Physical Sciences and Mathematics Commons^™

Synthesis Of Chemical Models Of Hydrolase Enzymes For Intramolecular Catalysis., Cornelius Ndi Ndi

Electronic Theses and Dissertations

Most nuclease enzymes can hydrolyze phosphoester bonds (in DNA and RNA) by using metal ions cofactors that coordinate and activate water molecules in the enzymes' active sites. However, there are some hydrolase enzymes (including nucleases) that can function without the aid of metal ions. 2,6-Di(1H-imidazol-2-yl)phenol, a model compound for hydrolase enzyme, was synthesized by the reaction between ethylenediamine and dimethyl-3-carboxysalicylate, initially resulting in the formation of diimidazoline. The diimidazoline was subsequently aromatized to the diimidazole by dehydrogenation over palladium. The overall reaction yield was low; therefore, other dehydrogenation transformation reactions were tried but all failed to improve the …

Self-Assemblies Driven By The Hydrophobic Effect, Haiying Gan

University of New Orleans Theses and Dissertations

Water is a simple molecule but is an essential part of life. One key aspect of the properties of water is the hydrophobic effect, and whilst there is an appreciation of this phenomenon at the macro-scale (raindrops falling off leaves) and the micro-scale (the structure of cellular systems), a complete understanding at the molecular level still eludes science. Addressing this issue, our studies involve synthetic supramolecular compounds that assemble in water via the hydrophobic effect.

First of all, a novel water-soluble deep-cavity cavitand was synthesized. It possesses four endo methyl groups on top rim of the cavitand, eight water-solubilizing carboxylic …

Synthesis And Biological Evaluation Of Aeruginosin Based Compounds And Self-Assembly Of Glucosamine Based Compounds, Navneet Goyal

University of New Orleans Theses and Dissertations

Aeruginosins are a family of marine natural products containing mostly non-proteogenic amino acids. These compounds contain a common 2-carboxy-6-hydroxy-octaindole (Choi) rigid bicyclic structure. Many aeruginosins are inhibitors for enzymes involved in the blood coagulation cascade, such as thrombin and Factor VIIa. In order to understand the structure activity relationship (SAR) of the aeruginosins and to discover novel anticoagulants with potentially improved inhibitory and pharmacokinetic properties, in the first part of my thesis I have discussed, synthesis of a series of novel analogs of aeruginosin 298-A, in which the Choi will be replaced with L-proline and oxygenated Choi analogs, and the …

Development Of A Glycoconjugate Tool Set For The Assembly And Presentation Of Carbohydrate Ligands On Surfaces, Irene Esah Abia

Doctoral Dissertations

Carbohydrate and protein interactions are often essential in viral and bacterial infection, the immune response, cell differentiation and development, and the progression of tumor cell metastasis. Therefore, an understanding of carbohydrate–protein interactions at the molecular level would lead to a better insight into the biological process of living systems and assist in the development of therapeutic and diagnostic strategies. Our goal was to synthesize different mannose derivatives, immobilize them on nano-patterned surfaces and carry out binding studies with mannose-binding lectins in order to characterize carbohydrate–protein interactions.

Different derivatives of D-mannose (monosaccharide, (1→2)-linked disaccharide, (1→3)-linked disaccharide, and (1→2, 1→3)-linked trisaccharide) with …

The Tetrafluoroborate Salt Of 4-Methoxybenzyl N-2-(Dimethylamino)Ethyl-N-Nitrosocarbamate: Synthesis, Crystal Structure And Dft Calculations, Helene Hedian, Vladimir Benin

Chemistry Faculty Publications

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å3, Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2–C3 bond, due to a stabilizing hydrogen bond between the carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of …

Synthesis And Characterization Of Catalysts For The Selective Transformation Of Biomass-Derived Materials, Isaac Tyrone Ghampson

Electronic Theses and Dissertations

The experimental work in this thesis focuses on generating catalysts for two intermediate processes related to the thermal conversion of lignocellulosic biomass: the synthesis and characterization of mesoporous silica supported cobalt catalysts for the Fischer-Tropsch reaction, and an exploration of the reactivity of bulk and supported molybdenum-based nitride catalysts for the hydrodeoxygenation (HDO) of guaiacol, a lignin model compound. The first section of the work details the synthesis of a series of silicasupported cobalt Fischer-Tropsch catalysts with pore diameters ranging from 2-23 nm. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, …

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Analysis Of Volatile Organic Compounds In Virgin Coconut Oil And Their Sensory Attibutes, Fabian M. Dayrit, Jaclyn Elizabeth R. Santos, Bianca J. Villarino, Anthony R. Zosa

Chemistry Faculty Publications

The volatile compounds in the headspace of twenty-four commercial virgin coconut oil (VCO) samples prepared by different methods (i.e. expeller, centrifugation, and fermentation with and without heat) were analyzed by solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS). The following volatile organic compounds (VOCs) were identified: ethyl acetate, acetic acid, 2-pentanone, hexanal, n-octane, 2-heptanone, limonene, nonanal, octanoic acid, ethyl octanoate, δ-octalactone, ethyl decanoate, δ-decalactone, and dodecanoic acid. Fermentation-produced samples were found to have higher levels of acetic acid and free fatty acids in the headspace compared to VCO produced using the centrifuge and expeller methods. Descriptive sensory analysis of the VCO …

The Design, Synthesis And Application Of A Novel Class Of N-Heterocyclic Carbene Catalysts, Abigail Lynn Hubbard

Graduate Theses and Dissertations

A copper carbenoid representative of a novel class of N-heterocyclic carbene (NHC) catalysts has been synthesized. This compound was characterized by X-ray crystallography and was found to confirm the rationale of our synthetic design: The C2-symmetric structure places four stereocenters in close proximity (<5Å) to the reactive site of the carbene via a trans-annular gearing effect. The copper carbenoid was found to catalyze the hydrosilylation of prochiral ketones with superb selectivity in high yield.

Dynamics And Catalytic Resolution Of Selected Chiral Organolithiums, Timothy Kum Beng

Graduate Theses and Dissertations

One of the most important developments of the last decade has been the emergence of new methods to dynamically resolve racemic organolithiums using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched organolithium compounds for use in asymmetric synthesis. Since certain electrophiles consume the chiral ligand, it is desirable to render this process catalytic in the chiral ligand.

As part of a larger study on the amenability of chiral organolithiums to a …

Direct Contact Pyrolysis Of Hydrocarbons: A Source Of Hydrogen And Interesting Carbon Formations, Peter G. Faught

UNLV Theses, Dissertations, Professional Papers, and Capstones

The work detailed in this document looks at a novel liquid metal supported catalytic system for the generation of hydrogen by decomposition of ethanol through direct contact pyrolysis. The hydrogen is produced at relatively low temperatures (500-600°C) and has carbon and water as co-products. It should be noted that CO is not observed as a product at these low temperatures. This is to be contrasted with the hydrogen produced at higher temperature from ethanol which does contain carbon monoxide. The presence of carbon monoxide in hydrogen complicates fuel cell operation and catalytic chemical processes. Thus, the lack of CO in …

Organometallic Acene Complexes For Electronics Applications, Ilya Vinogradov

Kaleidoscope

No abstract provided.

Concentration Oscillations In The Processes Of Unsaturated Compounds Oxidative Carbonylation. 2. Oxidative Carbonylation Of Alkynes In The Palladium Halogen Complexes Solutions (In Russian), Sergey N. Gorodsky

Sergey N. Gorodsky

No abstract provided.

Valine Sulfonamidecinnamic Acid Asymmetric Crystal Reactions, Kraig A. Wheeler, Steven H. Malehorn, Annie E. Egan

Faculty Research and Creative Activity

Racemic and homochiral valine sulfonamidecinnamic acidscrystallize with components aligned by use of thecomplementary features of hydrogen bonds and moleculartopology to give supramolecular dimers. These discretemotifs effectively organize adjacent olefins for UV initiated10 single-crystal-to-single-crystal [2+2] photodimerizationreactions. The racemic crystals produce inversion relatedcyclobutane products, while the desymmetrized crystallinearchitectures of the homochiral phase promote asymmetricphotodimerization with 90% conversion.

Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Synthetic Studies Directed Toward The Frondosins, Do W. Lee, Rajesh K. Pandey, Sergey Lindeman, William Donaldson

Chemistry Faculty Research and Publications

A short, 4-step route to the scaffold of frondosin A and B is reported. The [1-methoxycarbonyl-5-(2′,5′-dimethoxyphenyl)pentadienyl]Fe(CO)₃⁺ cation was prepared in two steps from (methyl 6-oxo-2,4-hexadienoate)Fe(CO)₃. Reaction of this cation with isopropenyl Grignard or cyclohexenyllithium reagents affords (2-alkenyl-5-aryl-1-methoxycarbonyl-3-pentene-1,5-diyl)Fe(CO)₃ along with other addition products. Oxidative decomplexation of these (pentenediyl)iron complexes, utilizing CuCl₂, affords 6-aryl-3-methoxycarbonyl-1,4-cycloheptadienes via the presumed intermediacy of a cis-divinylcyclopropane.

Silent, Fluorescent Labeling Of Native Neuronal Receptors, D Vytla, R E. Combs-Bachmann, A M. Hussey, I Hafez, James Chambers

James Chambers

We have developed a minimally-perturbing strategy that enables labeling and subcellular visualization of endogenous dendritic receptors on live, wild-type neurons. Specifically, calcium-permeable non-NMDA glutamate receptors expressed in hippocampal neurons can be targeted with this novel synthetic tri-functional molecule. This ligand-directed probe was targeted towards AMPA receptors and bears an electrophilic group for covalent bond formation with an amino acid side chain on the extracellular side of the ion channel. This molecule was designed in such a way that the use-dependent, polyamine-based ligand accumulates the chemically-reactive group at the extracellular side of these polyamine-sensitive receptors, thereby allowing covalent bond formation between …

6-[(4-Hydroxyphenyl)Diazenyl]- 1,10-Phenanthrolin-1-Ium Chloride Monohydrate, Akram Hazeen, Yan Zhang, Minchong Mao, Kraig A. Wheeler, Mark E. Mcguire

Kraig A. Wheeler

In the cation of the title molecular salt, C18H13N4O+_Cl__H2O, the dihedral angle between the mean planes of the 1,10- phenanthroline system and the phenol ring is 14.40 (19)_. The crystal packing is stabilized by O—H_ _ _O hydrogen bonds, weak N—H_ _ _Cl and O—H_ _ _Cl intermolecular interactions and _—_ stacking interactions [centroid–centroid distance = 3.6944 (13) and 3.9702 (12) [A °]

6-[(4-Hydroxyphenyl)Diazenyl]- 1,10-Phenanthrolin-1-Ium Chloride Monohydrate, Akram Hazeen, Yan Zhang, Minchong Mao, Kraig A. Wheeler, Mark E. Mcguire

Faculty Research and Creative Activity

In the cation of the title molecular salt, C18H13N4O+_Cl__H2O, the dihedral angle between the mean planes of the 1,10- phenanthroline system and the phenol ring is 14.40 (19)_. The crystal packing is stabilized by O—H_ _ _O hydrogen bonds, weak N—H_ _ _Cl and O—H_ _ _Cl intermolecular interactions and _—_ stacking interactions [centroid–centroid distance = 3.6944 (13) and 3.9702 (12) [A °]

Synthesis Of N-Acyl-N,O-Acetals From N-Aryl Amides And Acetals In The Presence Of Tmsotf, C. Wade Downey, Alan S. Fleisher, James T. Rague, Chelsea L. Safran, Megan E. Venable, Robert D. Pike

Chemistry Faculty Publications

Secondary amides undergo in situ silyl imidate formation mediated by TMSOTf and an amine base, followed by addition to acetal acceptors to provide N-acyl-N,O-acetals in good yields. An analogous, high-yielding reaction is observed with 2-mercaptothiazoline as the silyl imidate precursor. Competing reduction of the acetal to the corresponding methyl ether via transfer hydrogenation can be circumvented by the replacement of i-Pr₂NEt with 2,6-lutidine under otherwise identical reaction conditions.

An Integrated Systems Approach To Deconstructing Glycosylation, L. K. Mahal, John F. Rakus, Kanoelani Pilobello, P. Agrawal

Chemistry Faculty Research

Glycosylation involves the post-translational addition of carbohydrates to protein molecules and is an intricate and indispensable biochemical process. Study of this complicated network of interactions is hindered by the lack of a coding template analogous to the genetic code, and by the vast structural complexity inherent to carbohydrate polymers. We use lectins (non-enzymatic carbohydrate-binding proteins of non-immunological origin) as microarray probes to identify carbohydrate features expressed on cellular surfaces. Specifically, we utilized lectin microarray technology to investigate the differences in carbohydrates expressed by the cell lines of the Nation Cancer Institute’s NCI-60 panel. Our investigation identified tissue-specific expression differences in …

Strategies For The Thermal And Photochemical Modification Of Gold Nanoparticles (Aunps) And The Fabrication Of Aunp Hybrid Materials, Hossein Ismaili

Electronic Thesis and Dissertation Repository

Among the existing approaches for the functionalization of the gold nanoparticle (AuNP), a direct interfacial organic reaction of terminal functional groups exposed on the surface of template nanoparticles with various reactants has been shown as a promising strategy to incorporate desired functionality onto the AuNP monolayer. In our own attempts to extend the types of reactions that can be utilized for efficient interfacial modifications of AuNPs, we examined uncatalyzed Huisgen 1,3-dipolar click-type cycloaddition of azide-modified AuNPs to terminal alkynes. These particular reactions were found to be generally too slow to be useful at ambient temperatures but it was shown that …

Concentration Oscillations In The Processes Of Unsaturated Compounds Oxidative Carbonylation. 1. Processes Of Acetylene And Phenylacetylene Oxidative Carbonylation (In Russian), Sergey N. Gorodsky, Katarina Novakovic

Sergey N. Gorodsky

This review describes the processes of oxidative carbonylation of acetylene and phenylacetylene, occurring in the oscillatory mode under conditions of homogeneous catalysis by palladium complexes.

Synthesis And Structure Of A Substituted Pyridazine, Kiranmai Byrichetti

Masters Theses & Specialist Projects

Pyridazines are heterocyclic compounds with an N-N bond in their ring structure. Heterocyclic aromatic compounds are of great interest as a result of their novel properties and commercial applications. Our current research is focused on the potential role of pyridazines in next generation electronic devices that utilize organics as the semiconducting material. The synthesis of 5, 6-fused ring pyridazines beginning from fulvenes (Scheme 1) is described herein. These fused heterocycles will serve as synthetic models and building blocks for potential organic or organometallic conducting polymers.

Our goal was to modify the route of Snyder et al. previously reported for the …

High Yield Synthesis Of Positron Emission Tomography Ligands For Metabotropic Glutamate Receptor Imaging, Saraanne E. Hitchcock

Department of Chemistry: Dissertations, Theses, and Student Research

Positron Emission Tomography (PET) is a powerful and non-invasive imaging technique used for human and animal organ imaging. Currently, the market for PET is project to reach $5.4 billion per year by 2015.5 This research focuses on the direct incorporation of [18F]-fluoride into PET ligands. The widespread use of PET imaging is currently frustrated, in part, by the lack of efficient fluorination chemistry.

Glutamate, one of the 20 most abundant naturally occurring amino acids, serves as a neurotransmitter in the central nervous system. Glutamate functions in this capacity by binding to ionotropic and metabotropic receptors. Metabotropic receptors are Gcoupled proteins …

Conjugated Polymers And Inter-Chromophore Interactions: Synthesis, Photophysical Characterization And Application, Anshuman Mangalum

All Dissertations

Ever since the discovery of conducting polymers (CPs)in the late 1970s, organic conjugated materials and polymers is one of the most popular and fascinating research area among the scientists due to the remarkably unique properties and broad range of applications of (CPs), notably organic photovoltaic (OPVs), organic or polymer based light emitting devices (OLEDs / PLEDs), field effect transistors (FETs), nonlinear optical (NLO) devices and sensor for biologically relevant analytes, metal ions and anions. Optical properties of these materials depend on intra / interchromophoric interaction, geometry and relative orientation in space. Detailed study of such materials can also help us …

Regiospecific Synthesis Of Ortho Substituted Phenols, Ravindra Kotha Balasainath

Masters Theses & Specialist Projects

Phenol is highly reactive toward electrophilic aromatic substitution. By this general approach, many groups can be appended to the ring, via halogenation, acylation, sulfonation, and other processes. Phenol contains the hydroxyl group (–OH), which is a strongly activating ortho/para directing group in aromatic electrophilic substitution (AES). AES gives a mixture of ortho-and para isomers, which must be separated.

The strong directing ability of phenol can also result in multiple substitutions on the aromatic ring which could be a major concern in the regiospecific synthesis of phenols. AES and Directed ortho--Metalation (DoM) are the only ways to directly substitute …

Development Of Bifunctional Lysophosphatidic Acid & Lysophosphatidylcholine Activity Probes To Characterize Their Specific Binding Protein Receptors, Ritu Nandal

Masters Theses

Lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC) activity has been found to be dysregulated in cancer cells and therefore is a crucial target for research. Only a few LPA receptors have been identified to date, namely LPA 1, LPA 2, LPA 3, LPA 4 and peroxisome proliferator-activated receptors (PPAR). In order to identify receptors, we are designing and synthesizing bifunctional LPA and LPC activity probes to characterize their protein targets using activity based protein profiling (ABPP) among other proteomic technologies. By synthesizing bifunctional signaling probes that can mimic the naturally occurring LPA and LPC molecules and selectively capture receptors by virtue …

Homogeneous And Heterogeneous Approaches To 1,2,4-Triazine-Accelerated Copper-Catalyzed Azide-Alkyne Cycloadditions, Ashleigh Lauren Prince

Doctoral Dissertations

Over the last decade, the domain of click chemistry has grown exponentially and has significantly impacted the fields of organic synthesis, medicinal chemistry, molecular biology, and materials science. The ideal model of a click reaction has become the copper-catalyzed azide-alkyne cycloaddition (CuAAC). Inherent limitations of CuAAC, including high temperatures, long reaction times, and difficult purifications, have been minimized by the development of nitrogen-based ligands. Herein, we present a novel application of 1,2,4-triazines by investigating their use as accelerants for CuAAC.

A diverse library of 1,2,4-triazines were synthesized in order to examine the molecular determinants of their catalytic activity. These ligands …

Double Helical Hydrogen-Bonded Aaa-Ddd Complexes And Supramolecular Polymers, Hong-Bo Wang

Electronic Thesis and Dissertation Repository

The design and characterization of linear oligomers that self-assemble into double helical structures has been a subject of interest to chemists since the elucidation of the double helix structure of DNA in 1953. Transition metal templates have been widely used in the construction of artificial double helical complexes from linear multidentate ligands. The use of other non-covalent interactions as the driving force in the self-assembly of these types of complexes is less common. Aromatic stacking interactions, anion templates, and salt-bridges have all been applied in this context. The great majority of these investigations have been concerned with the dimerization of …

The Vaporization Enthalpies Of 2- And 4-(N,N-Dimethylamino)Pyridine, 1,5-Diazabicyclo[4.3.0]Non-5-Ene, 1,8-Diazabicyclo[5.4.0]Undec-7-Ene, Imidazo[1,2-A]Pyridine And 1,2,4-Triazolo[1,5-A]Pyrimidine By Correlation-Gas Chromatography., Dmitry Lipkind, Nigam Rath, James S. Chickos, Vasiliy A. Pozdeev, Sergey P. Verevkin

James Chickos

No abstract provided.