Fields, Mohammadmahdi Shafiei Alavijeh

Theses and Dissertations

Having a net dipole moment, water molecules tend to align with an external electric field. The re-orientation of water molecules to align with the field direction can result in structural and dynamic changes in liquid water. Studying these changes can help us to understand the role of an E-field in many biological systems, chemical reactions, and many technological advancements.

In short, the application of static electric fields causes molecules to stay aligned with the field, so, fewer hydrogen bonds break, and molecules have slower dynamics. This type of field can be used when the mobility of water molecules needs to …

The Investigation Of Oxidative Addition Reactions Of Metal Complexes In Cross-Coupling Catalytic Cycles Based On A Unique Methodology Of Coupled Ion/Ion-Ion/Molecule Reactions, Mariah L. Parker

Theses and Dissertations

Popular catalytic cycles, such as the Heck, Suzuki, and Negishi, utilize metal centers that oscillate between two oxidation states (II/0) during the three main steps of catalysis: reductive elimination, oxidative addition, and transmetallation. There has been a push to use less toxic, cheaper metal centers in catalytic cycles, leading to interest in first-row transition metals, such as nickel and cobalt. With these metals, the cycles can potentially pass through the +1 oxidation state, which acts as reactive intermediates, undergoing oxidative additions to form products, potentially with radical characteristics. The oxidative addition steps of catalytic cycles are critical to determining overall …

Development Of Photocatalysts Supported On Graphitic Carbon Nitride For The Degradation Of Organic Water Pollutants, Atanu Giri

Theses and Dissertations

Graphitic carbon nitride (g-C₃N₄) heterojunction composites with the semiconducting metal oxides, CeO₂, ZnO and TiO₂ are prepared in situ by co-calcination of the precursor materials or by a solvothermal method. The structural, morphological and the optical properties of the prepared materials are studied using various microscopy and spectroscopy techniques. The synthesized composite materials, CeO₂/g-C₃N₄, ZnO/g-C₃N₄ and TiO₂/g-C₃N₄ are more efficient in the photocatalytic degradation of the water pollutants indigo carmine (IC) and atrazine than the pure metal oxide, g-C …

Experimental Evaluation Of Uranyl Transport Into Mesoporous Silica Gel Using Fluorescence, Brandon M. Dodd

Theses and Dissertations

This research investigated parameters that can affect the use of nanoporous silica gel as a media for accumulating a detectable amount of uranium. The unique fluorescence of the Uranyl (UO₂²⁺) ion was used to evaluate the transport kinetics and accumulation within silica gel in a static fluid and under pressure driven flow. The addition of fluid flow decreased the time constant from on the order of an hour to approximately 2s with a very low fluid velocity of 0.36cm/s. The 0.36cm/s fluid velocity was found to be the critical velocity above which there was no gain in …

Nitrogen Rich Porous Organic Frameworks: Proton Conduction Behavior Of 3d Benzimidazole And Azo-Linked Polymers, Michael J. Anhorn

Theses and Dissertations

Nitrogen-rich porous organic frameworks show great promise for use as acid-doped proton conducting membranes, due to their high porosity, excellent chemical and thermal stability, ease of synthesis, and high nitrogen content. Aided by very high surface area and pore volume, the material has the ability to adsorb high amounts of H₃PO₄ into its network, which creates a proton rich environment, capable of facile proton conduction. The morphology and chemical environment, doping behavior, and proton conduction of these materials were investigated. With such high acid-doping, ex-situ studies revealed that under anhydrous conditions, PA@BILP-16 (AC) produced a proton conductivity …

Ion Trajectory Simulations And Design Optimization Of Toroidal Ion Trap Mass Spectrometers, Jessica Marie Higgs

Theses and Dissertations

Ion traps can easily be miniaturized to become portable mass spectrometers. Trapped ions can be ejected by adjusting voltage settings of the radiofrequency (RF) signal applied to the electrodes. Several ion trap designs include the quadrupole ion trap (QIT), cylindrical ion trap (CIT), linear ion trap (LIT), rectilinear ion trap (RIT), toroidal ion trap, and cylindrical toroidal ion trap. Although toroidal ion traps are being used more widely in miniaturized mass spectrometers, there is a lack of fundamental understanding of how the toroidal electric field affects ion motion, and therefore, the ion trap's performance as a mass analyzer. Simulation programs …