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Synthesis, Structural Variations And Trends In The Properties Of Unique Dinuclear And Polynuclear Complexes Of Bis(Pyrazolyl)Methane Ligands In Solid State And Solution, Andrea Eva Pascui

Theses and Dissertations

The semi-rigid ligands, p-[CH(pz)₂]₂C₆H₄, L_p, m-[CH(pz)₂]₂C₆H₂, L_m, and m-[CH(3,5-Me₂pz)₂]₂C₆H₄, L_m* (pz = pyrazolyl ring), link two bis(pyrazolyl)methane units into a single molecule by a rigid phenylene spacer and are used to study the structural variations and magnetic interactions in self-assembled first row, divalent transition metal complexes in polymeric, dinuclear and dinuclear metallacyclic settings. The formation of these architectures highly depend on the geometry of these ligands: anti, the …

Polybenzimidazole Membranes With Enhanced Mechanical Properties For Extended Lifetime Electrochemical Applications, Max Molleo

Theses and Dissertations

After approximately 20 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). Commerical PBI MEAs can operate reliably for over two years at elevated temperatures of 120-180°C due to the physical and chemical robustness of PBI membranes. Recently, the Department of Energy has issued a target of 40,000-80,000 hours for stationary (i.e. combined heat and power, back-up power) polymer electrolyte membrane / proton exchange membrane (PEM) fuel cells. It is known through observation that over time, PBI membranes at 180°C creep in a direction perpendicular to compressive forces, thus …

Instrument And Method Development For Single-Cell Classification Using Fluorescence Imaging Multivariate Optical Computing, Joseph Swanstrom

Theses and Dissertations

Multivariate optical computing (MOC) is an all-optical approach of predictive spectroscopy that utilizes multivariate calibration and spectral pattern recognition techniques while operating in a simple filter photometer instrument, removing the need for expensive instrumentation and post-processing of spectral data. This is accomplished with specially designed interference filters called multivariate optical elements (MOEs). MOC can provide analytical solutions for applications requiring low cost, rugged, and simple to operate instrumentation for use in remote and hazardous environments such as open ocean waters. These instrument specifications are central for developing a method for classifying phytoplankton in their natural environment. Phytoplankton are photosynthetic single …

A Silylation Based Kinetic Resolution Of Secondary Alcohols And The Synthesis And Structural Characterization Of Pyridyl-Oxazolidine Compounds, Cody Ian Sheppard

Theses and Dissertations

Described herein is the first enantioselective silylation based kinetic resolution of monofunctional secondary alcohols to achieve useful levels of enantioselectivity. Using commercially available reagents, the reaction conditions were optimized and found to successfully resolve several secondary alcohols with high enantioselectivity. It was discovered that the nucleophilic isothiourea compound (-)-tetramisole, with Ph3SiCl as the silyl source, gave superior results to other nucleophilic catalysts and was capable of performing the kinetic resolution in as little as 45 minutes using mild reaction conditions. The structural and electronic characteristics of successful and less successful substrates are also discussed.

Chapter three discusses mechanistic investigations and …

New Ruthenium And Osmium Carbonyl Cluster Complexes With Main Group Bridging Ligands Having Unusual Structures And Bonding, Yuwei Kan

Theses and Dissertations

The reaction of IrRu3(CO)13(µ-H), 2.1 with HSnPh3 in hexane solvent at reflux has provided the new mixed metal cluster compounds Ir2Ru2(CO)11(SnPh3)(µ-H)3, 2.2 and IrRu3(CO)11(SnPh3)3(µ-H)¬4, 2.3 containing SnPh3 ligands. Compound 2.2 which was obtained in low yield (3%) contains a closed cluster having two iridium and two ruthenium atoms, one SnPh3 ligand and three bridging hydride ligands. Compound 2.3 has a butterfly structure for the four metal atoms with three SnPh3 ligands and four bridging hydride ligands around the periphery of the cluster. When compound 2.3 was heated to 97 oC for 30min, IrRu3(CO)9(μ-η2-C6H5)(μ4-SnPh)2(μ-SnPh2), 2.4 was formed by cleavage of phenyl …

Single Crystal To Single Crystal Polymerization Of A Columnar Assembled Diacetylene Macrocycle, Weiwei Xu

Theses and Dissertations

Organic tubular materials have attracted lots of attentions for their potential applications as nanoscale fluidic transport systems, specific ion sensors, molecular sieves and confined molecular reaction containers. While conjugated polymers, due to delocalized Pi electrons, exhibit interesting solar cells and sensors applications. In this thesis, we developed a conjugated polymer which combines the attributes of conjugated polymers with tubular materials, which should have great potential to work as a sensing material.

We reproduced and scaled-up the synthesis of a polymerizable macrocycle 1 that contains two rigidly separated diacetylene units. We found that, through hydrogen bonding, 1 can assemble into columnar …

Investigations Of The Non-Covalent Ch-Π Interactions Using Molecular Torsional Balances, Chen Zhao

Theses and Dissertations

Several bicycle N-arylimide based molecular balances were designed to study aliphatic CH-pi interactions and aromatic CH-pi interactions (edge-to-face arene-arene interactions). In each case, the geometries of the interactions were characterized in the solid-state via X-ray analysis, and the strengths of interactions were characterized in solution by their folded/unfolded ratios, as measured by integration of their 1H NMR spectra.

The balances are very sensitive to variations in the strengths of weak non-covalent interactions. Several different aspects of the CH-pi interactions were studied, such as sterics, conformational entropy, cooperativity, deuterium isotope effect, substitution effects, and solvent effects. It showed that due to …

Silylation-Based Kinetic Resolution Of Α-Hydroxy Carbonyl Compounds And Synthesis Of Chiral Isothiourea Catalysts, Yan Zhang

Theses and Dissertations

The thesis describes the silylation-based kinetic resolution for α-hydroxy carbonyl compounds catalyzed by isothiourea catalyst as well as our effort to make novel chiral isothiourea catalyst.

In Chapter 1, general background will be introduced, including chirality, general methods to obtain enantiopure compounds and kinetic resolution. In Chapter 2, the mechanism of the chiral recognition was discussed and a novel isothiourea catalyst was design to investigate the mechanism. The synthesis of the new catalyst was also described in this chapter.

In Chapter 3, the silylation-based kinetic resolution for α-hydroxy carbonyl compounds will be discussed. Since silylation-based kinetic resolution have already been …

The Scope Of The Bis-Urea Macrocycle Assembly Motif, Michael F. Geer

Theses and Dissertations

From the formation of rock candy crystals, to the functionality of DNA in the cell, to the cosmic dust throughout the universe, supramolecular chemistry has a great impact and importance in the world around us. In this thesis, we explore the supramolecular interactions and self-assembly of bis¬-urea macrocyclic systems and investigate how their structure and assembly influences bulk properties and functionality. Specifically, in chapter one, we review the factors that guide, limit, and define supramolecular structures from the atomic to the centimeter scale.

In chapter two, we investigate the incorporation of benzophenone, a well known triplet sensitizer, within a bis-urea …

Development And Figures Of Merit Of Microextraction And Ultra-Performance Liquid Chromatography For Forensic Characterization Of Dye Profiles On Trace Acrylic, Nylon, Polyester, And Cotton Textile Fibers, Scott James Hoy

Theses and Dissertations

Methodology for the microextraction of basic dyes on acrylic, acid dyes on nylon, disperse dyes on polyester, and reactive dyes, direct dyes, and indigo on cotton textile fibers is reported. Although these processes are destructive to the fiber evidence, the ability to analyze dye extracts from sub-millimeter fiber lengths of single fibers, coupled with detection limits in the hundred picogram range by ultra-performance liquid chromatography (UPLC) with both diode array detection (DAD) and tandem mass spectrometry (MS-MS) makes routine forensic characterization feasible.

Microextraction, followed by UPLC, can often distinguish similar fibers containing different, but similar, dyes with the combination of …

Design And Synthesis Of Polymer-Based Advanced Nanomaterials Using Raft Polymerization And Click Reaction, Junting Li

Theses and Dissertations

This research focuses on exploring new synthetic approaches to prepare polymer-based advanced nanomaterials using highly efficient chemical tools, such as reversible addition-fragmentation chain transfer (RAFT) polymerization and click reactions.

In the first project, novel synthetic routes to produce fullerene-based polymers were designed. First, mono-alkynyl functionalized fullerene was prepared starting with pristine fullerene (C₆₀). Methyl methacrylate and 6-azido hexyl methacrylate were then randomly copolymerized via RAFT polymerization with well-controlled molecular weights and copolymer compositions. Finally, the two moieties were covalently assembled into a series of well-defined side-chain fullerene polymers (SFP's) via the copper-catalyzed click reaction. The TGA and UV-vis …

Thermal Infrared Imaging: Instrumentation And Method Development, Wayne O'Brien

Theses and Dissertations

A recently development thermal infrared camera system was improved by designing new components to downsize physical aspect and improve the instrument's performance. A new thermal infrared light source was developed and characterized. It is designed from a custom-made Macor backpiece that holds an alumina screw. High resistance wire is coiled around the screw. The coiled wire is covered with an alumina coating. Most light sources have a spectral emissivity similar to that of a blackbody emitter. This source has a spectral irradiance profile that is not similar to a blackbody source. Thus, the lamp has an improved efficiency in the …

Iridium-Ruthenium/Osmium-Gold Cluster Complexes: Unique Structures And Properties, Qiang Zhang

Theses and Dissertations

Chapter Two

The first Ir-Ru cluster complex was synthesized was the electron-rich, anionic, planar cluster complex [PPN][IrRu6(CO)23], 2.5, (PPN=Bis(triphenylphophoranylidene)-ammonium) which obtained from the reaction of [PPN][IrRu3(CO)13] with one equivalent ruthenium carbonyl (Ru3(CO)12) at 66 oC (THF reflux) for 12h. Compound 2.5 could also be synthesized by using the mono-Iridium compound [PPN][Ir(CO)4] reacts with two equivalent of ruthenium carbonyl. In compound 2.5, all seven metal atoms lie in a plane (max deviation = 0.043(1) Å) with the iridium atom in the center circumscribed by a hexagonal ring of six ruthenium atoms. The anion 2.5 contains 104 valence electrons while both the …

Study Of Porous, Crystalline Supramolecular Boronates, Vincenzo Michael Disantis

Theses and Dissertations

Porous materials with the ability to selectively absorb volatile organic compounds are of high interest for applications in sensing, sequestration and separations. Utilizing the covalent yet reversible boronate ester bonds between boronic acids and diols in conjunction with dative boron-nitrogen coordination bonds has allowed for the discovery of a new class of porous materials. Preliminary results show the ability to obtain porous, crystalline supramolecular boronate networks from the coordination of diamine linkers with boronate diester backbones. Further exploration of porous, crystalline supramolecular boronates has revealed the discovery of a porous crystalline coordination polymer that exhibits reversible, selective guest adsorption properties …

Plant Virus Based Materials For Cell Alignment And Differentiation, Elizabeth Balizan

Theses and Dissertations

This research focused on developing and using plant virus based scaffolds to understand substrate control over cell alignment and differentiation. The first part of this work centered on development of virus based patterns that were then used to align and elongate aortic smooth muscle cells (SMCs). Virus patterns were generated in capillary tubes via a simple drying method. Three experimental parameters were used to control pattern formation: (1) protein concentration, (2) salt concentration, and (3) hydrophobicity of the pre-deposition surface. By controlling these parameters several aspects of the final virus patterns were controlled. First, virus orientation was controlled. Patterns were …

New Bimetallic Iridium Cluster Carbonyl Complexes, Mingwei Chen

Theses and Dissertations

Platinum group metal derived bimetallic clusters have been used as precursors to nanoscale catalysts which have been proven to be more effective than their monometallic counterparts. Iridium is a platinum group metal and its applications in catalysis continue to grow. To take advantages of synergies between mixed-metals, we modified iridium clusters with other metal ligands like tin, germanium, and group IB (gold, silver, copper) etc. and obtained a fairly large amount of new iridium derived bimetallic clusters which could be precursors to catalysts with superior properties than that available nowadays. The reaction of Ir4(CO)12 with Ph3SnOH in the presence of …

Programmable Polymers Preparation Optimization And Applications On Solute Templates, Yinyan He

Theses and Dissertations

Programmable polymer is a type of stimuli-responsive polymer which can keep their induced properties after removal of the stimulu, as well as programmable polymers maintain the general properties as stimuli-responsive polymers, such as recognize and respond to the stimulus. The previous reported solvent Caryl-Nimide bonds based programmable polymers (SPP-1) can freely rotate and change the carboxylic acid recognition group orientation in response to templates. Solvent templates were used in the SPP-1. One potential application for SPPs is using their recognition and memory properties for the identification and separation of mixture solutions of various analytes. In my first project, I wanted …

Biomaterial-Induced Osteogenesis Of Mesenchymal Stem Cells By Surface Roughness And Functionalization, Pongkwan Sitasuwan

Theses and Dissertations

For tissue engineering and regenerative medicine, it is important to understand factors directing the stem cell fate, including self-renewal, proliferation, differentiation, and apoptosis. Bone marrow derived mesenchymal stem cells (BMSCs) have the potential to differentiate into osteoblasts, chondrocytes, adipocytes, and smooth muscle cells. Specifically, in the field of bone tissue engineering, BMSCs are commonly used for in vitro osteogenesis studies. However the mechanisms and signaling pathways that these cells recognize material surface and utilize to differentiate are still unclear. This dissertation focuses on investigating the effect of surface nanotopography and functionalization on the promotion of osteogenic differentiation of BMSCs. Surface …

Structural And Photoluminescent Characterization Of Substituted A3mo4f (A = Sr, Ba, Ca; M = Al, Ga, In, Si And Ge), Robert Lenwood Green

Theses and Dissertations

In this dissertation, the structure and photoluminescent properties of A3MO4F-type materials (A = Sr, Ba, Ca; M =Al, Ga, In, Si, Ge) are studied as potential phosphors for compact fluorescent lamps (CFLs) and phosphor converted light emitting diode (pc LED) lights. Chapter 1 outlines background information of the evolution of lighting technology as well as detailing the synthesis, structural characterization and photoluminescence measurements. Chapter 2 focuses on the changes that the Sr3AlO4F structure undergoes as a result of exposure to a 5% H2/95% Ar atmosphere. High-resolution neutron powder diffraction is used to probe for minute structural changes. Chapter 3 is …

Functional Block Copolymers For Applications In Advanced Materials, Energy Storage, And Lithography, Christopher George Hardy

Theses and Dissertations

Block copolymers spontaneously self-assembly into a wide variety of ordered nanostructures on the length scale of 5 - 100 nm due to the thermodynamic immiscibility between the covalently linked, chemically distinct polymer chains. Incorporating desirable functional groups into block copolymer systems can lead to confinement of the functional group to a specific domain upon microphase separation of the block copolymer. The resulting materials display desirable characteristics of the functional group in a well-ordered nanostructure. Such systems have been utilized in a wide variety of applications including catalysis, ceramic materials, and membranes. This dissertation is focused on the synthesis, characterization, self-assembly …

Renewable Bio-Based Polymers And Degradable Functional Polymers, Kejian Yao

Theses and Dissertations

In this dissertation, polymers derived from renewable bio-based resources and degradable functional polymers with stimuli-responsive properties by various polymerization techniques were investigated. The properties of these polymeric materials were characterized and discussed.

In Chapter 1, the overall background and recent development of renewable bio-based polymers as well as degradable stimuli-responsive polymers was introduced. Major research objectives of my doctoral work were described.

The first section of the dissertation, on the preparation of renewable bio-based polymers was provided from Chapter 2 to Chapter 4. In Chapter 2, the preparation of novel polymers derived from renewable gum rosin by atom transfer radical …