Chemistry Commons^™

Cyclodextrin-Based Supramolecular Drug-Delivery Nanomaterials And Shear-Thinning Hydrogels Using Ring-Opening Metathesis Polymerization, Ruihan Li

Arts & Sciences Electronic Theses and Dissertations

Cyclodextrins (CD) are a family of oligosaccharides that can non-covalently and precisely bind small hydrophobic drug molecules, such as antibiotics and anticancer drugs, through well-defined host-guest interactions inside the inner cavity of the macrocycle. Ring-opening metathesis polymerization (ROMP) is a versatile, functional group tolerant method of polymerization that is underexplored in biomedical applications relative to the more common controlled chain-growth polymerizations. In this dissertation, I describe my efforts to combine the supramolecular chemistry of CDs with that of ROMP using specialized functional monomers to synthesize several CD-based polymeric drug delivery nanomaterials. For example, in Chapter 2, a new type of …

Using Single-Particle Fluorescence Microscopy To Elucidate The Role Of Structural Distortions And Defects In The Chemical Reactivity And Photophysics Of Cesium Lead Halide Perovskite Nanocrystals, Dong Wang

Arts & Sciences Electronic Theses and Dissertations

Colloidal cesium lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br or I) are attractive for optoelectronic applications due to their unique chemical and physical properties including high photoluminescence quantum yield, tunable bandgaps, high defect tolerance, and low-cost processibility. A facile method to tune the emission wavelength of perovskite nanocrystals is through anion exchange. For light emission applications, it is desirable to prepare CsPbX3 nanocrystals of uniform size and composition. However, the complex reaction kinetics of this chemical transformation may limit the compositional uniformity and color purity of the CsPbX3 nanocrystals produced by anion exchange when the transformation is scaled …

Electro-Organic Chemistry: An Alternative Pathway To Handle Redox Organic Reactions, Tiandi Wu

Arts & Sciences Electronic Theses and Dissertations

Electrochemistry provides an alternative pathway to handle redox organic reactions, especially for certain chemical process that can be only achieved through electrochemical process. Herein, there research projects are introduced to enrich the whole synthetic community, including an anodic oxidative cyclization studies to develop methodology on heterocyclic ring skeleton constructions, an electroreduction pathway exploration to more effectively obtain hydrazine from nitroso compounds, as well as a study in paired electrolysis process on which both anode and cathode are simultaneously employed to maximize overall atom and energy efficiency. Future directions on these projects are also demonstrated at the end of each chapters..

Mass Spectrometry-Based Protein Footprinting: High-Throughput Maldi Platform And Large Protein Complexes Of Baf, Ruidong Jiang

Arts & Sciences Electronic Theses and Dissertations

Human’s advances in understanding biological processes rely heavily on the breakthroughs in biophysical tools. Mass spectrometry (MS)-based protein footprinting, which interrogates protein structures by measuring protein solvent assessable surface area (SASA), has grown rapidly in the last decade, successful in providing valuable data for numerous protein systems. This thesis focuses mainly on this technology.We set out to push the boundary of MS-based protein footprinting further into the new areas, preparing it for potential future applications including large-scale experiments that require high-throughput analysis the structure of large, complicated protein complexes. This thesis devotes five chapters to the method development of MS-based …

Computational Approaches For Screening Drugs For Bioactivation, Reactive Metabolite Formation, And Toxicity, Noah Flynn

Arts & Sciences Electronic Theses and Dissertations

Cytochrome P450 enzymes aid in the elimination of a preponderance of small molecule drugs, but can generate reactive metabolites that may adversely conjugate to protein and DNA, in a process known as bioactivation, and prompt adverse reaction, drug candidate attrition, or market withdrawal. Experimental assays are low-throughput and expensive to perform, so they are often reserved until later stages of the drug development pipeline when the drug candidate pools are already significantly narrowed. Reactive metabolites also elude in vivo detection, as they are transitory and generally do not circulate. In contrast, computational methods are high-throughput and cheap to screen millions …

Enantioselective Synthesis Of Β-Amino Acid Derivatives Using Amidine-Based And Bifunctional Organocatalysts, Matthew Robert Straub

Arts & Sciences Electronic Theses and Dissertations

Two new enantioselective methodologies have been developed that have important implications for the asymmetric synthesis of β-amino acids and their derivatives. First, chiral amidine-based catalyst (ABC) HBTM-2 catalyzed an asymmetric cyclocondensation between in situ activated fluoroacetic acid and N-sulfonyl aldimines to give α-fluoro-β-lactams in highly enantioenriched form, achieving modest to excellent diastereoselectivities. These reactive lactams can then be quenched with various alcohols and amines to deliver the α-fluoro-β-amino acid derivatives in moderate isolated yields. Secondly, bifunctional double hydrogen bond donor-amine organocatalysts enable the catalytic alcoholysis of various racemic N-carbalkoxy-3-substituted isoxazolidin-5-ones, resulting in their kinetic resolution. The enantioenriched unreacted isoxazolidinone and …

Method Development For Enhancing Sensitivity Of Dynamic Nuclear Polarization Nuclear Magnetic Resonance Spectroscopy For Structural Studies Of Pkc-Drug Interactions, Patrick Terrence Judge

Arts & Sciences Electronic Theses and Dissertations

To perform the most relevant structural studies on biological systems, experiments need to be carried out when the target proteins are in their endogenous cellular environment. Nuclear magnetic resonance (NMR) is well-suited to probe the structure and dynamics of a wide variety of systems, including biologically relevant proteins. However, NMR suffers from an inherent lack of sensitivity. Dynamic nuclear polarization (DNP) NMR is a powerful technique that is used to enhance NMR sensitivity by transferring the greater polarization of exogenously doped electron spins to nuclear spins of interest though the use of a high-power microwave source. Solid effect radicals offer …

Synthesis, Self-Assembly, And Material Applications Of Unimolecular Polyviologens, Abigail Delawder

Arts & Sciences Electronic Theses and Dissertations

Intellectual Gaps: Synthesis of high molecular weight, unimolecular, and sequence-defined polyviologens; spatiotemporal control over mechanical properties of materials using visible and near-IR light; on-demand, post hoc manipulation of materials

Intellectual Merit: Robust method for synthesizing higher-order polyviologens of distinct molecular weight; control the change in the mechanical properties of polymer-based, crosslinked materials using a wide range of wavelengths of light; degradation of viologen-crosslinked hydrogels

To understand fundamentally how viologens behave within a polymer chain, we needed a better and more efficient way of synthesizing these long chains of polyviologens. As simple as this process looks on paper, the synthesis is …

Computational Design Of Two-Dimensional Transition Metal Dichalcogenide Alloys And Their Applications, John Douglas Cavin

Arts & Sciences Electronic Theses and Dissertations

The discovery of bronze as an alloy of copper and tin is arguably the earliest form of material design, dating back thousands of years. In contrast, two-dimensional materials are new to the 21st century. The research presented in this dissertation is at the intersection of alloying and two-dimensional materials. I specifically study a class of two-dimensional materials known as transition metal dichalcogenides (TMDCs). Because of the large number of transition metals, there are many combinations of TMDCs that can be alloyed, making experimental exploration of the phase space of possible alloys unwieldly. Instead, I have applied first-principles methods to study …

Modeling Small Molecule Metabolism In Human Liver Microsome To Better Predict Toxicity Risk, Na Le Dang

Arts & Sciences Electronic Theses and Dissertations

Adverse drug reactions (ADRs) are a serious problem with increasing morbidity, mortality, and health care costs worldwide. In the U.S., ADRs are responsible for more than 50% of acute liver failure cases and are the fourth most common cause of death, costing 100,000 lives annually.Idiosyncratic adverse drug reactions (IADRs) are immune-mediated hypersensitivity ADRs that are difficult to foresee during drug development. IADRs are often caused by reactive metabolites produced during drug metabolism. These reactive metabolites covalently attach to cellular components, and the resulting conjugates may provoke toxic immune response. Because reactive metabolites are short-lived, they can be difficult to detect. …

Integrated Mass Spectrometry-Based Method In Protein Chemistry: Metal-Binding Protein And Integral Membrane Protein, Chunyang Guo

Arts & Sciences Electronic Theses and Dissertations

Most biological processes are associated with protein catalysis. Characterizing protein structure, therefore, is crucial for understanding biological function. Mass spectrometry (MS)-based methods have emerged as a pivotal biophysical tool to interrogate protein structures; they can characterize protein-ligand/protein complexes that are refractory to conventional high-resolution means such as X-ray crystallography, Cryo-EM, and nuclear magnetic resonance (NMR) spectroscopy, in part owing to high molecular weight and significant flexibility. The integrated MS-based platform will provide topology and structural information of proteins from sketch to detail; native MS identifies protein complexes’ composition and stoichiometry; hydrogen-deuterium exchange MS (HDX-MS) detects the protein complexes’ dynamic change …

In-Situ Imaging Of Surface Heterogeneity In Semiconductor Photocatalysts Using Singlemolecule Fluorescence Microscopy, Meikun Shen

Arts & Sciences Electronic Theses and Dissertations

Metal oxide semiconductors have been used as promising photocatalysts to convert solar energy into useful fuels, such as water splitting, carbon dioxide reduction, and nitrogen fixation reactions. However, the typical metal oxide photocatalysts' efficiency often suffers from their weak visible light absorption and low charge carrier mobilities. One common strategy to mitigate these limitations is to introduce oxygen vacancies into the lattice of the semiconductor photocatalysts. This strategy has been applied to many metal oxide photocatalysts, such as titanium oxide, tungsten oxide, and zinc oxide, and oxygen vacancies indeed enhance their catalytic activities. Various roles of oxygen vacancies have all …

Synthesis And Characterization Of Putative Triplet Sensitizers In The Dark Pathway To Cyclobutane Pyrimidine Dimers Of Dna, Yanjing Wang

Arts & Sciences Electronic Theses and Dissertations

The cyclobutane pyrimidine dimer (CPD) is the major photoproduct resulting from direct absorption of UVB radiation in sunlight by DNA that results in C to T mutations found in human skin leading to skin cancer. CPDs can also be produced through the action of photosensitizers that can absorb longer wavelength UVA that is not absorbed efficiently by DNA and transfer triplet energy to the DNA. Most recently, CPDs was discovered to be formed in the dark following UV irradiation of melanocytes. This dark pathway was proposed to result from an indirect pathway to CPDs that involves triplet energy transfer from …

Metal Salt Hydrolysis For Electrochemically Active Conducting Polymer Nanocomposites, Hongmin Wang

Arts & Sciences Electronic Theses and Dissertations

The diversity of nanostructures obtained from organic polymerization is limited when compared to the vast amount of inorganic nanostructures. This dissertation will focus on a synergistic mechanism between organic polymerization and in situ inorganic salt hydrolysis for developing electrochemically active organic-inorganic hybrid nanostructures. The degree of polymerization, crystallinity and doping level of the conjugated polymer backbone is controlled using oxidative radical vapor-phase polymerization resulting in organic semiconductors featuring high crystallinity and superior electrical conductivity. An aqueous metal salt solution of iron (III) chloride serves as an oxidant for initiating the polymerization and interestingly, this inorganic salt hydrolyzes in situ producing …

Synthesis, Core-Shell Growth, And Surface Chemistry Of 2-Dimensional Cadmium Telluride And Cadmium Selenide Nanocrystals, Haochen Sun

Arts & Sciences Electronic Theses and Dissertations

This dissertation presents the synthesis, shell deposition, and surface ligand-exchange chemistry of 2-dimensional cadmium telluride and cadmium selenide nanocrystals. Flat, colloidal 2-dimensional CdTe and CdSe nanoplatelets are promising materials for optical and electronic applications. The research presented here will enable better understanding of their properties and facilitate further applications.First, a new tellurium precursor, tris(dimethylamino)phosphine telluride is readily prepared and is found to have superior reactivity than the trialkylphosphine tellurides that are commonly used for nanocrystal synthesis. Wurtzite CdTe nanoplatelets, (CdTe)13 magic-size nanoclusters, and CdTe quantum wires are synthesized with this precursor, and are fully characterized. It is demonstrated that in …

Mass Spectrometry-Based Strategies In Protein Higher Order Structure Analysis: Fundamentals And Applications In Protein-Ligand Interactions, Xiaoran Liu

Arts & Sciences Electronic Theses and Dissertations

Protein ligand interaction is a fundamental question in biology and biochemistry, and many approaches including X-ray crystallography, nuclear magnetic resonance, cryogenic electron microscopy, mass spectroscopy (MS), infrared spectroscopy, circular dichroism, fluorescence spectroscopy and many others have been applied to address this question. Among these techniques, mass spectroscopy has the advantage of high throughput, low sample amount requirement, and mid-to-high spatial resolution. One of the MS-based approaches is protein footprinting, which utilizes labeling reagents to map the solvent accessible surface of the protein of interest thus deliver structural information. Irreversible labeling is represented by covalent labeling and radical labeling, in which …

Developing Methods For Diversifying Molecular Scaffolds Directly On A Microelectrode Array, Nai-Hua Yeh

Arts & Sciences Electronic Theses and Dissertations

Microelectrode arrays contain collections of spatially isolated electrodes that can be individually addressed. Thus, the arrays have the potential to support synthesis of molecular libraries if unique members of the library can be located next to unique electrodes in the array. The result would be an intriguing platform for screening the molecules in the library against biological receptors in order to identify high-affinity ligands for those targets, especially since the arrays themselves can be directly used in the signaling studies. To expand the capabilities of the arrays, the goal of this thesis is to develop the new array chemistry needed …

Surface Modification Of Ii-Vi Semiconducting Nanocrystals, Calynn Morrison

Arts & Sciences Electronic Theses and Dissertations

This dissertation presents the compositional analysis of semiconductor materials by inductively coupled plasma optical emission spectroscopy (ICP-OES), a novel low-temperature shell growth precursor and installation pathway, and L-type for Z-type ligand exchange experiments conducted with four metal dithiocarbamate ligands. The techniques employed in the compositional analysis of semiconductor materials by inductively coupled plasma optical emission spectroscopy (ICP-OES) have a profound influence on the accuracy and reproducibility of the results. In Chapter 3, we describe methods for sample preparation, calibration, standard selection, and data collection. Specific protocols are suggested for the analysis of II-VI compounds and nanocrystals containing the elements Zn, …

Light-Directed Growth Of Semiconductor Nanomaterials By Photoelectrodeposition, Chu Qin

Arts & Sciences Electronic Theses and Dissertations

In this work, the chemical and physical properties of semiconductor microcrystals and metastable polymorphs were transformed through photoexcitation during electrochemical synthesis. Interfacial charge transfer using photogenerated carriers were used to successfully control the growth of metal oxide semiconductors and change their morphology, composition improve their catalytic activity. The main material systems studied in this thesis are electrodeposited copper oxide (Cu2O) and manganese oxide (MnOx) semiconductor films. Illumination can direct the shape transformation of Cu2O crystals at the nanoscale by facet-selective charge transfer. During photoelectrodeposition on Cu2O microcrystals with well-developed facets, light mediates the deposition of copper metal selectively on the …