Organic Chemistry Commons^™

Converting Hydrazone-Based Photoswitches Into Functional Materials, Sirun Yang

Dartmouth College Ph.D Dissertations

The development of new classes of molecular switches with enhanced performance and brand-new functionalities enables practitioners to push the frontiers of adaptive materials. In the realm of photoswitches, the bistability of hydrazones (i.e., molecules that incorporate the C=N-NH functional group) allows for the kinetic trapping of polymer and supramolecular assemblies resulting in multistate actuation and emergent phenomena that are not tractable with other photoswitches. This property has transformed hydrazone photoswitches into powerful tools that can be used in understanding fundamental molecular interactions and how to apply them in modulating the physicochemical properties of materials.

Progressing from disordered to …

Material Analysis And Conservation Treatment Of Louise Nevelson’S Sculpture Dawn’S Image, Night, Kaela Nurmi

Art Conservation Master's Projects

Louise Nevelson’s large-scale, matte black assemblage sculpture Dawn’s Image, Night, 1969, is owned by and currently on display at SUNY Buffalo State College. The paint layers exhibited significant amounts of dust, some damages, vandalism, and unsightly fingerprints. Extensive scientific analysis and archival research were utilized to design an appropriate treatment and long-term preservation plan. Methods of analysis include: Fourier transform infrared spectroscopy, pyrolysis-gas chromatography-mass spectrometry, microchemical testing, and xray fluorescence spectroscopy. The project also addresses the ethical considerations surrounding the prior removal of original components for safety considerations, repainting as a possible treatment, and the overall obstacles of treating a …

Catalyzed And Uncatalyzed N1 Modifications Of Inosine And 2'-Deoxyinosine And N-Directed Remote Aroylation Of C6-Aryl Purine Nucleosides, Casina Malinchak

Dissertations, Theses, and Capstone Projects

Nucleosides, and their analogs, are important biological molecules that are integral to cell signaling, metabolism, and DNA and RNA synthesis. Because of their presence in all living systems, they are ideal candidates for drug development. Although extensive literature exists on the alkylation and alkenylation at N1 of inosine and 2’-deoxyinosine, few reports have been published on arylation at this position. Using diaryliodonium salts, a copper-catalyzed method has been developed for the efficient N1-arylation of silyl group-protected inosine and 2’-deoxyinosine. Diaryliodonium salts are easily synthesized and allow for the use of mild conditions to promote transfer of aryl groups to the …

Sensitized Photooxidation Of Prenylated Compounds: Mechanisms Of Downstream Dark Effects And Phototoxicity Priming, Shakeela Jabeen

Dissertations, Theses, and Capstone Projects

This thesis consists of four chapters as detailed below.

Chapter 1 discusses a singlet oxygen priming mechanism. Airborne singlet oxygen derived from photosensitization of triplet dioxygen is shown to react with an alkene surfactant (8-methylnon-7-ene-1 sulfonate) leading to ‘ene’ hydroperoxides that in the dark inactivate planktonic E. coli. The ‘ene’ hydroperoxide photoproducts are not toxic on their own, but they become toxic after the bacteria are pretreated with singlet oxygen. The total quenching rate constant (k_T) of singlet oxygen of the alkene surfactant was measured to be 1.1 × 10⁶ M⁻¹ s^{− …}

Visible Light Photocatalysis Of Organic Reactions In H2o, Sankarsan Biswas

Dissertations, Theses, and Capstone Projects

Visible-light photocatalysis in H₂O provides an attractive, green alternative to typical organic synthesis, which often involves toxic solvents, metal catalysts, and large energy demands. Hence, there is a growing need for an efficient photocatalytic methods that use either aqueous media as a solvent or can proceed solvent-free. However, commercially available photocatalysts do not work well for aqueous photocatalysis. Supramolecular systems in particular have been explored recently to address these issues associated with aqueous photocatalysis. Chapter 1 will review recent advances in aqueous supramolecular photocatalysis with examples of different supramolecular systems and how they have addressed some of the …

Lc-Ms/Tof Characterization And Stability Study Of Artesunate In Different Solvent Systems, Kogila Oke, Amos Mugweru

College of Science & Mathematics Departmental Research

Artemisinin (ART) is a sesquiterpene lactone and a popular malaria drug used in many parts of the world. Artesunate (ARTS) is a semi-synthetic derivative of ART with improved pharmacokinetic properties. However, the half-life of ARTS is less than an hour in vivo. The analysis of this drug in vitro in different solvent systems using LC-MS/TOF showed a solvent-driven breakdown. ARTS breakdown formed several derivatives, including dihydroartemisinin (DHA), artemether (ARTM) and DHA-dimer among others, at different rates in different solvent composition systems. The change in temperature from room temperature to physiological temperature (37 °C) was found to enhance the rate of …

Polyaniline-Derivatives Based On Poly (Heterocyclic Diphenylamine) With Improved Electrochemical Stability And Processability, Mohammed Noifa Almtiri

Theses and Dissertations

Today, smart innovation has become an essential part of human life; thus, contemporary technologies are always looking for intelligent, responsive, and efficient materials to satisfy these demands. Consequently, synthetic "metals" or, more precisely, intrinsically conducting polymers (CPs) have begun to find a place as valuable and practical materials for a new generation of devices. Amongst all intrinsic conducting polymers, polyaniline (PANI) has attracted significant attention due to its outstanding air and moisture stability, simple preparation technique, and high electrical conductivity (chapter I).

Chapter II represents the synthesis of a new PANI derivative that contains a phenoxazine unit co-polymerized with p-phenylenediamine …

Design, Synthesis And Characterization Of Triazole Based Glycoconjugates And 4,6-Acetal Protected D-Glucosamine Derivatives As Low Molecular Weight Gelators, Pooja Sharma

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are small molecules that can form gels in either organic solvents or water in their pure form or as mixtures. LMWGs self-assemble through noncovalent interactions such as hydrogen bonding, halogen bonding, van der Waals interactions and hydrophobic forces in solvents. They have shown great potential in biomedical industry, catalysis and environmental remediation to name a few. Moreover, the formation of metallogels can be used for detection of various ions as well as catalysis, which adds a new dimension to their applications. Among many classes of LMWGs based on the type of functional groups used, carbohydrate …

Development Of High Quantum Efficiency Strained Superlattice Spin Polarized Photocathodes Via Metal Organic Chemical Vapor Deposition, Benjamin Belfore

Electrical & Computer Engineering Theses & Dissertations

Spin polarized photocathodes are necessary to examine parity violations and other fundamental phenomena in the field of high energy physics. To create these devices, expensive and complicated growth processes are necessary. While integral to accelerator physics, spin polarized electrons could have other exciting applications in materials science and other fields of physics. In order to explore these other applications feasibly, the relative supply of spin polarized photocathodes with a high rate of both polarization and photoemission needs to be increased. One such way to increase this supply is to develop the means to grow them faster and at a larger …

Neoglycoproteins As Potential Biomarkers And Vaccines For Chagas Disease, Elisa Garcia Carvajal

Open Access Theses & Dissertations

Trypanosoma cruzi, the causal agent of Chagas disease (CD), currently affects 6-8 million people worldwide, predominantly in Latin America, where the parasite is endemic. The treatment of CD is based on two drugs, benznidazole (BZN) and nifurtimox (NFX). These drugs cause adverse effects and are more effective in the acute phase of the disease. Conventional serology assays can be used for diagnosis, but they are not suitable for determining chemotherapy effectiveness because patients take approximately 10-20 years to exhibit negative seroconversion. Although CD has become a global health problem, specific biomarkers are still needed for the follow-up of chemotherapy and …

Alkylthiocarbamate Metal Complexes With Antiproliferation Activity., Kritika Bajaj

Electronic Theses and Dissertations

Bis(thiosemicarbazones) (BTSCs) and their metal complexes have been extensively studied for various applications including catalysis for hydrogen evolution reactions, treatment of neurodegenerative diseases, hypoxia imaging, and a wide range of pharmacological purposes including antitumor, antiviral, antibacterial, and antifungal agents. The paramount property that makes BTSC metal complexes interesting for their use in these applications is the reduction potential of the coordinated metal, which can be selectively tuned by varying the substituents present on the ligand framework. Although the BTSCs have shown a great deal of success as potential cancer therapeutic agents, they lack selectivity towards cancer cells. For this matter, …

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 …

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 …

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 …

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 …