Organic Chemistry Commons^™

Efforts Towards The Asymmetric De Novo Synthesis Of Lanostanes And Euphanes, Htoo Tint Wai

Dartmouth College Ph.D Dissertations

Tetracyclic triterpenoids are ubiquitous in nature and biology, with members displaying a wide range of medically relevant properties and occupying rather distinct regions of chemical space. Members of this large class include well-known steroid hormones and sterols as well as structurally interesting subclasses such as lanostanes and euphanes, among others. Comprised of the tetracyclic skeleton with three stereodefined quaternary centers at ring-junction positions, lanostanes and euphanes present synthetic challenges that are different from those encountered in efforts targeting the structurally less complex steroid hormones. Lanostanes, in particular, stand as a historically important class of compounds as significant attention has been …

Visible Light-Assisted Deconstruction/Refunctionalization Of Strained And Unstrained N-Cycloalkylanilines, Elvis Duah Boateng

Graduate Theses and Dissertations

The exploitation of ring strain as a driving force to facilitate chemical reactions is a well-appreciated principle in organic chemistry. Of the strained carbocycles frequently explored in this respect, cyclopropane ring systems have drawn considerably more interest among synthetic chemists than their homolog, the cyclobutane ring systems, even though the strain energy of cyclobutane (26.7 kcal/mol) is similar to that of cyclopropane (27.5 kcal/mol). We have previously developed a [4+2] annulation reaction for the synthesis of aniline-substituted six-membered carbocycles under photoredox catalysis via the oxidative cleavage of N-cyclobutylanilines. The key reaction involved in this method is a ring-opening process of …

Folic Acid – Carbon Dots – Doxorubicin Nanoparticles As Cancer Theranostic, Michael Tetteh

Electronic Theses and Dissertations

This work focused on engineering bi-functionalized nanoparticles (NPs) based on carbon dots (CDs) to improve early cancer detection and treatment. Therefore, using folic acid (FA) as a targeting agent, the CDs were prepared to deliver high concentrations (HC) of doxorubicin (DOX) and gemcitabine (GEM) covalently and non-covalently to cancer cells. The prepared FA-CDs-DOX/GEM-HC NPs were characterized using ultraviolet-visible spectroscopy, fluorescence spectroscopy, and Fourier transform infrared spectroscopy. Assessment of the drug loading capacity (DLC) and drug loading efficiency (DLE) indicated that the non-covalent NPs have low DLC but high DLE compared to the relatively low DLE and high DLC of covalent …

Chromophoric Dissolved Organic Matter And Dissolved Organic Carbon In Lakes Across An Elevational Gradient From The Mountains To The Sea, Kyle Juetten, Angela L. Strecker, Aaron Harrison, Zachary Landram, Warren J. De Bruyn, Catherine D. Clark

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Dissolved organic matter (DOM) in lakes across elevation gradients is a complex function of topography, climate, vegetation coverage, land use, and lake properties. To examine sources and processing of DOM from sea level to mountain lakes (3–1,574 m), we measured dissolved organic carbon (DOC) concentrations and chromophoric dissolved organic matter (CDOM) optical properties, lake characteristics, and water quality parameters in 62 freshwater lakes in the Pacific Northwest, USA. Higher elevation lakes had lower DOC concentrations and absorbance. These lakes had higher forest cover and minimal wetlands in their watershed, in addition to low nutrients, water temperatures, and chlorophyll a in …

Alpha, Beta-Unsaturated Aldehydes: The Underrepresented Markers Of Disease., Saurin Sutaria

Electronic Theses and Dissertations

The peroxidation of unsaturated fatty acids is a widely recognized metabolic process that creates a complex mixture of volatile organic compounds including aldehydes. Elevated levels of reactive oxygen species in cancer cells promote random lipid peroxidation, which leads to an increase in a variety of aldehydes. Many of these volatile aldehydes are exhaled and are of interest as potential markers of disease. Chapter 1 presents a review of reported aldehydes in the exhaled breath of lung cancer patients. alpha,beta-Unsaturated aldehydes, detected primarily when derivatized during exhaled breath preconcentration, are underreported in the reviewed articles. Chapter 1 concludes with our hypothesis …

Hierarchical Structure And Material Integration For Electrocatalytic Co2 Reduction, Hamed Mehrabi

Graduate Theses and Dissertations

CO2 released by the combustion of fossil fuels is driving significant changes to the earth’sclimate. The natural cycle for removing CO2 from the atmosphere, namely photosynthesis, cannot keep up with the rate at which it is being added. Developing engineering approaches to remove CO2 from the atmosphere is becoming essential to reduce these effects. Removal leads to further issues of carbon sequestration and favorable CO2 reuse strategies, including the electrochemical transformation of recovered CO2 to useful products such as fuels and materials. Copper is an important electrocatalyst for the CO2 reduction reaction (CO2RR) because of its unique capability for producing …

A Study On Interactions Between Metal-Organic Frameworks And Biological Materials, Josh Phipps

Graduate Theses and Dissertations

Metal-organic frameworks or MOFs are an extremely useful tool in many areas of applications. Their popularity in recent years has arisen from their high efficiency in catalytic chemical reactions. This is made possible due to their porous interior and the ability of the MOFs components to be functionalized. These same traits make MOFs excellent for use in protein encapsulation or immobilization and have the potential to become excellent drug carriers. Their development in this utilization has been limited dramatically compared to MOFs chemical applications. This is due in part to the nature of biological processes taking longer to study, but …

The Binding Of The Micronutrient Transition Metals To The Alkylation Products Of Chemical Warfare Agent, Sulfur Mustard, And Thiols, Potentially Giving New Understanding To Physiological Effects Of Exposure And Increased Toxicity, Colin O'Donnell

Graduate Theses and Dissertations

Model compounds, 3,6,9-trithaiundecane-1,11-dicarboxylic acid (TTDPA), 2,5,8-trithianonane-1,9-dicarboxylic acid (TTDAA), and 1,11-diamide-3,6,9-trithiaundecane (TTDAce), closely related to the adducts formed by cysteine alkylation of the chemical weapon, sulfur mustard, were synthesized. It is shown that TTDPA forms complexes with key metal micronutrients: copper, nickel, cobalt, manganese, and zinc. Though the strength of binding to TTDPA varies, the complexes in many cases precipitate from solution. All metals produced a visible precipitate upon interaction with TTDPA under the conditions tested, however only Cu2+, Mn2+, and Zn2+ produced enough to be measured. The mass of formed precipitate seemed to peak at an equimolar ratio of TTDPA …

Synthetic Amphiphiles As Antibiotic Potentiators, Helena Spikes

Dissertations

Antibiotic resistance has become a massive threat to modern medicine. Bacteria acquire resistance either through genetic mutations or mobile genetic elements, such as plasmids. The growing resistance crisis is exacerbated by over-prescription of antibiotics and improper use. As antimicrobial resistance becomes more widespread, superbugs (bacteria resistant to more than one class of drug) have evolved. Since few new drugs reach clinical trials and even fewer are approved by the FDA, we must find a way to make existing drugs more potent. One technique to accomplish this is by using combination therapy. By administering two or more drugs at a time, …

Technical Note: On Uncertainties In Plant Water Isotopic Composition Following Extraction By Cryogenic Vacuum Distillation, Haoyu Diao, Philipp Schuler, Gregory R. Goldsmith, Rolf T. W. Siegwolf, Matthias Saurer, Marco M. Lehmann

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Recent studies have challenged the interpretation of plant water isotopes obtained through cryogenic vacuum distillation (CVD) based on observations of a large 2H fractionation. These studies have hypothesized the existence of an H-atom exchange between water and organic tissue during CVD extraction with the magnitude of H exchange related to relative water content of the sample; however, clear evidence is lacking. Here, we systematically tested the uncertainties in the isotopic composition of CVD-extracted water by conducting a series of incubation and rehydration experiments using isotopically depleted water, water at natural isotope abundance, woody materials with exchangeable H, and organic materials …

Study On New Strategy Toward Gold(I/Iii) Redox Catalysis, Shuyao Zhang

USF Tampa Graduate Theses and Dissertations

This dissertation mainly contains three parts: 1) the study of ligand assisted gold oxidative addition toward aryl iodide to achieve the alkene difunctionalization. 2) The selective arylation reaction via electrochemical anode oxidation promoted gold redox chemistry. 3) The π acid reactivity of gold redox chemistry under electrochemistry conditions.

In the first part, the gold-catalyzed intermolecular oxyarylation of alkene is reported. This work employed the oxidative addition of aryl iodide to Me-DalphosAu+ for the formation of Au(III)-Ar intermediate. The better binding ability of alkene over O nucleophiles ensured the success of intermolecular oxyarylation, giving desired products with broad substrate scope and …

Ferrocenium Salt Aided Substitution Reactions And Synthesis Of Glycosylated Curcumin Derivatives, Deva Saroja Talasila

Dissertations

Organic synthesis has been significantly advanced with the employment of transition metal complexes. The discovery of transition metal catalysts provided the synthetic community with powerful tools for accelerating reactions and making them more selective and efficient. Many chemical reactions do not happen without a catalyst.

Iron-based catalysts have several advantages for the chemical industry because it is a non-toxic and ecologically friendly metal. Our group previously found that ferrocenium cations with a 3+ oxidation state of iron-catalyzed propargylic substitution reactions at low temperatures. The sandwich structure of ferrocenes allows substituents to be introduced on the cyclopentadienyl rings, which allows for …

Design, Synthesis, And Characterization Of Nqo1-Activatable Luminescent Probes, Ovini Vionika Weeratung Kankanamge

LSU Doctoral Dissertations

Being among the top ten causes of death, cancer has constantly been able to grab the attention of researchers all around the world. While several treatment methods prevail to cure cancer, the seriousness of this medical condition requires continuous work in the development of novel treatments as well as scientific advancements in order to achieve early detection of the disease. Luminescence imaging is an emerging field in both diagnosis of diseases, as well as a means to provide guidance in clinical surgeries. While there exist only a few contrasting agents approved by the Food and Drug Administration, the need for …

Synthesis, Characterization And Cell Viability Of Novel Tripodal Amines, Kinsley Lupton

Honors College Theses

Cancer, over the years, has become a much more prevalent focus for the scientific community. Organizations and laboratories all over the world have spent countless hours searching for a cure, trying to learn more about what makes cancer so powerful and what is the best way to stop its growth. Iron-chelation drugs were already on the market, and it was shown that they did have the ability to act as both iron-chelators and anticancer drugs. Most of these iron-chelating drugs are not as effective at killing cancer cells as the medical field desires. Novel iron-chelating tris-indolyl derivatives, GSO2, GSO4 and …

Synthesis And Characterization Of Unique Pyridazines, William Hobbs

Senior Honors Theses

The field of semiconductive organic chemistry is vast and expanding as numerous applications are being discovered for semiconductors. The research reported in this thesis focuses on the synthesis and characterization of three pyridazines. Pyridazines are organic heterocyclic aromatic semiconductors containing nitrogen and are planar in structure. The three pyridazine compounds were successfully isolated as evidenced by a high percent yield and then characterized by melting point and infrared spectroscopy. The research goal was achieved as a small library of pyridazines was compiled to be further analyzed concerning their potential within various applications in the electronic and industrial world.

Design Of Possible Organic Photovoltaic Compounds And Their Initial Computational Assessment, Albert Ochoa Castillo, Joshua Smith

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

The excessive use of fossil fuels has surged the need for alternative energy sources, such as solar energy. Organic photovoltaic (OPV) cells can potentially be an alternative to silicon solar cells. OPV compounds are carbon-based and use organic electronics as a semiconductor to produce electricity from the sun. There is a large interest in OPV cells because they are strong absorbers and come at a low cost of synthesis. Herein, possible OPV compounds were designed, and theoretical computations were done to assess their efficiency. Density Functional Theory was used to calculate the HOMO-LUMO gap of the compounds designed. Semiconductors such …

Novel Thioglycosides As Versatile Glycosyl Donors For Oligosaccharide Synthesis, Ganesh Shrestha

Dissertations

This thesis is dedicated to the development of new methodologies for efficient synthesis of carbohydrate building blocks and their application to chemical glycosylation. S-Indolyl (SIn) anomeric moiety was investigated as a new leaving group. Understanding of the reaction pathways for the SIn moiety activation was achieved via the extended mechanistic study. The activation profile of indolylthio glycosides required large excess of activators. This drawback was partially addressed by the development of N-alkylated SInR derivatives. The activation process was studied by NMR and the increased understanding of the mechanism led to a discovery of different activation pathways taking place with …

Synthesis Of Carbon Nanohoops And Macrocycles Via Alkyne Metathesis, Xin Zhou

LSU Doctoral Dissertations

Cycloparaphenyleneacetylene (CPPA) and cycloparaphenylene (CPP) are called carbon nanohoops; they are fully conjugated macrocycles with radially oriented aromatic groups. Though many syntheses of CPPA and CPP were reported, in the macrocyclization step, the yields were usually not satisfying, as the reactions were irreversible. Our group utilizes alkyne metathesis to address this problem. Chapter 1 provides backgrounds and an introduction to the carbon nanohoops and alkyne metathesis.

Chapter 2 details the synthesis of the [3]CPP⁴A and [3]CPP⁵A, with good macrocyclization yields via alkyne metathesis. This study showed the error-correction ability of alkyne metathesis, especially with nonsymmetric substrates. …

Synthesis Of Novel Dna-Binding Polyamides To Prevent Cancer-Related Gene Overexpression, Huy Q. Nguyen

Dissertations

Pyrrole-imidazole polyamides (PIPs) are nanomolecular compounds designed to fit in the tight space of DNA minor grooves. As analogs of Netropsin and Distamycin A, PIPs are specifically designed to recognize the base pairs of DNA sequences. PIPs have many biological applications, such as regulating gene expression, biochemistry pathway regulations, and suppressing the development of cancer cells. SETMAR gene is the chimeric fusion of the SET domain with the mariner transposase. Its protein (Metnase) has functions involving DNA repairs in the NHEJ pathway, regulating gene expression, DNA decatenation, etc. Despite not having an active transposable element, SETMAR still has an unknown …

Solvation Of Large Polycyclic Aromatic Hydrocarbons In Helium: Cationic And Anionic Hexabenzocoronene, Miriam Kappe, Florent Calvo, Johannes Schöntag, Holger F. Bettinger, Serge Krasnokutski, Martin Kuhn, Elisabeth Gruber, Fabio Zappa, Paul Scheier, Olof E. Echt

Faculty Publications

The adsorption of helium on charged hexabenzocoronene (Hbc, C₄₂H₁₈), a planar polycyclic aromatic hydrocarbon (PAH) molecule of D_6h symmetry, is investigated by a combination of high-resolution mass spectrometry and classical and quantum computational methods. The ion abundance of He_nHbc⁺ complexes versus size n features prominent local anomalies at n = 14, 38, 68, 82, and a weak one at 26, indicating that for these “magic” sizes the helium evaporation energies are relatively large. Surprisingly, mass spectra of anionic He_nHbc^– complexes feature a different set of anomalies, namely at …