Chemistry Commons^™

Enabling Method To Design Versatile Biomaterial Systems From Colloidal Building Blocks, Shalini Saxena, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Development of materials with fine spatial control over topographical, mechanical, or chemical features has been investigated for a variety of applications. Here we present a method to fabricate an array of polyelectrolyte constructs including two-dimensionally and three-dimensionally patterned assemblies using both compressible and incompressible colloidal building blocks. This method eliminates prior constraints associated with specific chemistries, and can be used to develop modular, multi-component, patterned assemblies. In particular, development of constructs were investigated using microgels, which are colloidally stable hydrogel microparticles, polystyrene (PS) beads, and PS-microgel core-shell building blocks in conjunction with the polycation poly(ethyleneimine) (PEI). The topography, mechanical properties, …

Echo Behavior In Large Populations Of Chemical Oscillators, Tianran Chen, Mark R. Tinsley, Edward Ott, Kenneth Showalter

Faculty & Staff Scholarship

Experimental and theoretical studies are reported, for the first time, on the observation and characterization of echo phenomena in oscillatory chemical reactions. Populations of uncoupled and coupled oscillators are globally perturbed. The macroscopic response to this perturbation dies out with time: At some time τ after the perturbation (where τ is long enough that the response has died out), the system is again perturbed, and the initial response to this second perturbation again dies out. Echoes can potentially appear as responses that arise at 2τ,3τ,... after the first perturbation. The phase-resetting character of the chemical oscillators allows a detailed analysis, …

Effect Of 5-Hydroxymethylcytosine Modifications On Stability Of Vegf I-Motifs, Bethany Summerford

Honors Theses

DNA i-motifs are a secondary structure of DNA formed at low pH by internal folding of strands rich in cytosine. This study focuses on trying to determine if the DNA from the vascular endothelial growth factor (VEGF) promoter, which can form an i-motif, can be stabilized with the epigenetic modification to 5- hydroxymethylcytosine in four separate locations on the DNA strand, and to what extent the degree of stabilization depends on the location of the modification. Stability of the i-motif was determined by measuring pKa and melting point (Tm) of each VEGF modification using circular dichroism spectroscopy. The modified samples …

A Computational Study Of High Energy Density Materials And Their Detection Using Surface-Enhanced Raman Spectroscopy, Emily N. Hugo

Honors Theses

The purpose of this thesis is to theoretically predict the vibrational spectra of select high energy density materials (HEDMs) as well as some of their byproducts and to determine if using surface-enhanced Raman spectroscopy (SERS) could be a viable detection method for these compounds. Studying the vibrational patterns of these compounds will help in identifying them in the environment for remediation purposes. Because the byproducts are smaller and easier to model than the parent compounds, these were studied more in depth through analyzing their Infrared and Raman spectra. Ag2 was used to model the interactions between the Ag nanoparticles used …

Rhenium-Pyridyl-Nhcs For Photocatalytic Co2 Reduction, Emily Anne Sharpe

Honors Theses

The ability to transform CO2 into a useable fuel source would have a remarkably positive impact on the environment by taking the vast amounts of previous unusable CO2 from the atmosphere and reducing it to CO, which can then be turned into fuel. This project involves the synthesis and testing of air and water stable Re (I) pyridyl N- heterocyclic carbene (NHC) compounds for photocatalytic reduction of CO2 into CO using a simulated solar spectrum. Previous research in this area focused on the use of Re(bpy)CO3X, which quickly became the benchmark of homogeneous CO2 reduction photocatalysts. The Re (I) pyridyl …

Computational And Experimental Evaluation Of Α-(N-2-Quinolonyl)Ketones: A New Class Of Nonbiaryl Atropisomers, Andrea N. Bootsma, Carolyn E. Anderson

University Faculty Publications and Creative Works

Given the usefulness of atropisomers within both asymmetric catalysis and pharmaceuticals, a thorough computational study of substituted α-(N-2-quinolonyl)ketones has been conducted. This class of tertiary amides is unique, as the amide is embedded within an aromatic construct, and the nitrogen bears an aliphatic substituent. Using a computational approach, 8′-substituted quinolones were identified as potential class 2 and 3 atropisomeric targets with calculated C–N rotational barriers of greater than 20 kcal/mol. These results, along with experimental efforts toward the synthesis of these targets, are reported.

Sialyltransferase Inhibition And Recent Advances, Libo Wang, Ying Liu, Lijun Wu, Xue-Long Sun

Chemistry Faculty Publications

Sialic acids, existing as terminal sugars of glycoconjugates, play important roles in various physiological and pathological processes, such as cell–cell adhesion, immune defense, tumor cell metastasis, and inflammation. Sialyltransferases (STs) catalyze the transfer of sialic acid residues to non-reducing oligosaccharide chains of proteins and lipids, using cytidine monophosphate N-acetylneuraminic acid (CMP-Neu5Ac) as the donor. Elevated sialyltransferase activity leads to overexpression of cell surface sialic acids and contributes to many disease developments, such as cancer and inflammation. Therefore, sialyltransferases are considered as potential drug targets for disease treatment. Inhibitors of sialyltransferases thus are of medicinal interest, especially for the cancer …

Purification And Characterization Of Bromocresol Purple For Spectrophotometric Seawater Alkalinity Titrations, Taymee A. Brandon

Undergraduate Theses, Professional Papers, and Capstone Artifacts

The topic of my research is the purification of the sulfonephthalein indicator bromocresol purple (BCP). BCP is used as an acid-base indicator in seawater alkalinity determinations. Impurities in sulfonephthalein indicator salts often result in significant errors in pH values³. High-precision inorganic carbon (i.e. CO₂) measurements are necessary to document the changes in ocean chemistry and pH due to anthropogenic CO₂­ uptake by the earth’s oceans³. In order to reduce the error in seawater pH determinations and the general understanding of the CO₂ cycle, BCP must be purified and characterized. Previous work …

Studies Of The Effectiveness Of Bisphosphonate And Vanadium-Bisphosphonate Compounds In Vitro Against Axenic Leishmania Tarentolae, Amy Christensen, Craig C. Mclauchlan, Anne Dolbecq, Pierre Mialane, Marjorie A. Jones

Faculty Publications – Chemistry

Leishmaniasis is a disease that is a significant problem for people, especially in tropical regions of the world. Current drug therapies to treat the disease are expensive, not very effective, and/or of significant side effects. A series of alkyl bisphosphonate compounds and one amino bisphosphonate compound, as well as alendronate and zoledronate, were tested as potential agents against Leishmania tarentolae. Also, two polyoxometalates (POMs) with nitrogen-containing bisphosphonate ligands, vanadium/alendronate (V5(Ale)2) and vanadium/zoledronate (V3(Zol)3), were tested against L. tarentolae and compared to the results of the alendronate and zoledronate ligands alone. Of the compounds evaluated in this study, the V5(Ale)2 …

Acridine Orange Staining Of Virus Infected Host Cells To Monitor Proliferation Of Viral Infection, Ronald Bartzatt

Chemistry Faculty Publications

Acridine orange staining is a methodology for nucleic acid selective metachromatic staining that is useful for following cell cycle determination. The interaction of acridine orange with target molecules (i.e. DNA and RNA) is by intercalation or electrostatic attraction, respectively. This work presents methodology and results of a cell staining that utilizes acridine orange fluoresence. It is possible to visualize under dark field ultraviolet microscope the actual viral infected host cells. The color production is stark and easily selected. This method appears to be versatile for a number of various cell types in tissue culture, including human lymphocytes. This methodology is …

Four Compounds Suppressing Growth Of Mycobacterium Tuberculosis, Ronald Bartzatt, Preeti Sule, Woojung Kim, Jeffrey D. Cirillo

Chemistry Faculty Publications

Aims: To demonstrate the efficacy of several small molecular weight compounds having hydrazide groups, for inhibiting the growth of Mycobacterium tuberculosis. To show these same compounds have favorable drug-likeness properties.

Study Design: To synthesize tuberculostats and test their antibacterial activity in-vitro.

Place and Duration of Study: University of Nebraska, Durham Science Center, 6001 Dodge Street, Omaha NE 68182, and Texas A&M Health Science Center, Department of Microbial Pathogenesis and Immunology, 8447 State Hwy 47, Medical Research and Education Building, Room #3012, Bryan, TX 7780. From January 2015 to June 2015.

Methodology: Hydrazide groups were formed by covalently bonding hydrazine …

Investigating Alaskan Methane And Carbon Dioxide Fluxes Using Measurements From The Carve Tower, Anna Karion, Colm Sweeney Colm Sweeney, John B. Miller John B. Miller, Arlyn E. Andrews, Roisin Commane, Steven Dinardo, John M. Henderson, Jacob Lindaas, John C. Lin, Kristina Luus, Tim Newberger, Pieter Tans Pieter Tans, Steven C. Wofsy, Sonja Wolter, Charles E. Miller

Articles

Northern high-latitude carbon sources and sinks, including those resulting from degrading permafrost, are thought to be sensitive to the rapidly warming climate. Because the near-surface atmosphere integrates surface fluxes over large ( ∼ 500–1000 km) scales, atmospheric monitoring of carbon dioxide (CO2) and methane (CH4) mole fractions in the daytime mixed layer is a promising method for detecting change in the carbon cycle throughout boreal Alaska. Here we use CO2 and CH4 measurements from a NOAA tower 17 km north of Fairbanks, AK, established as part of NASA's Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE), to investigate regional fluxes of …

Exploration Of Bimetallic Nickel And Cobalt Complexes For Catalytic Oxidative Cleavage Of Alkenes And Hydroformylation, Ciera Vonn Duronslet

LSU Doctoral Dissertations

The “old” bimetallic nickel complexes, meso- and rac-Ni2Cl4(et,ph-P4) were investigated as possible “catalysts” for the oxidative cleavage of alkenes using an unsaturated fatty acid, oleic acid, as the substrate. The “new” bimetallic nickel complexes with a stronger chelating tetraphosphine ligand, meso- and rac-Ni2Cl4(et,ph-P4-Ph), were also synthesized and tested for the oxidative cleavage of oleic acid. All four dinickel complexes were found to be active for the oxidative cleavage of oleic acid, producing extremely small amounts of aldehyde product. The Stanley research group also discovered the oxidative cleavage of alkenes using only the “old” et,ph-P4 tetraphosphine ligands with no metal centers. …

Synthesis And Characterization Of Polyhalogenated Boron Dipyrromethenes And Carboranylbisthiophene Oligomers, Ning Zhao

LSU Doctoral Dissertations

Chapter 1 of this dissertation shows a brief overview of fundamental concepts and classic synthetic routes of BODIPY dyes. The synthetic strategies and various application (e.g. PDT sensitizers and fluorescent indicators) of halogenated BODIPYs are also presented in this chapter. Chapters 2-4 describe the synthesis of three new polyhalogenated BODIPY platforms and their regioselective functionalization. Such new platforms provide new methodologies for producing both symmetric and asymmetric BODIPYs. Pd(0)-catalyzed cross-couplings and aromatic substitution reactions were applied to investigate the reactivity and regioselectivity of different halogen groups on the BODIPY platforms. The studies showed that the reactivity order of the halogens …

Design, Synthesis And Biological Applications Of Polypeptoids And Boron Dipyrromethenes, Sunting Xuan

LSU Doctoral Dissertations

The dissertation is about the design, synthesis and biological applications of polypeptoids and boron dipyrromethenes (BODIPYs). The dissertation is divided into seven chapters reporting various aspects of the background to my field of study and the results obtained during my PhD program. Chapter 1 is a concise overview of the fundamental concepts of polypeptoids and hydrogels, as well as their recent developments on synthetic strategies, property investigations, and biological applications in different fields. Chapter 2 presents the design, synthesis and potential application as tissue engineering scaffold of thermoreversible ABC polypeptoid hydrogels. A series of ABC copolypeptoids were synthesized and their …

Contemporary Organic Transformations Enabled By Novel Cationic Processes, Caitlan Elizabeth Ayala

LSU Doctoral Dissertations

This dissertation focuses on the development of synthetic methodologies in organic synthesis in two different areas. Chapter 1 discusses the more recent examples of transforming alcohols to their corresponding alkyl chlorides. The first area of our group’s research interest is the development of a mild chlorination method from unactivated alcohols, detailed in Chapter 2. Chapter 3 provides an insight into the history of oxyallyl cations, the basis of the second methodology development project in our laboratory. This chapter focuses on the traditional reactions that utilize these reactive intermediates, and it also showcases the concept of direct nucleophilic addition and the …

Peptidomimetic Polymers: Advances In Monomer Design And Polymerization Methods, Brandon Andrew Chan

LSU Doctoral Dissertations

This work is focused on the design, synthesis and characterization of polypeptide and polypeptoid polymers. The former are composed of amino acid repeat units and possess intramolecular hydrogen bonding interactions allowing for the self-assembly into well-defined secondary structures (e.g. α-helix). Polypeptoids are based on N-alkyl substituted glycine and lack intramolecular hydrogen bonding interactions, resulting in enhanced proteolytic stability and thermal processability. Physicochemical properties of polypeptoids are strongly dependent on the side chain structures, allow for control of the solubility, crystallinity, and conformation of the polymers. Well-defined polypeptides and polypeptoids are synthesized by the ring-opening polymerization (ROP) of their corresponding N-carboxyanhydride …

Scanning Probe Investigations Of Multidentate Thiol And Spatially Confined Porphyrin Nanoassemblies Using Nanoscale Lithography, Xianglin Zhai Zhai

LSU Doctoral Dissertations

Approaches to prepare spatially selective surfaces were developed in this dissertation for constructing nanopatterns of organic thin film materials. Nanoscale surface patterns were prepared using immersion particle lithography and scanning probe lithography combined with organothiol chemistry. Organic thin films and nanomaterials can be patterned with tunable periodicities and designed shapes by selecting the diameter of mesospheres used as surface masks or scanning probe lithography, respectively. The surface platforms of well-defined nanopatterns are ideal for high resolution investigations using scanning probe microscopy (SPM). Local measurements of surface properties and conductive properties combined with nanolithography were accomplished at the molecular level. Sample …

An Investigation Of Environmentally Persistent Free Radical (Epfr) Formation In Contaminated Soils Using Surrogate-Based Model Systems, Ugwumsinachi Godwin Nwosu

LSU Doctoral Dissertations

Environmentally persistent free radicals (EPFRs) have recently attracted attention due to their properties that detrimental to the health of living organisms. Earlier studies devoted to the formation of combustion generated particulate matter (PM) showed that EPFRs formed as a result of the association of aromatic chlorinated hydrocarbons with transition metal centers. Based on our previous studies, the amounts of EPFRs formed at Superfund soil sites contaminated with pentachlorophenol (PCP) are ~30 times higher compared to those formed at the neighboring uncontaminated soil sites, showing that EPFR formation is not confined to combustion generated particle. In order to design viable remediation …

Careers With Chemistry, Daniel Wright

A with Honors Projects

This student poster features the career of Neurologist, and includes information on Nitric Oxide.

Careers With Chemistry, Ebru Taskan

A with Honors Projects

For this poster assignment, the student provides data on EDTA, it's chemical formula, composition, uses, and health effects, as well as featuring a career that uses chemistry, in this case nurse practitioner.

Synthesis And Evaluation Of Novel $N,N'$-Disubstituted Benzimidazolium Bromides Salts As Antitumor Agents, Hasan Küçükbay, Akin Mumcu, Suat Teki̇n, Süleyman Sandal

Turkish Journal of Chemistry

Novel benzimidazolium bromides salts having (4-methoxyphenyl)ethyl, (phthalimide-2-yl)methyl, 4-nitro- benzyl, 2-phenylethyl, penthyl, or allyl groups were synthesized and their characterizations were conducted by $^{1}$H and $^{13}$C NMR and IR spectroscopic methods, and microanalysis. In vitro antitumor activities of the novel benzimidazole compounds (1-7) were determined by using ovarian (A2780) and prostate (PC-3) cancer cell lines. Antitumor properties of all compounds were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. A time-dependent cell viability assay for the tested benzimidazole compounds was performed and the IC$_{50}$ values of the compounds were calculated after treatment for 24 and 48 h. Our results indicate that the tested …

Prediction Of Metal Remobilization From Sediments Under Various Physical/ Chemical Conditions “Design Of Experiments Cd, Co And Pb”, Eid A. Alkhatib, Trey Chabot, Danielle Grunzke

Chemistry & Physics Faculty Publications

The metal partition coefficient Kd (L/kg) is the ratio of sorbed metal concentration on the solid phase m (mg/kg) to the dissolved metal concentration at equilibrium. The behavior of metals in surface water is complex and their partition coefficients can be impacted by many factors. Organic matter (OM) content in sediments, pH and salinity, are factors that may influence speciation and partitioning of metals. In this study, the partitioning coefficient of three metals (Cd, Co and Pb) under different levels of salinity, pH, and OM content were examined. A series of factorial experiments were evaluated in which three levels of …

Effect Of Disulfide Bond Scrambling On Protein Stability, Aggregation, And Cytotoxicity, Colina Dutta

Dissertations, Master's Theses and Master's Reports

Proteins are nano-machines that carry out majority of the cellular functions. Thermodynamically they are functional and stable within a very narrow range (1 kcal/mol). External perturbations in the form of pH change, thermal, or oxidative/reducing stress can destabilize the protein resulting in misfolding and aggregation. Prolonged environmental stress can affect the cells adaptive response resulting in loss of ability to refold or recycle proteins. This can lead to accumulation of misfolded or aggregated proteins within the cell. Such accumulation of aggregated proteins have been associated with neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS), Parkinson’s, Huntington’s, and Alzheimer’s disease. There …

Decarbonylative Cross Coupling Of Phthalimides With Diorganozinc Reagents—Efforts Toward Catalysis, Kimberly S. Deglopper, Sarah K. Fodor, Thomas Bd Endean, Jeffrey B. Johnson

Faculty Publications

The decarbonylative coupling of phthalimides with diorganozinc reagents to form o-substituted benzamides has been previously demonstrated as a viable process, but only with stoichiometric nickel(0). Investigations into a number of reaction variables, including solvent, ligand, and substrate substitution, have yielded multiple sets of conditions capable of achieving up to 10 catalyst turnovers, most successfully with the use of electron withdrawing nitrogen substituents on the phthalimide. In addition, these investigations have provided insight into the intermediates within the catalytic cycle and have revealed new approaches to the development of a general catalytic methodology.

Methodologies Utilizing Protected Oxyallyl Cations For Molecular Design, Jacob Reuben Stepherson

LSU Master's Theses

This master’s thesis discusses developments of novel organic methodologies utilizing oxyallyl cationic systems in the pursuit of highly functionalized molecular scaffolds. Chapter 1 focuses on the discovery of the oxyallyl cation intermediate, and examines reported transformations. Detailed optimization and substrate studies following exploitation of a protected 2-oxyallyl cation for nucleophilc capture comprises the information in both Chapter 2 and Chapter 3. Chapter 4 extends methodologies performed by my colleagues and establishes a tandem process using 2-silyloxypentadienyl cations to furnish complex structures. In this report, reaction design and optimization are chronicled, followed by exploration into the reactivity, mechanism, and scope of …

Synthetic Approach Towards P3eht-B-Pss Conjugated And Ionic Block Copolymer, Zhaoyuan Liu

LSU Master's Theses

This work is focused on the design, synthesis and characterization of block copolymers (BCPs) containing both conjugated and polyelectrolyte blocks. This type of rod-coil BCP is considered to have microphase separation which is different compared to coil-coil BCPs. The conjugated block used for studies is regioregular poly(3-alkylthiophene) (P3AT), which can be synthesized by Grignard metathesis (GRIM) polymerization. The polyelectrolyte block used is polystyrene sulfonate with well-defined structure, which can be synthesized by atom transfer radical polymerization (ATRP). Chapter II is focused on evaluation of synthetic routes for P3EHT-b-PSS, including using bifunctional initiator to synthesize both blocks, and separately synthesizing end-functionalized …

Analysis Of An Adhesion Promoter For Rubber To Metal Bonding, Killian Barton

Doctoral

The intermolecular and intramolecular changes induced by thermal stress in an industrial rubber to metal coupling agent (the ‘green molecule’ or GM) are the subject of this thesis. The GM was analysed in-situ in a model application environment using vibrational spectroscopy. NMR spectroscopy was used in order to analyse the solution chemistry of the compound and how this changed as a result of thermal stress. The interaction of the GM and the substrate was analysed using a range of surface analysis techniques including XPS, AFMIR and EDX. An example of a complex substrate, the zinc phosphate conversion coating, was analysed …

Fundamental Studies Of Humic Acid's Influence On Pollutant Toxicity To Aquatic Organisms, Rachel Dawn Deese

LSU Doctoral Dissertations

The main purpose of the research presented in this dissertation was to further understand the intricate and convoluted interactions between natural organic material, biological entities, and pollutants. This was achieved by utilizing humic acids (HAs) from differing sources, chemically modified humic acid, two biological entities (model biomembranes and Artemia Franciscana), and three types of pollutants (cations, surfactants, and carbon nanotubes). Fluorescence spectroscopy and model biomembranes were used to measure the change in HA’s ability to interact with the biomembranes in the presence of cations. Three differently sourced HAs, chemical modified HAs, and a range of cations were studied to elucidate …

Measurement Of Non-Covalent Aromatic Interactions Using Molecular Balances, Jung Wun Hwang

Theses and Dissertations

Non-covalent aromatic interactions govern many of the unique structures and properties of biological and synthetic molecules. Despite the importance of these interactions, their weak nature makes it challenging to study the interactions. To accurately measure weak non-covalent aromatic interactions in solution, we have designed molecular torsion balances that provide a quantitative measure of non-covalent intramolecular interaction strengths. First, we investigated the importance of electrostatic interactions in aromatic interactions. Substituent effects were strongly correlated with electrostatic Hammett parameters. In addition, the substituent effects were additive and showed significant direct substituent-arene interactions that support the recent direct substituent effect model. Next, the …