Chemistry Commons^™

Wet Chemical Synthesis And Characterization Of Nanomaterials For Solar Cell Applications, Krystle N. Sy, Ramprasad Gandhiraman, Jessica E. Koehne

STAR Program Research Presentations

During long term space missions, it is necessary to have a reliable source of energy. Solar cells are an easy and reliable way to convert energy from the sun to electrical energy. NASA has used solar cells manufactured on Earth as an energy source for many of its missions. In order to develop technologies that will enable high efficiency solar cells, we are synthesizing nanostructured materials. A range of nanostructured materials, such as titanium dioxide nanowires, nickel nanoparticles, copper nanoparticles, and silver nanoparticles/nanowires, are synthesized. In this work, we are reporting on the synthesis of these nanomaterials and the electron …

Effects Of Allosteric Mutations On Dihydrofolate Reductase, Marian Okondo

Theses, Dissertations and Culminating Projects

Dihydrofolate reductase (DHFR) is an essential enzyme necessary in the synthesis of DNA precursors. DHFR acquires resistance to numerous known anti-folates and this has led to the continuous need to discover novel and selective DHFR inhibitors. Allosteric mutations on Bacillus stearothermophilus (Bs.) DHFR were previously found to alter inhibitor binding and specificity. In this work, we investigate how these mutations affect the conformational motions of DHFR associated with inhibitor binding. Two distal allosteric mutations, isoleucine at position 86 to alanine (I86A) and tyrosine at position 127 to alanine (Y127A) were separately introduced to C73A/S131C, a previously modified wild type DHFR …

Versatile Synthetic Methods For Photoluminescent Pyrylium Tosylates, Jung Jae Koh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Pyrylium salts are an important class of cationic organic molecules that exhibit good absorption, fluorescence, and photo-induced electron transfer properties. They can also function as precursors for synthesis of different heterocyclic organic molecules such as furan, pyridine, pyridinium salt, and betaine dyes. This thesis describes versatile methods of synthesis for a series of 2,4,6-triarylsubstitued pyrylium tosylates with different substituents by using p-toluenesulfonic acid monohydrate instead of conventional acid catalysts including perchloric acid or boron trifluoride diethyl etherate that accompany explosion danger and difficult storage problem, respectively. The chemical structures were established by ¹H and ¹³C NMR spectroscopic techniques …

Hydrothermal Routes To Technetium Cluster Compounds, William M. Kerlin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Transition metals of groups six through nine exhibit unique direct multiple metal-metal bonding cores. Technetium is a group seven transition metal and is the lightest radioelement in the periodic table. Technetium exhibits nine oxidation states (from -I to VII) and an extensive set of mixed oxidation states due to bi- or poly- nuclear complex formation. Technetium has no stable isotopes and thirty four technetium isotopes have been discovered. Two main isotopes are of great importance ⁹⁹Tc and its metastable nuclear isomer ^99mTc. The isotope ^99mTc (T_1/2 = 6.01 hours, γ = 140.5 keV) is used in …

Composition Effects On Sheen And Spread Rate Of An Interior Flat, One Coat Latex Paint Formulation, Dana James Christensen Ii

Master's Theses

Interior flat, white latex paint is a common coating applied to walls around the world. Development of a coating with one coat hide capability is a pinnacle achievement for paint formulators as it has the potential to save consumers both time and money. One coat paints already exist on the market, but they are limited in color, coverage, and often have many disclaimers. Work done was part of a project initiated by ChemoursTM Titanium Technologies.

The goal of the project presented in this article was to create an interior flat, white latex paint that yields a spread rate of greater …

Quantum-Mechanical Calculations Of Actinyl And Europium Sorption To Graphene Oxide, Edward Helvenston

All Theses

Quantum-mechanical calculations were performed to model the interactions of U(VI), Np(V), Pu(VI), and Eu(III) with carboxyl and hydroxyl functional groups of graphene oxide (GO). Models were created for sorption to a single sheet of GO. For U(VI) and Eu(III), models were also created for sorption to two sheets to evaluate the possibility of cation-induced GO aggregation via cation cross-linking of GO sheets. The quantum-mechanical calculations were used to characterize the sorption reactions in terms of energetics and vibrational peak shifts. The calculations performed used Gaussian09 with the B3LYP hybrid functional. Sorption was seen as favorable for all cations considered; the …

Comparison Of Activation Enthalpies For Aminoglycoside Modification Reactions, Brittany Sterling Soto

Masters Theses

At highly elevated temperatures, many biological reactions can proceed spontaneously from the ground state to the transition state. However, due to the long half-life of these reactions, catalysts are required to catalyze these reactions at modern day temperatures by lowering the activation energy. Wolfenden et al. has previously shown that catalysts enhance the rate of the reaction by reducing the enthalpy of activation. Therefore, the activation energies have been determined for three aminoglycoside modifying enzymes, APH(3’)-IIIa, AAC(3)-IIIb, and AAC(3)-VIa, to determine whether these three enzymes distinguish between the two classes of aminoglycoside antibiotics by reducing the enthalpy of activation during …

Biodegradable Nano-Hybrid Polymer Composite Networks For Regulating Cellular Behavior, Charles Henley Sprague

Masters Theses

Photo-crosslinkable polymeric biomaterials have emerged in the field of biomedical research to promote tissue regeneration. For example, scaffolds that can be crosslinked and hardened in situ have been known to make suitable implant alternatives. Since injectable and photo-crosslinkable biomaterials offer the advantage of being minimally invasive, they have emerged to compete with autografts, a current highly invasive method to repair diseased tissue. A series of novel photo-crosslinkable, injectable, and biodegradable nano-hybrid polymers consisting of poly(ε-caprolactone fumarate) (PCLF) and polyhedral oligomeric silsesquioxane (POSS) has been synthesized in our laboratory via polycondensation. To engineer the material properties of the nano-hybrid networks, varied …

Advances In High-Throughput Analysis: Automated Radiochemical Separations And Nanopillar Based Separations And Field Enhanced Spectroscopy, Jennifer Jeanne Charlton

Doctoral Dissertations

Often the need to analyze a large number of samples coincide with critical time consternates. At such times, the implementation of high-throughput technologies is paramount. In this work we explore some viable pathways for high-throughput analysis and develop advancements in novel forms of detection of materials that are vital in the environmental, biological as well as national security arenas. Through the use of new protocols with high sensitivity and specificity as well as simplified chemical processing and sample preparation we aim to allow for improved throughput, fieldable detection, and rapid data acquisition of extensive sample sets. The methods developed in …

Polymer Additives Effects On Structure And Dynamics, Adam Eugene Imel

Doctoral Dissertations

This dissertation presents work that expands the understanding of the effect additives have on the structure and dynamics of a polymer matrix. Polymer additives are molecules, nanoparticles or fibers that are added to a polymer to modify the properties of the host polymer. Due to the vast amount of additives available, our studies were limited to C₆₀ (C60), soft polystyrene nanoparticles, and poly(ethylene oxide).

The first part of this project examined the influence that C₆₀ nanoparticles have on the assembly of polyacrylonitrile using small angle and wide-angle x-ray scattering techniques and viscometry. The addition of C₆₀ (C60) …

Gas-Phase Electron Diffraction From Laser-Aligned Molecules, Jie Yang, Martin Centurion

Martin Centurion Publications

Electron diffraction is a valuable tool to capture structural information from molecules in the gas phase. However, the information contained in the diffraction patterns is limited due to the random orientation of the molecules. Additional structural information can be retrieved if the molecules are aligned. Molecules can be impulsively aligned with femtosecond laser pulses, producing a transient alignment. The alignment persists only for a time on the order of a picosecond, so a pulsed electron gun is needed to record the diffraction patterns. In this manuscript, we describe the alignment process and show the changes in the diffraction pattern as …

Asymmetric Synthesis Of All-Carbon Α-Aryl Quaternary Carbonyl Compounds By Palladium-Catalyzed Asymmetric Allylic Alkylation (Pd-Aaa) And Their Application To The Synthesis Of Biologically Important 3,3′-Disubstituted Oxindole And Α-Disubstituted Quaternary Β-Lactone Frameworks, Md. Sharif Al Asad

Theses and Dissertations

The development of catalytic, enantioselective methods for the construction of all-carbon quaternary stereocenters is an outstanding achievement in the recent history of organic chemistry. The palladium-catalyzed asymmetric allylic alkylation (Pd-AAA) reaction has played a key role in creating such stereocenters and has allowed researchers to synthesize a vast number of biologically potent natural products. However, synthetic methodologies to access compounds containing α-aryl groups to the quaternary carbon stereocenters are still rare. The increasing appearance of these all-carbon α-aryl quaternary stereocenters in a growing number of biologically active natural products and pharmaceutical agents creates a pressing need for the ability to …

Morphology-Property Relationship For Binary Organic Thin Films, Alyssa Lynn Griffin

Master's Theses

Organic thin films can be readily mass-produced through solution-based fabrication methods including ink-printing and solution-casting because their light weight, flexibility, and inexpensive sources. Their applications range from organic field-effect transistors (OFET), organic solar cells (OSC), to organic light emitting diodes (OLEDs). Compared with pure component films, binary organic thin films (BOTF) allows for novel characteristics and specialized features to handle more demanding tasks. Due to the complex intermolecular interactions in BOTF, various microscopic phases with different morphological and electronic properties may be formed and this information is difficult to extract through conventional bulk measurements.

Organic thin films can be readily …

Metal-Free Tandem Beckmann–Electrophilic Aromatic Substitution Cascade Affording Diaryl Imines, Ketones, Amines, And Quinazolines, Samuel Sarsah, Marlon R. Lutz Jr., Kailyn Chichi Bobb, Daniel Becker

Chemistry: Faculty Publications and Other Works

A cascade reaction sequence involving a Beckmann rearrangement on benzophenone oxime followed by an electrophilic aromatic substitution (EAS) on the intermediate nitrilium ion affords N-phenyl diaryl imines that may then be hydrolyzed to ketones, or reduced to the corresponding amines. Reaction with benzonitrile afforded 2,4-diphenylquinazoline through a Beckmann–Ritter–EAS cascade.

Methodology Study Of N-Deacetylation Of 4-Acetamido-Perfluoroalkylbenzenesulfonimide, Grace Abban

Electronic Theses and Dissertations

In order to improve the synthetic route for diazonium perfluoroalkyl benzenesulfonylimide (PFSI) zwitterionic monomers, N-deacetylation of the coupling product was proposed to replace the reduction of aromatic amine intermediates. A series of hydrolysis methods, such as acid and base catalyzed refluxing, were explored for the N-deacetylation to obtain the PFSI aromatic amine. Factors such as temperature, concentration of acid/base and the time needed for the reaction to take place were investigated in an attempt to optimize the reaction condition. The basic hydrolysis was preferred since it was expected to carry out the N-deacetylation and debromination in one …

Candida Albicans Hyphal Mannan Is Structurally Distinct From Yeast Mannan, Francis Kwofie

Electronic Theses and Dissertations

C. albicans is a polymorphic fungal pathogen which has the ability to shift from yeast to hyphae. C. albicans cell wall is composed of glucan, chitin, mannoprotein and mannan. It is not possible, using standard extraction methods, to isolate mannan from C. albicans hyphae. To isolate hyphal mannan, we developed a simplified alkali extraction method. Using this method it was determined that hyphal mannan has a much lower molecular weight, a smaller polymer distribution and altered conformation structure when compared to yeast mannan. The hyphal mannan was found to contain little to no acid-labile portion with only α-Man-PO₄ groups …

Linkage Analysis And Compositional Studies Of Β-Glucan From Saccharomyces Cerevisiae And Compositional Studies Of Mannan From Candida Albicans, Clara Arthur

Electronic Theses and Dissertations

The efficacy of a novel carbohydrate extraction procedure was investigated with methylation analysis and alditol acetate method by Gas Chromatography-Mass Spectrometry. A published extraction procedure for β-glucans was compared to one developed in house. Both procedures gave a dominant glucose peak in the Gas chromatogram indicative of successful β-glucan isolation. Further linkage studies showed four linkage positions for β-glucans isolated with the published method; terminal, 1,3-linkage, 1,6-linkage and 1,3,6-linkage, while β-glucans isolated using the new method showed six linkage positions; terminal, 1,3-linkage, 1,6-linkage, 1,4-linkage, 1,2,3-linkage and 1,3,6-linkage. Diminishing β-glucan linkage peaks in the chromatogram for the published method indicated structure …

Three-Dimensional Scaffolds Of Graphene, Carbon Nanotubes And Transition-Metal Oxides For Applications In Electronics, Sensors And Energy Storage, Gilbert N. Mbah

Department of Chemistry: Dissertations, Theses, and Student Research

Electronics, sensors and energy storage devices are the new waves behind economic development, security and communication¹. Engineering small sizes of electronic, sensors and energy storage devices is the hurdle limiting efficient, portable and vast applications of Nano-devices for economic, security and communication advancement². Silicon the major material used in transistors has approached its limit to fabricated Nano-devices³. The discovery of free standing, one atomic layer thick and two-dimensional graphene sheets with high conductivity, inert, high specific surface area, stable and high tensile strength material in 2004 has shown capabilities to replaced silicon in electronics, …

Nanostructured Cerium Oxide Based Catalysts: Synthesis, Physical Properties, And Catalytic Performance, Yunyun Zhou

Department of Chemistry: Dissertations, Theses, and Student Research

Cerium oxide is an extensively used industrial catalyst with applications as diverse as catalysts for automobile exhaust, petroleum cracking and organic chemicals synthesis. The catalytic activity of cerium oxide is dependent upon its structural properties, especially the oxygen vacancy defects. While recent advances in characterization techniques have dramatically improved our understanding of cerium oxide functionality, many atomic features in cerium oxide contributing to the overall catalytic reactivity are not yet well-understood. This dissertation focuses on the structural studies of catalytically active cerium oxides with different compositions, phases and morphologies, and their utilizations to establish fundamental understandings of cerium oxide based …

Life’S Lessons In The Lab: A Summer Of Learning From Undergraduate Research Experiences, Louis S. Nadelson, Don Warner, Eric Brown

Chemistry and Biochemistry Faculty Publications and Presentations

Research experiences for undergraduates (REUs) seek to increase the participating students’ knowledge and perceptions of scientific research through engagement in laboratory research and related activities. Various REU outcomes have been investigated, including influence on participants’ content knowledge, career plans, and general perceptions of their domains of research. The complexity of REUs and dynamic nature of student development provide opportunity for exploring how REUs influence student growth. Our research focused on first and second-year college students who participated in a residential REU program that took place in a chemistry department in a metropolitan university in the western United States. We assessed …