Chemistry Commons^™

Catalytic Activity Of Tungsten-Dioxo And Tungsten-Diimido Complexes, Kayla Denike

Graduate Theses and Dissertations

Due to the significant decline in the availability of petrochemical resources and the increasing demand for the useful olefin mixtures extracted from oil, a sustainable and efficient alternative to these materials has become vital. Fortunately, renewable biomass derived materials may serve as a sustainable solution to the limited resources problem. Molecules derived from the degradation of biomasses are highly oxygenated and highly functionalized. Developing processes to efficiently defunctionalize these oxygen-rich materials will lead to potential up-conversion to carbon chemicals. Homogeneous catalytic deoxygenation processes present an opportunity to access valuable carbon commodity chemicals from biomass derived polyols. This dissertation details the …

Designing Dynamic And Degradable Polymeric Materials With Thiol-X Chemistries, Reese Sloan

Dissertations

With plastic production poised to increase in coming years, there arises a need to develop new polymeric materials designed to combat the global pollution crisis. A commonly utilized approach in addressing this challenge is to employ a responsive functional moiety into the polymer architecture. Thiol-X reactions, a commonly utilized class of “click” reactions, have garnered broad implementation in new stimuli-responsive materials. This work specifically focuses on utilizing radical-mediated thiol-ene coupling and base-catalyzed thiol-isocyanate reactions to develop a library of ternary thiol-ene/thiourethane covalent adaptable networks (CANs) and hydrolytically labile poly(thioether ketal) thermoplastics. CANs are a class of network materials capable of …

Novel Synthetic Routes To Functionalized Tetrahydrobenzofurans And Chiral A-Quaternary A'-Hydroxy Ketones, Fatimat Oluwayemisi Badmus

LSU Doctoral Dissertations

Various naturally occurring organic compounds possess unique biological activities and have found exclusive applications in pharmaceuticals and agrochemicals. Their undeniable significance has necessitated the discovery and development of novel reactions that unveil advanced chemical transformations. This dissertation will detail our new approaches towards the synthesis of functionalized tetrahydrobenzofurans and chiral α-quaternary α’-hydroxy ketones. The transformations in these approaches were enabled by the chemistries of oxyallyl cations, Grignard reaction and Claisen rearrangement.

Chapter 1 introduces oxyallyl cations, their generation, reactions and applications. Our previous contributions, in the form of silyloxyallyl cations, to solve the regioselective issues associated with unsymmetrical oxyallyl cations …

Development Of 1,2-Cis-Selective Glycosylation Protocols And Multistep Synthesis Of Glycans From Acinetobacter Baumannii., Dancan Kamau Njeri

LSU Doctoral Dissertations

Access to various oligosaccharides has been made possible by glycosylation reactions. This is mainly through chemical synthesis and enzymatic approaches. Herein, I talk about glycosylation through chemical synthesis. In general, glycosylation reactions lead to a mixture of 1,2-cis and 1,2-trans stereoisomers. Stereoselective access to 1,2-trans isomer is highly developed; it efficiently relies on neighboring group participation. However, efficient access to 1,2-cis selective glycosylation is still a work in progress. In Chapter 1, I highlight notable efforts developed so far that address the 1,2-cis selectivity challenge in glycosylation.

In Chapter 2, I demonstrate how I improved …

Polychlorinated Organic Contaminants In Baleen From North Pacific Ocean Whales, Briana R. Coulter

All HCAS Student Capstones, Theses, and Dissertations

Persistent organic pollutants (POP) have been detected and analyzed in various baleen whale tissues (blubber, muscles, liver, etc.) This study concentrated on detecting 7 polychlorinated biphenyls (PCB) and 14 organochlorine pesticides from baleen, a baleen whale tissue never before analyzed for POPs. These data were used to investigate temporal and geographic trends by sampling at every 1 cm interval along the length of the baleen plate. Four species of baleen whales stranded in the North Pacific Ocean were included in this study: gray (n=2), humpback (n=2), minke (n=1), and blue (n=1) whales. Organic contaminant concentrations were analyzed with respect to …

Calcium Bistriflimide-Mediated Sulfur (Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Nicholas Ball, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, O Maduka Ogba

Pomona Faculty Publications and Research

We report a mechanistic investigation of calcium bistriflimide-mediated sulfur(VI)–fluoride exchange (SuFEx) between sulfonyl fluorides and amines. We determine the likely pre-activation resting state─a calcium bistriflimide complex with ligated amines─thus allowing for corroborated calculation of the SuFEx activation barrier at ∼21 kcal/mol, compared to 21.5 ± 0.14 kcal/mol derived via kinetics experiments. Transition state analysis revealed: (1) a two-point calcium-substrate contact that activates the sulfur(VI) center and stabilizes the leaving fluoride and (2) a 1,4-diazabicyclo[2.2.2]octane additive that provides Brønsted-base activation of the nucleophilic amine. Stable Ca–F complexes upon sulfonamide formation are likely contributors to inhibited catalytic turnover, and a proof-of-principle redesign …

Studies In The Use Of 1,1'-Di(1-Hydroxyethyl)Ferrocene As A Flame Retardant For Polyurethanes, Chanel Yeary

Electronic Theses & Dissertations

Significant research in non-toxic flame retardants (FR) has been performed in recent years since the dangerous consequences of halogenated FR were found. As early as the 1970’s, carcinogenic the side effects of halogenated compounds were being acknowledged. Since the early 2000’s halogenated FRs began being phased out of use due to these negative side effects. Since then, significant research has been exploring alternative effective flame retardants. Ferrocene (Fc) is a promising alternative to halogenated FRs due to its nontoxicity and FR properties. This research will report on the synthesis of 1,1’-di(1-hydoxyethyl) ferrocene (DHEFc) and its incorporation into a polyurethane. A …

The Synthesis Of Deuterated Isohumulones For Use As Internal Standards In Lc-Ms Stable Isotope Dilution Assays, Patrick Gleason, Bruce Hamper Dr.

Undergraduate Research Symposium

Humulones are compounds that are prevalent in the hops flowers (Humulus Lupulus) used in beer brewing. These compounds undergo isomerization during the brewing process, and the resulting isohumulones are considered to be the primary contributors to the bitter flavors present in beer. As such, quantifying their presence, and the relative presence of their homologs(n-, co-, ad-), is of great importance in the characterization of beer. In this effort, one of the homologs of humulone (co) was isolated before being subsequently isomerized and deuterated for the purpose of analyzing beer by stable isotope dilution assay mass spectrometry(SIDA-MS). The addition of this …

Synthesis Of Diaryl And Alkyl-Aryl Ethers Via Diaryl Iodonium Reagents, Rory Tennessee Gallagher

Dissertations and Theses

Substituted benzenoid rings are a prevalent motif in many industries including high tech, agrochemicals, and pharmaceuticals. As a result, the arylation of chemical compounds is a highly sought-after chemical transformation. There are many literature methods to achieve this chemical transformation, nucleophilic aromatic substitution and transition metal catalysis are both widely used and studied. Diaryliodonium salt mediated chemistry is an attractive alternative to these methods as it does not require the expensive toxic metals and designer ligands of transition metal catalysis and is not restricted to electron deficient aryl rings with specific substitution patterns like nucleophilic aromatic substitution.

Many diaryliodonium salt …

Synthesis, Characterization, And Bioactivity Of 3-Substituted Coumarins As An Undergraduate Project, Karsen King, Nicholas Campbell, Ronald Okoth, Wathsala Medawala

Georgia Journal of Science

Coumarins are an important class of phytochemicals, a chemical defense presumed to be secreted by plants. More recently, Coumarins have gathered popularity for their basis in anti-cancer agents. This paper dives into the organic synthesis of two 3-substituted coumarins from o-vanillin using the Knoevenagel condensation reaction. The 3-substituted coumarin were characterized using melting point analysis, ¹H-NMR, and UV-Vis spectroscopy. In addition, the anticancer activity of synthesized 3-substituted coumarin compounds were assayed against topoisomeraseIIα, which is the target enzyme of FDA approved anti-cancer drug etoposide since it is an active enzyme in cancer cell replication. The demonstrated procedures can be …

Trichloroacetimidates As Outstanding Electrophiles For The Carbon-Nitrogen, Carbon-Oxygen And Carbon-Carbon Bonds Formation And Synthetic Studies Of Protein Phosphatase-5 (Pp5) Small Molecule Inhibitors, Nilamber Mate

Dissertations - ALL

Trichloroacetimidates have been previously used for glycosidic bond formation in carbohydrate chemistry and in Friedel-Craft reactions. Traditionally, trichloroacetimidates had be synthesized using an alcohol and strongly basic conditions, but in recent years milder preparation methods have been reported. Given the ease of preparation of these versatile reagents, their chemistry has been explored intensely in recent years. While few reported methods suggest they can react under promoter free conditions, activation by Lewis or Brønsted acid leads to a formation of a carbocation from benzylic trichloroacetimidates. Work described herein makes use of these convenient carbocation precursors for new reactions.Isatin is an ambidentate …

Steps Toward The Total Synthesis Of The Chrysosporazine Family, Katie Kaczynski

Electronic Theses and Dissertations

Cancer is one of the leading causes of death worldwide, with 19.3 million new cancer cases and 10 million deaths in 2020 alone. In the United States, cancer was the second leading cause of death after heart disease. One of the reasons that cancer is so frequently terminal is that cancerous cells frequently develop multidrug resistance (MDR) to frontline chemotherapeutical treatments, resulting in cancers cannot be treated and are inevitably fatal. This makes the discovery of ways to combat MDR so important in the treatment of cancer. The chrysosporazines are a family of recently discovered (2019) natural products that have …

Synthesis Of Conjugated Polymers From Xanthene And Alkenyl Flanked Diketopyrrolopyrrole Monomers For High-Performance Electronic Applications., Ranganath Wijesinghe Wahalathantrige Don

Theses and Dissertations

In traditional electronics, inorganic materials such as silicon and germanium are used as semiconductors due to their outstanding semiconducting properties. Unfortunately, inorganic materials are rigid due to their high crystalline nature, and processing these materials is complex and expensive. Furthermore, traditional semiconducting materials do not have favorable mechanical properties in applications such as wearable devices and large-area applications with complicated shapes. Conjugated conducting polymers (CCPs) are being explored as alternative materials to conventional semiconductors due to their mechanical properties and high conductivity. CCPs offer properties such as solution and low-temperature processability, flexibility, thermal and optical properties that traditional semiconductors could …

A Modular Synthesis Of Processable And Thermally Stable Semi-Fluorinated Aryl Ether Polymers Via Step-Growth Polymerization Of Fluoroalkenes, Ketki Eknath Shelar

Theses and Dissertations

Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The …

Prediction And Confirmation Of A Switch-Like Region Within The N-Terminal Domain Of Hsirt1, Angelina T. Huynh, Thi-Tina N. Nguyen, Carina A. Villegas, Saira Montemorso, Benjamin Strauss, Richard A. Pearson, Jason G. Graham, Jonathan Oribello, Rohit Suresh, Brooke Lustig, Ningkun Wang

Faculty Research, Scholarly, and Creative Activity

Many proteins display conformational changes resulting from allosteric regulation. Often only a few residues are crucial in conveying these structural and functional allosteric changes. These regions that undergo a significant change in structure upon receiving an input signal, such as molecular recognition, are defined as switch- like regions. Identifying these key residues within switch-like regions can help elucidate the mechanism of allosteric regulation and provide guidance for synthetic regulation. In this study, we combine a novel computational workflow with biochemical methods to identify a switch-like region in the N-terminal domain of human SIRT1 (hSIRT1), a lysine deacetylase that plays important …

Synthesis And Characterization Of Sustainable And Biobased Copolymers From Lignocellulosic, Guery Saenz

Theses and Dissertations

Natural compounds have been the primary resource used to produce polymeric materials by humankind since the mid-1900s. Yet, progress in bio-based polymers from renewable feedstock has encountered some obstacles, mainly due to the low prices of petroleum-based monomers, compared to natural and sustainable materials. However, most commodity plastics are non-degradable materials, and solid plastic waste accumulation adversely affects the environment. As the world population is growing and demanding chemicals, energy, and plastics materials, polymer research is focusing on synthesizing bio-based and degradable polymers. Thus, biomass, a sustainable and inexpensive feedstock, is highly appropriate for designing alternative thermoplastics that are degradable …

Influence Of Citrate And Phosphate On The Adsorption Of Adenosine-5′-Monophosphate At The Hematite Water Interface, Sudipta Rakshit, Avedananda Ray, Ali Taheri, Michael E. Essington

Agricultural and Environmental Sciences Faculty Research

Nucleic acid derived organic phosphorus (Po) is an important source of plant available P when degraded to inorganic phosphate (P(V)i). It is known that when nucleic acids or components are adsorbed on mineral surfaces, the enzymatic degradation is hindered or delayed. Thus, understanding adsorption/desorption mechanisms of nucleic acids and their derivatives are key to assess the biogeochemical pathways of Po cycling. Here we report adsorption mechanisms of adenosine-5′-monophosphate (AMP) on hematite, a common iron oxide mineral, under various solution properties using macroscopic and in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic probes. The effects of citrate, mimicking organic …

Synthetic Investigations In Chemical Probe Development Part 1: Design And Synthesis Of Novel Triton X-405 Adenosine Conjugates; Part 2: Synthesis Of 2,8-Dihydroxychrysene, Rachel Irene Hammond

Honors Theses

Although not drugs themselves, chemical probes are a necessary tool in biomedical research for the interrogation of biological systems. In the present synthetic investigation, two chemical probes were developed – a Triton X-405 adenosine conjugate (TX-405A) and 2,8-dihydroxychrysene. The designed TX-405A conjugate was generated in four steps through tosylation and amination of TX-405 such that EDC-coupling of TX-amine with 2’,3’-Isopropylidene adenosine-5’-carboxylic acid afforded TX-405A following acetonide deprotection. The development of TX-405A represents the first report of the synthesis and utilization of a detergent-linked dosimeter. The synthesis of 2,8-dihydroxychrysene provided an in-depth exploration on the unique reactivity of chrysene. The desired …

C-H On The Oxo Ferryl Wheel: Comparison Of Pyridine And Imidazole-Substituted Ligands For C-H Activation And Functionalization, Elizabeth Milem

Electronic Theses and Dissertations

The selective and efficient transformation of hydrocarbon feedstocks is of high value for industry and research. While Shilov-type organometallic methods have facilitated this goal, systems designed after nature’s use of cheap and abundant iron-based enzymes are desired for wider-scale applications. This work establishes hydrocarbon oxidation efficiency of synthetic pyridine-based ligands (BPMEN, BPMPN) compared to commercially available TPA with in situ generated catalysts. Literature studies of traditionally synthesized BPMEN systems and initial in situ studies offered evidence for enhanced reactivity (TON) as compared to TPA. Expansion to a propyl backbone to produce BPMPN tested the increased chelate ring size’s impact on …

Nitro-Aromatic Polymers For Conversion-Style Battery Cathodic Materials, Brady P. Samuelson

Honors Thesis

The development of organic electrode materials in rechargeable batteries has seen a resurgence in recent decades. This spike in interest is mostly due to the increased investments in renewable energy sources, grid-scale energy storage, and the rapid transition to electric vehicles. Current lithium battery cathode materials typically use some form of lithium metal oxide (specific capacity: 272 mAh g^-1 which has problems with limited capacity, thermal runaway, and an unreliable supply chain. Our research group’s solution involves investigating new lightweight, organic redox groups combined with a conductive polymer backbone to serve as a possible replacement for the cathode in …

Synthesis And Transition Metal-Catalyzed Coupling Of A-Chloro-B-Lactones, Tyler Lynn

Honors Projects

No abstract provided.

Dicyanobenzothiadiazole-Based Organic Dye As A Visible Light Absorbing Strong Photoinduced Oxidant With A 16 Microsecond Long-Lived Excited State, Ivy Li

Honors Theses

Strong photoinduced oxidants are important to organic synthesis and solar energy conversion to chemical fuels or electric. For these applications, visible light absorption is important to solar energy conversion and long-lived excited states are needed to drive catalysis. With respect to these desirable qualities, a series of five 5,6-dicyano[2,1,3]benzothiadiazole ((CN)₂BTD) dyes are examined as organic chromophores that can serve as strong photooxidants in catalytic systems. The series utilizes a ((CN)₂BTD) core with aryl groups on the periphery varying electron donation strengths relative to the core. The dyes are studied via both steady-state and transient absorption and …

Analysis Of The Light Responsive Azobenzene Peptide Nucleic Acid Duplexes, Kat Nguyen

Honors College Theses

Peptide nucleic acids (PNAs) are oligonucleotide analogues in which the sugar-phosphate backbone has been replaced by a pseudopeptide skeleton. Since PNAs use the natural nucleobases (Adenine, Thymine, Cytosine, Uracil, and Guanine) found in either DNA and/or RNA, they are able to hybridize according to Watson-Crick base-pairing to form duplexes. PNA is a promising therapeutic agent because they can function as antigene or antisense chemical agents. To further enhance their utility, we aim to incorporate a photoswitchable moiety using azobenzene. Here, we report the results of the synthesis and purification of a photoswitchable 11 mer PNA along with initial characterization efforts.

Friedel-Crafts Alkylation Of Benzene With A Superacid Catalyst, Josh T. Cutright

Undergraduate Honors Theses

Long-chain alkylbenzenes are industrially synthesized precursors to commercial surfactants such as laundry detergent. The currently used catalysts in the processes of their synthesis are corrosive and harmful to the environment. These problems can be avoided utilizing heterogeneous highly acidic catalysts. Solid catalysts do not corrode equipment and are relatively simple to remove from the post-reaction mixture. Phosphotungstic acid (PTA) supported on silica gel could be a possible catalyst due to its high acidity with an estimated pKa ≈ -13. The catalyst PTA-SiO₂ was prepared via the sol-gel method to covalently embed it in a silica support. The catalyst was …

The Design Of A Efficient Production And Purification Of Fibroblast Growth Factor 2, Mandeep Kaur

Chemistry & Biochemistry Undergraduate Honors Theses

Chronic wounds pose a major problem in the United States with an estimate of twenty-five million dollars a year spent on associated treatments. Growth factors can be used as a potential treatment for chronic wounds since they promote cell proliferation and angiogenesis. This study employs one specific growth factor, fibroblast growth factor 2 (FGF2) so that it could potentially be used in future treatment. Wild-type FGF2 is thermally unstable, and it has a mean elimination time of 7.6 hours. This study attempted to improve upon its stability through a mutation on the heparin binding loop. The mutation performed was K134E. …

Investigation Of The Analytical Utility Of The Inductively Coupled Plasma Mass Spectrometer (Icp-Ms) For The Quantification Of Proteins Via Lanthanide Labeling, Caitlin Elizabeth Dunlap

Undergraduate Honors Thesis Collection

The discovery and ability to provide an absolute concentration of biomarkers in the body can facilitate early diagnoses of diseases. This information can also be used for more accurate and unique treatments for those patients. While major advances in molecular mass spectrometry allows for a sensitive identification of these biomarkers, they are limited to only four orders of magnitude in their dynamic ranges. Due to this, detection and quantitation of low abundant proteins, which tend to make up these vital biomarkers, is very difficult. On the other hand, ICP-MS offers a wider dynamic range (up to 12 orders of magnitude) …

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

All Dissertations

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) …

Ketone Hydrosilylation Studies Using A Carbodiphosphorane Catalyst, Liam Sullivan, Allegra Liberman-Martin

Student Scholar Symposium Abstracts and Posters

The objective of this research is to discover an effective, safe, and low-cost catalyst for ketone hydrosilylation reactions, which involve the addition of a silicon–hydrogen bond across a C=O double bond. Improving catalyst efficiency could benefit the organic synthesis industry, as carbonyl hydrosilylation is used industrially in the synthesis of alcohol products. Use of the carbodiphosphorane catalyst as a replacement for toxic heavy-metal-containing catalysts could reduce waste and emissions harmful to the environment, while also providing an alternative means for accomplishing ketone reduction. Using a cyclic carbodiphosphorane catalyst, we have compared catalytic activity toward acetophenone hydrosilylation for a range of …

Understanding Interfacial Reactions Initiating On Electrode Materials For Energy Storage Technologies, Jingnan Li

Graduate Theses and Dissertations

Since the first generation of lithium-ion batteries featured lithium cobalt oxide cathode and carbon anode commercialized in the 1990s, the high-capacity materials with lower cost are in demand to further increase the battery energy density. Lithium metal and silicon anode are promising high-capacity anode materials to achieve next-generation lithium batteries. However, both the materials actively react in electrolytes and suffer from dramatic volume change. Therefore, a reliable passivation layer at the electrolyte/electrode interphase (i.e., solid electrolyte interphase, or “SEI”) is required to support the long-term cycling of both materials. Cetrimonium hydro fluoride (CTAHF2) has been proposed and synthesized as an …

Understanding The Transition From General To Organic Chemistry, Hannah Chan

Student Scholar Symposium Abstracts and Posters

Organic chemistry is commonly known to have high failure rates and regarded as one of the most difficult courses offered in undergrad. This study assessed whether a modified general chemistry curriculum allowing for more time focused on foundational organic chemistry concepts in general chemistry can improve students’ grade outcome and/or self efficacy when transitioning from general to organic chemistry courses. Two separate variables were tested: grade outcome and self efficacy. Using an independent sample t-test, a comparison of the two groups (modified versus traditional general chemistry) was performed. Grades were assessed by giving students four questions (out of 4 points …