Physical Sciences and Mathematics Commons^™

Modelling Terrestrial And Potential Extraterrestrial Photopigments Via Density Functional Theory, Dorothea Illner

Theses and Dissertations

In the search for extraterrestrial life, biosignatures play a crucial role in identifying its putative traces. A commonly known and robust biosignature is the Vegetation Red Edge (VRE), which can be described as a sharp increase of reflectance observed from a planet and stems from the light absorption of photopigments in specific regions in the electromagnetic spectrum. For Earth, this VRE is known to occur around 700 nm, however, if the photopigments absorb light in different regions and have different structures the VRE could experience a wavelenght shift.

In this work, Chlorophyll a and a potential photopigment precursor called Phot0 …

A Work Towards A Single-Bridge Hydrazine Sensor, Brenden Jay Schmeltz

Theses and Dissertations

Hydrazine can currently be detected by irreversible methods, Carbazolopyridinophane (2,18-Dithia[3][1,8]carbazolo[3][2,6]pyridinophane) CP was synthesized by Brown et al. to detect hydrazine in real-time while also being reversible. The threshold for detection was 100 ppb, regulatory use requires 10 ppb as this is when permanent damage to humans can be caused. A more sensitive sensor will allow for safer workplaces for many people. A single, 3-atom bridge sensor will further examine the photophysical capabilities of carbazole-pyridine as an emitter/quencher pair. 1-Carbazole-1-methylpyridyl-2methyl sulfide SBCP will allow freedom of rotation as well as the bending of the bridge. These benefits will introduce conformers which …

Anti-Doping Crisis In Sports, What's Next? Ion Mobility-Mass Spectrometry For The Study Of Anabolic Androgenic Steroids, Diana Constanza Velosa

Theses and Dissertations

The main objective of this work is to augment both qualitative and quantitative measures of anabolic androgenic steroids (AAS) with ion mobility-mass spectrometry (IM-MS), laying the foundation for implementation into analytical drug testing laboratories. AAS testing requires high sensitivity and specificity. IM-MS is presented as an emerging technology workflow capable of targeted quantification of AAS and structural elucidation for potential unknowns, allowing ions to be separated and characterized based on their rotationally averaged collision cross section (CCS). Chapter 1 provides a background of the basic principles of IMS and the different types of analytical methods used for doping analysis currently …

1. Influence Of Metal Ions And Solvents On The Photo-Generation Of Reactive Oxygen Species In Mesoporous Silicate Embedded Porphyrins 2.Water-Soluble Rhodium(Iii) Porphyrin Complex For The Biological Inactivation Of Fentanyl, Hemant Pal

Theses and Dissertations

Porphyrins are differentiated π-conjugated compounds with unique photochemical and redox properties. The tetrapyrrole macrocycle core of porphyrins is extremely favorable for the complexation of metal ions, resulting in hybrid metal-organic molecules with good catalytic properties. Porphyrin-based systems are known for their oxidative properties and are frequently utilized as bio-mimicking catalysts and environmental remediation agents. My current research aims at both of these aspects. One of the most efficient methods to create photocatalytic systems with outstanding features and applicability is the use of porphyrins on supported solid materials. A series of novel mesoporous silicate-embedded metalloporphyrins were prepared via conjugation of novel …

Design And Synthesis Of Novel Peptide-Metal Organic Frameworks, Moustafa Mahmoud Abdel Wahid Hamaad

Theses and Dissertations

Metal-organic frameworks (MOFs) are a class of crystalline porous materials with extended network structures formed through the reticular assembly of inorganic and organic molecular building blocks through strong coordination bonds. Compared to other porous materials, MOFs offer a high degree of structural diversity as their shape and pore size as well as functionality can tuned by the precise selection and design of their metal centers and organic struts. Due to their high surface areas, pore volumes, and the possibility of introduction of a myriad of chemical functionalities in their structures, MOFs have gained popularity for applications in many fields such …

Water-Soluble Iron Porphyrin Complex For The Catalytic N-Dealkylation Of Fentanyl, Amanda Pitt

Theses and Dissertations

An increase in the misuse of opioids in the United States and the increasing potency of analogs necessitates novel treatments of opioid overdose. The chemical structure of synthetic opioids, such as fentanyl, carfentanil, and morphine possess a trialkyl amine functional group (-NR3) which makes for a promising target for potential catalysts. Iron (III)-tetrasulfonatophenyl porphyrin (complex 9) was synthesized as a potential catalyst for degradation of fentanyl. Complex 9a was prepared from the direct reaction of the free porphyrin and FeSO4. Complex 9b was prepared from the direct reaction of the free porphyrin and FeCl2 in refluxing DMF. The complexes were …

Analysis Of Steroid Hormone Isomers Using Ion Mobility-Mass Spectrometry, Shon Paul Neal

Theses and Dissertations

This dissertation presents a comprehensive study on the analysis of steroid hormone isomers using liquid chromatography-ion mobility-mass spectrometry (LC-IM-MS). The dissertation is divided into three main parts: the first part focuses on research using different drift gases and ion adducts to modify the mobility separations allowing for resolution between the isomers. The second part focuses on research exploring derivatization reactions that target structural differences between the steroid hormone isomers to amplify the differences and resolve the isomers in the ion mobility region. The final part covers a proposal on future study directions to include simultaneous derivatization reactions, mass spectrometry fragmentation, …

The Use Of Flexible Organic And Inorganic Building Blocks In Complex Metal- Organic Frameworks, Sahar Yahia Rajeh

Theses and Dissertations

Metal organic frameworks (MOFs) are new class of hybrid materials that draw the attention of scientists to discover new properties that help in many fields. The structural diversity of MOFs is accessible by incorporating different organic linkers to the same metal cluster. In this work, we reacted seven flexible organic linkers with different lengths varying from 4-carbons to 10-carbons to a copper-paddlewheel metal cluster. The flexibility of the linkers make the confirmation of MOFs a challenge, although we were able to prepare a new crystalline MOF from a 5-carbon organic linker with two different copper-clusters. Another MOF in powder form …

Control Of Irradiation Wavelength And Quantum Yield Of Photocleavable Cages, Jingxuan Ma

Theses and Dissertations

An important component of biological research is the precise regulation of biomolecules in their physiological environment. Recent advances in neuroscience, have made it possible to regulate the activity of neurotransmitters using photocleavable protecting groups (PPGs), which are also known as cages. This enables the use of light as a trigger to activate selected neurons via photo release of agonists with precise control of timing as well as synaptic site, popularly referred to as spatiotemporal control. In recent years, a variety of PPGs have been developed and applied to biomolecular cages. PPGs can be classified according to their absorption wavelengths (from …

Development Of Diagnostic Tools And Analysis Of The Density Functional Theory Zoo, Pierpaolo Morgante

Theses and Dissertations

The main goal of this dissertation is to give an overview of existing and new databases for density functional theory (DFT). It describes the procedures used to introduce A Collection of Chemistry DataBases (ACCDB) and its reduction to a smaller and statistically significant database called A Small(er) Collection of DataBase (ASCDB). Also, it presents an application of such databases in chemical education through the introduction of a notebook of twelve exercises that can easily complement a computational chemistry class. In addition, a new database of molecules having carbon-carbon long bonds (CLB18) is presented. Last, the databases are used in the …

Synthesis, Isolation And Structural Elucidation Of Cage-Shaped Aluminum And Gallium Phosphorous Aryloxide Complexes As Highly Reactive Lewis Acids And Carboxyboranes As Carbon Monoxide Releasing Molecules (Corms), Hussam Wannas Shinawa Alhamza

Theses and Dissertations

Group 13 Lewis acids have gained a lot of interest in over the years due to their reactivity, potency, and applications in the field of catalysis. Generally, there is a direct relationship between the catalytic activity of the organometallic Lewis acid and its acidity. However, this gives rise to a bigger challenge which is related to the stability of the catalyst. Our preliminary results from working on the catalytic reduction of CO2 have shown catalytic deactivation after one or two cycles. Utilizing bulkier substituents such as monodentate phenolates have shown promising increased stability and reactivity. The structural optimization (i.e., open-shape …

Development Of Axial-Chiral Lewis Base Catalysts For Asymmetric Synthesis, Carlyn Louise Reep

Theses and Dissertations

Asymmetric Synthesis has become an essential tool to provide materials necessary to our everyday lives. The asymmetric formation of carbon-carbon bonds is the most important process in the construction of asymmetric organic molecules as this is how the structure/shape of a molecule is formed. Synthetic chiral molecules exist as agrochemicals, food additives, and pharmaceuticals, among other applications. As the demand for these materials has increased along with the growing population and scientific/technological advancements in these areas, the need for sustainable and efficient synthetic methods has come forefront as a scientific challenge. Chlorosilanes have emerged as an attractive reagent class for …

The Aqueous Stability Of N-Acyl-L-Homoserine Lactones, Their Affinity For Cyclodextrin Inclusion, And The Investigation Of A Catalyst For Their Hydrolysis, Eric William Ziegler

Theses and Dissertations

Many bacteria demonstrate population-density dependent gene expression, a phenomenon known as quorum sensing, to regulate phenotypes that, if expressed by an individual bacterium, would be ineffective. While some of these phenotypes are innocuous (e.g., exhibiting bioluminescence), certain bacteria employ quorum sensing regulated phenotypes in their pathogenesis. Traditionally, infections by these pathogens have been treated with antibiotic therapies. However, with the emergence of multidrug resistant strains, alternative strategies are being considered for attenuation of quorum sensing regulated traits that do not apply selective pressures. Macrocycles — in particular the cyclodextrins — that are capable of forming inclusion complexes with Gram-negative quorum …

Metastable State Photoacids And Ultrasound Responsive Carbon Monoxide Releasing Polymer Micelle, Osamah Zaid Saleh Alghazwat

Theses and Dissertations

This dissertation described my Ph.D. work on the development of a novel metastable state photoacids (mPAH), which can be activated by near infrared light and a reversible mPAH switched by different wavelengths of light. Also, it described the development of a micelle that responded to ultrasound to localized carbon monoxide CO delivery. An introduction of metastable state photoacid is given in Chapter 1. In Chapter 2, described my work on the development of a novel mPAH, which can be activated by near infrared light is an important factor for various biological functions. mPAH was designed and synthesized with a donor-acceptor-donor …

Design And Synthesis Of Polymeric Metastable State Photoacid And Photo Co-Releasing Materials, Adnan Abdallah Muftah Elgattar

Theses and Dissertations

Metastable state photoacids (mPAHs) are molecules that possess a photoinduced metastable state with high acidity and good reversibility. The metastable state lasts long enough to produce a high proton concentration, which can drive various proton transfer processes. MPAHs have been intensively studied in recent years and applied to different chemical, material, biomedical areas. Covalently linking many mPAHs in a polymer allows the generation of a local proton concentration higher than that of the overall system. This dissertation described my PhD work on the synthesis of mPAH polymers using different radical and ring-opening polymerization methods. These polymers can repeatedly produce a …

Polymer-Based Capacitive Gas Sensor For Machine Olfaction, Mohamed Fathy Hassan

Theses and Dissertations

Transferring human abilities and knowledge to machines has been the focus of decades of work by scientists and engineers. With the progress in computation power and algorithms such as artificial neural networks, machines have surpassed humans in complicated games like chess and the Chinese game Go. Some senses can be mimicked including touch, with pressure sensors, hearing, with microphones, and vision with charged couple device (CCD)imaging chips. Yet, relatively little progress has been made with the senses of smell and taste. Machine olfaction, the ability to detect and quantify vapors in the environment, poses a range of challenges, which if …

Effect Of Electron Demand On Sensing Behavior Of Carbazolopyridinophanes, Grace Abban

Theses and Dissertations

Hydrazine (HZ), monomethylhydrazine (MMH), and 1,1-dimethylhydrazine (UDMH) are widely used as high energy rocket propellants in bipropellant rocket engines. However, hydrazine and its derivatives are highly flammable and carcinogenic. Currently, hydrazine sensors used for detection are irreversible which makes them costly. Two proposed carbazolopyridinophanes containing intramolecular hydrogen bonds were synthesized to detect hydrazine as real-time reversible sensors. However, their thresholds for detection (100 and 25 ppb for CPand 22OMeCPrespectively) were above the regulatory limit of 10 ppbdue to background fluorescence. It was established that the quenching of carbazole in the presence of the CP system has a direct correlation to …

Analysis Of Fatty Acids In Chukchi Sea Sediments, Damilola Ajadi

Theses and Dissertations

The Arctic Ocean and its marginal seas are key areas for understanding the global climate system. Climate change causes increased terrigenous materials to be carried into the ocean as well as higher production of marine organic matter in the ocean. This study determined the concentrations, distribution, and sources of fatty acids in core sediments from four locations: Stations H32, H30, BarC5 and H24 in the Chukchi Sea, which are in the Arctic Ocean. Fatty acids are valuable tracers of marine or terrigenous inputs and may give evidence to the extent of climate change. Fatty acids were analyzed, characterized using GC-MS …

Metastable-State Photoacids And Polymers With High Photoacidity, Thaaer Khalil

Theses and Dissertations

In recent years, metastable-state photoacids (mPAH) have been utilized to control various chemical processes using visible light and have found many applications in materials, energy, and biomedical areas. An introduction of metastable state photoacid is given in Chapter 1. In chapter 2, to clearly understand the relationship between the structures and the physicochemical properties of mPAHs, a series of mPAHs were designed and synthesized. The reversibility, stability, reverse reaction rate, and photoreaction of the mPAHs were studied in detail using UV/VIS spectroscopy. The results demonstrated that the electron-withdrawing groups on the electron-accepting moiety enhance the overall photoreaction and stability of …

Metastable-State Photoacid: A Comprehensive Theoretical Study Of The Photoreaction, Reverse Reaction, Thermal Isomerization, And Td-Dft Absorption In Solvent, Arwa Wasel Hamed Alharbi

Theses and Dissertations

The main objective of the research is to investigate the fundamentals of novel metastable-state photoacids. These photoacids can reversibly produce a large concentration of protons while undergoing photo-irradiation. This change in proton concentration can induce and catalyze chemical reactions, biological functions, and material properties that do not occur in the dark. (IMAGE) Scheme 1. Energy diagram of the photoreaction. (The red route is the forward photoreaction; the blue route is the reverse reaction; and the process that involves the proton dissociation of the photoacid in the dark is the green route; "t-" means trans- and "c-" means cis-). Scheme 1 …

Analysis Of N-Alkanes And N-Alkenes In Chukchi Sea Sediments, Salomey Asantewaa Sasu

Theses and Dissertations

This study determined the concentrations, distribution and sources of n-alkanes in core sediments from four locations: Stations H24, H30, H32 and BarC5 in the Chukchi Sea, which is in the Arctic Ocean. n-Alkanes are valuable tracers of aquatic, terrigenous and petroleum inputs and may give evidence to the extent of climate change. The study of climate change in the Arctic is important since the Arctic is warming faster than any other part of Earth. The increase in temperature is causing enhanced evaporation leading to a higher precipitation rate and hence enhanced erosion. The n-alkanes C12-C35 were analysed and characterized using …

Design And Synthesis Of 5-Oxo-Ete Receptor Antagonists; And Synthesis Of Neuroprostanes As A Biomarker For The Diagnosis Of Alzheimer’S Disease, Rui Wang

Theses and Dissertations

1) 5-Oxo-ETE (7, Scheme 1) is the most potent eosinophil chemoattractant among all lipid mediators and it can also stimulate a late-phase asthma attack. It is formed by the biotransformation of arachidonic acid (AA, 1, Figure 1). 5-Oxo-ETE (7) elicits eosinophil migration both in vitro and in vivo when injected intradermally in humans, acting via the highly selective OXE receptor (OXE-R). Our group postulated that a selective OXE-R antagonist might be a useful therapeutic agent in late phase asthma. As a result, the first and only series of OXE receptor antagonists which are structural mimics of 5-oxo-ETE (7) have been …

Synthesis Of Photoactive Molecules And Silicon Containing Compounds, Mozhgan Navidi

Theses and Dissertations

Retinoids are a class of synthetic and natural molecules that are functionally and structurally related to Vitamin A. They have various biological roles and potential therapeutic values. Providing treatment for eye diseases requires more detailed understanding of the visual process. However, investigating every aspect of the visual phenomenon is constrained by the difficulties involved in the synthesis of pure retinoids with the desired stereochemistry. Therefore, developing a suitable and valuable synthetic route for 11-cis-retinal and its analogues is highly desirable. The first chapter of this dissertation explains new synthetic pathways for 11-cisretinal. In addition, the total synthesis of stereoselectively deuterium-labeled …

Photocleavable Endogenous And Exogenous Molecules, Charitha Madhusanka Guruge

Theses and Dissertations

The spatiotemporal regulation of biomolecules in their physiological environment is an essential aspect of biological research. In neuroscience, the activity of neurotransmitters can be regulated by protecting the molecules with photoresponsive protecting groups (PPGs), also known as cages. Diverse set of PPGs have been developed for caging of biomolecules. PPGs can be categorized based on their absorbing wavelengths (ranging from UV to near-IR) and photochemical properties (quantum yield, photo-cross section, solubility). PPGs absorb light and undergo intramolecular electron transitions and bond rearrangements that result in the release of the caged substrates. Hence, the caging of a specific substrate is unique …

1. Synthesis And Characterization Of A Vanadium Based Transition State Mimic For Organophosphate Hydrolase 2. Catalytic Oxidation Of Thioanisole And 2-Chloroethyl Ethyl Sulfide Using Resin Bead Supported Oxoperoxidovanadium(V) Complexes, Efram Goldberg

Theses and Dissertations

Two vanadium(V) complexes were prepared for different projects. First the ONS tridentate ligand 14 was prepared according to literature procedure. This ligand was chosen to make the ONS dioxovanadium complex 15 for conjugation to a protein and to eventually elicit catalytic antibodies for the hydrolysis of the chemical weapon VX. Complex 15 was prepared in 65% overall yield and a full characterization was performed including X-ray diffraction. Initial screening performed at the Naval Research Laboratory indicated an IC50 of 84 nM for inhibition of a bacterial cholinesterase. It was also found to be 50% as effective as the control antiobiotic …

Design And Characterization Of Composite Membranes For Solar Fuel Generating Devices, Ibtehaj Fahad Alshdoukhi

Theses and Dissertations

Currently, there is a great need for research and development on new sources of energy in order to meet energy demands in a clean, efficient, sustainable, economical and environmentally friendly way. A system that promises to meet these requirements is water splitting through artificial photosynthesis, generating hydrogen and oxygen, effectively storing light energy in the form of fuel such as H2. One main limitation in artificial photosynthesis is that the membrane must be able to conduct the ions involved in redox reactions, as well as the electrons/hole carriers produced by light absorption, while being mechanically stable and optically transparent. No …

Determination Of Local Elastic Modulus Of Soft Biomaterial Samples Using Afm Force Mapping, Faieza Saad Ejweada Bodowara

Theses and Dissertations

Conventional methods of mechanical testing cannot measure properties of soft materials at the nanoscale. In fields such as tissue engineering, it is important to distinguish the bulk elastic modulus from the surface elastic modulus and to characterize the spatial distribution of material with non-uniform stiffness. One of the important new methods of testing is the force mapping using the atomic force microscope. The existing force mapping approaches often suffer from omitting important effects that might result in artifacts. The most important effects include taking into account sample’s adhesion and viscoelasticity and considering more realistic probe shapes. In this work, we …

Interaction Between Fragments Of Tau Protein Investigated By Force Spectroscopy Using Afm, Anad Mohamed Afhaima

Theses and Dissertations

Over the last couple of decades, there has been rapidly growing interest in research of natively unfolded proteins. Some proteins from this group are implicated in a number of neurodegenerative diseases. One group of neurodegenerative diseases, taupathies, is associated with tau protein. A number of biophysical and spectroscopic studies have revealed that tau protein can expand to a largely extended state and to transition rapidly between many different conformations. Although many of the techniques that elucidate structure of macromolecules have provided important information about the folded states of proteins, important information about the transition between the extended conformation states remain …

Metastable-State Nh Photoacids And Organic Photo Carbon Monoxide Releasing Materials, Aluthwatte Rallage Nawodi Madhusanka Abeyrathna

Theses and Dissertations

The recently discovered metastable-state photoacids (mPAHs) can produce a large proton concentration with high efficiency and good reversibility upon irradiation with visible light with moderate intensity. Therefore, mPAHs can be conveniently incorporated in to different systems to control various proton-transfer processes. Recently, several applications of mPAHs have been demonstrated. However, none of the previously reported mPAHs can function at a pH 7.4. Thus, biological applications of mPAHs are limited. In this work, mPAHs that can reversibly release a proton in PBS buffer (pH = 7.4) under visible light are designed and synthesized. NH-PAH-1 is the first of this type of …

Surface Modification Of Core-Shell Silver-Titania Nanocomposites With Copper Bipyridine–Phosphonates And Studies On Ag@Tio₂ Mediated Degradation Of Organophosphates, Somayeh Talebzadeh Farooji

Theses and Dissertations

Silver nanoparticles, coated with a titania shell were prepared and were shown to be catalytically active for the rapid degradation of organothiophosphate methyl parathion (MeP). Formation of the degradation product, p-nitrophenolate (PNP) was monitored as a function of pH, using UV-Vis spectroscopy, and 31P NMR spectroscopy confirmed the hydrolysis is the predominant pathway for substrate breakdown under non-photocatalytic degradation. We have demonstrated that the unique combination of TiO2 and silver nanoparticles is required for catalytic hydrolysis with good reproducibility. This work represents the first example of MeP degradation using TiO2 doped with AgNP under mild and ambient conditions. It is …