Chemistry Commons^™

Synergetic And Orthogonal Switching In Dual Photochromic Metal-Organic Frameworks, Gina Rene Wilson

Theses and Dissertations

Cooperative behavior and orthogonal responses of two classes of coordinatively integrated photochromic molecules towards distinct external stimuli were demonstrated on the first example of a photo-thermo-responsive hierarchical platform. Synergetic and orthogonal responses to temperature and excitation wavelength are achieved by confining the stimuli-responsive moieties within a metal-organic framework (MOF), leading to the preparation of a novel photo-thermo-responsive spiropyran-diarylethene based material. Synergistic behavior of two photoswitches enables the study of stimuli-responsive resonance energy transfer as well as control of the photoinduced charge transfer processes, milestones required to advance optoelectronics development. Spectroscopic studies in combination with theoretical modeling revealed a nonlinear effect …

Controlling Properties Of Hybrid Materials: Leaching Kinetics And Electronic Structure, Anna Berseneva

Theses and Dissertations

Hybrid materials are a unique class of materials that merge the properties of organic and inorganic building blocks. These materials are at the frontier of material science due to their wide modularity and applicability in numerous fields, ranging from catalysis to nuclear waste treatment. Unprecedented tunability of physical properties via changes in organic, inorganic moieties and their connectivity, enables for hybrid materials to address current challenges in the materials’ applications improving energy landscape.

The presented work consists of six chapters where the synthesis and design of new hybrid materials, fundamental understanding of electronic behavior and its modulation in organic-inorganic materials, …

Advances In Chalcogenide Crystal Growth, Anna Berseneva

Theses and Dissertations

Chalcogenides are the cornerstone of the semiconductor and thermoelectric industries and are up-and-coming materials for superconductors, catalysis, and battery applications. Challenges in the synthesis of those materials emerge from the chalcogen’s volatility and the tendencies of chalcogenide to react with even trace quantities of oxygen. Nonetheless, many techniques have been applied to the growth of chalcogenide single crystals, which are convenient for structure determinations and intrinsic property measurements. This dissertation will detail synthetic strategies applied to the crystal growth of novel chalcogenide materials via molten flux preparation (Chapters 2, 4, and 5), hydrothermal synthesis (Chapter 1 and 3), and single-crystal-to-single …

Molecular And Hybrid Catalysts For Selective Hydrodeoxygenation Of Lignin Model Compounds, Jacob G. Tillou

Theses and Dissertations

Lignin is a highly aromatic, branched polymer and could be utilized as a renewable source of liquid fuel. The advent of “lignin-first” depolymerization processes have allowed for the high-yield isolation of oxygenated aromatic monomers from lignin. These oxygenated aromatic compounds are lower in energy and stability than their deoxygenated counterparts. Selective deoxygenation of these compounds would result in stable, higher value liquid fuels. Using molecular catalysts, selective deoxygenation, or hydrodeoxygenation (HDO), of lignin-derived compounds in the presence of hydrogen is possible.

Immobilization of these molecular catalysts on metal oxide surfaces eliminates the possibility of bimolecular decomposition and allows for easier …

Making And Breaking Bonds: Studying Intrinsic Chemistry In The Gas-Phase, Luke Metzler

Electronic Theses and Dissertations

The nature of chemical interactions can be difficult to ascertain in the condensed phase; chemistry can be observed, but with the plethora of variables such as solvation, mixes of counter-ions, and complex equilibria, the true intrinsic chemical properties of a given chemical species may be obfuscated. By conducting research in the gas-phase, many of these variables can be reduced, if not eliminated entirely, which can allow for the careful observation of the true physical phenomena driving chemical reactivity.

The research presented herein focuses on the use of ion-trapping (specifically in a linear ion trap) as a method for unveiling the …

Proton-Coupled Electron Transfer To Drive Biomass Conversion, Cody Canote

Graduate Theses and Dissertations

Meeting rising demands for commodity chemicals while simultaneously easing reliance on fossil fuels presents one of the most substantial challenges for chemistry to date. Biomass has emerged as a sustainable precursor to commodity chemicals but requires substantial deoxygenation to displace petrochemicals. Development of efficient catalysts to achieve these transformations remains one of the central goals of inorganic and organometallic chemistry. Electrochemical strategies to propel biomass conversion are attractive, providing the driving force for reactivity and insights into catalyst mechanism. This work focuses on proton-coupled electron transfer (PCET) to facilitate redox catalysis in biomass up conversion and homolytic bond cleavage in …

Studying The Chemistry-Property Relationship In Magnetic And Optical Materials: Spin S = 3/2 Systems Of Neodymium, Manganese, And Cobalt Oxyanions, Xudong Huai

All Dissertations

This dissertation describes the design and tunability of new magnetic and optical materials, emphasizing the intricate relationship between their crystal structures and their optical, electronic, and magnetic properties.

Two new frustrated magnets, ANd(SO₄)₂ (A = Rb, Cs), were designed and synthesized to examine the influence of the the counter cation A site in Nd lanthanide materials featuring a distorted triangular magnetic lattice with S = 3/2. This work demonstrates how the tunability of magnetic and photoluminescent properties can be achieved through the A sites, with findings validated through density functional theory calculations.

AMnTeO₆ (A = Ca, …

Theoretical And Spectroscopic Insights Into Molybdenum- And Tungsten-Sulfur Bonding, Jesse Lepluart

Chemistry and Chemical Biology ETDs

Molybdenum and tungsten chemistry in biology is dominated by bonding interactions with sulfur and the other chalcogens. The highly-conserved structures of these enzymes’ active sites suggest an early evolution in the history of life, with molybdenum and/or tungsten enzymes likely expressed by the last universal common ancestor. Despite their active site similarities, molybdenum and tungsten enzymes catalyze a diverse array of reactions via equally diverse mechanisms. A deep understanding of the electronic structures of these enzyme active sites and their catalytic intermediates is key to understanding this remarkable chemistry.

The work presented here aims to deepen the understanding of molybdenum …

The Chemistry Of Heavy Elements: Probing Relativistic Chemical Bonding, Barbara Maria Teixeira Costa Peluzo

Chemistry Theses and Dissertations

The bottommost part of the periodic table has a unique chemistry, where the high velocities of the inner-shell electrons prevent their description by the usual Schrödinger equation. The resulting so-called relativistic effects have numerous chemical implications, on both macro and microscale, ranging from physical properties to reactivity. However, experimental probes on these intriguing atoms are limited by their natural availability and, more importantly, the danger associated with their radioactivity. Quantum chemical calculations, on the other hand, face the challenge of far more complex algebra, which demands substantial computational resources. Relativistic Hamiltonians, which act over all electrons in the system, are …

Modulating Covalency In A Ni-H-Al Subunit: Synthesis And Characterization Of A Series Of Electronically Differentiating Ni-Al Heterometallics, Aleida Guadalupe Gonzalez

Theses and Dissertations

Metal hydrides are moieties that are present in a variety of applications as intermediates in catalysis. Despite the vast utilization of metal hydrides, monometallic metal hydride complexes bear limitations in inert-bond activation and functionalization. A strategy to overcome these limitations and access more challenging reactivity is utilizing metal-metal cooperativity on a single platform to further activate hydride moieties. Although incorporating multiple metal centers on a single ligand scaffold has been realized, access to heterometallic hydride-bearing complexes is a greater synthetic challenge. Given the limitations in accessing such systems, the reactivity and electronic structure of heterometallic hydrides are seldom studied. Recently, …

Development Of Platinum(Iv)-Gold(I)-Based Anticancer Agents, Javier E. Lopez-Hernandez

Dissertations, Theses, and Capstone Projects

Heterometallic compounds have emerged as prospective multitarget anticancer drugs. These species may display improved efficacy and physicochemical properties compared to the individual metallic fragments, while helping combat drug resistance by exerting effects on multiple pathways. In this thesis we describe the synthesis of new bi- and tri-metallic compounds based on platinum(IV) compounds containing FDA-approved platinum agents, and gold(I) derivatives with known anticancer properties. We demonstrate their toxicity and selectivity against a small panel of renal, bladder, ovarian, and breast cancer cell lines, as well as their synergistic effects. We have selected a trinuclear PtAu₂compound containing the Pt(IV) core …

Quaternary Diamond-Like Sulfides For Nonlinear Optical Applications: Investigation Into Composition-Structure-Property Relationships Of The I2-Ii-Iv-Vi4 And I4-Ii-Iv2-Vi7 Formulae, Jordan Kelly

Electronic Theses and Dissertations

The research work presented in this dissertation focuses on the synthesis, characterization, and property assessment of new and existing quaternary diamond-like semiconductor (DLS) materials for the potential application in infrared (IR) nonlinear optics (NLO). Chapter 2 discusses the previously discovered temperature-dependent polymorphs of Cu₂ZnGeS₄ (CZGS); however, the IR NLO properties, neutron powder diffraction data, and single crystal X-ray diffraction structures were previously undetermined. The high-temperature α-CZGS polymorph was superior to the low-temperature β-CZGS analog in both second harmonic generation (SHG) and laser-induced damage threshold (LIDT). Chapter 3 presents the discovery of Li₂MgGeS₄ and comparison …

Towards Carbon Dioxide Reduction: Synthesis And Characterization Of Ccc-Nhc Pincer Iron Complexes., Joshua Mensah

Theses and Dissertations

The industrial revolution came with its downside of emission of greenhouse gases into the atmosphere. The NOAA reported in 2019 that, of the greenhouse gases emitted into the atmosphere, CO2 contributed to about 80% of the increased greenhouse gases hence the need for CO2 Sequestering and Storage (CSS) and ultimately leading to Carbon Capture and Recycling (CCR) as a viable option to convert CO2 into useful forms. The race to find the best catalyst for CCR has led to the synthesis of many organometallic compounds. Pincer complexes catalyzed CO2 reduction has gained notoriety recently because of the tunability and robustness …

Computationally Assisted Mechanistic Analysis Of The Protonolysis Of A Pt–Me Bond, Clement Dasilva

Student Research Symposium

Mechanistic study of the protonolysis of (cod)PtMe2 could give insight into the activation of C-H bonds by platinum because it is the microscopic reverse reaction. Two possible mechanisms for the protonolysis of dimethyl platinum complexes have been proposed, with experimental and computational data supporting the single step, SE2, over the multistep, SE(ox) mechanism. New experimental work from our group supports a multi-step mechanism with multiple acid molecules. In this work, the SE2 mechanism as well as a proposed SE(ox) mechanism were computationally modeled with a single equivalent of acid, TFAH, and two equivalents using density functional theory. The modeled pathways …

Model Of The Effect Of Voltage On Contact Angle In An Electrolytic Cell Reaction, Aaron Essilfie

Reviews, Analyses, and Instructional Studies in Electrochemistry (RAISE)

This paper investigates the hypothesis that the contact angle at the meniscus of an electrode-electrolyte can be altered during a redox reaction through the coupled understanding of electrowetting and capillarity rise. Recent studies in electrowetting have focused on dielectric surfaces but research on contact angle at the electrode-electrolyte surface is lacking. The study employs a basic electrolytic cell. By applying principles of electrowetting and capillary rise the research aims to understand the relationship between applied voltage and contact angle, to advancements in electrochemistry and microfluidics.

3d-Printed Microfluidic Devices For Electrochemiluminescence Detection Of Mirna, Oscar Clement

Honors Scholar Theses

This thesis outlines the research conducted over the past two years on the production and application of microfluidic devices (MFDs) in electrochemiluminescent-based bioanalytical assays. The work is categorized into two main projects: designing and manufacturing MFDs and developing electrochemiluminescent (ECL) assays for detecting Alzheimer's disease (AD) associated microRNAs (miRNAs) using CRISPR technology. The process of learning to design MFDs involved acquiring proficiency in computer-aided design (CAD) software, stereolithography (SLA) 3D printing, and iterative design techniques. The development of the ECL-based assay for AD miRNA was a multidisciplinary endeavor, combining elements of inorganic and biological chemistry. Although the research on the …

Synthesis, Electrical Conductivity, Electrocatalytic Activity For Water Splitting, And Pseudocapacitive Properties Of Perovskite Oxide Derivatives., Kinithi Meththa Kumari Wickramaratne

Electronic Theses and Dissertations

Developing green and sustainable energy solutions is crucial to addressing the energy and environmental challenges. Hydrogen is an attractive candidate given its high energy density and low carbon emission compared to gasoline and coal. Electrochemical water splitting through a water electrolyzer is recognized as a green method for generating hydrogen and oxygen gases. Developing cost-effective electrocatalysts to reduce overpotential in hydrogen and oxygen generation is essential for the overall process. The growing interest in perovskite oxides as versatile and sustainable catalysts is driven by their compositional flexibility, tunable electronic structure, earth abundance, and inherent catalytic performance. In our research, we …

Engineering Multifunctional Silicon Nanostructures From Biorenewable Cellulose Nanocrystals, Nancy Chen

All Dissertations

The imperative search for alternative materials to address the pressing demand for advance energy storage is underscored by the escalating environmental predicaments. Lithium-ion batteries (LIBs) with graphite anodes have become the benchmark in energy storage; however, they are approaching a saturation point in terms of energy density. Silicon emerges as a promising contender to supplant graphite, owing to its profuse availability, cost-effectiveness, and impressive specific capacity of 4200 mAh g^-1. By integrating silicon anodes, LIBs stand to undergo a radical transformation, markedly diminishing in weight and size, thus heralding a novel wave of compact, lightweight energy storage systems. …

Structure-Property Relationship Studies Of Electrically Conductive Metal-Organic Framework Materials, Shiyu Zhang

All Dissertations

Electrically conductive metal-organic frameworks (EC-MOFs) are among the most promising materials due to their tunable structures, properties, and diverse functions. However, the lack of comprehensive understanding of their structure-property relationship hinders the development of EC-MOFs. My dissertation focuses on the design, construction, and structure-property relationship studies of EC-MOFs.

Chapter 1 describes how MOFs' structural features and compositions affect the electronic properties and demonstrates conductive mechanisms and the corresponding design strategies to develop EC-MOFs.

Chapter 2 describes the synthesis, characterization, electronic and optical properties of four novel alkali-metal-based (Na, K, Rb, and Cs) 3D-MOFs with continuous tetrathiafulvalene tetracarboxylate (TTFTC) π-stacks, systematicly …

Synthesis And Characterization Of Indole-Based Zinc Dipyrrin Photosensitizers, Jean-Pierre Sanza

Electronic Theses and Dissertations

Metal complexes of dipyrromethene (dipyrrins) used as sensitizers in photocatalysis offer a way to harness solar energy in chemical bonds to create new fuels. This offers the dual role of reducing fossil fuel dependence and atmospheric CO₂ levels. Traditionally, metal dipyrrin complexes are synthesized using substituted pyrroles, aldehydes, and transition metals. Indoles have a more expanded pi-electron system and their dipyrrin-type complex may exhibit visible light absorption, suggesting that they can act as photosensitizers for CO₂ reduction processes. A novel indoledipyrromethene was synthesized using unsubstituted indole and mesitaldehyde. The complex exhibits visible light absorption at 422 nm. Its …

Utilizing Metal Ligand Cooperativity To Activate Small Molecules., Christine Burgan

Electronic Theses and Dissertations

The problems created from the excessive use of fossil fuels can be approached from two directions: capture the CO₂ from the atmosphere or develop alternative energy sources. The current industrial standards for these are environmental and/or health hazards and utilize precious metals, respectively. Metal ligand cooperativity (MLC) has emerged as a promising alternative to using precious metals to activate small molecules. In this dissertation, we focus on a series of metal complexes based on the ligand diacetyl-2-(4-methyl-thiosemicarbazone)-3-(2-hydrazinopyridine) (H₂L¹) for either hydrogen evolution or CO₂ capture. The novel complexes were characterized by ¹H NMR, …

Earth Abundant Catalyst For Evironmental Sustainability Applications, Javier Hernandez

Open Access Theses & Dissertations

The development of experimental methodologies for synthesizing a diverse range of metallic and metal oxide nanoparticles tailored for sustainable water treatment applications was investigated. These nanoparticles are prepared using environmentally friendly and scalable synthesis methods, underscoring their potential for large-scale production. Synthesized nanoparticles are harnessed for various processes, including catalysis and electrocatalysis, with a primary objective of degrading and removing organic pollutants from water. Key to this research is the encapsulation of nanoparticles within solid supports. Multiple methodologies are explored to engineer supports that ensure nanoparticle stabilization, monodispersion, and prevent unintended release into the environment. Two alternative approaches were evaluated …

Computational Investigation Of Transition Metal Photoredox Catalysis: Redox Property Tuning Via Ligand Modification, Christian Fernando Sandoval Pauker

Open Access Theses & Dissertations

In the last decade, photoredox catalysis has become a powerful tool in synthetic chemistry. It relies on the ability of catalytic systems that facilitate energy-demanding redox reactions thanks to photoinduced electron transfer processes. This dissertation focuses on the computational investigation of the redox properties of transition metal photoredox catalysts using density functional theory (DFT) calculations. The research systematically explores the effects of altering redox-active ligands on the thermodynamics of electron transfer events in the photoredox cycle. The electronic structure changes throughout oxidative and reductive quenching cycles are analyzed, with a particular focus on Cu(I) complexes. Through computational techniques, insights into …

Studies Of Novel And Well-Defined Dinickel Architectures Utilizing An N-Atom Bridge, David Anthony De Los Santos

Theses and Dissertations

There has been a growing interest in organometallic chemistry to utilize late Earth-abundant metals towards challenging molecular functionalization of abundant feedstocks to value-added products. There is precedent of utilizing cooperativity to try and address some of the shortcomings of traditional mononuclear complexes by integrating metal-metal and or metal-ligand cooperativity to facilitate multi-electron transformations. The utility of a redox-noninnocent scaffold allows for the metal centers to be stable over a range of oxidation states, using the ligand to store electrons. Despite recent progress, complexes harnessing cooperative states towards challenging transformations is still an emerging field. Our group has synthesized a multinucleating …

Synthesis And Characterization Of Silver(I) And Manganese(Ii) Complexes With Thione Imidazoles, Shannon Keyser, Audrey Lawrence, Jaime M. Murphy Ph.D.

Honors Theses

Coordination polymers are chemical complexes with versatile applications such as catalysts, electrical conduc-tors, non-linear optics, magnetics, chemical sensing, and molecular storage. The polymers are comprised of a repeating series of metal-ligand complexes, which form various structures in varying ratios depending on the metal and ligand used. Certain metal-ligand combinations have shown particular promise as potentially being polymers or, if not polymers, possessing other useful features such as electromagnetic conductivity. Complexes were synthesized using silver(I) and manganese(II) with the ligands methimazole, 2-mercaptoimidazole, and thiocarbanilide with counterions of either chloride or nitrate. These com-plexes were characterized using elemental analysis, infrared spectroscopy, and …

Investigation Of Surface Chemistry From Electron Irradiation Of Synthetic Schreibersite, Tyler Davis

Master's Theses

While phosphorus is one of the key elements for life on Earth, it has relatively low abundance in extraterrestrial environments, making it a target for astronomers and astrobiologists interested in the possibility of life beyond our planet. Schreibersite (Fe,Ni)₃P is one of the first P-containing minerals to condense during planetary cooling and one of the primary P-containing minerals in iron and stony-iron meteorites. Therefore, it is a likely P-bearing mineral in cometary cores and dust grains within the interstellar medium and circumstellar envelopes. Experiments in this project were performed with the aim of observing the formation of small …

Molybdenum Alkylidyne Complexes With Phenoxide Ligands For Alkyne Metathesis, Marvin L. Stewart Jr

LSU Doctoral Dissertations

Abstract

Alkyne metathesis is a powerful synthetic tool, which provides easy access to complex organic molecules in a single-step. It is a dynamic covalent reaction that scrambles alkynes, carbon-carbon triple bonds (C≡C). Molybdenum- or tungsten-alkylidyne (Mo≡C, W≡C) complexes are typically used as catalyst to cleave and reform alkyne bonds. Our goal has been to gain a deeper understanding of the intrinsic differences between functional ligands by the development of novel phenoxide ligands.

In chapter 2 we explore the detailed synthesis of novel phenoxide podand ligands in an effort to identify their mo-alkylidyne complexes. We were able to synthesize a variety …

Synthesis Of Trisubstituted Bismuth Complexes For Future Research, Cassidy Belk

Undergraduate Theses

Bismuth, a relatively inexpensive heavy metal with low toxicity, has the potential to be used in medicines and anticancer drugs. This project is exploring bismuth complexes with ligands based on chalcones, which are a type of small organic molecules with known anticancer properties. Preliminary results on a bismuth-chalcone complex indicate that substituted aryl bismuth complexes have better anticancer activity than triphenylbismuth or the chalcone ligand on its own. A series of trisubstituted bismuth molecules were synthesized using a BiCl₃ Grignard reaction under a nitrogen atmosphere with different substituents to provide electron donating groups, electron withdrawing groups or bulk. X-ray …

Structure Of Native Four-Repeat Satellite Iii Sequence With Non-Canonical Base Interactions, Erin Chen , '23, M. Trajkovski, Hyun Kyung Lee , '21, Samantha Nyovanie, Kailey N. Martin, W. L. Dean, M. Tahiliani, J. Plavec, Liliya A. Yatsunyk

Chemistry & Biochemistry Faculty Works

Tandem-repetitive DNA (where two or more DNA bases are repeated numerous times) can adopt non-canonical secondary structures. Many of these structures are implicated in important biological processes. Human Satellite III (HSat3) is enriched for tandem repeats of the sequence ATGGA and is located in pericentromeric heterochromatin in many human chromosomes. Here, we investigate the secondary structure of the four-repeat HSat3 sequence 5′-ATGGA ATGGA ATGGA ATGGA-3′ using X-ray crystallography, NMR, and biophysical methods. Circular dichroism spectroscopy, thermal stability, native PAGE, and analytical ultracentrifugation indicate that this sequence folds into a monomolecular hairpin with non-canonical base pairing and B-DNA characteristics at concentrations …

Killing Cancer: Manipulating Hydrophobic Vanadium Complexes To Improve Anti-Cancer Activity, Levi Ausherman, Debbie C. Crans, Peter A. Lay, Maggi Braasch-Turi

SACAD: Scholarly Activities

Hydrophobic vanadium complexes have recently shown improved anti-cancer activities compared to cisplatin. The hydrophobicity and anti-proliferative activity of [VO(Hshed)(dtb)] ([Hshed= N-(salicylideneaminato)-N’-(2-hydroxyethyl)-1,2-ethanediamine and dtb= 3,5-di(tert-butyl)catechol)]) have inspired the development of a library of hydrophobic vanadium complexes. Increasing the steric bulk of the catechol ligand has been shown to have a direct impact on hydrophobicity and anti-proliferative activities. Currently at Fort Hays State University, the Braasch-Turi group is synthesizing VO(HSHED)(dtb) to build up material to support the chemical analysis and biological assay performed by our collaborators at Colorado State University and the University of Sydney, Australia, respectively. In the future, we plan …