Chemistry Commons^™

Halide Substitution Of Ternary Bismuth Chalcogenides For Photovoltaic Applications, Thomas Boggess

Theses and Dissertations

Semiconductors play an integral part in modern society. From computing to LEDs their use is ubiquitous, and no field is more reliant on them than that of power generation. Current political movements have seen a push to decrease reliance on traditional forms of power generation, which relies on fossil fuels, to renewable sources such as solar power. However, current commercial solar panels, based on silicon, are lacking in efficiency, only reaching between 18% and 22% efficiency.¹ In recent years, materials called perovskites have been garnering significant attention as possible replacements for silicon cells due to their favorable optoelectronic properties. …

Halide Exchange And Transport In Halide Perovskite Lattices, Temban Acha Billy

Department of Chemistry: Dissertations, Theses, and Student Research

In recent years, metal-halide perovskites (MHPs) have risen quickly to prominence as promising materials across a variety of fields, from photovoltaics to optoelectronics in general. We show here a facile solution growth for creating a variety of mixed halide MAPbBr_3-xI_x crystals, which we will use to study halide exchange and transport in halide perovskites. We generated a calibration curve between the optical response and chemical composition in mixed Br/I MHPs at room temperature. All mixed Br/I MHP crystals were subjected to measurements of photoluminescence (PL) and Raman spectroscopy. A subset of mixed-halide MHP crystals exhibited multiple emission …

Biosynthesis Of Copper Nanoparticles Using Hylocereus Costaricensis Peel Extract And Their Photocatalytic Properties, Suriati Eka Putri, Netti Herawati, Ahmad Fudhail, Diana Eka Pratiwi, Sumiati Side, Abd Rahman, Susilo Sudarman Desa, Nur Ahmad, Subaer Junaedi, A. Surleva

Karbala International Journal of Modern Science

A green chemistry method was used for the first time to synthesize copper nanoparticles (Cu-NPs) using CuSO4 as a precursor and red dragon fruit (Hylocereus costaricensis) peel wasted extract as a bio-reductor. Cu-NPs produced were then used as a photocatalysts for acid orange 7 (AO7) dyes degradation. The results showed that the smallest average crystallite size of the products ranged from 8.84 - 8.86 nm, and the FCC crystal structure had a surface area of 244.38-278.85 m2g-1. Furthermore, the optimum degradation of AO7 dye occurred at a ratio of 1:3 with a percentage of 81.07% for four cycles. These findings …

Photodynamic Therapy Agents: The Power Of Mjöllnir To Eradicate Cancer, Sidney M. Hopper

Honors College Theses

After its discovery back in the 1900s, photosensitizers became a critical study for potential treatments and cures for medical issues, including cancer. It was discovered that porphyrins appeared to target and accumulate in proliferating cells, and to reach the cells, a certain wavelength of light with maximum absorbance associated with the porphyrin was necessary to achieve cell death. Photodynamic therapy involves making use of porphyrins or metalloporphyrins as activators when exposed to such light. When activated, these compounds generate reactive oxygen species (ROS), such as HO- or O2-, which can react with nucleic acids found in DNA and RNA. In …

Hollow Mn3o4 Nanoparticles For Catalytic Oxidation Of Alkenes In Air, Nathan R. Loutsch

Honors Thesis

Oxidized hydrocarbons (epoxides, alcohols, carboxylic acids, ketones, and aldehydes) have many uses including fuel production, pollution treatment, and chemical synthesis. These compounds can be formed by oxidizing alkenes and alkanes with the assistance of a catalyst. Heterogeneous catalysts have greater recyclability, but traditionally have lower activity and selectivity. Due to the increased relative surface area, nanomaterials can overcome some of the physical limitations. The Hoefelmeyer lab developed a new nanomaterial: hollow Mn3O4 nanoparticles. Sensitive synthetic conditions have been optimized. Due to the increased relative number of edge and corner atoms, the reactive properties of most small nanomaterials increase. Because of …

Excitation Power Dependence Of Blinking In Copper-Indium-Sulfide Quantum Dots, Nicholas Chambers

Physics Undergraduate Honors Theses

Under continuous excitation, quantum dots exhibit random transitions between fluorescent ON states and non-fluorescent OFF states --- a phenomenon known as blinking. A physical description of the mechanism responsible for blinking that applies broadly to many types of quantum dots remains under debate. We study the blinking behavior of the non-toxic CuInS2 quantum dot, a system that has seen little investigation at the single-particle level. In particular, the optical properties of CuInS2 quantum are often improved by adding ZnS to the nanoparticles, but this addition leads to complex structural-optical property relationships that are even less understood. To probe the relationship …

Carbon Dioxide Reduction On Large Area Liquid Metal Gallium-Indium Electrocatalysts, Thomas Hollis

Chemistry & Biochemistry Undergraduate Honors Theses

Carbon dioxide (CO₂) is widely known as a greenhouse gas that contributes to global warming due to the burning of fossil fuels. The carbon dioxide reduction reaction (CO₂RR) is widely studied to reutilize CO₂ to useful products, including methane, ethane, and carbon monoxide. This project studies the use of liquid metal gallium-indium as an electrocatalyst to perform CO₂ reduction to carbon monoxide (CO) or possibly solid carbon in various solutions. Gallium-indium is characterized and studied through its “wetting” properties and adhesion to substrate foil through the measurement of contact angles inside solution. These liquid …

Supramolecular Pi-Donor/Acceptor Arrays Based On Redox-Active Metal-Organic Coordination Assemblies, Paola Benavides

All Dissertations

Coordination-driven self-assembly is an attractive strategy for constructing thermodynamically stable supramolecular coordination complexes, ranging from discrete metallacycles and cages to infinite coordination polymers and metal-organic frameworks for a variety of applications.

Chapter 1 discusses strategies for preparing supramolecular charge-transfer π-donor/acceptor assemblies and their potential applications.

Chapter 2 demonstrates that tricomponent self-assembly method, which was believed to yield 3D-cages, based on tetrapyridyl porphyrin (M’TPP, M’ = Zn or H₂), dicarboxylate ligands (XDC), and caped cis-Pt(II) corners, actually yields 2D-bowties featuring an M’TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. The 2D-bowties showed …

Designing Noncentrosymmetric Multifunctional Materials, Ebube Oyeka

All Dissertations

Noncentrosymmetric (NCS) materials with crystal lattices lacking spatial inversion symmetry display a wide range of exciting functionalities. This dissertation covers two classes of functional NCS materials: magnetic skyrmion-host compounds and multifunctional materials. Magnetic skyrmion and multifunctional materials combining optical and magnetic responses are providing avenues for developing and optimizing the performance of electronic devices that can have uses in memory storage, laser technology, medicine, sensors, etc. The formation of skyrmions is driven by asymmetric Dzyaloshinskii–Moriya (DM) interaction facilitated by broken spatial inversion symmetry and large spin-orbit coupling (SOC), while multiple functionalities arise when spin carriers and optical chromophores are optimally …

Synthesis Of A Phenyl Substituted Zinc Dipyrrin Complex For The Purpose Of Analyzing Aromatic Substitutions On The Characteristics Of Compounds Of This Class, Kole Owen

Undergraduate Honors Theses

The field of photochemistry is as innovative in development as it is broad in application. However, utilization of energy from the sun’s electromagnetic radiation remains secondary to the combustion of fossil fuels for the global energy consumption. This is neither a sustainable nor renewable system, and it has contributed to a major decline in the health of our global environment as the greenhouse gases emission has led to an incline in global temperatures and ocean acidity. To develop effective ways to utilize solar energy, experimental effort is being directed towards the understanding of photosensitizers, molecules which absorb solar radiation and …

The Study Of Corrosion On Additive-Manufactured Metals., Braydan Daniels

Electronic Theses and Dissertations

The purpose of this study was to investigate and compare the corrosion mechanisms between wrought and additive-manufactured (3D-printed) copper and stainless steel. The experimental procedure consisted of measuring the open circuit potential, electrochemical impedance spectroscopy, linear sweep voltammetry, Tafel analysis, surface topology, and scanning electron microscopy for each metal within salt water, tap water, sulfuric acid, and synthetic body fluid (excluding copper in synthetic body fluid).

Overall, printed stainless steel was more corrosion-resistant than wrought stainless steel in tap water and synthetic body fluid based on OCP, LSV, and surface topology results. Additionally, printed copper was more corrosion-resistant than wrought …

Structural, Magnetic, Electrical, Pseudocapacitive, And Electrocatalytic Properties Of Bilayered Ruddlesden-Popper Oxides., Chandana Kananke-Gamage

Electronic Theses and Dissertations

Ruddlesden Popper (RP) oxides are perovskite-derived functional materials with the general formula An-1Aʹ2BnO3n+1, where A/Aʹ is often a lanthanide or alkaline earth metal, and B is usually a transition metal. These materials contain perovskite-like connectivity, where BO6 units share apexes to form layers that are stacked above each other. The number of layers in each stack is represented by n in the above formula. The spaces between stacks are often occupied by lanthanide or alkaline-earth metals (Aʹ-site metals), which also reside in intra-stack spaces (A-site) between the octahedra. Oxide materials derived from perovskites have been studied for a wide range …

Impacts Of Preferential Flow On Tc-99and Np-237 Vadose Transport In Soils At The Savannah River Site, Josh Parris

All Theses

Since the 1950s, the United States has produced approximately 90,000 metric tons of spent nuclear fuel (SNF) (Office of Nuclear Energy, 2022); however, no long-term storage solutions are available. Technecium-99 and neptunium-237, two fission products found in SNF, readily form highly mobile species in oxidizing conditions (Hu, 2008; Bondietti, 1979) and have respective half-lives of 2.13 x 10⁵ and 2.14 x10⁶ years (Hu, 2010). Considering these characteristics, ⁹⁹Tc and ²³⁷Np are two risk-driving isotopes found in SNF storage. The process of macropore-facilitated preferential flow, transport through cracks within a soil matrix, has been recognized to increase …

Hydrothermal Synthesis Of Frustrated Lanthanide Pyrochlores And Transition Metal Double Perovskites And Germanates, Matthew S. Powell

All Dissertations

Magnetically frustrated materials hold promise of unique behavior allowing for the novel study of quantum phenomena. Such materials are poised to become an integral foundation for technological advancement in the post-Silicon Age. Crystalline materials are given special focus where the rigid lattice allows more detailed study of these quantized effects and frustration behavior. As opposed to polycrystalline powders, large single crystals can be preferentially aligned enabling the study of anisotropic behavior. Two cubic structure types have garnered significant interest due to their 3-D tetrahedral arrangement of symmetry-related metal centers with the potential for magnetic frustration: pyrochlores and perovskites.

The supercritical …

Synthesis And Characterization Of Rhenium 2,2′-Pyridylnaphthyridine Metal Complexes, Benjamin F. Solomon

Honors Theses

Rhenium (Re) is a group 7 heavy 5d transition metal in the same family as manganese (Mn) and technetium (Tc). Re-carbonyl complexes are known to be catalysts for many different kinds of reactions from C-C bond formation to reduction reactions like CO₂ reduction (CO₂RR)^1,2. With this in mind, we have prepared a set of six Re-carbonyl complexes of 2,2′-pyridyl-1,6-naphthyridine (1,6- pynap) and 2,2′-pyridyl-1,8-naphthyridine (1,8-pynap), a redox non-innocent ligand containing a bpy moiety as well as an additional aryl nitrogen binding location at which another metal-ligand bond could form. We have synthesized these complexes as precursors …

Synthesis Of 2-Bromo-6-Alkylaminopyridines, 2,6-Dialkylaminopyridines, And Tren Based Ligands, Stephanie E. Carter

Honors College Theses

Extended metal atom chains (EMAC) are multimetallic complexes that feature a linear metal chain with metal-metal bonds surrounded by stabilizing ligand molecules. When EMACs are formed with paramagnetic metal ions, unique magnetic properties can be derived from direct metal to metal communication. The challenge is that EMAC complexes are challenging to synthesize due to the inherent weakness of most M-M bonds and the specificity of the ligands required to stabilize EMACs. In prior work by the Guillet group, the silyl aminopyridine (SAP) ligands were observed to stabilize very unique triiron complexes, but they were inherently unstable. In other work, scaffolded …

Chemically Responsive Hydrogels, Properties, Pharmaceuticals, And Agricultural Applications: A Review, Mohammad Alrbaihat, Qusay Abu-Afifeh, Firas Al-Zeidaneen

Al-Bahir

A review of the literature on chemically responsive hydrogels about the selection of selectivity based on classification, properties, and application is presented in this article. Chemically responsive hydrogels are a type of hydrogel that undergo changes in their properties in response to specific stimuli. These hydrogels have attracted significant attention due to their potential applications in various fields, including pharmaceuticals and agriculture. Chemically crosslinked hydrogels are synthesized by covalent crosslinking of end-functionalized macromeres. Currently, a great deal of research is being conducted on hydrogel networks, also known as smart networks or hungry networks. This is owing to their potential use …

Bis(Difluoroborylamidinates) With Flexible Ethylene Bridges As Bifunctional Aggregation-Induced Emitters, Connor Welch

Symposium of Student Scholars

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) represent one of the most prominent classes of dyes, since they are ubiquitously used in protein and DNA labelling, photodynamic therapies, as luminescent tags, sensors, laser dyes, paint and ink compositions, as well as for electroluminescent devices. [1] This is because of their robustness in terms of photochemical stability, polarity and pH changes of their environment, in particular under physiological conditions. The versatility to introduce multiple functional substituents and ability of BODIPYs to strongly absorb UV-light while providing sharp fluorescence peaks, combined with high quantum yields make these dyes highly attractive for numerous applications. Closely related azaBODIPYs offer …

Synthetic, Catalytic, And Mechanistic Studies Of Supermesityl Phosphiranes And Phosphines, Ryan M. Tipker

Dartmouth College Ph.D Dissertations

Methylation of P-stereogenic phosphiranes Mes*PCH2CH(R) (Mes* = 2,4,6-(t-Bu)3C6H2, R = Me, Ph) with MeOTf gave P-stereogenic phosphiranium cations; [Mes*P(Me)CH2CH(Ph)][OTf] underwent syn-anti isomerization via P-epimerization. Mechanistic studies suggested ring opening gave a hyperconjugation-stabilized carbocation in which pyramidal inversion at P was promoted by s-interaction with the pendant cation. Attempted phosphirane protonation with HOTf resulted in ring opening and C-H activation of an o-t-Bu group to give phospholanium cations. Treatment of [Mes*P(Me)CH2CH(Ph)][OTf] with LiPPh2 gave bis(phosphino)ethanes. Copper- catalyzed P-alkylation of the secondary phosphine PHPh(Mes*) with benzyl bromides gave P-stereogenic tertiary phosphines with a supermesityl substituent.

Epitaxial Single-Domain Cu-Btc Metal-Organic Framework Thin Films And Foils By Electrochemical Conversion Of Cuprous Oxide, Xiaoting Zhang, Bin Luo, Avishek Banik, John Z. Tubbesing, Jay A. Switzer

Chemistry Faculty Research & Creative Works

Metal-Organic Frameworks (MOFs) Are an Important Class of Crystalline Porous Materials with Extensive Chemical and Structural Merits. However, the Fabrication of MOF Thin Films Oriented Along All Crystallographic Axes to Achieve Well-Aligned Nanopores and Nanochannels with Uniform Apertures Remains a Challenge. Here, We Achieved Highly Crystalline Single-Domain MOF Thin Films with the [111] Out-Of-Plane Orientation by Electrochemical Conversion of Cuprous Oxide. Copper(II)-Benzene-1,3,5-Tricarboxylate, Cu₃(BTC)₂ (Referred to as Cu-BTC), is a Well-Known Metal-Organic Open Framework Material with a Cubic Crystal System. Epitaxial Cu-BTC(111) Thin Films Were Manufactured by Electrochemical Oxidation of Cu₂O(111) Films Electrodeposited on Single-Crystal Au(111). …

Synthesis And Characterization Of Terbium(Iii) Complexes: Can We Manipulate The Emission Signature?, Ryan Gagnon

[Archive] Belmont University Research Symposium (BURS)

Successful Lewis acid/base reactions of terbium(III) nitrate with 2,2’-bipyrdine (22’bpy), 1,10-phenanthroline (phen), and 2,6-pyridine dimethanol (pydm) have yielded the products: Tb(22’bpy)₂(NO₃)₃, Tb(phen)₂(NO₃)_3, and [Tb(pydm)₃](NO₃)₃, respectively. In accord with the well-known antenna-effect, the absorption spectrum of each complex is similar to the spectrum of the free ligand, while the emission spectrum of the complex is identical for the free terbium(III) ion. In contrast, the substitution of a ligand containing a third-row nonmetal strategically placed near the terbium may force interaction between the 3p nonmetal …

Synthesis And Characterization Of Some Disubstituted Cyclopentadienyl Rhenium Complexes As Potential Candidates In Semiconductive Materials, Chloe Vernon

Senior Honors Theses

Since 2000, when the Nobel Prize in Chemistry as awarded for conductive polymer research few studies have been performed concerning the conductive capabilities of discrete organometallic compounds. For this project, organometallic compounds were formed specifically with a transition metal included in the structure. Through oxidation and reduction reactions, the variation in the electrical conductivity could allow for an analysis of whether this unique structure would allow for tunability. The goal of this research was to begin with aromatic substituted fulvenes and perform various multistep synthesis processes, utilizing thallium salt intermediates, to produce several disubstituted cyclopentadienyl rhenium complexes. In this project, …

Increased Efficiency Of A Functional Sod Mimic Achieved With Pyridine Modification On A Pyclen-Based Copper(Ii) Complex, Magy A. Mekhail, Katherine J. Smith, David M. Freire, Kristof Pota, Nam Nguyen, Marianne E. Burnett, Kayla N. Green

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

A series of Cu(II) complexes with the formula [Cu^RPyN₃]²⁺ varying in substitution on the pyridine ring were investigated as superoxide dismutase (SOD) mimics to identify the most efficient reaction rates produced by a synthetic, water-soluble copper-based SOD mimic reported to date. The resulting Cu(II) complexes were characterized by X-ray diffraction analysis, UV–visible spectroscopy, cyclic voltammetry, and metal-binding (log β) affinities. Unique to this approach, the modifications to the pyridine ring of the PyN₃ parent system tune the redox potential while exhibiting high binding stabilities without changing the coordination environment of the metal complex within …

Synthesis, Characterization, And Cytotoxicity Studies Of A Copper(Ii) Complex With Vanillin 3-Ethyl-Thiosemcarbazone A Ligand, Novia Mann, Ifeoluwa Oyeyemi, Duaa R. Alajroush, Elizabeth A. Tonsel-White, Stephen J. Beebe, Alvin Holder

Undergraduate Research Symposium

Triple-negative breast cancer (TNBC) is one of the most aggressive and challenging breast cancer subtypes to treat, as these cancer cells lack three common receptors: estrogen, progesterone, and human epidermal growth factor receptor 2. The multiple oxidation states transition metals can occupy have made this narrowly explored group popular for anti-cancer research in recent decades. Furthermore, the success of cisplatin, which has platinum as a metal center, while being a cancer-fighting agent with serious side effects, has caused other metal centers to be investigated as possible alternatives as chemotherapeutic drugs. Copper, as a biologically essential metal, makes an attractive candidate …

Optimized Peptide Nanomaterials As Delivery Vehicles For Hydrophobic Metal-Based Anticancer Agents, Yaron Marciano

Dissertations, Theses, and Capstone Projects

Enzyme-responsive materials have been well explored, particularly as therapeutic and diagnostic agents. In this thesis we demonstrate that anionic self-assembling peptides can be utilized as delivery vehicles for metal-based hydrophobic payloads. The tunability of the system is highlighted as well as the increase in cytotoxicity and selectivity in vitro. The rapid degradation of peptides in cell media may lead to the formation of new peptide-drug bioconjugates with increased activity and selectivity. The physiological stability of these peptide delivery vehicles has been optimized by capping the N-terminus with an acetyl group. This simple backbone modification was shown to not prevent self-assembly, …

Influence Of Synthesis Conditions On The Physicochemical And Electrocatalytic Properties Of Non-Stoichiometric Ba2sr2la2ti4o12 Perovskites, Ofeliya Kostadinova, Iliyan Popov, Simeon M. Stankov, Hristo Kolev, Tamara Petkov

Karbala International Journal of Modern Science

Present work studies the influence of the pretreatment milling media (deionized water (BLTOS-H) and isopropanol (BLTOS-i)) on the surface characteristics, structure, chemical composition and catalytic activity of non-stoichiometric Ba2Sr2La2Ti4O12 perovskites. The IR spectroscopy and XRD analyses shows a difference in the structure and phase composition of the two materials. X-ray photoelectron spectroscopy detects a Ba2+- and La3+-enriched and Sr2+-depleted surface. The BLTOS-i sample appears to exhibit higher specific surface area (SSA) and pore volume in comparison to BLTOS-H. The electrochemical tests showed that BLTOS-H sample have similar behavior to platinum at current densi-ties up to 10 mA cm-2, while BLTOS-i …

Synthesis And Characterization Of Mixed Ligand Complexes Of Ruthenium(Ii) Containing 2,2’-Bipyridine And 3,3’-Dimethyl-1,1’- Methylenebisimidazolium Ligands; A New Synthetic Approach, Matthew Schneider

Theses and Dissertations

Research into solar cells has been prioritized given the global demand for better renewable energy technologies. This demand is a result of the long-term use of fossil fuels, which generates significant pollution in highly populated urban areas. One potential solar cell technology is the dye-sensitized solar cell (DSSC). This kind of solar technology utilizes organometallic dyes to expand the types of wavelengths solar cells can use to generate electricity.12 Ruthenium(II) metal complexes of this type have been investigated heavily for this purpose.13,14,36 The main reasoning behind this is the metal-to-ligand charge-transfer (MLCT) phenomenon that such complexes exhibit. MLCT has often …

Synthesis Of Cysteine-Tyrosine Crosslinks In Β-Hairpin Peptide Models, C.D. Tatko, David Benson, Sophie A. Hruska

Summer Research

The Cysteine-Tyrosine crosslink (Cys-Tyr) is - A unique Post-Translational Modification - Redox-active - Found in a handful of proteins, including Cysteine Deoxygenase (CDO), whose malfunction has been linked to Alzheimer’s Disease

Synthesis Of A Novel Terbium(Iii) Complex For Application In Metal Nanoparticle Surface Modification, Lauralee E. Hurst, Davon Ferrara, Justin Stace

Science University Research Symposium (SURS)

Lanthanide ions, such as terbium(III), exhibit bright luminescence when bound to organic ligands which strongly absorb light. This property has been used in creating chemical sensors or luminescent tags for microscopy. Complexes centered with terbium(III) exhibit a yellow-green luminescence upon excitation by shortwave ultraviolet light. In this work, a bifunctional ligand, 4-mercaptobenzoic acid (4mba), was chosen to selectively coordinate terbium(III) to the oxygens of the acid functional group, leaving the thiol group available for another compound. Thiol groups are effectively used in surface coordination to noble metal nanoparticles (NP). In efforts to create a novel 4mba-terbium(III)-NP system, a one pot …

Synthesis And Reactivity Of Xanthene-Based Heterobimetallic Systems For Co Oxidation, Umesh Kaluarachchige Don

Wayne State University Dissertations

Nature provides a useful guideline for the design of an efficient earth-abundant catalyst for CO oxidation that relies on bimodal heterobimetallic cooperativity. Molybdenum-copper carbon monoxide dehydrogenase (Mo-Cu CODH) is an enzyme of the xanthine oxidoreductase family that catalyzes reversible oxidation of CO; it is inhibited by cyanide CN- and inserts isocyanide CNR between Cu and O/S. The active site contains molybdenum(VI) in a square pyramidal configuration with apical oxo and basal dithiolene, oxo, and sulfide ligands. The two-coordinate Cu(I) is coordinated by cysteinate and Mo-sulfide to form Mo-S-Cu bridge.While several groups have reported structural models of the active site of …