Physical Sciences and Mathematics Commons^™

Uio-Type Metal-Organic Framework Derivatives As Sorbents For The Detection Of Gas-Phase Explosives, Matthew Ryan Sherrill

Legacy Theses & Dissertations (2009 - 2024)

The detection of energetic compounds – better known to the public as explosives – has is an important cornerstone of counterterrorism and homeland security . While significant advances have been achieved for the detection of trace explosives in various matrices such as soil, wastewater, and clothing, the detection of explosives in the gas phase remains challenging due to their infamously low vapor pressures. In this thesis, we leverage the high sensitivity of direct analysis in real-time mass spectrometry (DART-MS) and the microporosity of metal-organic frameworks (MOFs) to adsorb and therefore concentrate explosives from the vapor phase and subsequently detect them …

The Vagabond Flourine Atom Revisited: Dissociative Photoionization Of Tri- And Pentafluoropropene, Jessica K. De La Cruz

University of the Pacific Theses and Dissertations

Photoelectron Photoion Coincidence (PEPICO) Spectroscopy studies on two unsaturated hydrofluorocarbons (HFCs), also known as hydrofluoroolefines (HFOs), are presented here. Previously, the Sztáray group has studied the dissociation of trans-1,3,3,3-tetrafluoroprop-1-ene (ElixClean), which is a fourth-generation refrigerant and propellant and has lower global warming potential than its precursors. My study is an extension of the ElixClean study as it aims to explore how the different number of fluorine atoms impact the dissociation reactions of these molecules. Both 3,3,3-trifluoropropene (TFP) and cis-1,2,3,3,3- pentafluoropropene (PFP) are also utilized as propellants and refrigerants.Measurements were carried out with remote access to the CRF-PEPICO (combustion reactions followed …

Gas-Phase Acid-Base Properties And Conformations Of Oligopeptides Through Mass Spectrometry And Computational Studies, Yuntao Zhang

University of the Pacific Theses and Dissertations

This dissertation presents a comprehensive study of the peptides of interest to deeper understand the gas-phase acid-base properties in relation to their conformations and chirality. In the first part of the study, two pairs of alanine (A)-based isomeric peptides consisting of a basic probe, lysine (Lys) or 2,3-diaminopropionic acid (Dap), were investigated to understand the nature of the enhanced basicity when the basic probe was moved from the N-terminus to the C-terminus. In the second part of the study, alanine-based peptides containing a cysteine (C) as the acidic probe were investigated to understand the chirality effects on the gas-phase acidity …

Gene Vectors With Fluorescence Tracking Capabilities, Sophia Despina Angelopoulos

Browse all Theses and Dissertations

This project focuses on the optimization of benzothiazole-based chromophores to utilize them as fluorescent tags functionalized onto stimuli-responsive, or “smart,” polymers as non-viral gene delivery vectors for gene therapy applications. Blue-fluorescent emissive chromophores will allow tracking capabilities for the transfection pathway of the vector to be monitored as it delivers the DNA payload within intercellular space. The most appropriate chromophore must be covalently bound to a free amine within the vector, which is accomplished through NAS chemistry from fluorophenyl-benzothiazoles (F-BTZ-CBz) derivatives to amidated hyperbranched poly(ethyleneimine)(HPEI-IBAm0.61). HPEI is considered to be a synthetic polycation, which promotes tunable solubility through characteristics of …

Fabrication And Characterization Of Novel Agnps Functionalized With Chlorothymol (C@Agnps), Lirim Sopaj

Browse all Theses and Dissertations

In this study, novel silver nanoparticles (AgNPs) were successfully synthesized and functionalized with an antibacterial agent, namely chlorothymol (denoted C@AgNPs). The resulting colloid (C@AgNPs) was purified by two comparative methods: ultrafiltration and ultracentrifugation. Ultrafiltration proved to be more efficient in purifying and size selecting (10 kD filter) and concentrating the C@AgNPs than ultracentrifugation. The physicochemical properties of the filtered C@AgNPs were then characterized by UV-Vis absorption spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES), Raman spectroscopy, Cytoviva hyperspectral imaging, and Scanning electron microscopy. These measurements confirmed the functionalization of the core AgNPs with chlorothymol and suggest the proposed mechanism of …

Covalent Attachment Of Tadf Chromophores To Thermally Stable Poly(Arylene Ether)S, Samuel Farrar

Browse all Theses and Dissertations

The covalent attachment of a blue emitting, benzothiazole based TADF chromophore into poly(arylene ether) backbone polymers was explored. A benzothiazole derivative, 2-(2,4-difluorophenyl)-benzothiazole (2,4-diF-BTZ), was synthesized to form the electrophilic component of the host polymer. Two polymers were synthesized to have chromophore incorporated, using 2,4-diFBTZ and 4,4-dihydroxydiphenyl ether (DPE) or 4,4’-biphenol (BP). The chromophore was covalently incorporated at a 10% molar ratio into the polymer backbone by copolymerization with 2,4-diF-BTZ and BP, utilizing nucleophilic aromatic substitution (NAS). Structural characterization was provided via NMR spectroscopy and GC/MS analysis. The polymer syntheses provided high molecular weight materials that were able to be cast …

Detection And Identification Of Prevalent Cutting Agents In 'Street' Samples Utilizing Handheld And Benchtop Raman Spectroscopy And Surface-Enhanced Raman Spectroscopy (Sers), Nicole Kenny

Browse all Theses and Dissertations

Illicit and licit drugs continue to have a negative impact on the public’s health even with new regulations and laws. At local, state, and federal levels, crime laboratories analyze samples in a variety of mixtures and concentrations. Raman spectroscopy is a molecular fingerprinting, multiplex technique, which is considered a category A forensic characterization tool by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG). The sensitivity of the Raman technique can be further enhanced down to the single-molecule detection level when analytes of interest are located at the interstitial sites of aggregated silver nanoparticles (i.e., the “hot spots” …

Detection Of Benzotriazole And Related Analogues In Surface Samples Collected Near An Ohio Airpark, Clara Leedy

Browse all Theses and Dissertations

Benzotriazoles are a class of contaminant of emerging concern which are commonly used as anticorrosive agents in aircraft deicer and anti-icing fluids (ADAFs). The analogues 1H-benzotriazole (BTZ), 4-methyl-1H-benzotrizole (4m-BTZ), and 5-methyl-1H-benzotriazole (5m-BTZ) are commonly found in environmental occurrence together. The two methylated isomers, collectively known as tolytriazole (TTZ), have different toxicity and stability. These contaminants are highly water soluble and resistant to biodegradation, making them persistent through water treatment. Benzotriazoles have been detected worldwide; this investigation focuses on monitoring three sites near a small airpark in Wilmington, Ohio. Two sites that receive runoff from the airpark, Lytle Creek and Indian …

Quantum Mechanics-Based Computational Chemistry Has Become A Powerful Partner In The Scientific Research Of Nitrogen-Rich Compounds, Paving The Way For Important Advances In Biochemical, Pharmacological And Other Related Fields, Dobrushe Denburg

Student Theses and Dissertations

The Computational Chemistry of Nitrogen-Rich Compounds; Insight into Pioneering Research

Nitrogen-rich functional groups have long been studied for their diversity; nitrogen can form single, double and triple bonds with itself, and will therefore exist in a very broad range of molecular arrangements. Poly-nitrogen compounds are highly energetic and electron rich, and many compounds display unique properties that allow participation in very specialized chemical reactions. Of import is their ubiquity in biological systems, and throughout the past century and currently, their biological relevance is deeply and widely explored in biochemistry and biomedicine, from their involvement in natural biological processes and complex …

The Impact Of Project-Based Learning On Students In High School Chemistry In Rural Maine, Brianna Degone

Electronic Theses and Dissertations

Project-based learning (PBL) is an instructional strategy that is promoted throughout education for its use of active learning and ability to connect to real-world applications. Studies have been conducted on PBL ranging from early elementary grades through graduate courses, however little research considers the effectiveness of PBL at the secondary science level. This thesis considers the use of PBL and describes the implementation of a PBL unit in a rural Maine 11th grade chemistry classroom. The thesis aims to better understand the impact PBL has on students’ content learning and additional skills acquired through the PBL learning process. Along with …

Development Of Bioaffinity Based Assays For Forensic Applications, Juliana Maria Agudelo Cano

Legacy Theses & Dissertations (2009 - 2024)

In the field of forensic science, body fluids are a major contributor of evidence in investigations. However, body fluids are usually used only for their genetic content, overlooking its unique composition of proteins and low-molecular-weight compounds that often serve as biomarkers in clinical diagnostics. This investigation aimed to develop simple, effective, and economical models that can be used to identify different attributes of the originator. The focus of this research was to develop biocatalytic cascades that could analyze body fluids by using UV-Vis spectroscopy. These models could be implemented in forensic settings, as well as in biometric authentications. The central …

The Role Of Hydrogen Bonding And Hydrogen Migration In Different Environments, Nassim Beiranvand

Chemistry Theses and Dissertations

Hydrogen bonding is one of the most important topics in chemistry and has been a subject of many studies for years, using both experimental techniques and computational methods. My dissertation focuses on mechanistic studies of various types of intermolecu-lar and intramolecular hydrogen bonding in di˙erent systems based on quantum chemical calculations. In my work, I investigated the interplay of ring puckering and hydrogen bonding in DNA building blocks; hydrogen bonding in natural and unnatural base pairs and the nature of dihydrogen bonding by applying the Ring Puckering Analysis and the Local Vibrational Mode Theory (LVM). An additional aim of my …

From Small Molecules To Infinite Crystals: Probing Noncovalent Interactions Through Vibrational Spectroscopy, Sadisha Nanayakkara

Chemistry Theses and Dissertations

During my four years in the CATCO group supervised by Dr. Kraka, I have been exposed to various topics targeted to address a multitude of chemical problems, broadening our knowledge of modern chemistry research as we know it. In undertaking the age-old problem of understanding the nature of chemical bonding, I could modestly contribute with my work, using in-house tools based on vibrational spectroscopy.

First part of my dissertation is focused on inventing new methods and tools to efficiently investigate chemical bonding, followed by the study of some non-covalent interactions, imperative in catalysis and solid-state chemistry. This includes analysis of …

Quantum Chemical Investigation Of Novel Noncovalent Interactions Utilizing Vibrational Spectroscopy, Seth Francis Yannacone

Chemistry Theses and Dissertations

Theoretical/computational methods have been utilized to investigate a diverse array of questions currently at the forefront of modern chemistry research. The focus of this work is Local Vibrational Mode (LVM) Theory, originally formulated by Konkoli and Cremer, and under continuous development by the CaTcO research group. Derived from LVM theory, local stretching force constants (ka) represent physically meaningful measurements of chem- ical bond strength. Decomposition of normal vibrational modes into LVM contributions, also called characterization of normal modes (CNM), is another powerful manifestation of LVM theory; most notably when applied to the analysis of theoretical/experimental IR/Ra- man spectra. Recent developments …

Identification Of Chemical Structures And Substructures Via Deep Q-Learning And Supervised Learning Of Ftir Spectra, Joshua D. Ellis

MSU Graduate Theses

Fourier-transform infrared (FTIR) spectra of organic compounds can be used to compare and identify compounds. A mid-FTIR spectrum gives absorbance values of a compound over the 400-4000 cm^-1 range. Spectral matching is the process of comparing the spectral signature of two or more compounds and returning a value for the similarity of the compounds based on how closely their spectra match. This process is commonly used to identify an unknown compound by searching for its spectrum’s closes match in a database of known spectra. A major limitation of this process is that it can only be used to identify …

Structure And Reactivity Of The First Row Transition Metals Bearing Redox-Active Ligands And Tunable H-Bonding Interactions, Khashayar Rajabimoghadam

Chemistry Theses and Dissertations

Metalloenzymes, as natural catalysts, can break a reaction with high activation energy to multiple small reactions with lower activation energies; in these small reactions, multiple bonds form and dissociate rapidly, some metalloenzymes use redox-active ligands in their active site to provide the needed electrons for these multiple small reactions. Additionally, in the secondary coordination sphere in the vicinity of the metalloenzymes, the hydrogen bonding interactions facilitate the transfer and interaction of the substrates and the stabilization of the active intermediates. These unique features in metalloenzymes inspired chemists to design molecular models that can partially mimic the structure and reactivity of …

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 …

Emergent Photophysics In Diketopyrrolopyrrole Superstructures, Andrew Levine

Dissertations, Theses, and Capstone Projects

Organic semiconductors have received substantial attention as active components in optoelectronic devices because of their processability and customizable electronic properties. Tailoring the organic active layer in these devices to exhibit desirable optoelectronic properties requires understanding the complex and often subtle structure-property relationships governing their photophysical response to light. Both structural organization and frontier molecular orbitals (FMO) play pivotal roles in energy relaxation processes, and complex interplay between organization and orbital energies are difficult to anticipate based upon the molecular structure of the components alone, especially in systems comprised of multiple components. In pursuit of design rules, there is a need …

Cu-Promoted C-H Bond Hydroxylation Inspired By Cu-Dependent Metalloenzymes, Rachel Trammell

Chemistry Theses and Dissertations

From 2003 to 2015, Schӧnecker and Baran proposed a dinuclear Cu/O₂ species in their mechanistic proposal for the hydroxylation of sp³ C-H bonds within their systems (proposed based on yields). Inspired from the site selectivity of this methodology and poor analysis of the mechanism, the first project was inspired to re-examine the sp³ C-H bond hydroxylation by Schrӧnecker and Baran and perform an intensive investigation into understanding how Cu/O₂ interact which led us to propose a new mechanism based on the evidence collected (i.e., LCu^II-hydroperoxide species that undergoes homolytic O-O bond cleavage). From there …

Investigations Involving Mononuclear And Dinuclear Transition Metal Catalysts For Photochemical Carbon Dioxide Reduction, Ansu Edwards

Honors Theses

There is currently a global energy crisis, which is in desperate need of solutions. New energy sources are required that will not pollute as much as our longstanding reliance on nonrenewable fossil fuels as an energy source. This pollution involves large amounts of greenhouse gas emissions, predominantly carbon dioxide (CO₂), that contribute to environmental problems such as climate change. In this context, a fairly recent research direction to address this problem is the development of transition metal catalysts that can convert CO₂ into reduced carbon products that can serve as chemical fuels. This work focuses on the …

Applications Of Sodium Azide In The Synthesis Of Tetrazines And Hydrolysis Reactions, My Le

Honors Theses

The inverse electron demand Diels−Alder cycloadditions of heterocyclic azadienes have provided a robust methodology for synthesizing highly substituted and functionalized heterocycles. It is widely used in organic synthesis and the pharmaceutical industry in the divergent construction of screening libraries and bioorthogonal conjugation. Each heterocyclic azadiene was found to possess a unique reactivity toward different classes of dienophiles, display predictable modes of cycloaddition, and exhibit substantial substituent electronic effects impacting their intrinsic reactivity and cycloaddition regioselectivity. Synthesis of 1,2,4,5-tetrazine has been reported in the literature since the late 19th century, showing scientists' tremendous interest in its application.

Herein we attempt to …

Small Molecule Activation By Transition Metal Complexes: Studies With Quantum Mechanical And Machine Learning Methodologies, Justin Kyle Kirkland

Doctoral Dissertations

One of the largest areas of study in the fields of chemistry and engineering is that of activation of small molecules such as nitrogen, oxygen and methane. Herein we study the activation of such molecules by transition metal compounds using quantum mechanical methods in order to understand the complex chemistry behind these processes. By understanding these processes, we can design and propose novel catalytic species, and through the use of data-driven machine learning methods, we are able to accelerate materials discovery.

Synthesis Of A Dd-Π-Aa Organic Dye For Dye-Sensitized Solar Cells, Hope Lovell

Honors Theses

This project investigates the synthesis of a DD-π-AA (dual donor/dual acceptor) organic dye as a potential sensitizer for dye-sensitized solar cells (DSCs). The design of this dye was based off previous research that found dual donor/dual acceptor dyes exhibited promising results when used in a DSC. The donor groups, acceptor groups, and π-bridge were chosen for their stability, ability to absorb in the near-infrared (NIR) region, and intramolecular charge transfer (ICT) abilities.

While many components of the dye were synthesized, the final stages of the synthetic scheme were not completed due to the loss of time from COVID-19. Had the …

Synthesis Of A Zinc Dipyrrin Complex For Photocatalytic Reduction Of Co2, Sylvia Meredith

Undergraduate Honors Theses

Zinc dipyrrin complexes have the potential to act as cheap, effective photosensitizers. Synthesizing and studying different types could lead to more efficient solar energy harvesting processes, especially the production of solar fuel. Here, two attempts to synthesize 1,3,7,9-tetraphenyl-5-mesityldipyrromethene are reported and discussed. According to ¹H NMR, the first synthesis attempt was not successful. The second synthesis attempt was not purified effectively, so ¹H NMR produced inconclusive results. Further purification strategies or alternate synthesis methods are required.

A Project To Dye For : Differentiation Of Dyed And Non-Dyed Human Hairs Using Atr Ft-Ir Spectroscopy, Joseph John Greco

Legacy Theses & Dissertations (2009 - 2024)

IR spectroscopy is widely utilized for forensic purposes due to the chemical fingerprint the method provides. ATR FT-IR spectroscopy is particularly advantageous because it allows for spectra to be collected quickly, accurately, and perhaps most importantly for forensics, non-destructively. Human hair is commonly collected at a crime scene, and further analyzed using DNA analysis and microscopy. However, these techniques have limitations. In the past ATR FT-IR spectroscopy has shown promise in the analysis of human hair for forensic purposes. In this study, the differentiation of undyed hair versus dyed hair classes of varying colors based on their IR spectra were …

Synthesis And Conductivity Analysis Of A Methyl (Polyethylene Glycol) Comb Polymer, Olivia Fox

Honors Theses

The overall goal of work in this field is to improve materials for use in a variety of applications in fuel cell and battery production. This thesis specifically investigates the synthesis of two variations of a methyl (polyethylene glycol) comb polymer electrolyte (MePEG_nwhere n=7) to understand how the molecular structure of an ion-conducting polymer affects its electrochemical properties. The MePEG used in this synthesis contains seven ethylene glycol groups and was added to a poly (methylhydrosiloxane) comb polymer backbone. In the first sample, the polymer contained only the MePEG sidechain, and in the second sample, the polymer contained …

Progress Towards Synthesis And Characterization Of Bay-Annulated Indigo Chromophores, Katherine Weiss, Denise Femia

HON499 projects

Through acetylation, N,N’-diacetylindigo was synthesized from indigo. N,N’-diacetylindigo and 2-thiopheneacetyl chloride were combined in an attempt to synthesize 7-thiophenyl bayannulated indigo (BAI). After 1H NMR characterization, it was found that the product was not 7-thiophenyl BAI. A previously synthesized sample of 7-phenyl BAI was purified. UV-VIS absorbance, fluorescence, IR, and 1H NMR were used to characterize the compounds.

Indolizine Donor-Based Dyes For Applications In Fluorescence Biological Imaging, William Meador

Honors Theses

NIR emissive fluorophores are intensely researched due to their potential to replace modern imaging procedures. Many molecular strategies have been employed in the literature to optimize fluorophores for deeper NIR absorption and emission, biocompatibility, and higher fluorescence quantum yields. Amongst the fluorophores studied to date, proaromatic indolizine donors are attractive alternatives to traditional alkyl amine and indoline based donors due to their 1) lower energy absorption and emission facilitated by proaromaticity, 2) large Stokes shifts due to increased dihedral angles about the π-system, 3) ease of functionalization and capacity for bioconjugation at the phenyl ring, and 4) potential for further …

Synthesis And Conformational Study Of Triazolylcyclohexanols And Trans-2-(Azaarylsulfanyl)-Cyclohexanols, Mulinde R. Ruyonga

University of the Pacific Theses and Dissertations

Amino-cyclohexanol derivatives have been successful models for pH-triggered conformational switches. By changing the groups on the amine nitrogen, these models provide a wide pH-range in which a switch can occur. The pH-induced switch of conformation can be monitored by 1H NMR.In this work, structurally similar trans-2-(azaarylsulfanyl)-cyclohexanol derivatives (Scheme 1) and trans-2-triazolylcyclohexanol derivatives (Scheme 2) have been explored for the first time as compounds with a potential for the analogous pH-induced conformational switch. The azaarylsulfanyl groups showed selective conformational flexibility while the triazolyl group showed a strong preference for the equatorial position. Further, conformational studies were done on a series of …

Using Augmented Reality As A Tool For Distance Learning Of Vsepr Theory, Isabelle Lopez

Scripps Senior Theses

Distance learning poses challenges in most academic settings, especially at the undergraduate laboratory level. Improving this mode of learning diminishes the impact of current events on young scientists’ development of foundational laboratory concepts. Our work explores the use of augmented reality (AR) in a laboratory setting. We developed a completely virtual valence shell electron pair repulsion (VSEPR) theory lab activity consistent with the goals of Keck Science Department’s Introduction to Chemistry course’s in-person VSEPR lab activity. We were able to maintain a hands-on learning experience for students while using a tool many students already own: an iPhone as an alternative …