Chemistry Commons^™

A Screening Platform For Identification Of Compounds That Inhibit Protein Synthesis In Pseudomonas Aeruginosa, Yanmei Hu

Theses and Dissertations - UTB/UTPA

Pseudomonas aeruginosa is a Gram-negative pathogenic bacteria and a common cause of nosocomial infections. This pathogen has recently garnered attention due to its pan-resistance. We have developed a poly(U) mRNA-directed aminoacylation/translation (A/T) protein synthesis system from P. aeruginosa. The concentration of each component of the system has been arrived at through multiple rounds of optimization. Poly-phenylalanine synthesis in the system was monitored using scintillation proximity assays (SPA). This system has been used to screen two natural compound libraries (>1100) and a number of the compounds that inhibit greater than 50% of the activity of the system have been identified. …

Metal Oxide Nanostructures For Energy Conversion And Storage, Xing Sun

Theses and Dissertations - UTB/UTPA

With the depletion of non-renewable resources and the related problems such as environmental pollutions and global warming effect, the society urgently needs more efficient and controllable energy conversion and storage systems. Three-dimensional ZnO nanoforests were prepared and morphology-tunable, which benefits both of energy conversion and storage systems. Willow-like ZnO nanoforests led the highest conversion efficiency of photoelectrochemical water splitting in reported pure ZnO nanostructures. Compared with nanowire arrays, ZnO@MnO2 nanoforests delivered 5 times higher specific capacitances within the same footprint area. V2O5@PPy exhibited higher specific capacitance and better rate stability than pure V2O5 nanofibers. This work lays the foundation for …

Monitoring Citrus Nutrition In The Rio Grande Valley For Fertilizer Recommendations, Iram Lopez

Theses and Dissertations - UTB/UTPA

Soil fertility and plant nutrition is crucial for a better yield and consistent harvest in the Rio Grande Valley for local farmers growing citrus trees. A field of oranges and a field of grapefruits were monitored and nutrition deficiencies were noticed that played an important role during fruit set. Soil samples that were taken throughout the year were analyzed via a carbon dioxide extraction method that mimics the way plants naturally take up nutrients or extract nutrients from every soil type. Macronutrients such as the N, P, K, Na, Ca, Mg and some of the micronutrients (Zn, Fe, Mn, and …

The Impact Of Surface Ligands And Synthesis Method On The Toxicity Of Glutathione-Coated Gold Nanoparticles, Bryan Harper, Federico Sinche, Meenambika Gowrishankar, Grant Marquart, Marilyn R. Mackiewicz, Stacey L. Harper

Chemistry Faculty Publications and Presentations

Gold nanoparticles (AuNPs) are increasingly used in biomedical applications, hence understanding the processes that affect their biocompatibility and stability are of significant interest. In this study, we assessed the stability of peptide-capped AuNPs and used the embryonic zebrafish (Danio rerio) as a vertebrate system to investigate the impact of synthesis method and purity on their biocompatibility. Using glutathione (GSH) as a stabilizer, Au-GSH nanoparticles with identical core sizes were terminally modified with Tryptophan (Trp), Histidine (His) or Methionine (Met) amino acids and purified by either dialysis or ultracentrifugation. Au-GSH-(Trp)2 purified by dialysis elicited significant morbidity and mortality at …

Binary Technetium Halides, Erik Vaughan Johnstone

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, the synthetic and coordination chemistry as well as the physico-chemical properties of binary technetium (Tc) chlorides, bromides, and iodides were investigated. Resulting from these studies was the discovery of five new binary Tc halide phases: α/β-TcCl₃, α/β-TcCl₂, and TcI₃, and the reinvestigation of the chemistries of TcBr₃ and TcX₄ (X = Cl, Br). Prior to 2009, the chemistry of binary Tc halides was poorly studied and defined by only three compounds, i.e., TcF₆, TcF₅, and TcCl₄. Today, ten phases are known (i.e., TcF …

Expanding The Frontier Of Gold-Catalyzed Cyclizations And Rational Ligand Design., Deepika Malhotra

Electronic Theses and Dissertations

The focus of my dissertation work is to study the gold-catalyzed intramolecular and intermolecular cyclizations involving oxonium intermediates towards the application of synthetically interesting frameworks under ambient conditions and developing a rational approach for the effective catalyst design in gold catalysis. We explored the goldcatalyzed oxygen-transfer reactions of 2-alkynyl-1,5-diketones or 2-alkynyl-5-ketoesters to furnish five-membered rings bearing a quaternary carbon tethered to a carbonyl group. The detailed mechanistic investigation on the newly proposed intramolecular [4+2] cycloaddition mechanism was performed by means of isotopic experiments and quantum chemical calculations. The reactivity of alkynylenolate was investigated in the reactions of allenic ketones and …

Ligand Centered Reactivity Of Metal Stabilized Thiyl Radicals In Solution, Solid And Gaseous Phase., Rajat Rajat

Electronic Theses and Dissertations

This thesis presents ligand centered reactivity studies of metal stabilized thiyl radicals in solution, solid, and gaseous phases for catalysis and sensing based applications. Chemical oxidation of tris(2-diphenylphosphinebenzenethiolato )ruthenate(II) [Ru -1]- with ferrocenium hexafluorophosphate in the presence of ethylene yields [Ru-1·C,H.]PF6, from addition of the alkene across cis sulfur sites. In the presence of base [Ru-1·C,H.]+ is selectively deprotonated at the pseudoequatorial proton on the carbon a to the sulfur trans to phosphorus, yielding the vinyl metallosulfonium derivative [Ru-1·C,H3]. "H and 31p NMR spectra of [Ru-1'C,H3 ] are temperature dependent, associated with inversion of the sulfur lone pair at the …

Synthesis Of N-Heterocycles Through Cyclization-Triggered Tandem Additions To Alkynes And The Study Of Promoters In Ionic Reactions., Junbin Han

Electronic Theses and Dissertations

Our research mainly focused on three parts related to the rapid construction of N-heterocycles and the search for ionic reaction promoters. First, N-heterocycles of different ring sizes and with different substitution patterns constitute extremely important structure classes (e.g., alkaloids) in the search for bioactivity. A contemporary challenge in organic synthesis is the mapping of new chemical spaces through tandem or cascade reactions in an atom economical fashion. Our strategy to access these biologically important heterocycles is through a cyclization-triggered tandem addition to alkynes catalyzed by readily available alkynophilic coinage metals like copper. In this manner, a variety of functional groups …

Initial Characterization Of A Conserved Active Site Residue For The Cdc34 Ubiquitin Conjugating Enzyme, Arvin Akoopie

Honors College Theses

Ubiquitin-conjugating enzymes (E2s) covalently modify protein substrates with ubiquitins. The active site cysteine residues on E2s are essential for catalyzing the transfer of ubiquitin from the E2 active site onto the protein substrate, however there is a limited amount of information available concerning additional active site residues for E2s that may also participate in catalysis. Cdc34 is an essential E2 that has merited the lion’s share of attention for biochemical analysis of the E2 family. Previous phylogenetic analysis of Cdc34 amino acid sequences has identified an invariably conserved histidine residue close to the active site cysteine in the primary structure, …

Synthesis And Functionalization Of Bodipy Dyes For Applications In The Detection Of Colorectal Cancer, Logan Elise Leblanc

Honors Capstones

No abstract provided.

Catalytic Kinetic Resolution Of A Dynamic Racemate: Highly Stereoselective Β-Lactone Formation By N-Heterocyclic Carbene Catalysis, Ryne C. Johnston, Daniel T. Cohen, Chad C. Eichman, Karl A. Scheidt, Paul Ha-Yeon Cheong

Chemistry: Faculty Publications and Other Works

This study describes the combined experimental and computational elucidation of the mechanism and origins of stereoselectivities in the NHC-catalyzed dynamic kinetic resolution (DKR) of α-substituted-β-ketoesters. Density functional theory computations reveal that the NHC-catalyzed DKR proceeds by two mechanisms, depending on the stereochemistry around the forming bond: 1) a concerted, asynchronous formal (2+2) aldol-lactonization process, or 2) a stepwise spiro-lactonization mechanism where the alkoxide is trapped by the NHC-catalyst. These mechanisms contrast significantly from mechanisms found and postulated in other related transformations. Conjugative stabilization of the electrophile and non-classical hydrogen bonds are key in controlling the stereoselectivity. This reaction constitutes an …

Hydrothermal Synthesis Of Organically-Linked Polyoxometalates, Riyadh Alshammari

All Theses

One of the thrust areas of our research deals with exploratory synthesis of new inorganic-organic hybrid materials for energy storage. It is well-known that relevant to the research described later in this thesis, inorganic-organic hybrid solids studied thus far are largely made of coordination complexes where the organic molecules are acting like a ligand to coordinate around metal cations. In this research, we will employ polyoxometalate (POM) anions as an inorganic building block to replace otherwise oppositely charged metal cations in hopes to synthesize extended hybrid frameworks with rich redox chemistry. POM clusters are made of aggregates of transition-metal (TM) …

A Fluidic Fiber Platform Modified For The Selective Extraction And On Fiber Fluorescence Detection Of Proteins And Nucleic Acids, Natasha Khan

All Theses

Solid phase extraction has become a popular tool for analytical method development as a sample preparation technique. Solid phase sorbents can generally extract analytes based on polarity or selectively based on highly specific interactions between the analyte and an immobilized surface molecule. Biomolecular recognition based solid phases utilize antibodies, nucleic acids, and proteins as a secondary affinity layer on a solid phase support for selective analyte extractions and have been used for sample preparation, purification, separations, bioassays, and molecular diagnostics. Polymer supports for solid phase extraction are desirable for their low cost, abundance, chemical inertness, and pH stability. This thesis …

A Facile Route To Tailoring Peptide-Stabilized Gold Nanoparticles Using Glutathione As A Synthon, Rosina Ho Wu, Tan P. Nguyen, Grant W. Marquart, Thomas J. Miesen, Theresa Mau, Marilyn R. Mackiewicz

Chemistry Faculty Publications and Presentations

The preparation of gold nanoparticles (AuNPs) of high purity and stability remains a major challenge for biological applications. This paper reports a simple synthetic strategy to prepare water-soluble peptide-stabilized AuNPs. Reduced glutathione, a natural tripeptide, was used as a synthon for the growth of two peptide chains directly on the AuNP surface. Both nonpolar (tryptophan and methionine) and polar basic (histidine and dansylated arginine) amino acids were conjugated to the GSH-capped AuNPs. Ultracentrifugation concentrators with polyethersulfone (PES) membranes were used to purify precursor materials in each stage of the multi-step synthesis to minimize side reactions. Thin layer chromatography, transmission electron …

Miniaturization Of Chemical Analysis Tools: Micro-Solid Phase Extraction Tips For Protein Extractions And Development Of A Miniaturized Glow Discharge Source For Elemental Analysis, Benjamin Manard

All Dissertations

An increased interest has been placed on the miniaturization of chemical processes. Focus is placed on rapid chemical analysis, decreased operation cost, minimal generation of chemical waste, and reduced sample size. Presented here is an approached the goal of 'miniaturization' through two distinct areas of analytical chemistry: 1) employing capillary-channeled polymer (C-CP) fibers as a stationary phase in micro-SPE (solid phase extraction) tips for the extraction of proteins from buffered solutions (i.e. biofluids) with analysis by mass spectrometry (MS) and 2) the development of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) as an excitation source for elemental analysis. Determination of …

New Synthetic Methodologies For Chemo-, Stereo-, And Regioselective 1,4-Conjugate Additions Of Organometallic Reagents To Michael And Extended Michael Substrates And Alkene Halofunctionalization Reactions, Ramesh Dhakal

All Dissertations

The research discussed in this dissertation is focused on developing new synthetic methodologies for the construction of carbon-carbon and carbon-heteroatom bonds present in several natural products and synthetic intermediates employing organometallic reagents and/or organocatalytic procedure. The presence of rich functionality in the reactive synthons under study provides opportunities for studying a variety of reactions. Effecting a reaction in a regio- and stereoselective fashion is highly attractive as the resulting synthons can be used for the syntheses of larger molecules. We have explored unprecedented variation of Michael Initiated Ring Closure (MIRC) reactions for the syntheses of 1,2,3-trisubstituted cyclopropane derivatives, owing to …

Building Chemistry One Atom At A Time: An Investigation Of The Effects Of Two Curricula In Students' Understanding Of Covalent Bonding And Atomic Size, Barbara Bull

All Dissertations

Chemists have to rely on models to aid in the explanation of phenomena they experience. Instruction of atomic theory has been used as the introduction and primary model for many concepts in chemistry. Therefore, it is important for students to have a robust understanding of the different atomic models, their relationships and their limitations. Previous research has shown that students have alternative conceptions concerning their interpretation of atomic models, but there is less exploration into how students apply their understanding of atomic structure to other chemical concepts. Therefore, this research concentrated on the development of three Model Eliciting Activities to …

Kinetics Of Formation And Oxidation Of 8-Oxo-7,8-Dihydroguanine (8oxog), Derrick Ampadu Boateng

Electronic Theses and Dissertations

8-oxo-7,8-dihydroguanine (8oxoG) is one of the most important base lesions formed during oxidative damage of DNA. The aim of the present research was to investigate the effects of DNA concentration, G content, and the nature of oxidizing species on the kinetics of 8oxoG in model DNA solutions by using HPLC. The experimentally obtained yields of 8oxoG were typically in the range of 2-2.5% of total concentration of guanine. The ratios of the rate constant of hole diffusion in DNA to the rate constant of conversion of the hole into 8oxoG (k_d/k_r) were calculated from the experimental …

Functionalization Of Silica Surface Using Chan-Lam Coupling, George Appiah Kubi

Electronic Theses and Dissertations

The reaction of base-free Chan-Lam coupling was successfully used for functionalization of surface of mesoporous silica gel. Various aromatic, aliphatic, and heterocyclic compounds were immobilized by a copper-catalyzed reaction of corresponding boronic acids with surface amino groups at mild conditions. Obtained functionalized materials were mesoporous although their surface area decreased after immobilization. The reactivity of some surface functional groups was tested in their characteristic reactions.

Synthesis Of A 4-(Trifluoromethyl)-2-Diazonium Perfluoroalkyl Benzenesuflonylimide (Pfsi) Zwitterionic Monomer For Proton Exchange Membrane Fuel Cell, Chimaroke Nworie

Electronic Theses and Dissertations

In order to achieve a more stable and highly proton conducting membrane that is also cost effective, the perfluoroalkyl benzenesulfonylimides (PFSI) polymers are proposed as electrolyte for Proton Exchange Membrane Fuel Cells. 4-(trifluoromethyl)-2-diazonium perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonyl imide (I) is synthesized from Nafion monomer via a 5-step schematic reaction at optimal reaction conditions. This diazonium PFSI zwitterionic monomer can be further subjected to polymerization. The loss of the diazonium N₂⁺ functional group in the monomer is believed to form the covalent bond between the PFSI polymer electrolyte and carbon electrodes support. All the intermediates and final products …

The Dimerization Domain In Dape Enzymes Is Required For Catalysis, Boguslaw Nocek, Anna Starus, Magdalena Makowska-Grzyska, Blanca Gutierrez, Stephen Sanchez, Robert Jedrzejczak, Jamey C. Mack, Kenneth W. Olsen, Andrzej Joachimiak, Richard C. Holz

Chemistry: Faculty Publications and Other Works

The emergence of antibiotic-resistant bacterial strains underscores the importance of identifying new drug targets and developing new antimicrobial compounds. Lysine and meso-diaminopimelic acid are essential for protein production and bacterial peptidoglycan cell wall remodeling and are synthesized in bacteria by enzymes encoded within dap operon. Thereforedap enzymes may serve as excellent targets for developing a new class of antimicrobial agents. The dapE-encoded N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) convertsN-succinyl-L,L-diaminopimelic acid to L,L-diaminopimelic acid and succinate. The enzyme is composed of catalytic and dimerization domains, and belongs to the M20 peptidase family. To understand the specific role …

Template-Directed Synthesis And Post-Synthetic Modification Of Porphyrin-Encapsulating Metal-Organic Materials, Zhenjie Zhang

USF Tampa Graduate Theses and Dissertations

Metal-organic materials (MOMs) represent an emerging class of materials comprised of molecular building blocks (MBBs) linked by organic linker ligands. MOMs recently attract great attention because of their ability to exhibit permanent porosity, thereby enabling study of properties in the context of gas storage, gas separation, solid supports for sensors, catalysis and so on. Although MOMs have been studied for over 60 years, the porous nature of MOMs was not systematically and widely explored until the early 1990's. This may be one of the reasons why template-directed synthesis of MOMs remains relatively underexplored, especially when compared to other classes of …

Characterization And Optimization Of Extraction Chromatography Resins For Rapid Separations For Safeguard And Nuclear Forensics Purposes, Audrey Roman

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, extraction chromatography resins, DGA and UTEVA, were characterized under various conditions in order to identify novel rapid separations for safeguards and nuclear forensic purposes. For safeguards purposes, mixed matrices containing some of the largest components found in used fuel and either Am, Pu, or U were characterized on DGA and UTEVA resins in order to determine any effects from the addition of these constituents. Results indicated that 5 M HNO₃ would be an optimal loading condition due to the consistent actinide adsorption in the presence of the additional used fuel components. Investigations of varying the anion …

Understanding The Influence Of Interfacial Chemistry In Core, Core/Shell And Core/Shell/Shell Quantum Dots On Their Fluorescence Properties, Omondi Bernard Omogo

Graduate Theses and Dissertations

Colloidal semiconductor nanocrystals (quantum dots) have received a great deal of attention due to their superior size tunable properties and promising applications in many areas. Some of the most practical areas of their applications include light emitting diodes (LED), photovoltaic and biological studies. Synthetic methods of these crystals is becoming more established with new strategies being reported every now and then. However, quantitative studies connecting the processes at the interface, namely core-ligand, core-shell and shell-shells, to the overall quantum dots fluorescence properties are not well understood. Specifically for cores, relating surface-atoms interactions, solvents, ligands nature, density and functional groups on …

Selection Of The Process Parameters For The Mass Plating Of Discrete Electronic Components, Ann Hopper

Articles

The miniaturisation of electronic components coupled with requirements for high temperature lead free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLV’s) have been explored. The tooling selected was a “Rotary flow-thru’ plater” which achieved high volume plating with

Structure And Multi-Center Bonding: From Atomic Clusters To Solid Phase Materials, Timur R. Galeev

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The work presented in this dissertation has been focused on structure, stability, and chemical bonding of atomic clusters and solid-state compounds. The common thread was development of theoretical models and methods capable of interpreting bonding and hence, structures of these species. A major part of this work presents joint experimental and theoretical studies of a large series of doped boron clusters. The dissertation introduces a new theoretical tool for interpretation of bonding of solid phase materials in chemically intuitive terms of localized and multi-center bonds. Understanding how interactions between atoms in sub-nano clusters and solid-state compounds determine their structures, physical …

Detailed Analysis Of The Domains Of Mtr4 And How They Regulate Helicase Activity, Lacy Leigh Taylor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The central dogma states that DNA is transcribed into RNA, which is then translated into protein. This concept conveys a minimal view of the role of RNA, portraying it simply as an intermediary between DNA and protein. However, it is now known that the role of RNA in the cell is critical in regulating protein expression both directly and indirectly. RNA in the cell typically goes through modifications to become active (on) and inactive (off) to eventually become targeted for degradation and start the cycle all over again. The protein complex that regulates the proper maturation and degradation of RNA …

A Synthesis Approach Of Trp-Like Primary Amine Peptoid Side Chains Used In Cyclic Beta-Hairpin - Like Scaffolds, Josanne-Dee Woodroffe

USF Tampa Graduate Theses and Dissertations

In recent studies it was reported that the D-amino acid containing peptide HYD1 was used in the treatment of necrotic cell death in multiple myeloma cell lines and showed promising biological activity and in vivo activity. It was meaningful to explore strategies for increasing the therapeutic efficacy of HYD1, a linear peptide. These efforts led to the development of MT1-101 (cyclized peptidomimetics), a lead compound that showed increased in vitro activity and in vivo activity. MTI-101 was found to bind the cell adhesion molecule CD44 and induce programmed necrosis in myeloma cell lines. It was important to improve on the …

Investigation Of Energy Alignment Models At Polymer Interfaces, Wenfeng Wang

USF Tampa Graduate Theses and Dissertations

The presented study investigated the Induced Density of Interface States (IDIS) model at different polymer interfaces by using photoemission spectroscopy in combination with electrospray deposition.

In recent years, organic electronics have attracted considerable attention due to their advantages of low-cost and easy-fabrication. The performance of such devices crucially depends on the energy barrier that controls the interface charge transfer. A significant effort has been made to explore the mechanisms that determine the direction and magnitude of charge transfer barriers in these devices. As a result of this effort, the IDIS model was developed to predict the energy alignment at metal/organic …

Homochiral Metal-Organic Materials: Design, Synthetic And Enantioseletive Separation, Shi-Yuan Zhang

USF Tampa Graduate Theses and Dissertations

Owing to the growing demand for enantiopurity in biological and chemical processes, tremendous efforts have been devoted to the synthesis of homochiral metal-organic materials (MOMs) because of their potential applications in chiral separation and asymmetric catalysis. In this dissertation, the synthetic strategies for homochiral MOMs are discussed keeping the focus on their applications. Two distinct approaches have been taken to synthesize chiral structures with different topologies and accessible cavities. The chiral MOMs have been utilized in enantioselective separation of racemates.

Chiral variants of the prototypal metal-organic framework MOF-5, δ-CMOF-5 and [lambda]-CMOF-5, have been synthesized by preparing MOF-5 in the presence …