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- All Subjects: Molecules
- All Subjects: Lithium batteries
- Creators: Moore, Ana
Description
Sunlight, the most abundant source of energy available, is diffuse and intermittent; therefore it needs to be stored in chemicals bonds in order to be used any time. Photosynthesis converts sunlight into useful chemical energy that organisms can use for their functions. Artificial photosynthesis aims to use the essential chemistry of natural photosynthesis to harvest solar energy and convert it into fuels such as hydrogen gas. By splitting water, tandem photoelectrochemical solar cells (PESC) can produce hydrogen gas, which can be stored and used as fuel. Understanding the mechanisms of photosynthesis, such as photoinduced electron transfer, proton-coupled electron transfer (PCET) and energy transfer (singlet-singlet and triplet-triplet) can provide a detailed knowledge of those processes which can later be applied to the design of artificial photosynthetic systems. This dissertation has three main research projects. The first part focuses on design, synthesis and characterization of suitable photosensitizers for tandem cells. Different factors that can influence the performance of the photosensitizers in PESC and the attachment and use of a biomimetic electron relay to a water oxidation catalyst are explored. The second part studies PCET, using Nuclear Magnetic Resonance and computational chemistry to elucidate the structure and stability of tautomers that comprise biomimetic electron relays, focusing on the formation of intramolecular hydrogen bonds. The third part of this dissertation uses computational calculations to understand triplet-triplet energy transfer and the mechanism of quenching of the excited singlet state of phthalocyanines in antenna models by covalently attached carotenoids.
ContributorsTejeda Ferrari, Marely (Author) / Moore, Ana (Thesis advisor) / Mujica, Vladimiro (Thesis advisor) / Gust, John (Committee member) / Woodbury, Neal (Committee member) / Arizona State University (Publisher)
Created2016
Description
Mitochondria are crucial intracellular organelles which play a pivotal role in providing energy to living organisms in the form of adenosine triphosphate (ATP). The mitochondrial electron transport chain (ETC) coupled with oxidative phosphorylation (OX-PHOS) transforms the chemical energy of amino acids, fatty acids and sugars to ATP. The mitochondrial electron transport system consumes nearly 90% of the oxygen used by the cell. Reactive oxygen species (ROS) in the form of superoxide anions (O2*-) are generated as byproduct of cellular metabolism due to leakage of electrons from complex I and complex III to oxygen. Under normal conditions, the effects of ROS are offset by a variety of antioxidants (enzymatic and non-enzymatic).
Mitochondrial dysfunction has been proposed in the etiology of various pathologies, including cardiovascular and neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, ischemia-reperfusion (IR) injury, diabetes and aging. To treat these disorders, it is imperative to target mitochondria, especially the electron transport chain. One of the methodologies currently used for the treatment of mitochondrial and neurodegenerative diseases where endogenous antioxidant defenses are inadequate for protecting against ROS involves the administration of exogenous antioxidants.
As part of our pursuit of effective neuroprotective drugs, a series of pyridinol and pyrimidinol analogues have been rationally designed and synthesized. All the analogues were evaluated for their ability to quench lipid peroxidation and reactive oxygen species (ROS), and preserve mitochondrial membrane potential (Δm) and support ATP synthesis. These studies are summarized in Chapter 2.
Drug discovery and lead identification can be reinforced by assessing the metabolic fate of orally administered drugs using simple microsomal incubation experiments. Accordingly, in vitro microsomal studies were designed and carried out using bovine liver microsomes to screen available pyridinol and pyrimidinol analogues for their metabolic lability. The data obtained was utilized for an initial assessment of potential bioavailability of the compounds screened and is summarized fully in Chapter 3.
Mitochondrial dysfunction has been proposed in the etiology of various pathologies, including cardiovascular and neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, ischemia-reperfusion (IR) injury, diabetes and aging. To treat these disorders, it is imperative to target mitochondria, especially the electron transport chain. One of the methodologies currently used for the treatment of mitochondrial and neurodegenerative diseases where endogenous antioxidant defenses are inadequate for protecting against ROS involves the administration of exogenous antioxidants.
As part of our pursuit of effective neuroprotective drugs, a series of pyridinol and pyrimidinol analogues have been rationally designed and synthesized. All the analogues were evaluated for their ability to quench lipid peroxidation and reactive oxygen species (ROS), and preserve mitochondrial membrane potential (Δm) and support ATP synthesis. These studies are summarized in Chapter 2.
Drug discovery and lead identification can be reinforced by assessing the metabolic fate of orally administered drugs using simple microsomal incubation experiments. Accordingly, in vitro microsomal studies were designed and carried out using bovine liver microsomes to screen available pyridinol and pyrimidinol analogues for their metabolic lability. The data obtained was utilized for an initial assessment of potential bioavailability of the compounds screened and is summarized fully in Chapter 3.
ContributorsAlam, Mohammad Parvez (Author) / Hecht, Sidney M. (Thesis advisor) / Gould, Ian R (Committee member) / Moore, Ana (Committee member) / Arizona State University (Publisher)
Created2014
Description
This thesis focused on physicochemical and electrochemical projects directed towards two electrolyte types: 1) class of ionic liquids serving as electrolytes in the catholyte for alkali-metal ion conduction in batteries and 2) gel membrane for proton conduction in fuel cells; where overall aims were encouraged by the U.S. Department of Energy.
Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300ºC) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140ºC.
Battery testing based on [EMI+][FeCl4-] with NaAlCl4 functioned exceptional (range 150-180ºC) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br7, melted at 94ºC. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62ºC ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265ºC and less expensive chemical synthesis. [PBr4+][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements.
Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases producing water vapor. Principle advantage is high-energy efficiency of up to 70% in contrast to an internal combustion engine <40%. Nafion-based fuel cells are prone to carbon monoxide catalytic poisoning and polymer membrane degradation unless heavily hydrated under cell-pressurization. This novel "SiPOH" solid-electrolytic gel (originally liquid-state) operated in the fuel cell at 121oC yielding current and power densities high as 731mAcm-2 and 345mWcm-2, respectively. Enhanced proton conduction significantly increased H2 fuel efficiency to 89.7% utilizing only 3.1mlmin-1 under dry, unpressurized testing conditions. All these energy devices aforementioned evidently have future promise; therefore in early developmental stages.
Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300ºC) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140ºC.
Battery testing based on [EMI+][FeCl4-] with NaAlCl4 functioned exceptional (range 150-180ºC) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br7, melted at 94ºC. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62ºC ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265ºC and less expensive chemical synthesis. [PBr4+][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements.
Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases producing water vapor. Principle advantage is high-energy efficiency of up to 70% in contrast to an internal combustion engine <40%. Nafion-based fuel cells are prone to carbon monoxide catalytic poisoning and polymer membrane degradation unless heavily hydrated under cell-pressurization. This novel "SiPOH" solid-electrolytic gel (originally liquid-state) operated in the fuel cell at 121oC yielding current and power densities high as 731mAcm-2 and 345mWcm-2, respectively. Enhanced proton conduction significantly increased H2 fuel efficiency to 89.7% utilizing only 3.1mlmin-1 under dry, unpressurized testing conditions. All these energy devices aforementioned evidently have future promise; therefore in early developmental stages.
ContributorsTucker, Telpriore G (Author) / Angell, Charles A. (Committee member) / Moore, Ana (Committee member) / Seo, Dong-Kyun (Committee member) / Arizona State University (Publisher)
Created2014
Description
Small molecules have proven to be very important tools for exploration of biological systems including diagnosis and treatment of lethal diseases like cancer. Fluorescent probes have been extensively used to further amplify the utilization of small molecules. The manipulation of naturally occurring biological targets with the help of synthetic compounds is the focus of the work described in this thesis.
Bleomycins (BLMs) are a class of water soluble, glycopeptide-derived antitumor antibiotics consisting of a structurally complicated unnatural hexapeptide and a disaccharide, clinically used as an anticancer chemotherapeutic agent at an exceptionally low therapeutic dose. The efficiency of BLM is likely achieved both by selective localization within tumor cells and selective binding to DNA followed by efficient double-strand cleavage. The disaccharide moiety is responsible for the tumor cell targeting properties of BLM. A recent study showed that both BLM and its disaccharide, conjugated to the cyanine dye Cy5**, bound selectively to cancer cells. Thus, the disaccharide moiety alone recapitulates the tumor cell targeting properties of BLM. Work presented here describes the synthesis of the fluorescent carbohydrate conjugates. A number of dye-labeled modified disaccharides and monosaccharides were synthesized to study the nature of the participation of the carbamoyl moiety in the mechanism of tumor cell recognition and uptake by BLM saccharides. It was demonstrated that the carbamoylmannose moiety of BLM is the smallest structural entity capable for the cellular targeting and internalization, and the carbamoyl functionality is indispensible for tumor cell targeting. It was also confirmed that BLM is a modular molecule, composed of a tumor cell targeting moiety (the saccharide) attached to a cytotoxic DNA cleaving domain (the BLM aglycone). These finding encouraged us to further synthesize carbohydrate probes for PET imaging and to conjugate the saccharide moiety with cytotoxins for targeted delivery to tumor cells.
The misacylated suppressor tRNA technique has enabled the site-specific incorporation of noncanonical amino acids into proteins. The focus of the present work was the synthesis of unnatural lysine analogues with nucleophilic properties for incorporation at position 72 of the lyase domain of human DNA polymerase beta, a multifunctional enzyme with dRP lyase and polymerase activity.
Bleomycins (BLMs) are a class of water soluble, glycopeptide-derived antitumor antibiotics consisting of a structurally complicated unnatural hexapeptide and a disaccharide, clinically used as an anticancer chemotherapeutic agent at an exceptionally low therapeutic dose. The efficiency of BLM is likely achieved both by selective localization within tumor cells and selective binding to DNA followed by efficient double-strand cleavage. The disaccharide moiety is responsible for the tumor cell targeting properties of BLM. A recent study showed that both BLM and its disaccharide, conjugated to the cyanine dye Cy5**, bound selectively to cancer cells. Thus, the disaccharide moiety alone recapitulates the tumor cell targeting properties of BLM. Work presented here describes the synthesis of the fluorescent carbohydrate conjugates. A number of dye-labeled modified disaccharides and monosaccharides were synthesized to study the nature of the participation of the carbamoyl moiety in the mechanism of tumor cell recognition and uptake by BLM saccharides. It was demonstrated that the carbamoylmannose moiety of BLM is the smallest structural entity capable for the cellular targeting and internalization, and the carbamoyl functionality is indispensible for tumor cell targeting. It was also confirmed that BLM is a modular molecule, composed of a tumor cell targeting moiety (the saccharide) attached to a cytotoxic DNA cleaving domain (the BLM aglycone). These finding encouraged us to further synthesize carbohydrate probes for PET imaging and to conjugate the saccharide moiety with cytotoxins for targeted delivery to tumor cells.
The misacylated suppressor tRNA technique has enabled the site-specific incorporation of noncanonical amino acids into proteins. The focus of the present work was the synthesis of unnatural lysine analogues with nucleophilic properties for incorporation at position 72 of the lyase domain of human DNA polymerase beta, a multifunctional enzyme with dRP lyase and polymerase activity.
ContributorsBhattacharya, Chandrabali (Author) / Hecht, Sidney M. (Thesis advisor) / Moore, Ana (Committee member) / Gould, Ian R (Committee member) / Arizona State University (Publisher)
Created2014