Chemistry Commons^™

Synthesis And Characterization Of Three New Tetrakis(N-Phenylacetamidato) Dirhodium(Ii) Nitrile Complexes, Nkongho Atem-Tambe

Electronic Theses and Dissertations

Three new tetrakis [Rh₂(PhNCOCH₃)₄·xNCR] (R = {2-CH₃}C₆H₄ (x=2), R = {3-CH₃}C₆H₄ (x=1), R = (3-CN)C₆H_4∞ (x=1)) complexes have been synthesized and characterized. These complexes were characterized by IR and ¹H NMR spectroscopies and X-ray crystallography which solved with R₁<0.05.

[Rh₂(PhNCOCH₃)₄·2NC{2-CH₃}C₆H₄] was triclinic (a=9.79Å, b=14.79Å, c=16.36Å, α=103.84⁰, β=99.17⁰, γ=99.77⁰, P-1(#2), μCN=2227.78cm^-1, Rh-Rh=2.42Å, N-C=1.13Å, 1.14Å, Rh-N=2.34Å, 2.35Å, Rh-N-C=151.6⁰, 152.5⁰, Rh-Rh-N=173.0⁰, 174.6⁰).

[Rh₂(PhNCOCH₃)_{4 …}

Investigation Into The Effects Of Pegylation On The Thermodynamic Stability Of The Ww Domain, Sam S. Matthews

Theses and Dissertations

The covalent attachment of poly(ethylene glycol) (PEG) to a protein surface (known as PEGylation), has been demonstrated to increase the serum half-life of therapeutic proteins by reducing kidney clearance and immunogenicity and by protecting against proteolysis. Theses beneficial effects could be further enhanced if PEGylation consistently increased protein conformational stability (i.e. the difference in free energy between the folded and unfolded states). However, the effects of PEGylation on protein conformational stability are unpredictable; PEGylation has been reported to increase, decrease, or have no effect on the conformational stability of medicinal proteins.This thesis details the results of two studies aimed at …

Synthesis Of Resveratrol Ester Derivatives, Daniel Ressler

Electronic Theses and Dissertations

The goal of this research project was to synthesize derivatives of transresveratrol. In order for resveratrol to be activated and used by the body it needs to bind to Human Serum Albumin (HSA), a protein in blood plasma. The derivatives were synthesized to improve the ability of resveratrol to enter cells as well as improve their ability to bind to HSA. The three derivatives that were synthesized have converted one of the hydroxyl groups on resveratrol to an ether with a methylene chain terminated by a carboxylic acid. By varying the lengths of the methylene chain we varied the water …

Synthesis And Characterization Of A New Cyano-Substituted Tris(Pyrazolyl)Borate And Its Thallium(I) Complex, Bozumeh Som

Electronic Theses and Dissertations

A new cyanoscorpionate - tris(4-cyano-3,5-diphenylpyrazolyl)borate (Tp^Ph2,4CN) has been synthesized and characterized. The thallium complex of this ligand TlTp^Ph2,4CN has also been prepared and characterized by FT-IR, ¹H NMR, and single-crystal X-ray-diffraction. The complex TlTp^Ph2,4CN crystalized in the monoclinic space group C2/c with unit cell a = 14.6697(10) Å, b = 13.9493(10) Å, c = 19.3347(12) Å, and b= 91.761(2)°. Structural comparison of TlTp^Ph2,4CN with analogous complexes demonstrated the effects of both steric and electron-withdrawing substituents on coordination geometry and the electronic properties of the metal ion. There were short contacts between the cyano groups …

Synthesis Of Ferrocene Copolymers And Investigation Of Their Electrochemical Properties., Alzharani Ahmed

Electronic Theses & Dissertations

Ferrocene is an organometallic compound. It is a classical metallocene consisting of two cyclopentadienyl rings bound on opposite sides of a central iron atom. Such organometallic compounds are also called sandwich compounds. Ferrocene copolymers have well known electrochemical capabilities. The main objective of this thesis is to synthesize vinyl ferrocene copolymers and test their electrochemical properties in aqueous solutions with different electrolytes (sodium nitrate, sodium perchlorate, and phosphate buffered saline). Vinylferrocene and 3-phenyl[5]ferrocenophane-1,5- dimethylene were synthesized using a Wittig reaction. Both ferrocene monomers were copolymerized with N-ethylmaleimide and N-phenylmaleimide and the resulting polymers were analyzed by Gel Permeation chromatography, IR …

The Fabrication And Study Of Silver Nanoparticle Structures, Aubrie Pfirman

All Theses

Nanotechnology and the synthesis of nanoparticle systems are attractive in part because of interesting, tunable optical and electrical properties that are not observed with bulk material. Silver nanoparticles (Ag NPs) interact with visible light more efficiently than any other system due to the excitation of plasmon resonances, which are the collective oscillations of the free electron density. These collective oscillations produce an enhanced local electromagnetic (EM) field: this field is responsible for highly-utilized phenomena such as surface enhanced Raman scattering (SERS), enhanced fluorescence, surface enhanced infrared absorption (SEIRA), and many others. Many experiments have been conducted to optimize and tailor …

Neutron Study Of Structured Polymers At Interfaces, Thusitha Etampawala

All Dissertations

This work focuses on interfacial structure and dynamics of structured polymers in thin films and in solutions using neutron techniques accompanied by atomic force microscopy. We probed polymers with a common theme that were highly segregated either because of presence of ionic groups or topological constraints. In these polymers the interfacial regions often define their function in different applications such as clean energy, printing adhesions and drug delivery systems. Thin film studies include systems of polystyrene/sulfonated polystyrene, a rigid sulfonated polyphenylene and polystyrene three-arm stars/linear polystyrene. The first two systems include ionic components and the last exhibits topological constraints. Polystyrene …

Using Resonance Raman Cross-Section Data To Estimate The Spin State Populations Of Cytochromes P450, Piotr J. Mak, Qianhong Zhu, James R. Kincaid

Chemistry Faculty Research and Publications

The cytochromes P450 (CYPs) are heme proteins responsible for the oxidation of xenobiotics and pharmaceuticals and the biosynthesis of essential steroid products. In all cases, substrate binding initiates the enzymatic cycle, converting ferric low-spin to high-spin state, with the efficiency of the conversion varying widely for different substrates, so documentation of this conversion for a given substrate is an important objective. Resonance Raman (rR) spectroscopy can effectively yield distinctive frequencies for the ν₃ ‘spin state marker’ bands. Here, employing a reference cytochrome P450 (CYP101), the intensities of the ν₃ modes (I_LS) and (I_{HS …}

Quantum Dot Enhanced Epitaxial Lift-Off Solar Cells, Mitchell F. Bennett

Theses

Embedded nanostructures such as quantum dots (QDs) have been studied for many applications in solar cells including enhanced mini-band absorption in intermediate-band solar cells and current matching in multi junction cells. The major drawbacks of using such techniques to decrease intrinsic solar cell loss mechanisms are twofold: first, it is difficult to maintain partially populated states using QDs due to a quick thermal extraction of carriers; second, QDs have a weak absorption which necessitates a near-perfect control of QD growth mechanisms to carefully ensure a balance between dot size and density. One avenue for improving absorption into QDs is to …

Developing A Presumptive Test For Select Synthetic Cannabinoids, Carrie Snyder

Graduate Theses and Dissertations

Synthetic cannabinoids (SC's) began to gain popularity around the world in 2009. Since then, many of the compounds have been outlawed and methods developed to detect them and their metabolites using mass spectrometry. Our work investigated the possibility of developing a colorimetric presumptive test. The SC JWH-019 was synthesized and its ketone targeted as a possible reaction site. Many SC's contain ketones and thus a reaction at this site would be applicable to many of the compounds. Since JWH-019 is costly and time consuming to synthesize, much of the experimental work was done using benzophenone (BP). BP contains a diaryl …

Towards The Total Synthesis Of Antascomicin B. Efforts To Construct The C1-C21 Fragment, Juliette Rivero-Castro

Graduate Theses and Dissertations

Antascomicin B is a macrolide isolated from a strain of Micromonospora. It possesses structural similarities to FK506 and rapamycin and exhibits potent binding ability to FKBP12. Recent reports suggest that small molecule ligands of FKBP12 possess potent neuroprotective and neurodegenerative properties in mouse models of Parkinson's disease. Our approach to the C1-21 fragment of antascomicin B involves an asymmetric amino-Claisen rearrangement originally developed by Tsunoda et al.35 report the scalability of the preparation and rearrangement of an allylic amide possessing a silyloxy group at the terminal position of the alkene. The Tsunoda-Claisen rearrangement uses inexpensive (S)-α-methylbenzylamine as the chiral …

Tin Sensitization For Electroless Plating, Xingfei Wei

Graduate Theses and Dissertations

The tin sensitization process has been used in electroless plating since 1940s Brenner and Riddell developed the electroless plating for surface metallization method. It was found to be an interesting topic to study tin sensitization for chemically controlling metal deposition on different substrates, because the tin sensitization process had critical effects on the electroless plated metal thin films. Nowadays electroless plating metal deposition is still an important method for depositing metals. It has a few advantages over the vapor deposition and electrodeposition method, such as work in an ambient condition, on nonconductive substrates, and without extra power input. Applying electroless …

Nanoparticles And Polymer Crystallization Kinetics In Hybrid Electronic Devices, Taylor William Wagner

Master's Theses

Conjugated semi-conducting polymers have become well known for their potential applications in hybrid electronic devices like solar cells, LEDs, and organic displays. These hybrid devices also contain inorganic nanoparticles, which complement the polymer when they are combined into the same layer. Control over the conformation and crystallinity of the polymer is critical for device performance, yet not much is known about the effect that these nanoparticles have on the polymer. Here, zinc oxide nanowire was surface modified with mono-substituted-carboxylic acid tetraphenylporphyrin and dodecanethiol, and introduced to poly(3-hexyl thiophene) in solution. The electron transfer, kinetics, and thermodynamics of this system were …

Phase Behavior And Rheology Of Latex, Thickener, Surfactant Mixtures And Liquid Crystal Based Compositions For Printing High-Efficiency Flexible Electronics, Franceska Anna Santos

Master's Theses

This project consists of two parts. One area of focus in the first part is understanding the interactions between a non-ionic, block copolymer type dispersant and hydrophobically-modified, ethoxylated urethane (HEUR) associative thickeners in water. The dispersant was mixed at various concentrations (0-2% by weight) with HEUR thickeners at 1% by weight concentration in the aqueous medium. This study is an integral part of our attempts to determine mechanisms of viscosity drop when colorant dispersions are added to latex tint base formulations thickened with associative thickeners. One of the HEUR thickeners is a product that has been available for over three …

Substrate Binding And Reduction Mechanism Of Molybdenum Nitrogenase, Zhiyong Yang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As a key constituent of proteins, nucleic acids, and other biomolecules, nitrogen is essential to all living organisms including human beings. Dinitrogen represents the largest pool of nitrogen, about 79% of the Earth’s atmosphere, yet it is unusable by most living organisms due to its inertness. There are two ways to fix this inert dinitrogen to usable ammonia. One is the industrial Haber-Bosch process, which needs to be conducted at high temperature and pressure. This process uses a lot of the non-renewable fossil fuel as the energy source. The other major pathway is the biological nitrogen fixation carried out by …

The Spectral Properties Of (-)-Epigallocatechin 3-O-Gallate (Egcg) Fluorescence In Different Solvents: Dependence On Solvent Polarity, Vladislav Snitsarev, Michael N. Young, Ross M.S. Miller, David P. Rotella

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

(-)-Epigallocatechin 3-O-gallate (EGCG) a molecule found in green tea and known for a plethora of bioactive properties is an inhibitor of heat shock protein 90 (HSP90), a protein of interest as a target for cancer and neuroprotection. Determination of the spectral properties of EGCG fluorescence in environments similar to those of binding sites found in proteins provides an important tool to directly study protein-EGCG interactions. The goal of this study is to examine the spectral properties of EGCG fluorescence in an aqueous buffer (AB) at pH=7.0, acetonitrile (AN) (a polar aprotic solvent), dimethylsulfoxide (DMSO) (a polar aprotic solvent), and ethanol …

New Bis(Imino)Pyridine Complexes Of Iron(Ii) And Iron(Iii), And Their Catalytic­ Activity In The Mukaiyama Aldol Reaction, Pushkar Shejwalkar, Nigam Rath, Eike Bauer

Chemistry & Biochemistry Faculty Works

New iron(II) and iron(III) complexes bearing bis(imino)pyridine ligands were synthesized and successfully applied to the Mukaiyama aldol reaction. The two complexes [FeCl2 L] (L = bis(imino)pyridine ligand, 55% isolated yield) and [LFe(μCl)3FeCl3] (76%) were obtained employing FeCl2 and FeCl3 iron sources, respectively, and characterized by elemental analyses, mass spectrometry, IR spectroscopy and, one example, by X-ray diffraction. The two new iron complexes were subsequently employed as catalysts in the Mukaiyama aldol reaction after abstraction of two chlorides by AgSbF6 to obtain the aldol products in 43% to virtually quantitative yield (CH2Cl2 solvent, room temperature, 3.5 to 16 h reaction time). …

Acoustic Droplet Vaporization In Biology And Medicine, Chung-Yin Lin, William G. Pitt

Faculty Publications

This paper reviews the literature regarding the use of acoustic droplet vaporization (ADV) in clinical applications of imaging, embolic therapy, and therapeutic delivery. ADV is a physical process in which the pressure waves of ultrasound induce a phase transition that causes superheated liquid nanodroplets to form gas bubbles. The bubbles provide ultrasonic imaging contrast and other functions. ADV of perfluoropentane was used extensively in imaging for preclinical trials in the 1990s, but its use declined rapidly with the advent of other imaging agents. In the last decade, ADV was proposed and explored for embolic occlusion therapy, drug delivery, aberration correction, …

Follicular Dendritic Cells As Reservoirs Of Diverse Human Immunodeficiency Virus: A Phylogenetic Analysis, Trever Bradley Burgon, Dr. Gregory F. Burton

Journal of Undergraduate Research

Human Immunodeficiency Virus (HIV), the retrovirus that causes Acquired Immunodeficiency Syndrome (AIDS), currently infects over 42 million people; more than three million of them are children under the age of 15. The Joint United Nations Program on HIV/AIDS calls the current AIDS epidemic: “the most devastating disease mankind has ever faced.”

Collision Cross Section Measurements In A Fourier Transform Ion Cyclotron Resonance Mass Spectrometer, Daniel E. Austin, Dr. David Dearden

Journal of Undergraduate Research

I explored the possibility of using spectral linewidths in a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) to measure ion collision cross sections. A measurement of an ion’s collision cross section would provide important information about its conformation, or the spatial arrangement of the atoms and functional groups that make up the ion.

Cyclometalated Iridium(Iii) Complexes With Deoxyribose Substituents, Ayan Maity, Jung-Suk Choi, Thomas S. Teets, Nihal Deligonul, Anthony J. Berdis, Thomas G. Gray

Chemistry Faculty Publications

Fundamental study of enzymatic nucleoside transport suffers for lack of optical probes that can be tracked noninvasively. Nucleoside transporters are integral membrane glycoproteins that mediate the salvage of nucleosides and their passage across cell membranes. The substrate recognition site is the deoxyribose sugar, often with little distinction among nucleobases. Reported here are nucleoside analogues in which emissive, cyclometalated iridium(III) complexes are “clicked” to C-1 of deoxyribose in place of canonical nucleobases. The resulting complexes show visible luminescence at room temperature and 77 K with microsecond-length triplet lifetimes. A representative complex is crystallographically characterized. Transport and luminescence are demonstrated in cultured …

Investigation Of The Structure And Dynamics Of Regioisomeric Eu³⁺ And Gd³⁺ Chelates Of Nb-Dotma: Implications For Mri Contrast Agent Design, Benjamin Charles Webber

Dissertations and Theses

The detection of disease and abnormal pathology by magnetic resonance imaging (MRI) has been aided significantly by the use of gadolinium (Gd³⁺)-based contrast agents (CAs) over the past three decades. MRI and MRI CAs play a critical role in diagnosing tumors and diseases of the central nervous system. The agents used clinically have been shown to safely increase MRI contrast despite the toxicity of Gd³⁺, owing to the high kinetic and thermodynamic stability of these chelates. However, current CAs enhance contrast at a small fraction of what is theoretically possible. This leads to the necessity of …

Poly (N-Isopropylacrylamide) Microgel-Based Etalons And Etalon Arrays For Determining The Molecular Weight Of Polymers In Solution, Molla R. Islam, Michael J. Serpe

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Positively and/or negatively charged poly (N-isopropylacrylamide)-based microgels were deposited on a single substrate and isolated regions of Au overlayers were deposited on top of the microgels. Each spatially isolated Au overlayer region had a different thickness to make an etalon array.We found that areas with a thin Au overlayer (5 nm) responded to a range of polymer molecular weights (MW), while areas with a thick overlayer (35 nm) can only respond to low molecular weight polyelectrolytes. By comparing the optical responses of the device’s individual array elements, a good approximation of the polyelectrolyteMWin solution can be made.

N-Body:Many-Body Qm:Qm Vibrational Frequencies: Application To Small Hydrogen-Bonded Clusters, J. Coleman Howard, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

We present an efficient method for reproducing CCSD(T) (i.e., the coupled-cluster method with single, double and perturbative connected triple excitations) optimized geometries and harmonic vibrational frequencies for molecular clusters with the N-body:Many-body QM:QM technique. In this work, all 1-body through N-body interactions are obtained from CCSD(T) computations, and the higher-order interactions are captured at the MP2 level. The linear expressions from the many-body expansion facilitate a straightforward evaluation of geometrical derivative properties (e.g., gradients and Hessians). For (H₂O)_n clusters (n = 3-7), optimized structures obtained with the 2-body:Many-body CCSD(T):MP2 method are virtually identical to CCSD(T) optimized geometries. …

Examination Of Tyrosine/Adenine Stacking Interactions In Protein Complexes, Kari L. Copeland, Samuel J. Pellock, James R. Cox, Mauricio L. Cafiero, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The π-stacking interactions between tyrosine amino acid side chains and adenine-bearing ligands are examined. Crystalline protein structures from the protein data bank (PDB) exhibiting face-to-face tyrosine/adenine arrangements were used to construct 20 unique 4-methylphenol/N9-methyladenine (p-cresol/9MeA) model systems. Full geometry optimization of the 20 crystal structures with the M06-2X density functional theory method identified 11 unique low-energy conformations. CCSD(T) complete basis set (CBS) limit interaction energies were estimated for all of the structures to determine the magnitude of the interaction between the two ring systems. CCSD(T) computations with double-ζ basis sets (e.g., 6-31G*(0.25) and aug-cc-pVDZ) indicate that the MP2 method overbinds …

Troika Of Single Particle Tracking Programing: Snr Enhancement, Particle Identification, And Mapping, Lydia Kisley

Faculty Scholarship

Single particle tracking (SPT) techniques provide a microscopic approach to probe in vivo and in vitro structure and reactions. Automatic analysis of SPT data with high efficiency and accuracy spurs the development of SPT algorithms. In this perspective, we review a range of available techniques used in SPT analysis programs. In addition, we present an example SPT program step-by-step to provide a guide so that researchers can use, modify, and/or write a SPT program for their own purposes. © 2014 the Owner Societies.

Role Of Ser-257 In The Sliding Mechanism Of Nadp(H) In The Reaction Catalyzed By The Aspergillus Fumigatus Flavin-Dependent Ornithine N ⁵-Monooxygenase Sida, Carolyn Shirey, Somayesadat Badieyan, Pablo Sobrado

Chemistry Faculty Research & Creative Works

SidA (siderophore A) is a flavin-dependent N-hydroxylating monooxygenase that is essential for virulence in Aspergillus fumigatus. SidA catalyzes the NADPH- and oxygen-dependent formation of N5-hydroxyornithine. In this reaction, NADPH reduces the flavin, and the resulting NADP+ is the last product to be released. The presence of NADP+ is essential for activity, as it is required for stabilization of the C4a-hydroperoxyflavin, which is the hydroxylating species. As part of our efforts to determine the molecular details of the role of NADP(H) in catalysis, we targeted Ser-257 for site-directed mutagenesis and performed extensive characterization of the S257A enzyme. Using a combination of …

Two Homologous Ef-G Proteins From Pseudomonas Aeruginosa Exhibit Distinct Functions, Stephanie O. Palmer, Edna Y. Rangel, Yanmei Hu, Alexis T. Tran, James M. Bullard

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Genes encoding two proteins corresponding to elongation factor G (EF-G) were cloned from Pseudomonas aeruginosa. The proteins encoded by these genes are both members of the EFG I subfamily. The gene encoding one of the forms of EF-G is located in the str operon and the resulting protein is referred to as EF-G1A while the gene encoding the other form of EF-G is located in another part of the genome and the resulting protein is referred to as EF-G1B. These proteins were expressed and purified to 98% homogeneity. Sequence analysis indicated the two proteins are 90/84% similar/identical. In other …

Thiol-Containing Compounds For The Removal Of Elements From Tissues And Formulations Therefor, Boyd E. Haley, David A. Atwood, Niladri Gupta

Chemistry Faculty Patents

Methods and pharmaceutical formulations for ameliorating heavy metal toxicity and/or oxidative stress are disclosed, comprising administering pharmaceutically effective amounts of ligands according to the present disclosure.

To see the remainder of the abstract, please download this patent.

Co Oxidation Over Au/Tio2 Catalyst: Pretreatment Effects, Catalyst Deactivation, And Carbonates Production, Johnny Saavedra, Camilah Powell, Basu Panthi, Christopher J. Pursell, Bert D. Chandler

Chemistry Faculty Research

A commercially available Au/TiO₂ catalyst was subjected to a variety of thermal treatments in order to understand how variations in catalyst pretreatment procedures might affect CO oxidation catalysis. Catalytic activity was found to be inversely correlated to the temperature of the pretreatment. Infrared spectroscopy of adsorbed CO experiments, followed by a Temkin analysis of the data, indicated that the thermal treatments caused essentially no changes to the electronics of the Au particles; this, and a series of catalysis control experiments, and previous transmission electron microscopy (TEM) studies ruled out particle growth as a contributing factor to the activity loss. …