Chemistry Commons^™

Covalent Inhibition Of Enzyme Sortase A As A New Pathway Against Bacterial Resistance Of Staphylococcus Aureus, Umyeena Bashir

Master's Theses

The continued rise of antibiotic-resistant bacteria, such as MRSA (methicillin-resistant Staphylococcus aureus), has made the discovery of novel antibiotics critical. While bacteriostatic and bactericidal antibiotics inevitably exert evolutionary pressure on bacteria to develop resistance, small molecules that target mechanisms of bacterial virulence present a promising alternative for treatment. Sortase A (Srt A), a cysteine protease of S. aureus, promotes bacterial virulence by covalently attaching proteins such as pilin to the bacterial surface, enabling bacterial adhesion to mammalian cells. Inhibitory studies of this enzyme have gained prominent interest as a new pathway for drug development since blocking this enzyme's ability to …

Pressure Driven Desalination Utilizing Nanomaterials, Fangyou Xie

Master's Theses

Nanomaterials such as graphene oxide and carbon nanotubes, have demonstrated excellent properties for membrane desalination, including decrease of maintenance, increase of flux rate, simple solution casting, and impressive chemical inertness. Here, two projects are studied to investigate nanocarbon based membrane desalination. The first project is to prepare hybrid membranes with amyloid fibrils intercalated with graphene oxide sheets. The addition of protein amyloid fibrils expands the interlayer spacing between graphene oxide nanosheets and introduces additional functional groups in the diffusion pathways, resulting in increase of flux rate and rejection rate for the organic dyes. Amyloid fibrils also provide structural assistance to …

Mechanistic Investigations Of The Iron(Iii)-Catalyzed Carbonyl-Olefin Metathesis Reaction, Susan Phan

Master's Theses

Iron(III)-catalyzed carbonyl-olefin ring-closing metathesis represents a new approach toward the assembly of molecules traditionally generated by olefinˆ’olefin metathesis or olefination. Herein, we report detailed synthetic, spectroscopic, kinetic, and computational studies to determine the mechanistic features imparted by iron(III), substrate, and temperature to the catalytic cycle. These data are consistent with an iron(III)-mediated asynchronous, concerted [2+2]-cycloaddition to form an intermediate oxetane as the turnover-limiting step. Fragmentation of the oxetane via Lewis acid-activation results in the formation of five- and six-membered unsaturated carbocycles.

Development Of An Improved Synthesis Of S-D-Ribosyl-L-Homocysteine (Srh) And Progress Toward Srh Analogs Modified At The C3 Position, Emily Rouse

Master's Theses

Quorum sensing is a system that facilitates bacteria turning on and off gene expression depending on population density. System 2 quorum sensing is utilized by both Gram positive and Gram negative bacteria, and the quorum sensing molecule used in this system is AI-2. AI-2 is biosynthesized by the enzyme LuxS from the precursor SRH. This thesis describes an improved synthesis of SRH through the exploration of different protecting group strategies. The knowledge gained from the improved synthesis of SRH is then applied toward the synthesis of SRH analogues with increased steric bulk installed through use of a stereoselective anti-Mannich reaction. …

C(Sp2)–H Functionalizations Employing 2-Aminophenyl-1h-Pyrazole As A New Removable Directing Group, Wan-Chen Lee

Master's Theses

2-Aminophenyl-1H-pyrazole (2-APP) was discovered as a novel removable bidentate directing group for copper-mediated aerobic oxidative C(sp2)–H bond amidation and sulfonamidation bearing a wide range of sulfonamides, When Cu(OAc)2 was employed as the copper source, 1,1,3,3-tetramethylguanidine (TMG) as an organic base, the reaction, optimally carried out overnight in DMSO at 80 °C in open air, produced a variety of products in moderate to excellent yields. In addition, C(sp2)–H bond chlorination has been developed by using this auxiliary, employing trichloroacetamide as a new chlorine source. Furthermore, this unprecedented directing group also can assist copper-mediated regio-selective hydroxylation, and ortho-alkynylation/annulation by using Cu(OAc)2 as …

A Comparison Of Solvent And Water-Borne Alkyd Coatings And The History Of Voc Regulations In The United States, Molly Elise Burns

Master's Theses

A Comparison of Solvent and Water-Borne Alkyd Coatings Abstract

Conventional solvent based alkyd coatings have gone out of favor due to concerns over volatile organic compound (VOC) content. However, due to recent focus on renewable raw materials, alkyds are making a comeback in waterborne form. Water based alkyd coatings are known to have poor shelf stability and corrosion resistance, as well as other problems during the formulation process. This project focused on comparing solvent borne to two types of water-borne alkyds, water reducible alkyds and alkyds emulsions. The purpose was to understand the differences between the three types of alkyds …

Correlation Of Polymer Performance And Hansen Solubility Parameters, Daniel Jobse Mania

Master's Theses

Ready-to-use (RTU) grout is becoming more important to the finish and remodeling construction industry. Market research shows it is a fast-growing product that not only is creating its own space, but is beginning to supplant existing technology.

The original intent of this research was to investigate formulation parameters and how they affect grout performance. It was learned that particle size and oil absorption (OA) value are important filler properties that affect performance as much as adequate packing density and optimal pigment volume concentration (PVC) without going beyond critical PVC (CPVC).

Polymer architecture was also determined to be extremely important, but …

Production And Harvest Of Microalgae In Wastewater Raceways With Resource Recycling, Alexander Colin Roberts

Master's Theses

Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.

A pilot facility was operated with nine CO₂-supplemented raceway ponds, each with a 33-m² surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014. The ponds were operated as three sets of triplicates with two sets continuously fed …

Investigations Of Thioether Generation For S-D-Ribosyl-L-Homocysteine Synthesis, Brendan Corcoran

Master's Theses

Creation of the thioether linkage is a fundamental step for the chemical preparation of the bacterial quorum sensing molecule S-D-ribosyl-L-homocysteine (SRH). Although previous preparations of SRH and its analogues have been reported in the literature, they employ assorted methods with varied results. Therefore, a reassessment of the methodology used for synthetic preparation of the thioether bond in SRH-like molecules is here considered. This work examines four methods of thioether generation following two mechanisms, bimolecular nucleophilic substitution (S_N2) and radical-initiated thiol-ene coupling, in an attempt to generate SRH in a more efficient and reproducible manner. Both mechanisms address …

Lipid Production By Microalgae Treating Municipal Wastewater, James Edward Kelley

Master's Theses

Microalgae hold much promise as a feedstock in liquid biofuel production. Lipid content of microalgae cells range from 30-80% dry weight of biomass. It is projected that microalgae can produce between 1,000-6,500 gallons/acre/year of oil. Currently, production of industrial algae operates in open raceway ponds that use minimal capital and energy inputs to culture algae. Raceway ponds can also be used to grow microalgae from municipal waste streams. Although high biomass productivity can be achieved in these systems, there remains a large production gap between large volumes of biomass cultivation and high lipid content from microalgae cells. Low lipid content …

Re-Healable Coating Based Upon Thermally Responsive Linkages, Dahlia Ningrum Amato

Master's Theses

The goal of this thesis was to design thermally responsive polyol resins that would be compatible with isocyanates. Two approaches were made to reach this goal, the first involved functionalizing soybean oil and the second involved post-polymerization modification of a methacrylate based resin.

A soybean based coating with thermally responsive Diels-Alder linkages has been prepared following an automotive two-component formulation. The resulting coatings displayed the capability to be healed following physical deformation by a thermal stimulus, and such a material has significant potential for end users. Various curing agents were employed, and resulted in variation of scratch resistance and re-healablity. …

Latent Cysteine Residues From Polymers Prepared Via Free And Controlled Radical Polymerizations, Douglas Vincent Amato

Master's Theses

One less commonly used “click” reaction is thiazolidine chemistry. Thiazolidine chemistry is a commonly used reaction used in biological systems because the reaction requires the presence of both cysteine (a common amino acid) and an aldehyde or ketone. If cysteine residues could be incorporated into a polymer then a variety of applications could be developed. Polymers containing free thiols (aka thiomers) have developed in the last decade to become great mucoadhesives. If there was a facile route to control the amount of free thiols along the polymer then more fine-tuned and potentially stronger adhesives could be made. For these reasons …

Preparation Of Organofluorine Compounds: Exploring Mono-, Di-, And Tri-Fluorination, Diandra M. Rudzinski

Master's Theses

Organofluorine compounds exhibit biological activity and have advantageous properties for drug design. Natural occurring fluorinated molecules are rare, demanding new synthetic methods for their preparation. A novel route to access trifluoromethyl ketones from Weinreb amide precursors is discussed. This is the first documented method for the use of the Ruppert-Prakash reagent, (trifluoromethyl)trimethylsilane, for the production of trifluoromethyl ketones from amide starting materials. This method is tolerant of aryl and alkyl substrates exhibited by their moderate to excellent yields. A discussion of the unusual reactivity of these amides, their selectivity for mono-trifluoromethylation, and other mono-, and di-fluorination attempts are reported.

Preparation Of Nitrogen-Containing Heterocycles Via Cyclization Of Pyridine-Tethered Organolithiums, Elizabeth Archer

Master's Theses

No abstract provided.

Synthesis Of Half-Loaded Nitroimidazole Indocyanine Green Dyes Attached To Carbon Nanotubes, Courtney L. Stanford

Master's Theses

Indocyanine green dye is the only FDA approved NIR fluorescent dye that can be used in humans. 2-Nitroimidazoles are very effective radiosensitizers, have low cytotoxicity, and target hypoxic tissue. By coupling the two together, hypoxic tumors can be targeted and imaged. Previous work has been done to couple 2-nitroimidazole to both sides of the indocyanine green dye. This work focuses on expanding that concept to couple 2-nitroimidazole to only one side of the dye, thus allowing for the other end to be available to couple to another compound, generating a half loaded 2-nitroimidazole indocyanine green dye. In theory, this half-loaded …

Fluorescence Tagging Of Marine Low Molecular Weight Carboxylic Acids, Brian C. Gismervik

Master's Theses

This thesis aims at the evaluation of the best amide bonding strategy that places a fluorescence aminomethyl coumarin tag onto a LMW organic acid in aqueous solution. A three-stage study was conducted. First, a suitable aminomethyl coumarin fluorophore was synthesized. Second, a library of acid-derivatized standards was synthesized for use in optimizing the anticipated HPLC separation of a mixture of LMW acids expected to be found in marine samples. Third, the aforementioned amide coupling strategies were screened to identify the most applicable method for our reaction conditions to the tagging of LMW organic acids in a large number of field …

The Development Of Transparent, Processable, Thermally-Responsive Coatings, Christopher David Roland

Master's Theses

Polymer matrices are commonly used as guest-host systems for organic chromophores for use in non-linear optical materials. The chromophores must be aligned or poled in an electric field in order to impart anisotropy and non-linear activity to the material. This poling process raises several issues, the two largest being the eventual relaxation of the chromophores back into random orientations due to brownian motion, and high molecular weight polymer matrices limiting chromophore mobility during poling. The prevention of this relaxation process is an area of significant interest, especially in applications that require long term coating stability and activity. In this study, …

Synthesis Of S-Ribosyl-L-Homocysteine And Analogs Modified At The Homocysteine-C3 Position, Ruoyi Liu

Master's Theses

Quorum sensing (QS) is a process of bacterial cell-to-cell communication that conveys population density information in order to coordinate gene expression to produce synchronized behaviors. QS regulates the expression of virulence genes in many species of bacteria; hence, the manipulation of QS pathways may lead to treatment options against many bacterial diseases. The LuxS enzyme converts S-ribosyl-L-homocysteine (SRH) into homocysteine (HCys) and 4(S),5-dihydroxypentane-2,3-dione (DPD), which is the precursor of autoinducer-2 (AI-2). Thus, inhibitors of LuxS could prevent QS by halting the conversion of SRH to AI-2 rendering the cell “uncommunicative”. This work shows the successful chemical synthesis …

The Synthesis Of A Homologous Series Of Alkyl Lumazines And Their Application To The Dispersion Of Carbon Nanotubes, William P. Kopcha

Master's Theses

In this thesis, the synthesis of a series of alkyl lumazine surfactants (LC_n) is reported. Their application to the dispersion of both CoMoCAT and HiPco single-walled carbon nanotubes (SWNTs) is examined in detail and the thermal stability and chirality selection properties of dispersions made with these surfactants were compared both between themselves and with an alkyl flavin surfactant (FC₁₂). Lumazine alkyl chain length exhibited some control over the quality and the quantity of SWNTs dispersed. LC₁₀ was deemed most appropriate for comparison with FC₁₂ based on considerations of solubility and nanotube individualization. …

Improved Synthesis Of The Longtailed Mealybug Pheromone, Johanna M. Bakonyi

Master's Theses

No abstract provided.

Part A: The Use Of Nonionic Associative Polymers For The Thickening And Emulsifying Of Personal Care Products/ Part B: The Synthesis Of A Manganese Sod Mimetic For Reactive Coatings, Mallory Lynn Mcmahon

Master's Theses

Part A

The use of nonionic associative thickeners was proposed for personal care applications. Various limitations of current rheology modifiers used in personal care were discussed. Nonionic associative polymers were examined as both thickeners and emulsifiers. The structure/property relationship for nonionic polymers and their ability to thicken and emulsify were fully examined. Results showed an increase in thickening efficiency for nonionic associative polymers with higher log(P) (partition coefficient) values. This was due to the formation of smaller aggregates and increased bridging between aggregates. The connection between oil polarity, log(P) of the associative polymer, and emulsion stability showed no relationship however; …

The Preparation Of Functional Surfaces, Philip Thomas Dirlam

Master's Theses

Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates in reversible manner. Glass slides and capillaries were functionalized with hydrophobic dieneophiles resulting in a non-wetting surface. A retro Diels-Alder reaction facilitated by the thermal treatment of the surface’s function to cleave the hydrophobic dieneophile and resulted in the fabrication of a hydrophilic surface. Contact angle (CA) measurements were used as preliminary measurements for monitoring the changes in surface energy exhibited during the initial hydrophobic state (CA - 70±3°), after attachment of the dieneophile creating a hydrophobic state (CA - 101±9°) followed by reestablishment of the hydrophilic state …

Towards The Synthesis Of Alpha-Aminogalactosylceramides, Shaun C. Christian

Master's Theses

No abstract provided.

The Synthesis Of Chiral Building Blocks Using Beta-Hydroxy Sulfoxide Dianions, Carla M. Edwards

Master's Theses

No abstract provided.

Potential Pharmaceutical Derivatives Of Β-Aminoethylpiperazine, Brian A. Dementi

Master's Theses

This thesis is concerned with the design and preparation of certain organic compounds which are expected to have medicinal properties. A discussion will be given which has essentially a two-fold purpose. The first is to discuss somewhat briefly the currently accepted method of rug design, and the second to show to what extent this method has been followed in the design of the compounds prepared.

Polyhydroxyamines, John Wotiz

Master's Theses

"The industrial growth of aliphatic chemistry, which has constituted one of the outstanding advances of recent years, has been almost entirely in the field of hydrocarbons and their simpler chlorine and oxygen derivatives… Representative of the aliphatic amines, possibly only the methyl, amyl and ethanol amines may be said to have been commercially available. And yet the field of aliphatic nitrogen chemistry possesses the greatest variety of known aliphatic compounds; there are at least several nitrogen analogs of each oxygen compound, often more stable, more definitely characterized, and more reactive chemically." Relatively few aminoalcohols, especially polyhydroxyaminoalcohols have been prepared. Due …

Some Reactions Of Creatinine With Certain Aliphatic Halogen Derivatives, Howard Edwards Wright Jr

Master's Theses

The object of this investigation is to prepare some derivatives of creatinine from certain aliphatic halogen compounds with emphasis on the nature of the reactions through which condensation takes place.