Chemistry Commons^™

Polymer Mimetics For Soil Modeling And Detection Of Biomarkers, Md Ragib Hasan

LSU Doctoral Dissertations

The population of the world is increasing day by day and is expected to reach 9.8 billion by the year 2050. The ever-increasing demand for agricultural products is putting an unprecedented strain on the world's soils as the human population continues to expand. Soil degradation caused by over-farming and the agrochemicals (fertilizers, pesticides, etc.) used in agriculture is a growing problem, although its causes remain murky. In addition, little is understood about the molecular-level interactions of substances that are subsequently introduced to soils, such as agricultural chemicals (ACs). Therefore, it is expected that these constraints may be circumvented by the …

Synthesis Of Carbon Nanohoops And Macrocycles Via Alkyne Metathesis, Xin Zhou

LSU Doctoral Dissertations

Cycloparaphenyleneacetylene (CPPA) and cycloparaphenylene (CPP) are called carbon nanohoops; they are fully conjugated macrocycles with radially oriented aromatic groups. Though many syntheses of CPPA and CPP were reported, in the macrocyclization step, the yields were usually not satisfying, as the reactions were irreversible. Our group utilizes alkyne metathesis to address this problem. Chapter 1 provides backgrounds and an introduction to the carbon nanohoops and alkyne metathesis.

Chapter 2 details the synthesis of the [3]CPP⁴A and [3]CPP⁵A, with good macrocyclization yields via alkyne metathesis. This study showed the error-correction ability of alkyne metathesis, especially with nonsymmetric substrates. …

Novel Synthetic Routes To Functionalized Tetrahydrobenzofurans And Chiral A-Quaternary A'-Hydroxy Ketones, Fatimat Oluwayemisi Badmus

LSU Doctoral Dissertations

Various naturally occurring organic compounds possess unique biological activities and have found exclusive applications in pharmaceuticals and agrochemicals. Their undeniable significance has necessitated the discovery and development of novel reactions that unveil advanced chemical transformations. This dissertation will detail our new approaches towards the synthesis of functionalized tetrahydrobenzofurans and chiral α-quaternary α’-hydroxy ketones. The transformations in these approaches were enabled by the chemistries of oxyallyl cations, Grignard reaction and Claisen rearrangement.

Chapter 1 introduces oxyallyl cations, their generation, reactions and applications. Our previous contributions, in the form of silyloxyallyl cations, to solve the regioselective issues associated with unsymmetrical oxyallyl cations …

Development Of 1,2-Cis-Selective Glycosylation Protocols And Multistep Synthesis Of Glycans From Acinetobacter Baumannii., Dancan Kamau Njeri

LSU Doctoral Dissertations

Access to various oligosaccharides has been made possible by glycosylation reactions. This is mainly through chemical synthesis and enzymatic approaches. Herein, I talk about glycosylation through chemical synthesis. In general, glycosylation reactions lead to a mixture of 1,2-cis and 1,2-trans stereoisomers. Stereoselective access to 1,2-trans isomer is highly developed; it efficiently relies on neighboring group participation. However, efficient access to 1,2-cis selective glycosylation is still a work in progress. In Chapter 1, I highlight notable efforts developed so far that address the 1,2-cis selectivity challenge in glycosylation.

In Chapter 2, I demonstrate how I improved …

Determining The 3d Structure And Dynamics Of Mouse Notch1 Epidermal Growth Factor-Like Repeat 26 Using Nuclear Magnetic Resonance Spectroscopy, Kendra D. Jenkins

LSU Doctoral Dissertations

NOTCH is a transmembrane protein that transmits signals between cells in direct contact and alters gene expression. The signaling pathway is important because it is involved in cell fate determination. The NOTCH1 extracellular domain has 36 epidermal growth factor-like (EGF) repeats that are responsible for ligand binding. Mutations in the EGF-like repeats cause various neurological and developmental disorders. NOTCH1 signaling initiates when DSL ligands bind to EGF11-12, the minimum Ligand Binding Domain (LBD). The Abruptex region of the NOTCH1 protein (EGF24-29) is a highly glycosylated, flexible region with calcium binding sites that regulates NOTCH1 signaling and binding by interacting with …

New Chemoselective Dehydration And Cyclization Strategies Enabled By Triphosgene, Moshood Oreofeoluwa Ganiu

LSU Doctoral Dissertations

Since Friedrich Wöhler’s synthesis of urea in 1828, the techniques of organic synthesis have developed and advanced greatly. This advancement has facilitated the discovery of new organic synthetic methods, and enabled access to a more expansive chemical space. The purpose of this dissertation is to present the development of new organic synthetic reactions that were uncovered through previous discoveries. Additionally, the main theme of this work relies on exploiting the versatility of triphosgene in organic synthesis. To this end, the developed chemistries rely on the ability of triphosgene to serve as an activating agent, and a chloride source.

Chapter 1 …

New Synthetic Reactions Enabled By Protected Oxyallyl And Amidoallyl Cations, Binod Nepal

LSU Doctoral Dissertations

This dissertation entails design and development of two new synthetic methodologies made possible through the generation of cationic species, namely oxyallyl and amidoallyl cations. Chapter 1 involves literature survey on generation and trapping of oxyallyl cations. Mostly known for cycloaddition reactions with these elusive species, the most recent approach of direct nucleophilic capture of oxyallyl cations are discussed. Apt design of substrates and reaction conditions by Kartika Group to access a-electrophilic carbon towards the synthesis of a variety of value-added compounds, i.e., 1,4- and 1,6-dicarbonyls, carbazoles, densely substituted pyrroles and furans are elaborated.

Chapter 2 focuses on our discovery of …

Synthesis, Characterization, And Photo-Reactivity Studies On Mo(Vi) Dioxo Complexes For C-H Activation And O-Atom Transfer, Saeed Fosshat

LSU Doctoral Dissertations

Metal oxos are important intermediates in various chemical transformations that include electron transfer, proton-coupled electron transfer (PCET) and and O-atom transfer. Various extent of π-bonding from the oxo ligands to the central metal causes changes in nucleophilicity and overall reactivity of these species. Several factors can influence the electronic structure of the M=O bonds such as central metal oxidation state, geometry, ancillary ligands and spin state of the metal. A general strategy to increase the reactivity of metal oxos is to use electron rich metal centers that are less oxophilic. As a result of this, extensive amount of research has …

Competitive Sorption And Transport Of Heavy Metals In Soil And Mn Oxide-Coated Sand, Joshua Tyler Padilla

LSU Doctoral Dissertations

This study investigated the competitive sorption of Ni, Pb, and Zn as well as synergistic interactions between Ni and phosphate (P) in soils and Mn oxide-coated sand. During stirred-flow experiments, the sorption of heavy metal cations by Olivier soil was mutually reduced when applied simultaneously. When applied consecutively, the cation of higher affinity was able to displace the cation of lower affinity from the soil surface, however, no evidence for the reverse case was observed. A novel general exchange kinetics model was able to correctly describe such displacement. Competition between Ni and Zn mutually increased mobility in Olivier and Windsor …

Synthesis Of Thiol-Acrylate Hydrogels For 3d Cell Culture And Microfluidic Applications, Anowar Hossain Khan

LSU Doctoral Dissertations

Globally cell culture is an $18.98 billion industry as of 2020, with an 11.6 percent annual growth rate. Drug discovery has an estimated worth of $69.8 billion in 2020 and is predicted to grow to $110.4 billion by 2025. Three-dimensional (3D) cell culture of cancer cells is one of the rapidly growing felids since it better recapitulates in vivo conditions compared to two-dimensional (2D) models. However, it is challenging to grow 3D tumor spheroids outside the body, and some of the existing technology can generate these spheroids outside the human body but poorly mimic in vivo tumor models. Therefore, there …

Computational Study Of The Reactions Of Heteroatomic Compounds On Ceo2, Suman Bhasker Ranganath

LSU Doctoral Dissertations

The mechanisms of ambient-temperature reactions of heteroatomic compounds catalyzed by ceria (CeO₂), an archetypical reducible oxide, for enzyme mimetics, environmental protection, and chemical synthesis are investigated in this dissertation using theoretical methods. CeO₂ is modeled with thermodynamically stable low-index surfaces exposed by commonly studied ceria thin films and nano particles. To understand phosphatase-like dephosphorylation activity, stable adsorption states and surface reactions of model phosphates are examined. Binding of the central P-atom to surface lattice oxygen (O_latt) supplemented by phosphoryl O-Ce interaction is the only stable adsorption state for the un-dissociated molecule. Deprotonation of phosphate monoesters, …

Kinetics, Characterization, And Applications In The Development Of Next-Generation Cure-On-Demand Polymeric Materials Through Frontal Polymerization, Daniel Paul Gary

LSU Doctoral Dissertations

Frontal polymerization (FP) is a process in which a front propagates in a localized reaction zone converting monomer into polymer. This work explored the kinetics and applications of FP for the development of cure-on-demand materials.

The kinetic effects of fillers on frontal polymerization have not been thoroughly explored. In Chapter 2, various fillers were used, and their effects on front velocity and front temperature were determined. Clay minerals are primarily used, but the thermal conductive effects of milled carbon fiber were also explored. It was found that some fillers inhibit frontal polymerization through radical scavenging, while others increased the front …

Infrared Investigation Of Lithium Ion Electrolytes: Characterization Of Structure And Dynamics Via Linear And Nonlinear Spectroscopy, Jeramie Christopher Rushing

LSU Doctoral Dissertations

Lithium ion batteries are widely employed in energy storage, but the connection between the molecular interactions in their electrolytes and the macroscopic properties remains elusive. Across three vastly different electrolytes, speciation and dynamics were studied via linear and nonlinear infrared spectroscopy to shed light on this relationship. The impact of mixed solvation on ionic speciation was studied from the perspective of the anion, which revealed a significant energetic favorability for the formation of contact ion pairs in linear carbonate solvents over cyclic carbonates. Infrared spectroscopy and density functional theory calculations described a complete inversion of the speciation due to solvent …

Functional Structure Of Biomacromolecules In Plant Biomass Using Solid-State Nmr And Dynamic Nuclear Polarization, Alex Kipchirchir Kirui

LSU Doctoral Dissertations

This dissertation summarizes the recent findings on complex biomacromolecules in cell wall of plants and fungi which perform important roles in cell recognition, structural build up, and energy storage. Because of the technical difficulty in characterizing these biomacromolecules, which are often polymorphic and disordered in structure, the functional structure of these biomacromolecules remains elusive. In this dissertation, I present two solid-state nuclear magnetic resonance (ssNMR) and dynamic nuclear polarization (DNP) studies of carbohydrate-rich biosystems: the energy-rich plant biomass and disease-relevant, pathogenic fungi.

First, we have investigated the secondary cell wall of plant biomass which is a carbohydrate-rich biosystem using solid …

3-Dimensional Structural Determination Of Epidermal Growth Factor-Like Repeat 27 From Mouse Notch1 Using Nuclear Magnetic Resonance Spectroscopy, Justin Grennell

LSU Doctoral Dissertations

NOTCH1 has been associated with a variety of human ailments, such as cancer and heart disease. NOTCH1 is a transmembrane protein that contains 36 epidermal growth factor-like (EGF) repeats, which facilitate cell signaling by binding proteins on neighboring cells. Each repeat contains about 40 amino acids and has to be folded in a specific manner to function properly. The amino acid sequence, carbohydrate pattern, and calcium-binding sites of EGF-like repeats vary, but the pattern along the 36-repeat chain is conserved. The Abruptex region (EGF24-29) of NOTCH1 is a highly glycosylated (having undergone sugar addition) and flexible region, which gained its …

Non-Adiabatic Excited State Molecular Dynamics Using Ehrenfest And Modulated X-Ray Absorption In Titania, Alexander Matthew Meyer

LSU Doctoral Dissertations

This dissertation contains two separate sections aside from an introduction (Chapter 1): theory and methods (Chapter 2), time dependent density functional theory with Ehrenfest for excited state lifetimes in materials (Chapter 3), and simulated field modulated X-ray absorption in titania (Chapter 4).

Excited state lifetime in insulators and semiconductors can be difficult to compute using quantum chemistry due to their dense excited states. Non-radiative decay in these materials requires the use of non-adiabatic effects to dissipate energy through the means of electron-nuclear coupling such as coherent phonon generation. One method of approaching this challenge in these materials is using Ehrenfest …

Colloidal Nanomaterial Surface Chemistry And Characterization Studied By Linear And Nonlinear Spectroscopy, Asela Sampath Dikkumbura

LSU Doctoral Dissertations

Recent studies have demonstrated the use of nanomaterials such as metallic nanoparticles, liposomes, and polymer microparticles for biomedical applications, encompassing the field of nanomedicine. For developing novel core-shell metallic nanoparticles with controlled surface morphology, the in situ growth dynamics of colloidal silver-gold core-shell (Ag@Au CS) nanoparticles (NPs) in water are monitored in a stepwise synthesis approach using time-dependent second harmonic generation (SHG) and extinction spectroscopy. Transmission electron microscopy images show that the CS NP surface morphology becomes more smooth and uniform as the reaction proceeds, corresponding to lower, stable SHG signals and narrower plasmonic spectra that are compared to finite-difference …

Indicators Of Senescence And Their Relationship With The Antioxidant Response Element In Ovarian Cancer Cells—Toward A More Encompassing View Of Enzyme Activity Levels In Cells, Shaniqua Analycia Hayes

LSU Doctoral Dissertations

Enzymes and other related proteins are promising targets as biomarkers for cancer diagnostics, and it is therefore important to be able to quantify intracellular enzyme activity levels, not just presence of enzyme. Thus, there is a great need for the development of methods that offer spatiotemporal quantification of intracellular enzyme activity levels in respiring 2- and 3-dimensional cultures or their sample-processed variants. Previous studies have demonstrated that ß-gal is upregulated in senescence and in select ovarian cancers, and its expression/activity is upregulated when cells are under oxidative stress conditions. To that end, the primary goal of this work was to …

Investigation On The Structure And Dynamics Of Lithium Ion Solvation Shell By Linear And Non-Linear Infrared Spectroscopy, Xiaobing Chen

LSU Doctoral Dissertations

Lithium ion battery (LIB) is a lightweight, rechargeable and powerful battery that is used widely from mobile phones to laptops to electric cars. It has many exceptional advantages such as high energy density, high output power, relatively low self-discharge, etc. However, it has some disadvantages such as safety issues, capacity loss, and expensive manufacture. LIB is composed of three main components: electrolytes, positive and negative electrodes. Researchers have been working on improving the performance of LIB for the past decade, but only a few have focused on investigating the electrolytes at the molecular level. In addition, the molecular mechanisms behind …

Adsorption And Transport Of Colloids At Interface And In Bulk, Jingyun Lee

LSU Doctoral Dissertations

Colloids are suspensions of microscopic insoluble particles dispersed in a continuum phase such as liquid or gas. Colloids are found in our everyday life from food and cosmetic industries to pharmaceutical and biomedical applications. Depending on a global minimum of the free-energy landscape, colloidal suspensions can be classified as two major classes: equilibrium or active colloidal system. This Ph.D dissertation presents strategies to engineer equilibrium self-assembled structures and out-of-equilibrium active matter using various interparticle forces.

First, we introduce the means to promote the equilibrium self-assembled structures driven by adsorption of colloids at interface. Typically, adsorption of colloids at interface is …

A Systematic Multiscale Investigation Of Nanoparticle-Assisted Co2 Enhanced Oil Recovery (Eor) Process For Shale Oil Reservoirs, Dayo A. Afekare

LSU Doctoral Dissertations

Shale oil reservoirs are prolific on the short term due to hydraulic fracturing and horizontal drilling but experience significant production decline, leading to poor ultimate recovery and leaving billions of barrels of oil buried in the ground. In this study, a systematic multi-scale investigation of an enhanced oil recovery (EOR) process using relatively inexpensive silicon dioxide nanoparticles and carbon dioxide for shale oil reservoirs was conducted. Using the Tuscaloosa Marine Shale (TMS) as a case study, aqueous dispersions of nanosilica in conjunction with CO₂ were investigated at nano-to-core scales. At the nanoscale, atomic force microscope was used to investigate …

Investigations Of The Structure And Protein-Protein Interactions Of Chlamydia Trachomatis Scc4, Thilini Oshadhi Senarath Ukwaththage

LSU Doctoral Dissertations

Chlamydia trachomatis (CT) is the most common, sexually transmitted bacterial disease (STD) in the world. In the developmental cycle of CT, specific chlamydia chaperone 4 (Scc4) is a unique protein with essential and multiple roles. Hence, Scc4 is significant as a virulence target for therapeutic approaches to treat chlamydial infections. A novel approach was discovered to purify tag free Scc4 by utilizing a 6X-histidine-tag on Scc1 in the co-expressed Scc4:Scc1 complex by capturing the complex on nickel-charged immobilized metal affinity chromatography resin, followed by dissociation of Scc4 with sarkosyl. Using triple resonance NMR experiments, backbone and sidechain resonances …

Novel Synthetic Transformations Targeting Δ-Valerolactone And Isocoumarin, Joshua Paul Van Houten

LSU Doctoral Dissertations

The purpose of this dissertation is to describe the efforts undertaken to develop synthetic methodology targeting δ-valerolactone and isocoumarin. At the onset, an introduction to the δ-valerolactone and isocoumarin is given. Relevant examples of δ-valerolactone being utilized in the production of materials of biological and industrial application are then discussed. Following, current methods for forming δ-valerolactone are presented. After, an introduction to isocoumarin is begun. Current methods for producing isocoumarin are then discussed.

The results and discussion section of this dissertation will focus on two methods that were explored with the goal of producing α-acyl-δ-valerolactone with two different substitution patterns. …

Characterization, Immobilization, And Polymer Related Applications Of Watermelon Seed Powder, A Practical Source Of Urease Enzyme, Anthony Quan Quoc Mai

LSU Doctoral Dissertations

Urease enzyme was crystallized almost a century ago, and to this day its intrinsic stability is not ideal for everyday applications. This work introduces a new process by which a naturally encapsulated material, watermelon seed powder (WMSP), is characterized for its stability and activity. WMSP enzymatic activity has been measured for over a year at various storage conditions—exposed to ambient atmosphere for a year, WMSP retained above 90% activity. In aqueous conditions, the enzyme maintained above 60% activity after two months; with the addition of a preservative that number stays at about 90%. There is a pH shift of the …

Investigation Of The Structure And Dynamics Of Novel Battery Electrolytes By Utilizing Multidimensional Infrared Spectroscopic Techniques, Susith Rajitha Abeythunga Galle Kankanamge

LSU Doctoral Dissertations

Novel battery technologies are being developed due to the high global demand for energy in many fields where different specifications are required. The battery electrolyte provides a medium for ions to diffuse between electrodes and its composition determines the compatibility with the electrode pair. While many works focus on characterizing novel electrolyte systems to advance new batteries, the understanding of the microscopic structure and dynamics of speciations present in these electrolytes is limited. Many experiment methods have obtained incomplete time-averaged structure information due to lack of instrumental time resolution compared to the molecular intrinsic time sales of electrolytes that range …

Development Of Engineered Soil Surrogates For Modeling Natural Soil Sorption Behavior, Ghada Yehia Abdalla

LSU Doctoral Dissertations

The land produces more than 95% of the global food supply, and with a continuously growing population, we need to optimize the use of the available agricultural land. Soil organic matter (SOM) is an essential component of soils, especially concerning their fertility and sorption behavior. The chemical composition of the SOM consists of lipids, lignin, and cellulose. However, the heterogeneous and complex nature of SOM, and real soils, makes their study challenging and introduces uncontrollable factors.

Therefore, structural mimics of natural soils with increasing complexity representing the real soil functionality were synthesized and evaluated for bulk properties related to their …

Synthesis Of Structurally Diverse Molecular Scaffolds Enabled By Protected Oxyallyl Cations, Joshua Andrew Malone

LSU Doctoral Dissertations

This dissertation focuses on the synthesis of diverse molecular scaffolds through the use of protected oxyallyl cation intermediates. Chapter One provides background on the generation and applications of oxyallyl and silyloxyallyl cations, while focusing on the direct nucleophilic capture of theses intermediates to generate functionalized ketones and silylenolates. Chapter Two depicts our approach to generate six-membered silyloxyallyl cations through the use of mild Brønsted acid activation. Regioselective nucleophilic capture of these intermediates successfully produced diverse a,a’-substituted silylenol ethers enabled by polar solvent and residual water.

Chapter three details strategies to generate 1,4-dicarbonyl compounds, focusing on the capture of cationic intermediates …

Deep-Ultraviolet Laser Ablation For Biomolecular Analysis, Oluwaremilekun Omowunmi Lawal

LSU Doctoral Dissertations

New sampling and ionization techniques were developed using a deep-ultraviolet (DUV) laser at 193 nm wavelength for analysis of large biomolecules. A micrometer spatial resolution DUV laser ablation and capture system was constructed to sample tissue biomolecules. The spot size measurements of the focused beam showed that subcellular spots with ca. 2 μm diameter can be readily achieved with this wavelength. To demonstrate the extraction of tissue biomolecules with the DUV laser, regions of tissue sections were ablated and captured for offline proteomic and genomic analysis. The proteomic studies revealed that the tissue proteins were ejected without fragmentation and that …

Structure And Dynamics Of Phospholipid Vesicles And The Dependence On Nanoscale Interactions With Molecules Of Varying Complexity, Lakshapathy Widanelage Judith Upeka De Mel

LSU Doctoral Dissertations

In this dissertation, molecular interactions and changes imposed by nano-scale structures on phospholipid vesicles were investigated. 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) large unilamellar vesicles (LUVs) were used as the model system. Understanding changes of the bilayer structure, interfacial properties, lipid dynamics, and self-assembly, allows bridging relationships between biological cell membrane structure and dynamics to cellular functionalities. For example, membrane curvature changes are linked to membrane protein functions, although the exact mechanisms of control are not yet understood. Moreover, the knowledge gained from vesicle models allows exploring novel strategies for drug delivery applications. To achieve this, DOPC LUVs were synthesized and characterized by a …

Computational Investigations Of Battery Electrolytes, Ke Li

LSU Doctoral Dissertations

In this dissertation, the structure and dynamics of battery electrolytes were investigated using atomistic molecular dynamics (MD) simulations. Battery electrolytes play a key role in transporting ions between the cathode and anode. The chemical stability and ionic conductivity of electrolytes influence battery performance. In order to design better electrolytes, one needs an understanding of the relationship between electrolyte structure, dynamics, and bulk properties. To bridge the gap between the macroscopic phenomenon and the hidden molecular physics, in the first project we focused on probing an ether-based electrolyte, chosen for its relevance in sodium-based batteries. Through studying the impact of concentration …