Chemistry Commons^™

Carbon "Quantum" Dots: Structures, Properties, And Issues, Weixiong Liang

All Dissertations

Carbon dots (CDots) are small carbon nanoparticles (CNPs) with effective surface passivation. The effective passivation has been achieved by the surface functionalization of pre-existing CNPs with organic molecules, mostly molecules containing primary or secondary amine moieties. In the studies highlighted in this dissertation, CNPs were functionalized by selected organic molecules, including especially the use of radical addition reactions, to generate CDots with strong absorption and bright fluorescence emissions. A good demonstration of the approach was the N-ethylcarbazole (NEC) radical addition to CNPs under microwave irradiation. Spectroscopy and microscopy methods were employed to characterize the resulting NEC-CDots, and the results …

Expansion Of The Diazacyclobutene Motif For Antiparasitic Evaluation, Brock Alexander Miller

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Molecules containing N-heterocycles are prevalent in pharmaceutical settings. The ability to generate highly functionalized molecules containing N-heterocycles in very few synthetic operations is valuable for drug discovery. Our group has developed a two-step synthesis to access a rarely studied diazacyclobutene scaffold via a formal [2+2] cycloaddition between 4-phenyl-1,2,4-triazolinedione and electron-rich thioalkynes. Our interest in this scaffold increased exponentially from promising preliminary biological evaluations against a protozoan parasite, Trypanosoma brucei. While we were able to double the number of historical examples of this scaffold, there were significant limitations in our methodology. The most notable limitations were the lack …

Composite And Polymer Formulation Employing Sulfur And Bio-Olefin Feedstocks, Claudia V. Lopez

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Environmental sustainability represents a challenge for society since industrial growth has a direct impact on natural resources and waste production. New technologies that effectively incorporate waste into renewable resources are critical to the development of a sustainable and circular economy. The manufacturing of structural materials like Portland cement (OPC) is responsible for >8% of the global anthropogenic emissions of carbon dioxide, with ~ 1 kg of CO₂ released to the atmosphere for every kilogram of OPC produced. For instance, the development of sustainable structural materials is a key factor to reduce the greenhouse emissions and to attenuate the climate …

Supramolecular Pi-Donor/Acceptor Arrays Based On Redox-Active Metal-Organic Coordination Assemblies, Paola Benavides

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Coordination-driven self-assembly is an attractive strategy for constructing thermodynamically stable supramolecular coordination complexes, ranging from discrete metallacycles and cages to infinite coordination polymers and metal-organic frameworks for a variety of applications.

Chapter 1 discusses strategies for preparing supramolecular charge-transfer π-donor/acceptor assemblies and their potential applications.

Chapter 2 demonstrates that tricomponent self-assembly method, which was believed to yield 3D-cages, based on tetrapyridyl porphyrin (M’TPP, M’ = Zn or H₂), dicarboxylate ligands (XDC), and caped cis-Pt(II) corners, actually yields 2D-bowties featuring an M’TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. The 2D-bowties showed …

Light Harvesting And Electrically Conducting Metal-Organic Frameworks, Monica Gordillo Varela

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Composed of metal clusters nodes and organic linkers, metal-organic frameworks (MOFs) have emerged as versatile platforms with unparalleled chemical and structural tunability, synthetic facility, permanent porosity, and size-selective guest encapsulation capability. These features make them potential candidates for a variety of applications such as gas storage,drug delivery, catalysis,and sensing. In recent years, the introduction of redox- and photoactive components have yielded stimuli-responsive electronic and photonic MOFs and expanded their utility in molecular electronics and energy storage devices/technologies.

Chapter one describes the light-harvesting ability of a porphyrin-based MOF. Herein, we have demonstrated spontaneous solvothermal growth of [100]-oriented uniform pillared-porphyrin framework-11 (PPF-11) …

Valorization Of Biopolymers And Biomass To Produce Materials For A More Circular Economy, Moira Lauer

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With a globally increasing population and largely unchecked consumption of raw materials, human society is on track for devastating consequences. Two industries responsible for utilizing massive amounts of raw materials and generating equally gargantuan quantities of waste are the packaging and infrastructure sectors. In 2017 in Europe, for example, packaging reached a record 173 kg of packaging waste per capita. One of the largest packaging consumers is the food industry, in which 40% of packaging is made of petroleum-derived single-use plastic, leading to a massive carbon imbalance. “The Built Environment,” on the other hand, is responsible for about 50% of …

Conjugated Polymers And Inter-Chromophore Interactions: Synthesis, Photophysical Characterization And Application, Anshuman Mangalum

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Ever since the discovery of conducting polymers (CPs)in the late 1970s, organic conjugated materials and polymers is one of the most popular and fascinating research area among the scientists due to the remarkably unique properties and broad range of applications of (CPs), notably organic photovoltaic (OPVs), organic or polymer based light emitting devices (OLEDs / PLEDs), field effect transistors (FETs), nonlinear optical (NLO) devices and sensor for biologically relevant analytes, metal ions and anions. Optical properties of these materials depend on intra / interchromophoric interaction, geometry and relative orientation in space. Detailed study of such materials can also help us …

Targeting A-Form Nucleic Acids: A Neomycin Based Approach, Nicholas Shaw

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This manuscript reflects our most recent advancements in the recognition of nucleic acids. Chapter one focuses on previously established methods in nucleic acid recognition. Nucleic acid targeting by small molecules affords a unique way to potentially inhibit biological functions, which is different from targeting enzyme and protein bio-macromolecules. We seek to further develop an aminoglycoside approach to targeting nucleic acids. Since aminoglycosides were first introduced, over 60 years ago, as treatment for tuberculosis, natural product discovery and demands for therapeutically more effective aminoglycosides, with lowered toxicity, have dominated the landscape of aminoglycoside research. More recently, our group has established neomycin …

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 …

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 …

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 …

Polymeric Carbon Nanocomposites - Preparation, Characterization, And Properties, Lucia Veca

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Excellent thermal properties of carbon nanomaterials such as carbon nanotubes and newly discovered graphene make them the filler of choice for the development of thermal management materials. Graphene has been viewed as “ unrolled single-walled carbon nanotube and as a wonder material with many superlatives to its name ” thus there is an excessive interest in developing new synthetic routes towards large scale production of high quality graphene nanosheets.
In this dissertation, we report different methods that could further exfoliate the commercially available expanded graphite to nanometer sized carbon structures, “carbon nanosheets ”, for their use in highly thermal conductive …

Organocuprate Mediated Syntheses Of O, And N-Heterocycles, Fenghai Guo

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ABSTRACT
The δ-lactone moiety comprises structural subunits in a number of natural products. Highly substituted δ-lactones are important both in synthetic applications and also as naturally occurring compounds. We have reported a one-pot procedure for the synthesis of trans-4,5-disubstituted tetrahydropran-2-ones from 3-hydroxy-3,6-dihydropyran-2-one involving sequential cuprate mediated allylic substitution and 1,4-conjugate addition reactions. We have now examined the same protocol for synthesis of 4,5,6-trisubstituted δ-lactones.
The rich functionalities(i.e. the epoxide, olefin and ester functional groups) in ,δ-epoxy-α,β-enoates provide opportunities for SN2-epoxide opening, allylic substitution, and 1,4-conjugated addtion. The opening of the epoxide with AcCl, AcBr, and benzoyl chloride afforded the -acetoxy--halo-,-enoates …

Novel Lactide Derived Polymers; Synthesis, Properties And Applications, Dahlia Haynes

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This dissertation primarily encompasses the synthesis, characterization, properties and discussion of applications for lactide derived polymers. The methodology focuses on altering polylactide's (PLA's) dynamic and physical properties increasing its broad market utility in both traditional and non-traditional applications. The fundamentals of this work include understanding and enhancing the polymer chemistry and materials related processes through the use of copolymerization, fluorination, composite chemistry and materials science.
The first chapter discusses the important of this research with emphasis on current world issues that focuses on the feasibility of renewable resources and sustainability implementation. Modification of renewable resource materials like lactic acid is …

Synthesis And Pharmacology Of N-Alkyl-3-(Halo-Naphthoyl)Indoles, Valerie Smith

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The medicinal values of marijuana have often been overshadowed due to the psychotropic, 'recreational' effects it brings about in a user. For hundreds of years the therapeutic uses of cannabis sativa were appreciated, but the inability to control the dosage of the main constituent, and therefore the psychotropic effects, rendered the drug a liability. The elucidation of the structure of this main psychoactive constituent, ∆9-tetrahydrocannabinol (∆9-THC) by Gaoni and Mechoulam in 1964 opened the door to the discovery of a vast array of knowledge about cannabinoids. From the multiple classes of cannabinoids and the ways these compounds interact with the …

Functionalized Carbon Nanotubes For Biological Applications, Lingrong Gu

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Carbon nanotubes with their unique pseudo-one-dimensional nanostructures and related electronic, optical, and mechanical properties have been attracting much attention for potential biological applications, such as biosensors, bio-delivery, bioimaging and so on. In this dissertation, recent studies and advances toward bioapplications of carbon nanotubes are critically reviewed, followed by detailed reports on my research projects concerning the use of carbon nanotubes as unique scaffolds for multivalent display of sugars and the relevant results from bio-evaluation of these novel nanomaterials.
Single-walled (SWNTs) and multiple-walled carbon nanotubes (MWNTs) were functionalized with amine-derivatived monosaccharides (galactoses and mannoses) and their dendritic constructs. These sugar-functionalized carbon …

Perfluorocyclobutyl Aryl Ether Polymers: A Modular Approach To Tailored Emission, Andrew Neilson

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Aryl trifluorovinyl ethers (TFVE) are versatile precursors to perfluorocyclobutyl aryl ether (PFCB) polymers. TFVE functionalized chromophores of a variety of colors have been synthesized for copolymerization to form PFCB polymers with tunable emissive properties. TFVE small molecule chromophores containing fluorene, benzothiadiazole, and bisthiophene show superb emissive properties and prove that the TFVE and PFCB structures have no effect on chromophore emission. Copolymerization of these chromophores with commercial TFVE monomers produced high molecular weight, thermally stable, emissive materials. With the use of trifunctional TFVE monomers these materials can be made into optical glasses. PFCB-phenylene vinylenes were prepared by Wittig polymerization and …

Post-Production Separation And Functionalization Of Single-Walled Carbon Nanotubes, Kurukulasuriya Fernando

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ABSTRACT
Single-walled carbon nanotubes (SWNTs) are considered to have many potential applications due to their unique structural, physical, chemical and electronic properties. Because the rigid structure of carbon nanotube determines its toughness in dissolution, the processing capability of carbon nanotube is strongly limited. My carbon nanotube functionalization research was mainly focused on developing innovative methods to functionalize nanotubes with various polymers and large aromatic molecules to make them soluble to study their interesting properties and applications. In this dissertation, different methods for the functionalization and solubilization of carbon nanotubes are described. The co-existence of metallic and semiconducting carbon nanotubes has …

Functionalized Nanomaterials: Synthesis, Characterization, And Applications, Liangwei Qu

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Due to their unique electronic, optical, catalytic and mechanical properties, nanomaterials (nanoparticles and nanotubes) have been attracting much attention over the past decades. In this dissertation, polymeric nanoparticles bearing derivatized D-mannose and galactose molecules were prepared via dispersion polymerization and their interactions with various bacterial cells were studied. The results show that there are strong adhesin-specific interactions of the nanoparticles with E. coli cells, resulting significant nanoparticles-madiated cell agglutination.
Poly(ethylene glycol)-coated magnetic polymer nanoparticles were synthesized through miniemulsion polymerization by using macromonomer as both a comonomer and a surfactant. The resulting magnetic polymer nanoparticles were successfully used for bio-detection and …

Perfluoroalkyl (Aryl) Sulfonimide Zwitterions, Hua Mei

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This research focuses on superacid perfluoroalkyl(aryl) sulfonimides and their derivatives as a source of stable zwitterionic salts. The strong resonance stabilization of sulfonimides imparts unexpected stability to the zwitterions.
Two types of zwitterions were investigated. The first are symmetrical diaryliodonium zwitterions (DZs) as potential photo acid generators (PAGs) for microlithography. Driven by the demand for smaller feature sizes in the microelectronics industry, microlithography using shorter wavelength light has evolved and new PAGs are of interest. New DZs are potentially useful because they have good thermal stability and may be structurally modified to alter their spectral absorption characteristics. As an extension …