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Toward Accurate And Efficient Computational Screening Of The Electronic Structure And Band Gaps Of Semiconductors, Linda Grabill

WWU Graduate School Collection

With increasing population, growing energy demands, and environmental concerns the search for greener energy resources has intensified in recent decades. For example, in the ongoing effort to harness solar energy, researchers have worked to identify and optimize the efficiency of semiconductors beyond traditional silicon photovoltaic materials.

In the development of new materials, synthetic chemists and materials scientists often look to computational chemistry to guide and understand experiments. In the case of semiconductors for solar energy conversion, this includes calculations of electronic band structure and band gap. The most precise computational approaches, such as density functional theory (DFT) are both time …

Development Of A Samarium Based Allylic Benzoate Elimination/Isomerization: Application To A Total Synthesis Of Honokiol, Alicia M. Wright

WWU Graduate School Collection

We have developed a new samarium diiodide-mediated elimination/isomerization reaction of benzoyl esters, capable of delivering olefinic products with high yield and selectivity depending on substrate structure and the additives used. The ability to selectively synthesize terminal, non-conjugated alkene substituents inspired us to use these optimized conditions in order to complete the total synthesis of the natural product, honokiol. Honokiol is a biaryl natural product isolated from magnolia trees that displays desirable oncological properties as evidenced by several biological studies in recent years. We found that our initially proposed pathway for completing the synthesis of honokiol was not a feasible route …

The Deoxygenation And Hydrogenation Properties Of Noble Metal-Based Bimetallic Phosphide Catalysts, Paul M. Cochran

WWU Graduate School Collection

With increasing concern regarding the environmental impacts of fossil fuels, and the difficulty of extracting petroleum feedstocks, alternative liquid fuels are becoming more desirable. Bio-oil, which is oil derived from biomass, is a renewable source of liquid fuels. However, the high oxygen and water content of bio-oil results in high corrosivity and low energy density, making it unusable in the current liquid fuel infrastructure. The process of removing heteroatom impurities from oil is known as hydrotreating. Current hydrotreating catalysts are optimized for refinement of petroleum, and are not suitable for bio-oil deoxygenation. Transition metal phosphides (such as Ru₂P) …

Ring-Closing Metathesis Reactions Of Acyloxysulfones: Synthesis Of Γ-Alkylidene Butenolides, Iris T. Phan

WWU Graduate School Collection

As we set out to investigate ring-closing methatesis reactions of acyloxysulfones, we discovered that treatment with triethylamine resulted in its quantitative conversion into the γ-alkylidene butenolides. γ-Alkylidene Butenolides are common to a number of biologically important natural products, and have been of great interest. To date, there has been no metathesis-based synthesis of γ-alkylidene butenolides making our approach the first. Development of the metathesis-based approach has allowed us to synthesize a variety of γ-alkylidene butenolides from the RCM products in high yields (69-100%). The elimination is proposed to proceed via an E1cb mechanism leading to (Z)-γ-alkylidene butenolides as …

Synthesis & Reactivity Of Iron (Ii) Pyridinediimine Complexes For The Reduction Of Nitrite, Yubin Kwon

WWU Graduate School Collection

The activation of small molecules has been studied by the scientific field for many decades as it plays a key role in nature such as photosynthesis and respiration. Many of these reactions are catalyzed by metalloenzymes in nature where the transfer of electrons and protons are coupled for the reaction to move forward. Noncovalent interactions in the secondary coordination sphere of metalloenzymes play an important role in determining the activity and selectivity. Hydrogen bonds are the most common noncovalent interactions that metalloenzymes utilize to control the reactivity in the secondary coordination sphere. Therefore, it is important to develop compounds and …

Development Of 2d And 3d Conductive Biomaterial Composites For Use As Electromechanical Actuators, Sean Severt

WWU Graduate School Collection

Flexible and conductive biocompatible materials are attractive candidates for a wide range of biomedical applications including implantable electrodes, tissue engineering, and controlled drug delivery. Here we demonstrated that chemical and electrochemical polymerization techniques can be combined to create highly versatile silk-conducting polymer (silk-CP) composites with enhanced conductivity and electrochemical stability. Interpenetrating silk-CP composites were first generated via in situ deposition of polypyrrole during chemical polymerization of pyrrole. These composites were sufficiently conductive to serve as working electrodes for electropolymerization, allowing an additional layer of CP to be deposited on the surface. This two-step technique expanded the range of available polymers …

Exploring The Biofuel Potential Of Isochrysis Sp., John R. Williams Ii

WWU Graduate School Collection

A select few strains of marine microalgae, such as Isochrysis sp., produce high-melting (∼70 °C) lipids known as long-chain alkenones that detrimentally affect biodiesel fuel quality. A method has been developed for the production of an alkenone-free Isochrysis biodiesel. This material was prepared on sufficient scale to allow for extensive analysis according to ASTM standards. Results revealed that while cold flow improved by removal of these high-melting components, a cloud point was still unattainable due to the fuels dark pigment. Further effort in relating the presence of alkenones and the resulting cloud point of the biodiesel, led to decolorization of …

Comprehensive Solution Structure Analysis Of Dna Duplexes Containing Chemical Base Alterations, Joanna Hoppins

WWU Graduate School Collection

Most types of chemical modifications of DNA bases are endogenous processes which are sensitive to the intracellular conditions. For example, the enzymatically catalyzed methylation of canonical cytosine to 5-methylcytosine (5metC) is a key form of epigenetic regulation of gene expression patterns. This modification is catalyzed and controlled by DNA methyltransferases (DNMTs). Perturbed rates of enzymatic DNA methylation leads to hyper- or hypo-methylation, both of which are a common initiating step in several forms of cancer. In addition to epigenetics, DNA bases can be chemically altered, or damaged, in response to reactive oxygen species (ROS). The oxidation of DNA by ROS …

Copper Indium Disulfide Nanocrystal Luminescent Solar Concentrators, Ryan I. (Ryan Isaac) Sumner

WWU Graduate School Collection

The sun is the most prominent renewable energy resource. Technologies such as photovoltaics (PVs) have yet to emerge as a cost effective alternative to non-renewable energy resources such as fossil fuels. Luminescent solar concentrators (LSC) possess the ability to lower the cost of solar energy by the reduction of the photovoltaic cell area and yet increase photovoltaic conversion efficiency. LSC’s offer an attractive approach to concentrating both specular and diffuse light, which eliminates expensive solar tracking methods. Luminophores for LSC applications are often dominated by reabsorption losses and absorb a small part of the solar spectrum, which prevents LSC’s from …

Progress Toward Structural Studies Of A Circularly Permuted Human Hemoglobins Containing T-State Stabilizing Mutations, Rachel J. (Rachel Joy) Hubbard

WWU Graduate School Collection

Our research is focused on the production of a hemoglobin based oxygen carrier (HBOC) which can be used as a therapeutic in the event of acute blood loss. The administration of cell-free hemoglobin is associated with severe adverse effects due to dissociation of the tetrameric α₂β₂ complex into αβ heterodimers. Our approach to the design of an effective HBOC, is based on a recombinant circularly permuted human hemoglobin in which all of the subunits are linked in a single-chain fashion. This design would prevent the dissociation of the tetramer and allow for the biosynthesis of polymeric hemoglobins of defined mass. …

Structures And Nuclear Quadrupole Coupling Tensors Of 1,2-Dichloroethane, 1-Chloro-2-Fluoroethane And 2,3-Dichloropropene Studied Using Microwave Spectroscopy And Computational Chemistry, Asela Sampath Dikkumbura

Masters Theses

The Fourier-transform microwave (FTMW) spectra of 1,2-dichloroethane (12DCE), 1-chloro-2-fluoroethane (1C2FE) and 2,3-dichloropropene (23DCP) have been studied in the 6 to 18 GHz range to determine experimental rotational constants, nuclear quadrupole coupling constants (NQCC) and quartic centrifugal distortions constants. These three molecules have different spatial arrangements (anti and gauche) resulting from different relative orientations of chlorine and/or fluorine atoms about the C-C single bond. The lowest energy anti conformer of 12DCE is non-polar and it is not detectable by microwave spectroscopy, but rotational spectra of gauche-12DCE with three isotopologues, gauche-1C2FE with three isotopologues, and both anti- …

Functionalized Bodipy Dyes For Dye-Sensitized Solar Cells, Mahmoud A. Elkhalifa

Masters Theses

It is predicted that more than 20 terawatts of carbon-free energy will be demanded by 2050 to maintain a sufficient energy supply for the increasing global population, and photovoltaics are predicted to contribute significantly to the global energy needs. Dye-sensitized solar cells (DSCs) are an emerging class of photovoltaics (PV) that has produced promising power conversion efficiencies at low costs. Currently, electron recombination, dye aggregation, weak adsorption, and inefficient absorbance are among of the largest contributors to low DSC efficiencies.

BODIPY dyes are one of the most promising classes of dyes emerging for DSC application. These low molecular weight fluorophores …

Synthesis And Characterization Of Dicopper(Ii) Complexes With Biological Relevance, Ashley E. Hall

Masters Theses

The research discussed in this study focused on the design, synthesis, and characterization of new model complexes that mimic the type-3 enzyme, catechol oxidase, which oxidizes catechols to their corresponding quinones. Our approach focused on the design and synthesis new model complexes that contain a dicopper(II) center that can be fine-tuned in a variety of ways, such as sterics and exogeneous bridging molecules. This method allows a multitude of complexes to be created and compared to determine how the overall structure affects the catecholase activity of the complexes.

Two ligands were synthesized; they contain a phenolate body, two amide groups, …