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Development Of Novel Efficient Organocatalytic Reactions For The Construction Of Complex Molecular Architectures, Aiguo Song Sep 2014

Development Of Novel Efficient Organocatalytic Reactions For The Construction Of Complex Molecular Architectures, Aiguo Song

Chemistry and Chemical Biology ETDs

Facile construction of synthetically and medicinally significant optically active molecular architectures from simple and readily available materials via catalytic enantioselective cascade processes is the cental goal in organic synthesis. Toward this end, my Ph. D. work focuses on the development of novel organocatalytic asymmetric cascade reactions and their application in the synthesis of versatile molecular structures. A novel amine catalyzed decarboxylative enantioselective Diels—Alder reaction between aldehydes and readily available coumarin-3-carboxylic acids as dienophiles via dienamine catalysis has been realized. Notably, the decarboxylation facilitates the release of the catalyst in the Diels—Alder reaction adducts and achieves high reaction efficiency in terms …


Criteria For Evolution Of Successful Proteins: Fold Fitness And Domain Dynamics Explored, Tyrel Bryan Sep 2014

Criteria For Evolution Of Successful Proteins: Fold Fitness And Domain Dynamics Explored, Tyrel Bryan

Chemistry and Chemical Biology ETDs

The Haloacid Dehalogenase Superfamily (HADSF) is a ubiquitous family of enzyme with more than 32,000 members. A variety of reactions are catalyzed by HAD members, but a majority of HAD members are phosphatases. Dephosphorlyation of organophosphate metabolites are carried out in the conserved Rossmann-like core domain. The Rossman-like core domain houses the conserved active site residues necessary for catalysis and also supports domain inserts associated with substrate binding. This dissertation will focus primarily on investigating fold fitness and domain dynamics of HAD proteins more specifically three C2 capped proteins. The first part will focus on whether or not the prevailing …


Spectroscopic Studies Of Conjugated Polymer Nanostructures And Polymer/Acceptor Blends, Jian Gao Sep 2014

Spectroscopic Studies Of Conjugated Polymer Nanostructures And Polymer/Acceptor Blends, Jian Gao

Chemistry and Chemical Biology ETDs

This dissertation presents the results of investigations into organic semiconducting systems at the nano- to mesoscales through spectroscopic and electrical imaging techniques. Particular emphasis was put on capturing the role of conformation and morphology on electronic properties and processes. The combination of experimental methods and data analysis techniques used in this work reveals useful insights into the correlations between polymer structures and their photovoltaic device performance, and provide clues to developing better performing organic solar cells. The main approach of this work is using prototypical conjugated polymer systems, either ensemble or in their nanostructures, to study the solar cell active …


Theoretical Studies Of Transition Metal Catalysis, Ryan Johnson Sep 2014

Theoretical Studies Of Transition Metal Catalysis, Ryan Johnson

Chemistry and Chemical Biology ETDs

Transition metal catalysis, being critical to nearly all aspects of the modern industrial world, is the focus of a series of theoretical studies which seek to elucidate the fundamental and electronic origins of enhanced chemical activity and selectivity. The application of density functional theory on extended single metal and alloyed surfaces, supported single metal atoms, and gas phase cationic species illuminate various aspects of transition metal catalysis in a wide range of enviornments. Adsorption, reactivity, and other mechanistic details developed here suggest possible mechanisms used to aid interpretation of experimental results and guide developement of future catalysts.


Development Of Novel Small Molecules For Imaging And Drug Release, Yanting Cao Sep 2014

Development Of Novel Small Molecules For Imaging And Drug Release, Yanting Cao

Chemistry and Chemical Biology ETDs

Small organic molecules, including small molecule based fluorescent probes, small molecule based drugs or prodrugs, and smart multifunctional fluorescent drug delivery systems play important roles in biological research, drug discovery, and clinical practices. Despite the significant progress made in these fields, the development of novel and diverse small molecules is needed to meet various demands for research and clinical applications. My Ph.D study focuses on the development of novel functional molecules for recognition, imaging and drug release. In the first part, a turn-on fluorescent probe is developed for the detection of intracellular adenosine-5'-triphosphate (ATP) levels based on multiplexing recognitions. Considering …


Stable Solar Cells Through Controlled Block Copolymer Self-Assembly And Cooperative Hydrogen Bonding Interactions, Fei Li Sep 2014

Stable Solar Cells Through Controlled Block Copolymer Self-Assembly And Cooperative Hydrogen Bonding Interactions, Fei Li

Chemistry and Chemical Biology ETDs

Current state-of-the-art polymer solar cells adopt the bulk-heterojunction (BHJ) morphologies where the electron donors (i.e. conjugated polymer) and electron acceptors (i.e. fullerenes) as active layers are mixed in an intimate way. The phase separation that modulates the exciton diffusion and charge transport in the current BHJ morphology is an uncontrolled process and thus results in random domain sizes of the polymer/fullerene blend. In addition, the polymer and fullerenes in the blend are intrinsically two immiscible materials and they tend to undergo macrophase separation eventually, which leads to deteriorated device performance. One way to address the abovementioned issues is to attach …


Spectroscopic Studies Of Conformation And Packing In Polythiophenes, Edwards Niles Feb 2014

Spectroscopic Studies Of Conformation And Packing In Polythiophenes, Edwards Niles

Chemistry and Chemical Biology ETDs

This thesis employs variants of spectroscopic techniques to evaluate intermolecular interactions between P3HT chains in solution and in the solid state. Emphasis was put on understanding not only how intermolecular interactions within P3HT chains affect electronic properties, but also to assess changes due to the addition of weak and strong electron acceptors. To this end, optical and magnetic spectroscopies were focused on to correlate observed changes in electronic properties to physical changes in the polymer structure. To assess changes in intermolecular interactions, self-assembly was used to form P3HT nanofibers and were studied using resonance Raman, and transient absorption, and temperature- …


Synthesis, Characterization, And Electrochemical Evaluation Of Novel, Highly Active Catalysts For The Oxygen Reduction Reaction In Alkaline Media, Danae Jacquelyne Davis Feb 2014

Synthesis, Characterization, And Electrochemical Evaluation Of Novel, Highly Active Catalysts For The Oxygen Reduction Reaction In Alkaline Media, Danae Jacquelyne Davis

Chemistry and Chemical Biology ETDs

Efficient electrocatalysts for the oxygen reduction reaction (ORR) are needed for fuel cells and next generation metal-air batteries, as the overall efficiency of these systems is currently limited by cathode kinetics. While Pt and Pt-based alloys demonstrate excellent electrocatalytic activities, their prohibitive cost and rarity ultimately prevents their widespread utilization. Catalyst materials that are highly active, stable, and cost effective are needed. Manganese oxide (α-MnO2) catalysts doped with varying amounts of Cu or Ni were synthesized, characterized, and evaluated for their performance as catalysts for the oxygen reduction reaction in alkaline electrolyte. Cu-α-MnO2 nanowire catalysts consistently attained higher terminal current …


Simulations Of Chemical Catalysis, Gregory K. Smith Feb 2014

Simulations Of Chemical Catalysis, Gregory K. Smith

Chemistry and Chemical Biology ETDs

This dissertation contains simulations of chemical catalysis in both biological and heterogeneous contexts. A mixture of classical, quantum, and hybrid techniques are applied to explore the energy profiles and compare possible chemical mechanisms both within the context of human and bacterial enzymes, as well as exploring surface reactions on a metal catalyst. A brief summary of each project follows. Project 1 — Bacterial Enzyme SpvC The newly discovered SpvC effector protein from Salmonella typhimurium interferes with the host immune response by dephosphorylating mitogen-activated protein kinases (MAPKs) with a -elimination mechanism. The dynamics of the enzyme substrate complex of the SpvC …


Determining The Function Of Hotdog-Fold Thioesterases, Yajun Wu Feb 2014

Determining The Function Of Hotdog-Fold Thioesterases, Yajun Wu

Chemistry and Chemical Biology ETDs

The enzymes that hydrolyze thioesters to the free acids and free thiols are called thioesterases. Based on the different folding strategy, most thioesterases are classified into two superfamiles: the hotdog-fold enzyme superfamily or alpha/beta-fold hydrolase enzyme superfamily. Hotdog-fold thioesterases share high degree similarity in structure which resembles a hotdog'. YigI is one of the last two uncharacterized hotdog-fold thioesterases from E.coli. To study the function of YigI, substrate specificity profile was determined by thioesterase activity assay. YigI possesses a preference for long chain acyl-CoA over shorter chain acyl-CoA. The highest activity was found in catalysis of myristoyl-CoA. By alignment with …