Browsing by Author "Reynolds, Melissa M., committee member"
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Item Open Access Defect tolerance, anharmonicity, and organic-inorganic coupling in hybrid organic-inorganic semiconductors(Colorado State University. Libraries, 2018) Maughan, Annalise E., author; Neilson, James R., advisor; Prieto, Amy L., committee member; Reynolds, Melissa M., committee member; Sites, James R., committee memberImplementing and improving sustainable energy technologies is predicated upon the discovery and design of new semiconducting materials. Perovskite halides represent a paradigm shift in solar photovoltaic technologies, as devices utilizing perovskites as the active semiconductor can achieve power conversion efficiencies rivaling those of commercial solar cells after less than a decade of dedicated research. In contrast to conventional semiconductors, perovskites are unique in that they exhibit excellent photovoltaic performance despite the presence of significant materials disorder. This disorder manifests as (1) a large concentration of crystallographic defects introduced by low-temperature processing, and (2) as dynamic disorder due to the deformable metal-halide framework and the presence of dynamic organic species within the crystalline voids. Vacancy ordered double perovskites of the general formula A2BX6 are a defect-ordered variant of the archetypal perovskite structure comprised of isolated [BX6] units bridged by cationic species at the A-site. The presence of ordered vacancies and relatively decoupled octahedral units presents an ideal system to investigate defects and lattice dynamics as they pertain to optical and electronic properties of perovskite halide semiconductors. This work aims to illuminate the fundamental structure-dynamics-property relationships in vacancy-ordered double perovskite and hybrid organic-inorganic semiconductors through a combination of advanced structural characterization, optical and electrical measurements, and insight from computation. We begin with a study of the Cs2Sn1-xTexI6 series of vacancy-ordered double perovskites to inform the chemical and bonding characteristics that impact defect chemistry in vacancy-ordered double perovskites. While the electronic properties of Cs2SnI6 are tolerant to the presence of crystallographic defects, introducing tellurium at the B-site yields an electronic structure that renders Cs2TeI6 defect-intolerant, indicating the importance of the B-site chemistry in dictating the optoelectronic properties in these materials. Next, we elucidate the interplay of the A-site cation with the octahedral framework and the subsequent influence upon lattice dynamics and optoelectronic properties of several tin-iodide based vacancy-ordered double perovskites. The coordination and bonding preferences of the A-site drive the structural and dynamic behavior of the surrounding octahedra and in turn dictate charge transport. A-site cations that are too small produce structures with cooperative octahedral tilting, while organic-inorganic coupling via hydrogen bonding yields soft, anharmonic lattice dynamics characterized by random octahedral rotations. Both regimes yield stronger electron-phonon coupling interactions that inhibit charge transport relative to undistorted analogs. The final study presented here details the discovery of two hybrid organic-inorganic semiconductors containing the organic tropylium cation within metal iodide frameworks. In C7H7PbI3, the tropylium electronic states couple to those of the lead iodide framework through organic-inorganic charge transfer. Electronic coupling between the organic and inorganic sublattices within a singular material provides an avenue to elicit unique optical and electronic properties unavailable to either components individually. The above work is then placed in context of other recent studies of vacancy-ordered double perovskite semiconductors, and a set of design principles are constructed. Future avenues of research are proposed. These structure-dynamics-property relationships represent an important step towards rational design of vacancy-ordered double perovskite semiconductors for potential optoelectronic applications.Item Open Access Development of biomass-derived furanic monomers for biorenewable polyesters and polyurethanes(Colorado State University. Libraries, 2019) Wilson, Jedediah Forrest, author; Chen, Eugene Y.-X., advisor; Reynolds, Melissa M., committee member; Ackerson, Chris J., committee member; Radford, Donald W., committee member; Crans, Debbie C., committee memberDevelopment of Biomass-Derived Furanic Monomers for Biorenewable Polyesters and Polyurethanes This dissertation describes the development of difuranic diol monomers through the N-heterocyclic carbene (NHC) catalyzed cross-coupling of the biomass-derived platform chemicals, 5-hydroxymethylfurfural (HMF) and furfural (FF), and their subsequent utilization in the synthesis of renewable polyesters and polyurethanes with tunable thermal and mechanical properties through the use of soft and rigid co-monomers. The resulting polymers can undergo reversible cross-linking with bis-maleimide cross-linkers through the thermally reversible Diels-Alder reaction involving both the internal and pendent furan rings. The ability to construct a thermally reversible cross-linked network, coupled with formation of a significant amount (up to 34%) of stable carbonaceous materials when heating the polymers to 700 °C, demonstrates some promising features of this class of new difuranic polymers. To address the need to enhance the molecular weight of the current furan-based polymers produced by the step-growth polycondensation process, alternative monomer structures have been designed to adopt the chain-growth mechanism. The first such alternative monomer belongs to a class of furan-derived lactones as candidates for ring-opening polymerization (ROP), which have been shown to produce high molecular weight polyesters because they follow the chain-growth mechanism. Two synthetic routes have been explored to produce such lactone monomers, and their polymerization behavior has been subsequently examined. The second such alternative is centered on a multifunctional furan acrylate monomer, methacrylate furan aldehyde (MFA). The studies tested a hypothesis that auto-tandem or cascading reaction involving the aldehyde functionality in MFA would undergo a benzoin condensation, then the consequent diacrylate would have the appropriate functionality for NHC catalyzed tail-to-tail coupling resulting in a proton transfer polymerization (HTP). It was found that the benzoin condensation was successful but an oxidation occurred at the α-hydroxy of the furoin diacrylate resulting in a highly electrophilic diketone furil diacrylate. Exploration of the coupling mechanism suggests that the enolate acts as a base catalyzing the oxidation. Through careful analysis of the adducts formed when the NHC was reacted with the furil diacrylate showed that the NHC had strong affinity for the diketone moiety thus blocking the HTP pathway. Overall, this work added significantly to our understanding of furans as monomers, NHC catalysis in furan monomer synthesis as well as polymerizations, and enhanced our ability to control thermal and mechanical properties of furan containing polymers.Item Open Access Development of paper-based devices for point-of-need, bioanalytical applications(Colorado State University. Libraries, 2020) Noviana, Eka, author; Henry, Charles S., advisor; Reynolds, Melissa M., committee member; Chung, Jean, committee member; Geiss, Brian J., committee memberThe growing demand for reliable analytical tools to perform testing at the point-of-need has necessitated the development of novel sensors that are low cost (USD 1-10), portable, sensitive, selective, easy to use, and rapid (i.e. provide results within minutes or a few hours). Miniaturization of the sensors into microfluidic platforms has become a promising approach to achieve these sensors. However, traditional microfluidics often require relatively expensive and complicated pumping mechanisms that increase the cost and limit the portability of the sensors. From a material perspective, cellulosic paper is an attractive substrate for constructing point-of-need sensors due to its affordability, vast availability, self-pumping ability via capillary action, and easy fabrication using various printing and patterning techniques. My dissertation research has been focused on developing paper-based devices to address several key gaps that exist between the current technologies and the desired properties of point-of-need sensors. Chapter 2 describes the development of a steady flow paper device that enabled a function similar to conventional flow injection analysis (FIA) without external pumps. Two-layer paper devices increased the attainable flow rate and reduced the analysis time to only a minute, compared with 10-20 min analysis time reported in previous paper-based FIA. Disposable Pt microwire electrodes were used as a detector in the electrochemical paper-based device (ePAD) and the proposed sensor has been used to detect the activity of β-galactosidase (a bacterial indicator for coliform detection and a common detection label in enzyme-linked immunosorbent assay). Similar enzyme kinetics to those reported in the literature was obtained using the proposed sensor, showing a great promise for semi-automation in bioanalysis. Implementing a similar flow ePAD, the goal has now expanded toward improving the detection sensitivity as well as reducing the cost of the sensors. In Chapter 3, low-cost (~1 USD) and reusable thermoplastic electrodes (TPEs) were fabricated by mixing carbon and a plastic binder and pressing the material into an acrylic mold. These TPEs showed an improved electrochemical activity over conventional carbon paste electrodes typically used in ePADs. In addition, electrode arrays can also be fabricated using the technique to improve detection sensitivity via a generation-collection experiment, where the first electrode in the array oxidizes the analyte, the second reduces it, and the process is repeated across the entire array to provide an enhanced cumulative signal. Nanomolar detection limits were achieved using TPEs in both single detector and detector arrays configurations. A 5× improved sensitivity was obtained by employing electrode arrays over the single detector. In Chapter 4, the dissertation shifts focus to a more specific application, detecting nucleic acid, an important biological analyte that has been largely targeted to diagnose various diseases including genetic disorders, cancer, neurodegenerative, and infectious diseases. This chapter describes the integration of nuclease protection assay (NPA), a highly specific hybridization-based technique, with a reader-free colorimetric detection via lateral flow assay (LFA). In NPA, the hybridization of an antisense probe to the target sequence is followed by single-strand nuclease digestion. The protected double-stranded target-probe hybrids are then captured on the LFA device, followed by the addition of a colorimetric enzyme-substrate pair for signal visualization. The proposed paper-based NPA can detect sub-femtomole (~108 copies) of target DNA with high specificity. While the paper-based NPA can serve a good screening tool for several types of chronic infection in which large copies of pathogen DNA is present in the samples, the high detection limit hinders the application of this method for early disease diagnosis and detecting pathogens in environmental samples. In Chapter 5, polymerase chain reaction (PCR), a nucleic acid amplification technique, was coupled to the colorimetric LFA to improve the detection limit and enable the detection of antimicrobial-resistant (AMR) genes and bacteria in environmental samples. Six orders of magnitude lower detection limit (i.e. 102 plasmid DNA copies) was achieved by the PCR-LFA. The proposed method can be applied for rapid detection (less than 3 h) of AMR bacteria in environmental samples. Several works presented in this dissertation provided different approaches to achieve viable paper-based sensors for point-of-need applications. Progress has been made in improving both analytical figures of merit (i.e. sensitivity and detection limit) and practical specifications of the paper sensors (i.e. reduced sensor cost, semi-automation via an external pump-free flow-based system, instrument-free colorimetric readout, and improved assay time).Item Embargo Hydrophobic vanadium complexes for use in anticancer activity(Colorado State University. Libraries, 2023) Murakami, Heide, author; Crans, Debbie C., advisor; Reynolds, Melissa M., committee member; Zadrozny, Joseph M., committee member; Crick, Dean C., committee memberThis dissertation contains the development, synthesis, and characterization of vanadium metal complexes in both biological environment and organic solutions for the purpose of novel medical treatments. As cancer is a disease that causes uncontrollable growth of mutated cells over time, treatments need to also improve to account for an ever-increasing cancer types. Although platinum-based drugs have found successful in treating multiple forms of cancer, inorganic metal based drugs are relatively uncommon in the medical field. It was found in 2020, that a vanadium compound was more potent than cisplatin and efforts were made to investigate and improve that compound. The compound is a ternary V(V) complex that consists of VOL1L2 where L1 is N-(salicylideneaminato)-N'-(2-hydroxyethyl)ethane-1,2-diamine and L2 is 3,5-di-tert-butylcatechol. It is believed that that hydrophobicity of the catechol ligand was significant in keeping the compound intact long enough to cause cytotoxicity in bone cancer cells. In Chapter 1, the biological effects of vanadium and the reasoning that vanadium may be used as a potent medical treatment for various illnesses such as bone cancers, brain cancers and/or tuberculosis are investigated. Chapter 2 describes the synthesis and characterization of halogenated version of the original vanadium Schiff base complexes to test how electronegativity affects the activity as well as testing how modification of the salicyaldehyde portion affects the metal complex. Chapter 3 reports the development of adamantanol catechol ligands to improve hydrophobicity in the vanadium Schiff base complex. Chapter 4 explains the speciation of working with a metal complex in a biological system by comparing two different vanadium systems and how they hydrolyze and form multiple different species in various environments. Chapter 5 summarizes the conclusions and proposes future works based on the research done that can move new projects forward.Item Open Access Phototunable block copolymer hydrogels(Colorado State University. Libraries, 2017) Huq, Nabila A., author; Bailey, Travis S., advisor; Kipper, Matthew J., committee member; Reynolds, Melissa M., committee member; Snow, Christopher D., committee memberThermoplastic elastomer (TPE) hydrogel networks, based on swelling of nanostructured blends of amphiphilic, sphere-forming AB diblock and ABA triblock copolymers, provide direct access to thermally processable plastics that exhibit exceptional elastic recovery and fatigue resistance even after hydration. In such two-component systems, the ratio of ABA to AB block copolymer (BCP) is used to control the resultant swelling ratio, system modulus, and overall mechanical response. This dissertation focuses on developing material strategies through which adjustment of such AB/ABA ratios, and thus the resultant properties, can be accomplished using light. The chapters within capture the manipulation of a photoreactive AB diblock copolymer micelle-like spheres to controllably generate ABA triblock copolymer and the network nanostructure in situ, both in the melt state and after dispersal in solution. This was accomplished using efficient photoinduced [4 + 4]cycloaddition (λ = 365 nm) between terminal anthracene units on a ω-anthracenylpolystyrene-b-poly(ethylene oxide) diblock copolymer precursor to produce the desired amount of polystyrene-b-poly(ethylene oxide)-b-polystyrene triblock copolymer. This direct, UV-mediated handle on tethering between adjacent micelles in the BCP matrix was found to be capable of controllably manipulating hydrogel material properties using (1) duration of irradiation, (2) hydration level and consequent micelle spacing upon exposure, and (3) photopatterning strategies to spatially direct swelling and mechanics. This level of control yielded an array of hydrogels, ranging from those irradiated in the dry melt to produce high-modulus, elastic materials suited for fibrocartilage repair and replacement, to moldable or injectable precursor solutions irradiated into soft, conformally shaped TPE hydrogels ideal for use in high contact applications such as wound healing. The development and scope of this versatile new photoactive BCP system is enclosed.Item Open Access Physical and chemical characteristics behind membrane interactions of small molecules and electron transporters(Colorado State University. Libraries, 2018) Peters, Benjamin J., author; Crans, Debbie C., advisor; Crick, Dean C., committee member; Reynolds, Melissa M., committee member; Ross, Eric D., committee memberThere are many types of molecules that interact with and within membranes whereas many factors can dictate how they interact with membranes. Often, the interactions with the membrane interface can affect the mechanism of action of these molecules. Here, the interactions of small molecules and an electron transporter with model membranes under varying conditions are described. In the first chapter, the pH dependence of membrane association of a commonly used food preservative, benzoic acid was discussed and compared to the mechanism of action of general weak acid preservatives. Next the interactions of many structurally very similar compounds with model membranes were compared. These studies outline the importance of both the environment and that by just altering the molecules slightly, the interactions of the molecules can be changed. Chapter 4 outlines the importance of lipid density on the interactions of the electron transporter used within the electron transport system of Mycobacterium tuberculosis (menaquinone-9) to show that menaquinone is capable of membrane transport of protons and electrons. Together, these studies show how interactions and diffusion across membranes are not straight forward and more research is necessary to fully understand the interactions of molecules with cell membranes.Item Open Access Pump-free magnetophoresis for improved point-of-care diagnostics(Colorado State University. Libraries, 2022) Call, Zachary D., author; Henry, Charles S., advisor; Reynolds, Melissa M., committee member; Dandy, David S., committee member; Snow, Christopher D., committee memberInfectious diseases are one of the largest health burdens for low-income countries and claim millions of lives every year. The loss of life in low-income countries is largely due to the lack of access to preventative healthcare and appropriate diagnostic testing. Several health agencies have recognized the need for improved diagnostics to reduce the burden of infectious diseases. The following works described in this thesis are focused on improving the capabilities of point-of-care (POC) testing to improve patient healthcare. Microfluidic devices are a popular approach for diagnostics because they offer reduced assay times, reduced sample volume, and are small (<10 cm). Additionally, microfluidic devices can be used with magnetophoresis to improve sensitivity and specificity. However, traditional microfluidic devices have difficulty translating to the POC because of tedious and expensive fabrication. Microfluidic paper-based analytical devices (µPADs) are a popular alternative to traditional microfluidics due to the natural capillary action through cellulose fibers and simple fabrication. µPADs are portable, low-cost, and do not require external instrumentation, making them ideal for POC settings. However, µPADs often suffer from poor analytical performance resulting in failing to translate to POC testing. In Chapters 2, 3 and 4 of this thesis, I described combining µPADs with magnetophoresis to improve the analytical performance without sacrificing the advantages of µPADs. Coupling magnetophoresis with µPADs is a novel approach and was not reported until the publication of chapter two. Chapter 2 of this thesis describes the first reported example of paper-based magnetophoresis. Magnetophoresis has always needed external pumps to drive flow, however we demonstrate the ability to perform magnetophoresis completely pump-free in a µPAD. We demonstrated the ability to detect E.coli at 105 colony forming units (CFU/mL) with a fluorescent label in a pooled human urine sample. Chapter 3, describes improvements to the device described in chapter two. The limit of detection was improved by three orders of magnitude and calculated at 4.67 x 102 CFU/mL in pooled human urine, which is below detection limits for commercial urinary tract infection tests. Colorimetric detection was used instead of fluorescence detection to eliminate any instrumentation needed and create an easy read-by-eye assay. Additionally, the device design was modified to incorporate a burst valve to generate more consistent laminar flow and simplify user-end steps. We envision this technology to be used a platform for future paper-based devices incorporating magnetophoresis for improved POC devices. In Chapter 4 of this thesis, we describe a new platform for microfluidic magnetophoresis that simplifies user-end steps further through a simple magnet sliding operation. Here we introduce a MagnEtophoresis Slider Assay (MeSA) for sequential binding and washing steps without the need for any external instrumentation. A competitive biotin assay and a sandwich immunoassay are demonstrated to display the functionality of this new platform. The limit of detection was calculated at 1.62 x 103 CFU/mL using colorimetric detection. The MeSA is extremely user-friendly, provides sensitive and rapid results (<15 min), and can be applied to a wide range of applications.Item Open Access Redesigning organic catalysts and polymers for recycling towards sustainable catalysis and materials(Colorado State University. Libraries, 2021) Cywar, Robin Marcelle, author; Chen, Eugene Y.-X., advisor; Beckham, Gregg T., advisor; Reynolds, Melissa M., committee member; Borch, Thomas, committee member; Peebles, Christie A. M., committee memberThis dissertation describes the development of catalysts and polymers designed for a sustainable, circular materials economy in which end-of-life is considered during the design stage through properties of inherent recyclability. Products that are recyclable-by-design contrast with those of the current, linear economy, which has led to global environmental crises: greenhouse gas emissions due to finite fossil fuel consumption, contributing to climate change, and tremendous accumulations of plastic waste in landfills and the environment. A major challenge associated with the development of circular lifecycle products, including both catalysts and polymers (plastics, in particular), is achieving performance properties competitive with those of their incumbents, which this work aimed to address. A critical literature review provides an overview of materials derived from renewable, biomass feedstocks (referred to as bio-based polymers) which exhibit performance-advantaged properties relative to petroleum-based polymers. Bio-based chemicals and materials are considered to have a circular carbon lifecycle (carbon-neutral), but those with a circular lifecycle (i.e., recyclable or biodegradable) are given special emphasis. To increase the circularity of all aspects of production of bio-based chemicals and polymers, a polymer-supported organocatalyst has been explored for the coupling of biomass-based furaldehyde platform chemicals; these products can be used for bio-fuels or polymers after further transformations. The developed thermally activated N-heterocyclic carbene (NHC) organocatalyst can be recycled for furfural coupling in excellent yield simply by controlling the temperature, demonstrating promising features for improved circularity in catalyzed chemical processes and ultimately, waste reduction. The discovery of acid-base interactions between the catalyst and hydroxylated substrates has enhanced the understanding of NHC catalysis and contributed to improved design principles for these catalysts. To address plastic waste accumulation by designing for recyclability, polyester and polyamide materials with full chemical recyclability to monomers have been demonstrated from lactone and lactam monomers, respectively. In each case, study of polymerization activity through chemical catalysis revealed fundamental information about the thermodynamic (de)polymerizability of the novel systems, including selectivity considerations, and enabled synthesis of robust structural models for thermomechanical characterization. Overall, understanding the resultant structure-property relationships informs further development of materials with full chemical recyclability and attractive materials properties, including copolymer formulations and design of new monomers to explore for addressing tradeoffs between (de)polymerization activity and material properties.Item Open Access Synthesis and exploration of biologically important, hydrophobic, redox-active molecules: investigation of partial saturation of mycobacterial electron transport lipids(Colorado State University. Libraries, 2019) Koehn, Jordan T., author; Crans, Debbie C., advisor; Reynolds, Melissa M., committee member; Shi, Yian, committee member; Crick, Dean C., committee memberThere are many types of molecules that are biologically important because they either carry out crucial functions or exhibit exploitable biological activity. Some of the most interesting and challenging molecules to work with are those that are redox-active and hydrophobic or water insoluble. Herein, the synthesis and investigation of two classes of hydrophobic redox-active molecules are explored. Chapter one provides background on menaquinone (MK) and vanadium chemistry and primes the reader for the subsequent chapters. Chapter two describes the synthesis and characterization of truncated MK derivatives with varying isoprenyl side chain length and degrees of saturation. Chapter three explores the conformational flexibility of the isoprenyl side chain of MK and shows that a truncated MK analog, MK-2, can adopt folded conformations in hydrophobic environments and within a model membrane system. Chapter four isolates the conformational and chemical effect of saturation of the isoprenyl side chain on MK and shows that saturation minimally affects folded conformations of truncated MK derivatives but remarkably, a 20 mV redox potential difference was observed between unsaturated MK-1 and the saturated analog MK-1(H2). Then in chapter five, hydrophobicity and steric bulk are explored as properties to enhance membrane affinity and anti-cancer properties of Schiff base vanadium(V) catecholate complexes, where the hydrophobic [VO(Hshed)(ditertbutylcatechol)] complex was found to have enhanced hydrolytic stability and potent activity against a bone cancer cell line. Together, the findings of the studies presented herein help to further understand how the conformation and the degree of saturation in the isoprenyl side chain of MK affects the recognition, reactivity, and function of MK within the electron transport system of pathogenic bacteria. These studies are important because they begin to explain and provide a working model behind the chemical rationale as to why partially saturated MK-9 is observed in pathogenic M. tuberculosis. Furthermore, the studies with the hydrophobic vanadium(V) catecholate metallo-complexes underpin a drug design concept exploiting hydrolytic stability imparted by hydrophobicity and steric bulk of a non-innocent ligand.Item Open Access Thermoplastic electrodes for detection of biomarkers(Colorado State University. Libraries, 2021) McCord, Cynthia P., author; Henry, Charles S., advisor; Reynolds, Melissa M., committee member; Neilson, James R., committee member; Bark, David L., Jr., committee memberTo view the abstract, please see the full text of the document.Item Open Access Trifluoromethylated fullerenes and polycyclic aromatic hydrocarbons and anaerobically milled silicon nanoparticles(Colorado State University. Libraries, 2015) Castro, Karlee P., author; Strauss, Steven H., advisor; Reynolds, Melissa M., committee member; Farmer, Delphine K., committee member; McCullagh, Martin J., committee member; Ramsdell, Howard S., committee memberWell characterized molecules and materials are essential to understand trends and predict future performance. Fundamental studies provide information about molecular properties which may be useful in other applications such as electronic devices. The focus of this dissertation is the characterization of three different classes of molecules/materials with the goal of understanding the fundamental underlying reasons for any trends observed. The first chapter of this dissertation examines the photophysical properties of C70(CF3)n (n = 8 or 10) molecules. Four of the compounds exhibited quantum yields higher than for any previously reported C70 derivative and three exceeded 0.24, the highest fluorescence quantum yield for any fullerene or fullerene derivative. A difference in the location of only one CF3 group in C70(CF3)8 and C70(CF3)10 isomers resulted in 200-fold and 14-fold increases in fluorescence quantum yields respectively. The isomer of C70(CF3)10 with the highest fluorescence quantum yield (0.68 in toluene) also exhibited the longest fluorescence lifetime (51 ns). Formation of the S1 state in one of the C70(CF3)10 isomers occurred within 0.6 ps and its nanosecond-long decay was monitored by ultrafast transient absorption spectroscopy. Time-dependent density functional theory calculations provide a physically meaningful understanding of the photophysical properties. High fluorescence quantum yields are correlated with high oscillator strengths for the S0→S1 transition, large ΔS1−T1 energy gaps, and small spatial extension of the S0→S1 excitation. The second chapter of this dissertation explores trifluoromethyl derivatives of polycyclic aromatic hydrocarbons (PAH(CF3)n). First, the effects of PAH size and shape on the product distribution are examined. Second, the electronic properties, including reduction potential and gas-phase electron affinity, are examined. Third, the influence of number and orientation of the CF3 groups on the crystalline morphologies of these compounds is explored. Finally, charge-transfer complexes made with PAH(CF3)n molecules mixed with PAHs are prepared and examined spectroscopically and crystallographically. From this work it was determined that when PAHs with 8–10 substitutable carbons are reacted with at least 10 equivalents of CF3I gas the PAH(CF3)n products had n values of 4–6 regardless of the size or shape of the PAH core. The reduction potential and gas-phase electron affinity exhibit a regular, incremental increase as a function of the number of trifluoromethyl groups. The number and position of CF3 groups influences the π-π stacking and crystalline morphologies and typically the more CF3 groups added, the lower the intermolecular overlap. Charge-transfer complexes made from mixing PAH(CF3)n and PAH form mixed stacks in the solid-state and exhibit weak association constants in solution. The third chapter of this dissertation examines the effects of oxygen and aromatic molecules on stirred media milling of silicon. Metallurgical-grade silicon was wet-milled in a stirred media mill to produce nanoparticles. Several milling fluids, additives, and milling parameters have been tested and compared between aerobic and anaerobic milling. It was determined that oxygen and aromatic molecules serve as surface passivating additives and lead to higher specific surface areas, indicating smaller particles. Particle amorphization occurs rapidly in a stirred media mill, within two hours crystallite size is on the order of 2-50 nm regardless of whether surface passivating additives are present. In all milling experiments, even in the presence of oxygen, new Si–C bonds are formed, the most Si–C bonds are formed when aromatic molecules are present during the milling process.Item Open Access Using chemical ionization mass spectrometry to probe indoor and outdoor atmospheric chemistry(Colorado State University. Libraries, 2021) Mattila, James M., author; Farmer, Delphine K., advisor; Reynolds, Melissa M., committee member; Willis, Megan D., committee member; Carter, Ellison M., committee memberPeople spend the majority of their time in indoor environments. Knowledge of the sources, sinks, and chemistry of indoor pollutants is therefore imperative to indoor air quality and human health. We studied the indoor chemistry of cooking and cleaning at the House Observations of Microbial and Environmental Chemistry (HOMEChem) field campaign during summer 2018 at the University of Texas test house (UTest house) in Austin, TX. We performed measurements of several gas-phase cooking- and cleaning-related analytes using a fast (1 Hz), online chemical ionization mass spectrometry (CIMS) measurement technique utilizing iodide reagent ions. Combining these and other measurements of gas-phase analytes and particulate matter present in indoor air during HOMEChem enables us to piece together a holistic story of the indoor chemistry of cooking and cleaning. We observed enhanced levels of several chlorinated and nitrogenated compounds when cleaning indoors with a commercial bleach solution during HOMEChem. We observed production of several inorganic chlorinated and nitrogenated pollutants from bleaching, including hypochlorous acid, chlorine gas, and chloramines. Levels of hypochlorous acid and nitrogen trichloride observed during cleaning are likely detrimental to human health. Bleach cleaning indoors also lead to the production of secondary organic aerosol—a common outdoor atmospheric pollutant associated with respiratory and cardiovascular issues—as well as potentially harmful organic isocyanates, cyanogen chloride, and chlorocarbons. These results collectively demonstrate bleach cleaning as a source of indoor pollution which impacts indoor air quality and occupant health. We characterized indoor reactive organic carbon (ROC) emissions from cooking and cleaning during HOMEChem, and directly compared resultant chemical complexity of indoor air to outdoors. Cooking indoors greatly impacts ROC concentrations and physiochemical properties, and thus carbon reactivities and lifetimes. Cleaning indoors yielded relatively insubstantial changes. Consistently higher indoor ROC concentrations compared to outdoors demonstrated that indoor emissions were a net source of reactive carbon to the outdoor atmosphere, following their removal by ventilation. ROC dominated indoor and outdoor oxidant reactivity compared to other atmospheric carbon species, thereby greatly influencing secondary pollutant formation, including carbon dioxide, ozone, and secondary particulate matter. Most oxidation chemistry to produce these secondary pollutants likely took place outdoors following the ventilation of ROC species, given the low oxidant levels typical of indoor environments. Moving outdoors, we demonstrated the efficacy of a CIMS instrument utilizing acetate ionization toward quantifying various gas-phase acids in the troposphere. Here, we performed measurements during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) field campaign in summer 2014. Diurnal increases in mixing ratios were consistent with photochemical sources of nitric, isocyanic, formic, propionic, butyric, valeric, and pyruvic acid. Vertical profiles taken on the 300 m Boulder Atmospheric Observatory tower demonstrated net surface-level emissions of alkanoic acids, but net surface deposition of nitric and pyruvic acid. Nearby traffic emissions and agricultural activity were a primary source of propionic, butyric, and valeric acids, and likely contributed photochemical precursors to nitric and isocyanic acids. The combined diel and vertical profiles of the alkanoic acids and isocyanic acid were inconsistent with dry deposition and photochemical losses being the only sinks, suggesting additional loss mechanisms.Item Open Access "You are young and can afford to do something stupid": fostering an understanding of electronic spin in chemistry(Colorado State University. Libraries, 2021) Joyce, Justin P., author; Shores, Matthew P., advisor; Rappé, Anthony K., advisor; Neilson, James R., committee member; Reynolds, Melissa M., committee member; Ross, Kathryn A., committee memberTo view the abstract, please see the full text of the document.