Chemistry Commons^™

Cationic Metallocene-Containing Polymers: From Synthesis To Applications, Jiuyang Zhang

Theses and Dissertations

Metallopolymers, with the combination of metals and polymeric framworks, have attracted a lot of attention during the past decades. The development of metallopolymers has been largely driven by the desire to combine the synthetic efficiency and versatility of an organic polymer framework with the unique redox, responsive and catalytic properties of inorganic metals. Among different kinds of metallopolymers, metallocene-containing polymers， have been widely utilized for applications ranging from electrochemical sensors to templates for advanced inorganic catalysts to battery materials, due to their unique physicochemical properties. In the first part of my thesis, we showed controlled/living polymerization strategies to prepare well-defined …

Toward The Combinatorial Development Of Hydrophobic-Tagged Antifolate-Directed Degradation Of Human Thymidylate Synthase, Daniel J. Menasco

Theses and Dissertations

Direct post-translational control over a protein of interest (POI) can be exploited by manipulating the cells protein quality-control systems responsible for either intracellular turnover through ubiquitination (POI half-life) or repairing and degrading misfolded proteins.1 In an effort to target and degrade a high value POI we selected the enzyme human thymidylate synthase (TS) for post-translational degradation through ligand-directed ubiquitination and hydrophobic tagging. Thymidylate synthase catalyzes the reductive methylation of 2’-deoxyuridine monophosphate (dUMP) to 2’-deoxythymidine monophosphate (dTMP). As the de novo source of dTMP the regulation of intracellular TS is strictly controlled by ubiquitinindependent proteasomal degradation mediated by an internal TS-degron …

Universal Two-Electron Correlation Operator On Excited States, Bryan Thomas Nichols

Theses and Dissertations

Excited states of chemical systems are extremely important in understanding spectra, chemical phenomena, as well as how a particular compound behaves in reactions. Computationally, excited states are normally very expensive to calculate. The difficulty in calculating these states with wavefunction based methods can be mainly attributed to the calculation of large multi-determinant wavefunctions. One reason to use a complicated multi-determinant wavefunction is to include some of the effects of correlation energy. The quantity of correlation energy can most simply be defined as the reduction in energy caused by any two or more electrons trying to avoid each other. The most …

Surface Functionalization Of Inorganic Substrates With Polymeric Ligands Using Raft Polymerization, Anand Viswanath

Theses and Dissertations

This work focused on using polymers to modify the surface of various inorganic substrates, ranging from TiO2, ITO, CDSe and CdS nanostructures to micron sized silica particles. The synthesis of the polymers using the RAFT technique and the characterization of the functionalized substrates were analyzed in detail to provide insights into their use for various applications. In the first part of this work, novel phosphate based RAFT agents and phosphate containing polymers, including poly(methyl methacrylate) (PMMA), poly(glycidyl methacrylate) (PGMA) and poly(dimethyl siloxane) (PDMS) were synthesized. Alkyne functionalized PGMA was used to click to ITO surfaces in a grafting-to method, and …

Design, Synthesis, Characterization, And Evaluation Of Surface Modified Boronate Ester Covalent Organic Frameworks, Matthew W. Di Carmine

Theses and Dissertations

Covalent Organic Frameworks (COFs) were first reported in 2005 and are analogous to Metal Organic Frameworks (MOFs), with proposed applications in separation, storage and sequestration. Since COFs are comprised of lighter elements they are considered more advantageous for weight-sensitive applications. However, COFs are susceptible to degradation by weak nucleophiles such as water (i.e. hydrolysis). The Lavigne group has focused on developing structure-property relationships for COFs. It was previously demonstrated that the porosity of the COFs could be tailored by incorporating small alkyl chains on one monomer. Inclusion of these alkylated monomers into COF materials effectively increased the COF hydrophobicity resulting …

Biopolymeric Hydrogels Functionalized With Tobacco Mosaic Virus For In Vitro Three Dimensional Culture And Differentiation Of Stem Cells And In Vivo Tissue Regeneration, Jittima Amie Luckanagul

Theses and Dissertations

Plant viruses have been highlighted among material research due to their well-defined structures in nanoscale, mono-dispersity, stability, and chemical functionalities. Each of the thousands coated protein subunits on a viral nanoparticle can be homogenously modified, chemically, and genetically with a functional ligand leading to a high-density and spatial distribution of ligands on each particle (multivalency). Many reports from our group have clearly shown that virus coated substrates induced the acceleration of bone marrow stromal cells differentiation into bone cells. We hypothesized that this phenomenon could rely on the multivalency that the viral nanoparticle has to offer. Moving to a more …

Investigation Into The Synthesis And Characterization Of Poly(Dioxaborolane)S, Shakena Daniel

Theses and Dissertations

Boronate esters have evolved from being primarily used as sensors to being the integral linkage in complex materials such as macrocycles, covalent organic frameworks, and linear polymers. Poly(boronate)s, linear polymers that are linked via a boronate ester, have not been extensively researched. In 2005, the Lavigne group published the first manuscript on poly(dioxaborolane)s, i.e., six-membered, nonconjugated polyboronates. The behavior of the materials in solution was studied extensively, but little is known about the solid state properties of the material other than they form brittle films.

Poly(dioxaborolane)s are generated in high yield through a facile step-growth polymerization, but the reaction parameters, …

Synthesis, Characterization And Optical Properties Of Conjugated Boronate-Linked Materials And Their Applications In Optical Sensing Of Lewis Bases, Min Cai

Theses and Dissertations

Organoboron compounds, with Lewis acidic boron centers, have been emerged as an important class of materials, especially in the area of chemical sensors. Herein, boranes and boronate esters in the sensing perspective were overviewed in Chapter 1. Examples of synthesis and sensing applications of boron-containing conjugated polymers were highlighted.

Boronate ester formation provides the advantages of facile synthesis, tunable optical properties, enhanced stability and planar geometry. Thus, boronate esters, especially dioxaboroles, were proposed to use as alternatives of boranes to design better sensors for Lewis bases. Based on the previous investigation of fluorenyl bis- and poly- dioxaboroles by our group, …

Insights Into The Evolutional Adaptations And Functional Switching Mechanism In Dual Function Hemoglobin/Dehaloperoxidase (Dhp) And Modeling Of Cytochrome P450 Active Site With H93g Myoglobin Cavity Mutant, Shengfang Sun

Theses and Dissertations

The coelomic hemoglobin, dehaloperoxidase (DHP), from the sea worm Amphitrite ornata, is a dual function oxygen-binding heme protein that also possesses a significant peroxidase activity. As evolved from an ancient oxygen carrier globin, several structural adaptations have enabled DHP to evolutionally gain significantly enhanced peroxidase capability for self-protection while only minimally compromising its primary function as an O2 carrier. To elucidate these adaptations, the peroxidase activities and O2 affinities of several DHP and sperm whale myoglobin (Mb) mutants have been prepared. Several heme environmental structural factors that regulate the dual functions of DHP have been found, providing insight into how …

Synthesis And Characterization Of Polymer Nanomaterials Using Controlled Radical Polymerization, Lei Wang

Theses and Dissertations

This research focuses on creating and investigating polymer/organic bound interfaces on nanoparticles with advanced architectures to tailor the properties of polymer nanocomposites for various applications. Reversible addition-fragmentation chain transfer (RAFT) polymerization and a toolbox of surface functionalization from the simple to the advanced were developed to prepare the polymer nanomaterials.

In the first part (Chapter 2), a variety of RAFT agents (xanthate, dithiocarbamate and trithiocarbonate) were used to mediate the polymerizations of several classes of free radical polymerizable monomers. These monomers consist of styrene, methyl acrylate, methyl methacrylate, vinyl acetate and isoprene, which have different activities and require different classes …

Mechanistic Investigation Of A Silylation-Based Kinetic Resolution Using Linear Free Energy Relationships And Its Application To Substrate Expansion And Polymer Supported Kinetic Resolutions, Ravish K. Akhani

Theses and Dissertations

This dissertation represents our preliminary mechanistic investigations on the silylation-based kinetic resolution of secondary alcohols, and how we use that knowledge for further expansion of this methodology. Chapter 2 describes how we came up with a preliminary mechanism of our silylation-based methodology using a linear free energy relationship and a rate study. In this chapter, several para substituted triphenylsilyl chlorides were prepared that varied electronically and sterically in order to understand the substituent effects on the rate and the selectivity of the reaction. Selectivity factors and initial rates were experimentally determined for the kinetic resolution reactions with the newly designed …

Novel Monomers And Solution Polymerization Methods For Polybenzimidazole Polymers, Jason Hoffman

Theses and Dissertations

The goal of this work was to identify and study various monomers and polymerization methods for polybenzimidazole polymers. Beginning with the solution polymerization of polybenzimidazole via a bisulfite adduct monomer, Chapter 2 describes the efforts to optimize and scale up this process. Chapter 3 then covers an alternative method to prepare polybenzimidazole in solution by using an orthoester monomer. Finally, in Chapter 4, the research to incorporate an adamantane moiety into the backbone of polybenzimidazole is described.

Carboxylate Selective Lanthanide Imprinted Polymer Sensors For Sensor Array, Yang Xu

Theses and Dissertations

A europium-based molecularly imprinted polymer (MIP) was developed and characterized, which combined the highly luminescent properties of europium and the recognition properties of molecularly imprinted polymers. The europium-based MIPs were used as selective sensors for different types of carboxylates. The ultimate goal of this work was to develop a europium-based sensor array to differentiate carboxylates anions. The polymer was synthesized by using a europium–salen complex as the monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker. First, a europium containing non-imprinted polymer (NIP) and a series of europium containing MIPs imprinted with acetate, benzoate and phenylacetate were synthesized by free …

Hydroflux Synthesis: A New And Effective Technique For Exploratory Crystal Growth, Michael William Chance

Theses and Dissertations

Exploratory crystal growth is the best way to discover new phases with potentially improved properties or new crystal structures that could lead to new properties. As time goes on and researchers explore the synthetic techniques in the literature, diminishing returns will be met. Innovation in the synthetic tools used for synthesis is necessary to keep the field of materials chemistry advancing at its current pace and to allow us to reach more shallow minima of phase space. By combining wet hydroxide flux synthesis and hydrothermal synthesis, a hybrid technique for crystal growth has been created.

Using hydroxide hydrofluxes, a number …

Characterization Of Suf Pathway For Fe-S Cluster Assembly In Escherichia Coli, Yuyuan Dai

Theses and Dissertations

Fe-S clusters are critical metallocofactors required for cell function. Because of the toxicity of ferrous iron and sulfide to the cell, in vivo Fe-S cluster assembly is carried out by multiprotein biosynthetic pathways. Escherichia coli contains a stress-responsive Fe-S cluster assembly system, the SufABCDSE pathway, working under iron starvation and oxidative stress conditions. The cysteine desulfurase SufS and its accessory protein SufE work together to mobilize persulfide from L-cysteine. We collaborated with Dr. Laura S. Busenlehner to use hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize SufS-SufE interactions and protein dynamics. HDX-MS analysis shows that SufE binds near the SufS active …

Advancements In The Design, Synthesis, And Application Of Polybenzimidazoles, Alexander Lanier Gulledge

Theses and Dissertations

The overall goal of the work presented within this thesis is to investigate, understand, and develop structure-property relationships in regards to polymer structure, membrane stability, and device performance. Previous work has shown that material properties such as acid loading, proton conductivity, mechanical integrity, and device performance can be attributed to polymer structure, chemical functionality, and polymer architecture (homo, random, co-polymer etc.). Developing and understanding these relationships is critical to the advancement of fuel cell technology. Within this thesis, several of these relationships are investigated and reported.

Novel polymers and copolymer systems have been developed in this research and have significantly …

Approximate Quantum Trajectory Method For Modeling Chemical Reaction Dynamics: Application To Enzymatic Proton Transfer, James William Mazzuca

Theses and Dissertations

Molecular dynamics simulations, providing a detailed picture of the reaction mechanism, is an essential tool for theoretical and experimental chemists. In these simulations the nuclei are typically treated as classical particles, but under some conditions (low energies and temperatures, processes involving multiple electronic states) a classical description is inappropriate. Quantum effects of nuclear motion, such as tunneling and zero-point energy can play an important role in determining a reaction mechanism, yet exact quantum dynamics methods are limited to reactive systems of just 3-4 atoms. Central to this work is the development and implementations of an efficient trajectory-based methodology, in which …

Structure-Property Relationships In Polybenzimidazole Materials For Gas Separation And Fuel Cell Applications, Xin Li

Theses and Dissertations

The central theme of my research lies in the investigation of novel polybenzimidazole (PBI)-based materials for different energy related applications ranging from proton exchange membrane fuel cells (PEMFC) to high temperature gas separation. With the aid of a deeper understanding of the structure-property relationships in this class of materials, a better control on PBI chemistry - from monomer structure to polymer morphology to membrane/film processing method was able to be performed in order to achieve greater performance in targeted applications.

In Chapter 1, the overall background of two energy related applications - fuel cells and gas separation was first introduced …