Physical Sciences and Mathematics Commons^™

Improved Synthesis Of Pincer Ligand Precursor, And Synthesis And Structural Characterization Of Terphenyl Scaffolded S–C–S Palladium Pincer Complex., Paul Schroder, Thomas Spilker, Wilson Luu, James Updegraff, Man Lung Kwan, Paul Challen, John Protasiewicz

Man Lung Desmond Kwan

An easier and more expedient synthesis of 2,6-(BrCH2C6H4)2-4-I-C6H3 (2) is reported. This material allowed easy synthesis of the new pincer ligand precursor 2,6-(4-CH3C6H4SCH2C6H4)2-4-I-C6H3 (3) in 87% yield. Compound 3 reacts with Pd2(dba)3 to give the new palladium pincer complex 4. Compound 4 has been fully characterized, including structural characterization by single crystal X-ray diffraction methods. The results of the crystallographic work on 4 reveal a twisted type pincer complex not unlike related terphenyl pincer complexes.

Detection Of Psilocybin Mushroom Analogs In Chocolate: Incorporating Current Events Into The Undergraduate Teaching Laboratory, Brandon Huskins, Christopher Dockery

Faculty and Research Publications

In this experiment, tryptamine is used as a psilocin analog and is dispersed onto a Fisher brand cellulose laboratory sponge to simulate dehydrated mushrooms. The resulting “mushroom” material is ground, molded into chocolate, and presented to student groups for real-world and applied analyses. Students isolate the tryptamine from the chocolate using their knowledge of drug chemistry, solubility, pH, extractions, etc. Qualitative analysis is conducted by comparison to standards (Thin Layer Chromatography or Gas Chromatography) and quantitative analysis is conducted by Gas Chromatography using the method of internal standards.

Highly Nitrated Cyclopropanes As New High Energy Materials: Dft Calculations On The Properties Of C3H6−N(No2)N (N=3–6), Aloysus K. Lawong, David W. Ball

Chemistry Faculty Publications

As part of a continuing study of new potential high energy materials, here we present results of calculations on cyclopropane molecules with three or more nitro groups. DFT calculations suggest that all molecules can exist as minimum-energy stationary states. Energy calculations indicate that some nitrocyclopropanes have a specific enthalpy of decomposition in excess of 8kJg⁻¹, suggesting that they be explored as new potential high energy materials.

Indirect Gravimetric Determination Of Waters Of Hydration, Marina C. Koether

Faculty and Research Publications

An alternate gravimetric experiment is described that can be employed in the general chemistry or the quantitative analysis laboratory course. The procedure takes less time than conventional methods and introduces students to waters of hydration and indirect determinations.

Polymeric Ionic Liquids As Co2 Selective Sorbent Coatings For Solid-Phase Microextraction, Qichao Zhao, Jonathan C. Wajert, Jared L. Anderson

Jared L. Anderson

Two polymeric ionic liquids (PIL) were synthesized and employed as sorbent coatings in solid-phase microextraction (SPME) for the selective extraction of CO2. The two coatings, poly(1-vinyl-3-hexylimidazolium) bis[(trifluoromethyl)sulfonyl]imide [poly(VHIM-NTf2)] and poly(1-vinyl-3-hexylimidazolium) taurate [poly(VHIM-taurate)], exhibited varied selectivity toward CO2 due to functional groups within in the PIL that imparted different mechanisms of CO2 capture. Extraction efficiencies were compared to those of two commercial SPME fibers [poly(dimethylsiloxane) (PDMS) and Carboxen−PDMS]. The poly(VHIM-NTf2) PIL fiber exhibited comparable extraction efficiency at high CO2 pressure compared to the Carboxen−PDMS fiber, even though the PIL-based fibers possessed much smaller film thicknesses. Calibration curves generated in pure CO2 …

Double Superhelix Model Of High Density Lipoprotein, Zhiping Wu, Valentin Gogonea, Xavier Lee, Mathew A. Wagner

Chemistry Faculty Publications

High density lipoprotein (HDL), the carrier of so-called “good” cholesterol, serves as the major athero-protective lipoprotein and has emerged as a key therapeutic target for cardiovascular disease. We applied small angle neutron scattering (SANS) with contrast variation and selective isotopic deuteration to the study of nascent HDL to obtain the low resolution structure in solution of the overall time-averaged conformation of apolipoprotein AI (apoA-I) versus the lipid (acyl chain) core of the particle. Remarkably, apoA-I is observed to possess an open helical shape that wraps around a central ellipsoidal lipid phase. Using the low resolution SANS shapes of the protein …

Selective Complexation And Reactivity Of Metallic Nitride And Oxometallic Fullerenes With Lewis Acids And Use As An Effective Purification Method, Steven Stevenson, Mary A. Mackey, Jane E. Pickens, Melissa A. Stuart, Bridget S. Confait, J. Paige Phillips

Faculty Publications

Metallic nitride fullerenes (MNFs) and oxometallic fullerenes (OMFs) react quickly with an array of Lewis acids. Empty-cage fullerenes are largely unreactive under conditions used in this study. The reactivity order is Sc₄O₂@I_h-C₈₀ > Sc₃N@C₇₈ > Sc₃N@C₆₈ > Sc₃N@D_5h-C₈₀ > Sc₃N@I_h-C₈₀. Manipulations of Lewis acids, molar ratios, and kinetic differences within the family of OMF and MNF metallofullerenes are demonstrated in a selective precipitation scheme, which can be used either alone for purifying Sc₃N@I_{h …}

Solid State And Solution Dynamics Of Pyridine Based Tetraaza- Macrocyclic Lanthanide Chelates Possessing Phosphonate Ligating Functionality (Ln-Pctmb): Effect On Relaxometry And Optical Properties, Garry Kiefer, Mark Woods

Chemistry Faculty Publications and Presentations

The macrocyclic ligand 3,6,9-tris(methylenebutyl phosphonic acid)-3,6,9−15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-triene (PCTMB) was synthesized and complexes of Eu³⁺, Tb³⁺, and Gd³⁺ studied by X-ray crystallography, luminescence, and relaxometry. In the crystal these complexes are dimeric and possess 8-coordinate Ln³⁺ centers that are linked by bridging phosphonates. The rigidity introduced by the pyridyl nucleus forces the EuPCTMB and TbPCTMB to adopt a twisted snub disphenoid (TSD) coordination geometry. Examination of the ⁵D₀ → ⁷F₀ luminescent transition of EuPCTMB in the solid state confirmed the existence of a single distinct Eu³⁺ coordination environment, whereas two …

Determination Of The Activation Parameters Of Reaction Between [Fe(Cn6]-4 And K[Co(Hedta)No2]., Sammy Eni Eni

Electronic Theses and Dissertations

The kinetics of the oxidation of [Fe(CN)₆]^-4 by K[Co(HEDTA)NO₂] was studied in order to get the mechanism and the activation parameters of the reaction. Using a freshly-made Na₃PO₄ solution as the reaction medium with a pH of 6.00 the ionic strength was maintained at 0.10 M and the buffer molarity was 0.001 M.

The rate constant (k_obs) of the reaction between [Fe(CN)₆]^-4 and K[Co(HEDTA)NO₂] was determined at temperatures of 25.0°C, 27.5°C, 30.0°C, 35.0°, and 40.0°C. We explored this reaction by monitoring the evolution of ferricyanide, …

Modulation Of Restriction Enzyme Pvuii Activity By Metal Ion Cofactors, Charulata Bhaskaran Prasannan

Dissertations

Metal ions like Ca2+, Mn2+, Tb3+, Eu3+ etc., can bind at the active site and have varying effects on the enzymatic activity. In a crystal structure with DNA, two Ca2+ ions were bound to the active site of each PvuII monomer, and the metals share the ligands. Ca2+ ions promote DNA binding and not cleavage in many nucleases. We explored the role of Mg2+ and Ca2+ binding at the metal binding sites of PvuII to elucidate the role of each metal site. We monitored the cleavage kinetics of PvuII in presence of mixed metals. The cleavage kinetics data for Ca2+ …

Replacing Hydrogen Bonds With Coordinate Covalent Bonds In Coordination Networks, Colin Stewart Rodger

Dissertations

The overall theme of the dissertation is that metal ions such as silver(I) can replace H+ in hydrogen bonded organic frameworks. Because organic solids have been extensively studied, we can insert metal ions into the supramolecular assemblies, thus creating predictable coordination solids of varying dimensions. One example of an organic solid tested involves the organic compounds terephthalic and isophthalic acids. These dicarboxylic acids have previously been shown to self-assemble into tape-like structures via hydrogen bonding, with neighboring dicarboxylic acids located at angles of 180° and 120° respectively. By substituting the hydrogen bonds with coordination metal-ligand bonds similar assemblies are formed. …

Design And Synthesis Of Boronic Acid-Modified Nucleotides For Fluorescent Sensing And Cell Imaging, Xiaochuan Yang

Chemistry Dissertations

With the rapidly increasing interest in the field of glycomics, which is the comprehensive study of the roles carbohydrates play in a living system, urgent need for developing quick and highly selective carbohydrate sensors is growing. The boronic acid group, with its electron-deficient structure (6 valence electrons with an open shell), acts as a Lewis acid with high intrinsic affinity towards Lewis bases such as fluoride, cyanide and hydroxyl groups. Specifically, formation of a 5- or 6- membered ring between the boronic acid moiety and a1,2- or 1,3-diol in aqueous solution has been fully explored as a strategy of carbohydrate …

Progress Toward The Total Synthesis Of Lyconadin A, Yu Zhang

Theses and Dissertations

Lyconadin A is a pentacyclic Lycopodium alkaloid isolated from the club moss Lycopodium complanatum with antitumor properties. We have developed a novel 7-exo/6-exo acyl radical cascade cyclization as a method of making the bicyclo[5.4.0]undecane ring system of lyconadin A. The model products are trans-fused ring systems, while a cis-fused ring system is needed in lyconadin A. We have discovered a method to convert the trans-fused model cascade cyclization product into the desired cis isomer. Based on Donohoe's pyridone synthesis, we developed a method for the construction of 5-alkyl and 3,5-dialkyl-6-carbomethoxy-2-pyridones, the former of which …

Rfx2 Is A Candidate Downstream Amplifier Of A-Myb Regulation In Mouse Spermatogenesis, Gary C. Horvath, Malathi K. Kistler, Wilson Stephen Kistler

Faculty Publications

Background: Mammalian spermatogenesis involves formation of haploid cells from the male germline and then a complex morphological transformation to generate motile sperm. Focusing on meiotic prophase, some tissue-specific transcription factors are known (A-MYB) or suspected (RFX2) to play important roles in modulating gene expression in pachytene spermatocytes. The current work was initiated to identify both downstream and upstream regulatory connections for Rfx2.

Results: Searches of pachytene up-regulated genes identified high affinity RFX binding sites (X boxes) in promoter regions of several new genes: Adam5, Pdcl2, and Spag6. We confirmed a strong promoter-region X-box for Alf, a germ cell-specific variant of …

Multidimensional Methods: Applications In Drug-Enzyme Intrinsic Clearance Determination And Comprehensive Two-Dimensional Liquid Chromatography Peak Volume Determination, Dennis Thekkudan

Theses and Dissertations

The goal of the first project was to evaluate strategies for determining the in vitro intrinsic clearance (CLint) of dextrorphan (DR) as metabolized by the UGT2B7 enzyme to obtain dextrorphan glucuronide (DR-G). A direct injection liquid chromatography-mass spectrometry (LC-MS) method was used to monitor products using the pseudo-first-order (PFO) model. Standard enzymatic incubations were also quantified using LC-MS. These data were fit utilizing both PFO and Michaelis-Menten (MM) models to determine estimates of kinetic parameters. The CLint was determined to be 0.28 (± 0.08) µL/min/mg protein for a baculovirus insect cell-expressed UGT2B7 enzyme. This is the first confirmation that dextrorphan …

Carbamothioates In The Synthesis Of Diaroyl Sulfides; Selectivity In The Addition Of Diaroyl Sulfides To Acetylenic And Ethylenic Π−Deficient Compounds, Ashraf A. Aly, Alan B. Brown, Alaa A. Hasaan, Kamal M. El-Shaieb, Tarek M. Bedair

Chemistry and Chemical Engineering Faculty Publications

Diaroyl sulfides were prepared in one-pot reaction from ethylenediamine and carbon disulfide, via reaction of in situ generated ethylene-bis- carbamodithioates with aroyl chlorides. The reaction of diaroyl sulfides with acetylenic and ethylenic π-deficient compounds such as dimethyl acetylenedicarboxylate, ethyl propiolate, (E)-1,4-diphenylbut-2-ene-1,4-dione and 1,4-diphenylbut-2-yne-1,4-dione afforded the corresponding thionylated products. NMR spectroscopic data of the isolated products were discussed. © ARKAT USA, Inc.

Isolation And X-Ray Structural Characterization Of A Dicationic Homotrimer Of 2,3,6,7-Tetramethoxy-9,10-Dimethylanthracene Cation Radical, Matthew J. Modjewski, Ruchi Shukla, Sergey Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

Electrochemical oxidation of 2,3,6,7-tetramethoxy-9,10-dimethylanthracene (1) showed that it undergoes a highly reversible electrochemical oxidation (E_ox = 0.81 V vs SCE) and forms a modestly stable cation-radical salt in solution. X-ray crystallography established that 1⁺SbCl₆^- crystallizes as a (centrosymmetric) dicationic homotrimer via a close cofacial association of a pair of cationic and one neutral molecule of 1 with an interplanar separation of ∼3.2 Å. The structure of the dicationic homotrimer was also reproduced by DFT calculations. Furthermore, the structure of a dicationic spiro adduct, formed by a slow decomposition of a solution of 1^{+ …}

Expression Artifact With Retroviral Vectors Based On Pbmn, Yoshitaka Fukunaga, Robert A. Svoboda, Ronald Cerny, Keith R. Johnson, Margaret J. Wheelock

Ronald Cerny Publications

While characterizing various splice forms of p120 catenin, we observed what appeared to be a novel posttranslational modification of p120, resulting in a higher molecular weight form that was dependent on the splicing pattern. Further investigation revealed the higher molecular weight form to be a fusion protein between sequences encoded by the retroviral vector and p120. We found that the publicly available sequence of the vector we used does not agree with the experimental sequence. We caution other investigators to be aware of this potential artifact.

Physical Adsorption Of Ethylene On Mgo(100): Effects Of Substrate Ionicity And Symmetry On Wetting, Andi Barbour

Doctoral Dissertations

The wetting behavior of ethylene adsorbed on MgO(100) was investigated from 83{ 135 K using high resolution volumetric adsorption isotherms. Layering transitions for ethylene on MgO(100) are observed below the bulk triple point at 79.2 K and 98.4 K, respectively. From these isotherms, thermodynamic quantities associated with physical adsorption are determined. It was found that the average area occupied by ethylene on MgO(100) is around 22.6 squared angstroms per molecule. Using the two dimensional isothermal compressibility, the location of two potential phase transitions are identified at 108.6 K and 116.5 K for the first and second layer, respectively. The potential …

Studies Of Tungsten Alkyl Alkylidyne Compounds And Iron Porphyrin Derivatives, Brenda Ann Dougan

Doctoral Dissertations

This dissertation focuses on two research projects. The first project examines the reactions of tungsten(VI) alkyl alkylidyne and bis-alkylidene complexes with phosphines and water and the studies of thermodynamics and kinetics of the reactions. These studies have been conducted in part to determine the mechanistic pathway in the formation of novel tungsten(VI) species. The second portion of this dissertation focuses on the spin density and structures of biomimetic Fe(III) porphyrin derivatives using neutron and X-ray diffraction techniques. The spin density and magnetic properties of an Fe(III) porphyrin derivative has been determined by polarized neutron diffraction.

In the first portion of …

The Design And Synthesis Of Biotinylated Tylophorine Analogues For Use As Affinity Probes In The Elucidation Of The Cellular Targets Of Dcb-3503, Samson Francis

Doctoral Dissertations

The tylophorine analogue, DCB-3503 (1-62b, NSC-716802), has been found to exhibit broad spectrum activity in vitro in the National Cancer Institute’s (NCI) panel of 60 human-derived cell lines. Recent studies involving HepG2, a human hepatocellular carcinoma cell line, and two pancreatic ductal carcinoma cell lines (PANC-1 and HPAC), have suggested that DCB-3503 (1-62b) exerts its unique growth inhibition properties by modulating nuclear factor kappa B activity as well as through the inhibition of nuclear protein synthesis. However, the physiologically relevant protein binding partner(s) of DCB-3503 (1-62b) have not been identified. Herein, the design and …

Synthesis And Characterization Of Branched Polyelectrolytes: Star-Branched Napss, Daniel W. Holley

Doctoral Dissertations

In this thesis, we examined the effect of branching on the solution characteristics of polyelectrolytes using a set of star-branched NaPSS. The polystyrene precursors to these polyelectrolytes were synthesized using anionic polymerization allowing for the production of three distinct groups of star-branched polystyrenes with varying functionality and arm length.

Following sulfonation, several methods commonly employed in the literature for evaluation of sulfonation degree we established that sulfonation was quantitative. TGA was also demonstrated to reveal important characteristics of the sample.

We used aqueous SEC coupled with a multiple angle light scattering detector to determine several molecular characteristics of the star-branched …

Design And Synthesis Of Novel Tylophorine Analogs And Their Biological Activity, Julio Gutierrez

Doctoral Dissertations

Alkaloids containing the nitrogen atom in the bridgehead position of two rings, such as indolizidine, pyrrolizidine, and quinolizidine alkaloids, have a wide and varied distribution in nature. Some of these alkaloids demonstrate a broad range of pharmacological activities and have generated substantial synthetic interest. This thesis covers the total synthesis of novel tylophorine analogs called DCB 3503, DCB 3506, DCB 3507, DCB 3508, DCB 3509, and a derivative with a biotinylated chain attached to DCB 3506 for use as a biological probe. This thesis discusses the biological activity of these compounds as well.

2,5-Dichlorothiophene 1,1-Dioxide, Jonathan B. Briggs, Wenling Jia, Mikael D. Jazdzyk, Glen P. Miller

Chemistry

The complete molecule of the title compound, C(4)H(2)Cl(2)O(2)S, is generated by crystallographic twofold symmetry, with the S atom lying on the rotation axis. In the crystal, the molecules are linked by C-H center dot center dot center dot O hydrogen bonds..

Reactor R&D: Synthesis And Optimization Of Metallic Nitride Fullerenes And The Introduction Of Two New Classes Of Endohedral Metallofullerenes, Metallic Nitride Azafullerenes And Oxo-Metallic Fullerenes, Curtis Earl Coumbe

Dissertations

Metallic nitride fullerenes (MNFs) were discovered in 1999. This class of endohedral fullerenes show promise in a new diverse range of useful applications. Since then, focus has shifted to the selective synthesis of these molecules with yields that would accommodate adequate sample distribution. Using the electric arc method, the traditional yield of these molecules has been very low (i.e. < 5 mg), and only a small percentage of the fullerene products (i.e. < 5%). This dissertation introduces the novel CAPTEAR (Chemically Adjusting Plasma Temperature, Energy, And Reactivity) method that allows the targeted synthesis of MNFs in high purity and yield. This method utilizes a nontraditional oxidizing method for fullerene synthesis that has not only provided optimization of MNFs, but also resulted in the discovery of two new classes of fullerenes: metallic nitride azafullerenes (MNAFs) and oxo-metallic fullerenes (OMFs). Evidence suggests that the nitrogen of the MNAF cage provides stability for the trimetallic nitride clusters, while the OMFs are the first fullerenes to encapsulate oxygen and incorporate a seven atom cluster inside a Cgo cage.

Other efforts to increase yields resulted from scaling up production of fullerenes by using larger quantities of starting materials. These larger quantities required energy (electrical current) beyond the capacity of the traditional electric arc generator. Therefore, a new electric arc generator …

Tuning Pig Liver Esterase Enantioselectivity For The Synthesis Of Unnatural Serine And Tyrosine Analogues, Dale Anthony Rosado Jr.

Dissertations

The synthesis of disubstituted and homologated unnatural amino acids and the development of a mass spectrometry based assay for enantioselectivity are presented here. Disubstituted and homologated unnatural amino acids have proven to be effective for the treatment of diseases and for use as imaging agents. Peptides that contain unnatural amino acids have also proven to be effective treatments for various disease states including cancer. The potential to evaluate such unnatural amino acids for pharmaceutical properties is limited by the available syntheses. No method currently exists that will allow for the synthesis of homochirally similar unnatural amino acids from a common …

Study Of Thermal Frontal Polymerization Utilizing Reactive And Non-Reactive Additives, Veronika Grace Viner

Dissertations

Thermal frontal polymerization is a process that involves a propagating front travelling through a monomer/initiator solution and converting monomer into polymer. The effects of different reactive and non-reactive additives on front temperature, front velocity, and pot life were studied in a thermal frontal polymerization system of multifunctional acrylates. One issue with thermal frontal polymerization of acrylate monomers is the amount of smoke and fumes produced due to high front temperatures. The effect of thermally-expandable microspheres was studied utilizing a variety of monomers. Solid additives including fillers, inert phase changer materials, and high thermal conductive fillers were investigated. The addition of …

Transcript Analysis Of The Cso Operon And Characterization Of Two Sets Of Conserved Bacterial Microcompartment Genes In The Model Organism Halothiobacillus Neapolitanus, Fei Cai

Dissertations

This study was designed to achieve better understanding of (1) how carboxysome genes are regulated and expressed to yield with precise relative ratios and (2) the in vivo roles of two sets of conserved bacterial microcompartment genes, namely the three csoSl and two csoS4 genes of H. neapolitanus, in the biogenesis and function of the carboxysome. For the first goal, a detailed transcriptional profile of carboxysomal genes in H. neapolitanus was established using absolute quantification real-time RT-PCR and transcript ends analysis. This transcriptional profile revealed that a single promoter, denoted cso promoter, was located upstream from the clustered carboxysomal genes. …

The Ecology Of The Peaks Of Otter Salamander (Plethodon Hubrichti) In Sympatry With The Eastern Red-Backed Salamander (Plethodon Cinereus), Norman Reichenbach, Andrew Kniowski

Faculty Publications and Presentations

The Peaks of Otter Salamander, Plethodon hubrichti, is found along a 19 km length of the Blue Ridge Mountains, Virginia, USA, often in sympatry with the Eastern Red-backed Salamander, P. cinereus. In a sympatric area of Bedford County, Virginia, we conducted a mark-recapture study on a 10 × 10 m site. Surface densities of salamanders increased as the number of days without precipitation prior to a collection event increased. This suggests vertical movements in response to surface moisture. When salamanders returned to the surface after rain, individuals appeared to “shuffle” between rocks and likely, leaf litter. That is, we were …

Computational Exploration Of The Interaction Of Molecular Hydrogen With An Anionic Hydrogen Atom, Patrick Karl Moehlen

Doctoral Dissertations

The focus of this dissertation is to facilitate the computation of the infrared absorption line shape of solid para-hydrogen with an anionic hydrogen atom dopant. For this, we compute the complete potential energy surface for the interaction of H¯ with H². The coupled cluster with singles, doubles, and perturbative treatment of triple excitations method was used with augmented correlationconsistent polarized valence triple-zeta atom-centered basis sets and a set of bonding functions.

The focus then turns to describing the rovibrational Hamiltonian of the system with the coupledchannel method. We find bound and quasi-bound stationary states of the system for …