Chemistry Commons^™

Diversity Oriented Synthesis Of Sulfur Containing Epoxide Compounds, Monica Stefaniak, Jeff Hansen Phd

Annual Student Research Poster Session

Diversity oriented synthesis is a drug discovery approach that allows the creation of a wide variety of new compounds that can each have exciting new characteristics. Previous research involving the opening of epoxide rings with amine groups has shown promising results with regards to bioactivity. Our research involved finding a simple procedure to open the epoxide ring using various thiol groups such as octanethiol, hexanethiol, and benzenethiol. We are hoping to develop a library of new sulfur containing compounds that show promising characteristics, such as pharmacological activity. In our project, we synthesized multiple new sulfur containing compounds and verified their …

Awegnn: Auto-Parametrized Weighted Element-Specific Graph Neural Networks For Molecules., Timothy Szocinski, Duc Duy Nguyen, Guo-Wei Wei

Mathematics Faculty Publications

While automated feature extraction has had tremendous success in many deep learning algorithms for image analysis and natural language processing, it does not work well for data involving complex internal structures, such as molecules. Data representations via advanced mathematics, including algebraic topology, differential geometry, and graph theory, have demonstrated superiority in a variety of biomolecular applications, however, their performance is often dependent on manual parametrization. This work introduces the auto-parametrized weighted element-specific graph neural network, dubbed AweGNN, to overcome the obstacle of this tedious parametrization process while also being a suitable technique for automated feature extraction on these internally complex …

Electrochemical Deposition In Energy Storage Devices, Witness Atutala Martin

Graduate Theses and Dissertations

Metals, whether in a solid or soluble ion form, are a vital part of any electrochemical storage system. More so, Li metal is widely considered as the ideal anode because of its low density and low electrochemical potential (-3.04 V vs. the standard hydrogen electrode – SHE). However, just like most metals, it does not plate or strip evenly during cycling which can lead to cycling performance issues, short cycling lifespans, and even safety concerns brought about by dendrites that can cause internal short-circuiting within cells. This research focused on investigating the electroplating of metals in both aqueous and non-aqueous …

Investigation Of Factors Influencing Recombination Versus Disproportionation Of Complex Radicals Formed By C-N Homolysis Of Breslow Type Intermediates And Related Compounds, Taylor Burnett

Graduate Theses and Dissertations

Electron rich enamines are capable of C-N bond homolysis and subsequent recombination and/or disproportionation. It is unclear what causes these radicals to undergo recombination or disproportionation. Density Functional Theory (DFT) calculations do not provide a transition state for the recombination and disproportionation processes and therefore they cannot be used to predict the favorable reaction. Breslow intermediates formed by deprotonation of thiazolium salts and reaction with aromatic aldehydes are examples of electron rich enamines. These breslow intermediates can undergo C-N bond homolysis to form a radical pair the either recombine or disproportionate. Upon investigation of the factors influencing recombination and disproportionation, …

Copper-Catalyzed Transfer Hydrogenation, Deuteration, And Selective Transfer Hydrodeuteration Of Aryl Alkynes, Kiera Behlow

Master's Theses (2009 -)

Transfer hydrogenation utilizes a non-H2 source of hydrogen to reduce double and triple bonds, utilizing transition metal catalysts in addition to some organocatalysts. The use of earth-abundant first row transition metals with ligands that fine tune the reactivity of the catalyst allows for the selective reduction of unsaturated functionalities by utilizing cheap and ubiquitous hydrogen sources such as water and various alcohols. This precludes the need for highly flammable H2 gas, which is often used with heterogeneous catalysts that offer limited selectivity and functional group tolerability. Catalysts optimized for the transfer hydrogenation of the desired functionality can be implemented to …

Metal-Assisted Catalytic Etching (Mace) For Nanofabrication Of Semiconductor Powders, Kurt W. Kolasinski

Chemistry Faculty Publications

Electroless etching of semiconductors has been elevated to an advanced micromachining process by the addition of a structured metal catalyst. Patterning of the catalyst by lithographic techniques facilitated the patterning of crystalline and polycrystalline wafer substrates. Galvanic deposition of metals on semiconductors has a natural tendency to produce nanoparticles rather than flat uniform films. This characteristic makes possible the etching of wafers and particles with arbitrary shape and size. While it has been widely recognized that spontaneous deposition of metal nanoparticles can be used in connection with etching to porosify wafers, it is also possible to produced nanostructured powders. Metal-assisted …

Resonant Two-Photon Ionization And Velocity Mapped Ion Imaging Studies Of Aromatic Van Der Waals Complexes, James T. Makuvaza

Dissertations (1934 -)

The study of van der Waals complexes provides a means for understanding the nature and strength of non-covalent interactions. Non-covalent interactions including C-H/, C-H/O, C-H/N, C-H/F, halogen and chalcogen bonding are found in important intermediates that regulate chemical and biological processes in many forefront areas of science including molecular self-assembly, drug substrate interactions, supramolecular chemistry, crystal engineering and biochemistry. To better understand these interactions, laser spectroscopic techniques that include mass selected two color resonant two photon ionization (2CR2PI) and velocity mapped ion imaging spectroscopy in combination with complementary ab initio calculations were used to probe the electronic structure, geometries, and …

Harnessing Surface Chemistry And Instabilities In Silicone Elastomers To Synthesize Adaptive Systems With Mechanically Tunable Surface Properties And Functionality, Ali Jamal Mazaltarim

Department of Chemistry: Dissertations, Theses, and Student Research

Material interfaces are of critical importance to numerous fields, including nanomaterials, electronics, microfluidics, synthesis, bioanalysis, pharmaceuticals, and catalysis, and they have been extensively researched. The materials used in these fields are often rigid/hard (such as silicon wafers) resulting in static surface properties. Consequently, the chemical/morphological properties of a surface may be modified using synthetic or mechanical means to tailor the interfacial properties of a material (i.e., surface energy, adhesion, topography, and reactivity). Recently, emphasis has been placed on designing dynamic materials with adaptive interfacial properties that respond to a variety of environmental stimuli. To this end, the surface chemistry and …

Continuous Measurement Of Reactive Oxygen Species Inside And Outside Of A Residential House During Summer, Azin Eftekhari, Claire F. Fortenberry, Brent J. Williams, Michael J. Walker, Audrey Dang, Annalise Pfaff, Nuran Ercal, Glenn C. Morrison

Chemistry Faculty Research & Creative Works

Reactive oxygen species (ROS) are an important contributor to adverse health effects associated with ambient air pollution. Despite infiltration of ROS from outdoors, and possible indoor sources (eg, combustion), there are limited data available on indoor ROS. In this study, part of the second phase of Air Composition and Reactivity from Outdoor aNd Indoor Mixing campaign (ACRONIM-2), we constructed and deployed an online, continuous, system to measure extracellular gas- and particle-phase ROS during summer in an unoccupied residence in St. Louis, MO, USA. Over a period of one week, we observed that the non-denuded outdoor ROS (representing particle-phase ROS and …

Developing And Understanding Catalysts For Organic Synthesis, Shelby Dickerson

Theses and Dissertations

Organic synthesis relies on improving catalyst designs and understanding reaction mechanisms for the advancement of the field. This dissertation will describe projects in both of these areas. First it will cover new photocatalysts in the aim of maintaining reactivity while increasing solubility in less polar solvents, and second understanding the importance of intermolecular interactions between new nucleophilic catalysts and substrates.

Photocatalysis has become a major focus as a sustainable pathway for chemical reactions with visible light photocatalysts performing a large range of reactions such as redox reactions, cyclization reactions, and energy transfer reactions. Chapter 1 will discuss classes of organic …

Bioethanol Production: Glucose Testing And Quantification Using Dns Analysis And Addition Analytical Methods, Dineen Vogler, Barnabas Gikonyo

McNair Scholars Program

The search for alternative ways to create a more sustainable and environmentally friendly source of energy, other than fossil fuels, has been ongoing for many years. Particularly, the production of biofuels has become of interest. One effort has been through the creation of first-generation biofuels that curb greenhouse gas emissions, unlike fossil fuels. However, first generation biofuels lead to the increase in food prices which negatively impacts developing countries, as they use food sources to produce biofuel. To mitigate this issue, second generation biofuels are considered as a better alternative. Instead of hindering the food supply, second generation biofuels aim …

Development Of Axial-Chiral Lewis Base Catalysts For Asymmetric Synthesis, Carlyn Louise Reep

Theses and Dissertations

Asymmetric Synthesis has become an essential tool to provide materials necessary to our everyday lives. The asymmetric formation of carbon-carbon bonds is the most important process in the construction of asymmetric organic molecules as this is how the structure/shape of a molecule is formed. Synthetic chiral molecules exist as agrochemicals, food additives, and pharmaceuticals, among other applications. As the demand for these materials has increased along with the growing population and scientific/technological advancements in these areas, the need for sustainable and efficient synthetic methods has come forefront as a scientific challenge. Chlorosilanes have emerged as an attractive reagent class for …

Ahr Expression On Rorc-Expressing Immune Cells Is Essential For I3c-Mediated Protection Against Colitis, Michal C. Williams

Senior Theses

Colitis is an inflammatory bowel disorder (IBD) whose etiology is attributed to modification in the luminal microbiota and dysregulation in the immune response. Indole is a signaling molecule which is naturally produced by gut luminal microbiota. Indole-3- carbinol (I3C) is a compound commonly found in vegetables and a ligand for the aryl hydrocarbon receptor (AhR). Previous studies have detected decreased expression and activation on the AhR receptor in colitis patients, thought to possibly alter gut microbiota metabolism, subsequently promoting colitis. 1 AhR, expressed in a variety of immune and epithelial cells, contributes to gut homeostasis by affecting vital mediators such …

An Experimental Study Of Evaporites On Titan: Implications For Lake Composition And Future Missions, Ellen Czaplinski

Graduate Theses and Dissertations

Titan is the only other planetary body in the solar system with liquid on the surface. With a surface temperature and pressure of 89 – 94 K and 1.5 bar (N2), respectively, Titan’s lakes are comprised of liquid hydrocarbons, predominantly methane and ethane. Over time, Titan’s lakes may evaporate, leaving behind residual deposits (evaporites). The evaporation processes and composition of the evaporites is poorly understood. I address these outstanding questions by experimentally investigating the physical and spectral properties of evaporites at Titan surface conditions using an experimental chamber.

Chapter 1 addresses the formation of ethylene evaporites. Ethylene evaporites form more …

Microfabrication And Electrochemical Characterization Of A Novel Su-8 Probe With An Array Of Individually Addressable Electrodes Suitable For Redox Cycling Experiments In Ultra-Small Volumes, Mahsa Lotfi Marchoubeh

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that utilizes closely spaced generator and collector electrodes to cycle reversible redox species between their oxidative states. With advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanism, and limited or no background subtraction, this technique is well suited for selective detection of important electrochemically active molecules such as dopamine at basal or slowly changing levels.

Miniaturized medical devices have become an area of great interest for measurement of chemicals in limited volumes with low concentrations or in sensitive tissues. A probe on a polymeric SU-8 substrate with suitable dimensions and …

Machine Learning Using Host/Guest Energy Histograms To Predict Adsorption In Metal–Organic Frameworks: Application To Short Alkanes And Xe/Kr Mixtures, Zhao Li, Benjamin J. Bucior, Haoyuan Chen, Maciej Haranczyk, J. Ilja Siepmann, Randall Q. Snurr

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A machine learning (ML) methodology that uses a histogram of interaction energies has been applied to predict gas adsorption in metal–organic frameworks (MOFs) using results from atomistic grand canonical Monte Carlo (GCMC) simulations as training and test data. In this work, the method is first extended to binary mixtures of spherical species, in particular, Xe and Kr. In addition, it is shown that single-component adsorption of ethane and propane can be predicted in good agreement with GCMC simulation using a histogram of the adsorption energies felt by a methyl probe in conjunction with the random forest ML method. The results …

Disorder Driven Asymmetry And Singular Red Emission In Doped Lu2hf2o7 Nanocrystals With No Charge Compensating Defects, Santosh K. Gupta, Mitzy A. Penilla Garcia, Jose P. Zuniga, Bhupendra B. Srivastava, Yuanbing Mao

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

High performance luminescent materials possess low symmetry, high color purity, no charge compensating defects, and high quantum yield. In this work, we have synthesized Lu2Hf2O7 (LuHO) and Lu2Hf2O7:Eu3+ (LuHOE) nanocrystals (NCs) using a molten salt synthesis and confirmed that both are stabilized in defect fluorite structure with a high degree of structural disordering. The LuHO NCs depicted green emission under ultraviolet irradiation, which decreases and increases after being treated in oxidizing and reducing environments, respectively, confirming the role of oxygen vacancies in the emission process. The LuHOE NCs (i) show excitation wavelength-dependent host to dopant energy transfer efficiency, …

Strain Fields In Twisted Bilayer Graphene, Nathanael P. Kazmierczak, Madeline Van Winkle, Colin Ophus, Karen C. Bustillo

University Faculty Publications and Creative Works

Van der Waals heteroepitaxy allows deterministic control over lattice mismatch or azimuthal orientation between atomic layers to produce long-wavelength superlattices. The resulting electronic phases depend critically on the superlattice periodicity and localized structural deformations that introduce disorder and strain. In this study we used Bragg interferometry to capture atomic displacement fields in twisted bilayer graphene with twist angles

Characterization Of Ph – Responsive Nanocage Based On The Ferritin Iron Storage Protein, Satyam Singh

Theses and Dissertations

The iron-storage protein ferritin (Ftn) assembles into a protein cage structure with 24 subunits and octahedral (4-fold, 3-fold, 2-fold) symmetry. Each monomeric subunit contains a robust four-helix bundle fold. The fully assembled Ftn structure has a high degree of thermal stability (up to 100°C), a mono dispersed size (12 nm in diameter), and a large central cavity (7-8 nm in diameter). The central cavity stores ferric iron in phylogenetically diverse group of organisms, including humans. The central cavity has been used for encapsulation of cargoes such as other metals, contrast agents for imaging, small molecule drugs for therapy, …

Alkyne Cyclization Involving A Zwitterionic Hexaruthenium Carbido Carbonyl Complex And The Synthesis Of The First-Nitrido Heterometallic Carbonyl Cluster Complexes, Nutan Damodhar Wakdikar

Theses and Dissertations

Chapter 1 introduces two related topics with the primary focus on the background of zwitterions and the conceptual understanding of a metal-complexed zwitterion. It also discusses the potential of a metal-complexed zwitterion for a carbon-carbon bond formation reaction. Synthesis of the metal carbonyl cluster, Ru6(µ6-C)(µ-CO)(CO)16, is also discussed in detail. Then, the background with the importance of heterometallic cluster complexes is discussed with the help of various examples used for catalysis.

The reaction of hexaruthenium carbido carbonyl cluster, Ru6(µ6-C)(µ-CO)(CO)16, with C2H2 and Me3NO yielding first examples of two new zwitterionic complexes, Ru6C(CO)15(μ−η2−C2H2NMe3), 2.2, and Ru6C(CO)14(μ3−η4−C4H4NMe3), 2.3, are presented in Chapter …

Characterization Of A High Affinity Glutathione Transporter And Its Impact On Glutathione Depleted Saccharomyces Cerevisiae, Tirthankar Bandyopadhyay

Theses and Dissertations

Thiol-disulfide redox homeostasis is integral for maintaining the redox status of proteins and other thiol-containing molecules within the cell. Among the many antioxidants and detoxifying enzymes and small peptides, glutathione (GSH) has proven to be critical for the preservation of function and structural integrity of the cell due to its functionality in areas like oxidative protein folding, thiol redox control, reactive oxygen species (ROS) and xenobiotics removal as well as iron regulation and Fe-S cluster biogenesis. Therefore, our studies are aimed at elucidating the factors that control GSH trafficking and metabolism in the model eukaryote Saccharomyces cerevisiae (baker’s yeast). Using …

Exploration Of Vase As An Extraction Method For Emerging Disinfection By-Products And Acidic Methanol As A Safe And Effective Derivatization Method For Haloacids, Madison Leigh Kilpatrick

Theses and Dissertations

This project aims to create an environmentally friendly, robust, and efficient extraction and preconcentration method in both the detection and quantification of various disinfection by-products (DBPs). Vacuum assisted sorbent extraction (VASE) is a newly developed method in the extraction of both volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). This extraction method is paired with a Thermo Scientific TSQ Quantum Triple Quadrupole GC-MS system for the quantification of DBPs. VASE outperforms current DBP extraction methods, with liquid-liquid extraction (LLE) being the most used alternative, because of its minimal use of solvent, high level of automation, and over-all ease of …

Plasmonic Metallic And Semiconductor Nanomaterials, Mengqi Sun

Theses and Dissertations

The earliest account of localized surface plasmon resonance (LSPR) has to date back to the ancient age of Rome in 400 A.D. The famous glass of Lycurgus cup told the story of unique light-and-matter interaction at the nanoscale that confines the electromagnetic field resonance at its surface and therefore allows LSPR feature to noticeably arise. The conventional metallic LSPR nanomaterials, like Au and Ag nanoparticles attract constant attentions due to their synthetic simplicity, chemical robustness, and visible spectral response. Its ability to generate sensitive dielectric sensing of the surroundings, strong electromagnetic field and active charge carriers upon optical excitation triggered …

Colloidal Semiconductor Quantum Dots: Solution Processing And Heterostructure-Based Optoelectronics, Mathew L. Kelley

Theses and Dissertations

Colloidal semiconductor quantum dots (QDs) are attractive candidates for high-efficiency solar cells and uncooled multiplexed photodetectors due to their favorable characteristics including large absorption cross-sections, size-tunable bandgap energies spanning the ultraviolet (UV) to short wave infrared, and solution processability. These QD-based optoelectronic devices operate on the basis of efficient photogenerated charge migration within QD solids and charge separation and recombination at electrical junctions, underscoring the need for (1) processing strategies that facilitate charge transport and (2) characterization techniques that robustly interrogate charge separation at QD interfaces. Here, my work on the post-synthetic processing and surface modifications of several semiconductor QDs, …

Efficient Method For An Approximate Treatment Of The Coriolis Effect In Calculations Of Quantum Dynamics And Spectroscopy, With Application To Scattering Resonances In Ozone, Igor Gayday, Dmitri Babikov

Chemistry Faculty Research and Publications

A numerical approach is developed to capture the effect of rotation–vibration coupling in a practically affordable way. In this approach only a limited number of adjacent rotational components are considered to be coupled, while the couplings to other rotational components are neglected. This partially coupled (PC) approach permits to reduce the size of Hamiltonian matrix significantly, which enables the calculations of ro-vibrational states above dissociation threshold (scattering resonances) for large values of total angular momentum. This method is employed here to reveal the role of the Coriolis effect in the ozone formation reaction at room temperature, dominated by large values …

In Situ Activated Co3–XNiXO4 As A Highly Active And Ultrastable Electrocatalyst For Hydrogen Generation, Kailu Guo, Yantao Wang, Junfeng Huang, Min Lu, Hua Li, Yong Peng, Pinxian Xi, Haoli Zhang, Jier Huang, Siyu Lu, Cailing Xu

Chemistry Faculty Research and Publications

The spinel Co₃O₄ has emerged as a promising alternative to noble-metal-based electrocatalysts for electrochemical water electrolysis in alkaline medium. However, pure Co₃O₄, despite having high activity in anodic water oxidation, remains inactive toward the hydrogen evolution reaction (HER). Here, a Ni-doped Co₃O₄(Co_3–xNi_xO₄) prepared by a simple method exhibits favorable HER activity and stability (>300 h, whether in 1 M KOH or the realistic 30 wt % KOH solution) after in situ electrochemical activation, outperforming almost all of the oxide-based electrocatalysts. More …

Computational Analysis Of Type 3 Iodothyronine Deiodinase: Potential Inhibitors, Substrate Binding, And Dimer Structure, Eric Scott Marsan

Chemistry & Biochemistry Theses & Dissertations

Thyroid hormones (THs) in mammalian tissues are crucial for development and maintaining metabolic homeostasis. Iodothyronine deiodinases (Dios) remove iodines from THs by a selenocysteine (Sec) residue, which either activates or inactivates them. Halogen bonding (XB) has been proposed to describe the interaction between the Se and I atoms of the T4-Dio complex. Disruption of TH homeostasis by xenobiotics, such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) can cause deleterious effects on the endocrine system. Experimental studies have indicated that PBDEs and PCBs could disrupt TH homeostasis by inhibiting Dio through XB formation. However, no current quantitative study exists …

The Development Of Novel Carbohydrate-Based Gelators And Their Applications As Advanced Soft Materials, Joedian Morris

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are attractive molecules that have been explored extensively due to their practical applications in many disciplines. These small molecules self-assemble forming solid-like gels via three-dimensional cross-linked networks with the solvent as the key component within the matrix. Carbohydrate-based LMWGs are small molecules that can form solid-like gels in water, organic solvents, and aqueous solutions. They have great potential to be utilized in different applications because carbohydrates are biocompatible and can be made from easily accessible and renewable resources. Designing gelators is still a challenge within the field, even though researchers have developed tools to predict …

Implications Of The Links Between Demography And Ecology For The Economy Of The Republic Of Karakalpakstan, Keunimjay Allanazarov, Gulya Khodjaeva, Katherine Shields

Karakalpak Scientific Journal

This article analyzes the impact of demographic factor on territorial organization of production in rural areas of the Republic of Karakalpakstan and reveals the main trends in production development. The analysis of statistical data of rural areas is given and proposals to improve the negative situation are given. More than 1306.8 thousand people live in rural areas of the Republic of Karakalpakstan, where they are concentrated in 1187 settlements, 26 urban settlements, and 11 towns of district subordination. All this testifies to the presence of large undeveloped production reserves and huge human potential. However, due to reduction of Amudarya water …

Investigation Of The Twist Of A Yarn With A Square Structure, Liza Toreniyazova, R. Orazbayeva, D. Kadirova, R. Rakhimkhodzhaev

Karakalpak Scientific Journal

The article presents the results of a study of the effect of yarn twist on the surface density of clothing fabrics with a square structure and the filling calculation of the fabric depending on the weave. The tension in the process of weaving square fabric on a loom with short overlaps is higher relative to weaving of fabric with long overlaps. With an increase in the twist of the yarn, the surface density of the fabric, the coefficient of filling (CST) and the coefficient of connectivity of the fabric (FTC) of the square structure increase.