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Chemistry

All Dissertations

2010

Articles 1 - 13 of 13

Full-Text Articles in Physical Sciences and Mathematics

Design And Regioselective Synthesis Of Two And Three-Pronged C60 Fullerene Derivatives And Their Applications In Molecular Electronics, Angy Ortiz-Hernandez Dec 2010

Design And Regioselective Synthesis Of Two And Three-Pronged C60 Fullerene Derivatives And Their Applications In Molecular Electronics, Angy Ortiz-Hernandez

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Since the introduction of semiconductors in the second half of the 20th century, advancements in electronics and technology have been tremendous. In particular, the rapid development of silicon-based computer chip technology and miniaturization of electronic components has been tremendous. Since silicon-based materials have a limit in terms of size, scientists proposed that individual molecules could behave as single electronic components for high degree of miniaturization.
Given that the molecules of interest must have dimensions on the nanometer scale, be able to bind to the electrode surface and have electron donor-acceptor properties, C60 fullerene has been a prime candidate for …

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Novel Neomycin Conjugates For Multi-Recognition Of Nucleic Acids, Albert Willis Dec 2010

Novel Neomycin Conjugates For Multi-Recognition Of Nucleic Acids, Albert Willis

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Neomycin is an aminoglycoside antibiotic known for its high affinity for RNA duplex structures. Recent developments from our labs have indicated that aminoglycoside binding is not limited to RNA, but to nucleic acids that, like RNA, adopt conformations similar to A-form. Our group sought to further expand the utility of aminoglycoside binding to B-DNA structures by conjugating neomycin, an aminoglycoside antibiotic, with the B-DNA minor groove binding ligand Hoechst 33258. Envisioning a dual groove-binding mode, we have extended the potential recognition process to include a third, intercalative moiety. Furthermore, we observe remarkable recognition of such conjugates with RNA duplex. Spectroscopic …

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Synthesis And Optical Properties Of Silver Nanostructures, John Heckel Dec 2010

Synthesis And Optical Properties Of Silver Nanostructures, John Heckel

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Silver nanoparticles interact with light via the excitation of plasmon resonances that are the collective oscillations of the free electron density. This excitation represents the most efficient mechanism for the interaction of light with matter and therefore the nanoparticles are of great interest for both fundamental and practical points of view. In the following dissertation, silver nanoparticles, core-shell nanoparticles, and silver nanoparticle clusters were synthesized and there optical properties were investigated.
Chapter 1 contains general background information about the optical properties of bulk and silver nanoparticles. It also contains a concise description of two of my collaborative projects that did …

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Synthesis Of Trimetallic Nitride Endohedral Metallofullerene Derivatives For Enhanced Solar Energy Conversion, Julio Pinzon Joya Dec 2010

Synthesis Of Trimetallic Nitride Endohedral Metallofullerene Derivatives For Enhanced Solar Energy Conversion, Julio Pinzon Joya

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The preparation and electrochemical properties of donor - acceptor systems based on trimetallic nitride endohedral metallofullerenes (TNT-EMFs) for enhanced solar energy conversion is described. It was found that TNT-EMFs have an enhanced ability to stabilize charge separated states formed upon light irradiation when compared to empty cage fullerene analogues. The influence of the linker connecting the donor and acceptor moieties was studied in two different systems. Optimal conditions for preparing cyclopropanated Bingel-Hirsch derivaties of the most common TNT-EMFs were found; this functionalization approach is a very useful alternative to the 1,3-dipolar cycloaddition reactions that yield pyrrolidine derivatives, because the latter …

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Preparation And Studies Of Fluorescent Carbon Nanomaterials, Xin Wang Dec 2010

Preparation And Studies Of Fluorescent Carbon Nanomaterials, Xin Wang

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There have been rapid advances in the development and applications of semiconductor quantum dots (QDs) represented by CdSe/ZnS. However, a serious limitation of these QDs is the necessary use of toxic heavy metals. Fluorescent 'carbon dots' (surface passivated carbon nanoparticles) are developed as alternative to classical semiconductor QDs.
The carbon dots could be made to be highly fluorescence, with emission quantum yields close to 60%. Their optical properties resemble bandgap transitions found in nanoscale semiconductors, suggesting that carbon particles at the nanoscale acquire essentially semiconductor-like characteristics.
The fluorescence in carbon dots could be quenched efficiently by electron acceptor or donor …

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Poly (Acrylonitrile-Co-1-Vinylimidazole): A New Melt Processable Carbon Fiber Precursor, Wenjin Deng Dec 2010

Poly (Acrylonitrile-Co-1-Vinylimidazole): A New Melt Processable Carbon Fiber Precursor, Wenjin Deng

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Carbon fiber polymer composites have attracted worldwide interest in sporting goods and aerospace industries due to their excellent specific strength, stiffness and lightweight. The replacement of solution-spinning process by melt-spinning process is one of the major approaches to make cost effective carbon fiber. In recent years, researchers have explored the possibilities to synthesize melt processable carbon fiber precursors, but their thermal stabilization is still a challenge. The goal for this research project is to prepare melt processable carbon fiber precursors which have the capability of thermal stabilization. Acrylonitrile/1-vinylimidazole (AN/VIM) copolymers containing various mol% of VIM were synthesized by free radical …

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Perfluoroalkyl Phosphonic And Phosphinic Acid Electrolytes For Proton Exchange Membrane Fuel Cells, Mahesha Herath Aug 2010

Perfluoroalkyl Phosphonic And Phosphinic Acid Electrolytes For Proton Exchange Membrane Fuel Cells, Mahesha Herath

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Perfluorinated sulfonic acid polymers have been considered as the state-of-art membrane materials for proton exchange membrane fuel cells. A major technical issue with these polymers is that they do not function well at temperatures above 80 °C and at low humidities. Therefore, research has been focused on developing PEM materials that can operate independent of hydration requirements. The operation of fuel cells at high temperature (e.g. 120 oC) increases fuel cell system efficiency due to faster electrode kinetics and better CO tolerance. This dissertation will describe a study of proton-transport rates and mechanisms under anhydrous and aqueous conditions using a …

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Chemical Modification And Biological Activity Exploration Of The Natural Product-Gossypol, Juanjuan Yin Aug 2010

Chemical Modification And Biological Activity Exploration Of The Natural Product-Gossypol, Juanjuan Yin

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Gossypol is a naturally occurring, highly colored yellow pigment indigenous to the small intercellular pigment glands of the cotton plant genus Gossypium, which is proposed to be part of plant's defense system. Gossypol is characterized by wide contraceptive, antiviral, anticancer and antifungal properties. However, the relatively high toxicity of gossypol precludes its application in medical therapy. For this reason the syntheses and tests of gossypol derivatives, have been tried to enable their application as drugs. In our study, gossypol based methylation, glycosylation and nanoconjugate reactions were explored. The gossypol derivatives were all fully characterized by NMR, MS, FT-IR, UV spectrometry, …

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Novel Π-Conjugated Materials Plus Their Characterizations And Applications, Xiuxian He Jul 2010

Novel Π-Conjugated Materials Plus Their Characterizations And Applications, Xiuxian He

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The theme of this dissertation will focus on the syntheses and characterization of bipyridine (bipy) containing π-conjugated polymers (CPs). Specifically, poly(p-phenylene ethynylene), polyfluorene and poly(p-phenylene vinylene) derivatives have been prepared via Sonogashira coupling, Suzuki coupling and Heck coupling, respectively. Derivatives of poly(p-phenylene ethynylene), polyfluorene and poly(p-phenylene vinylene) are known to have applications in optical and electronic devices. Through this study, polymers condensed with bulky bipy-containing TAB as one of the copolymer units have shown increased solubility and diminished intrachain/interchain aggregation in solution and in film due to the effectiveness of TAB in controlling the relative orientations of individual polymer chains. …

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Self-Assembly Of Architecturally Complex Block Copolymers, Juan Hinestrosa May 2010

Self-Assembly Of Architecturally Complex Block Copolymers, Juan Hinestrosa

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The term self-assembly denotes the formation of complex structures from simpler building blocks, resembling the manner in which Nature generates functional systems. In this pursuit, block copolymers present a great opportunity to study the interactions, dynamics and self-assembly of soft matter. Block copolymers have the ability to self-assemble into thermodynamically stable microphase segregated domains of precise shape and size, which are controlled by the chemistry of the constituent blocks, their size and connectivity, temperature and solvent conditions. Specifically, in this body of work two different types of branched copolymers with polystyrene (PS) and polyisoprene (PI) constituents are studied. The complex …

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Chemical Characterization Of Botanical Products: Comprehensive Speciation By Liquid Chromatography Particle Beam Mass Spectrometry, Joaudimir Castro Georgi May 2010

Chemical Characterization Of Botanical Products: Comprehensive Speciation By Liquid Chromatography Particle Beam Mass Spectrometry, Joaudimir Castro Georgi

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The dietary supplement industry has expanded and many of these supplements have become an important aspect of people's everyday lives. In 1994, the U.S. Dietary Supplement Health and Education Act (DSHEA) classified numerous nutraceutical/botanical products as dietary supplements because of their beneficial medicinal properties and provided the necessary regulation to the supplement producers. Since then, the interest of the scientific community towards dietary supplements has grown intensively and numerous studies have been carried out in order to understand the chemical behavior of the active molecules in the human body. The development towards analytical methods for the quantification of the active …

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Synthesis Of Meta-Terphenyl Scaffolded Molecules For Catalysis And Sensor Applications, Brad Morgan May 2010

Synthesis Of Meta-Terphenyl Scaffolded Molecules For Catalysis And Sensor Applications, Brad Morgan

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The utility of the m-terphenyl has been observed in a wide variety of applications since its first discovery. The tunable conformational flexibility contributes to the unique properties and resulting applications thereof. Chapter 1 goes into detail about the concepts used throughout and defines the tools needed to understand the chemistry in the
resulting chapters.
The primary use of the m-terphenyl herein is as a canopy that shields a pocket created underneath the central ring. Functionalization within this pocket allows metal binding in defined coordination environments. with the use of donor ligands attached to the flanking rings. The applications of these …

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Molecular Mechanics Studies Of Enzyme Evolutionary Mechanisms, Manoj Singh Jan 2010

Molecular Mechanics Studies Of Enzyme Evolutionary Mechanisms, Manoj Singh

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In the current dissertation, closely related studies to quantify the mechanism underlying enzyme evolution have been discussed. The HIV-1 protease and beta-lactamase enzymes were used as model systems for these studies. These are well known enzymes that are associated with drug resistance and are associated with the pathogenic diseases, and therefore, developing molecular level understanding of drug resistance through these enzymes has fundamental as well as practical importance.
In chapter 2, the relationship between errors in modeled protein structures and associated binding affinity predictions to small molecules is established. The results of this study are applicable in addressing a wide …

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