Chemistry Commons^™

13c-Methyl Isocyanide As An Nmr Probe For Cytochrome P450 Active Site, Christopher R Mccullough, Phani Kumar Pullela, Sang-Choul Im, Lucy Waskell, Daniel S. Sem

Chemistry Faculty Research and Publications

The cytochromes P450 (CYPs) play a central role in many biologically important oxidation reactions, including the metabolism of drugs and other xenobiotic compounds. Because they are often assayed as both drug targets and anti-targets, any tools that provide: (a) confirmation of active site binding and (b) structural data, would be of great utility, especially if data could be obtained in reasonably high throughput. To this end, we have developed an analog of the promiscuous heme ligand, cyanide,with a ¹³CH₃-reporter attached. This ¹³C-methyl isocyanide ligand binds to bacterial (P450cam) and membrane-bound mammalian (CYP2B4) CYPs. It can be …

The Synthesis And Characterization Of Imidazolium Lithium Phthalocyanines, John J. Kelley

Browse all Theses and Dissertations

A series of 1,3-di-substituted-imidazolium lithium phthalocyanines, in which the substituents on the imidazolium nitrogens were combinations of methyl, ethyl, pentyl, hexyl, isopropyl, adamantyl or 2,4,6-trimethylphenyl groups, was synthesized. The cation exchange of a single lithium ion of dilithium phthalocyanine for a 1,3-disubstituted-imidazolium ion was performed by mixing their salts in common organic solvents under ambient conditions. This afforded a number of imidazolium lithium phthalocyanines in moderate yields. They exhibited poor solubility in most solvents. Their composition and purity were initially verified by 1H and 13C-NMR and elemental analysis. The 1H-NMR spectra also indicated that the imidazolium and lithium phthalocyanine ions …

Exploration Of Gradient-Type Poly(Arylene Ether)S Via An Abb' Monomer System, Alex V. Dolgov

Browse all Theses and Dissertations

Evidence shows that a gradient like copolymer can be synthesized using nucleophilic aromatic substitution, NAS, chemistry. Using the 4-chloro-3-fluoro-4'hydroxydiphenylsulfone monomer, 5, it is possible to control the ratios of the leaving groups, in this case the fluorine and the chlorine, with the right solvent and temperature. Alternating the temperatures will alter the substitution of the leaving groups, thus forming a polymer backbone of gradient characteristics. Initial reactions to determine the relative rates of displacement of the chlorine and fluorine atoms were carried out using a model compound, 1, which possessed the chlorine and fluorine leaving groups, but not the phenol …

Het Acid Based Oligoesters – Tga/Ftir Studies, Thangamani Rajkumar, Chinnaswamy Thangavel Vijayakumar, Palanichamy Sivasamy, Charles A. Wilkie

Chemistry Faculty Research and Publications

One of the important reactive halogenated dicarboxylic acids used in the synthesis of flame retardant unsaturated polyester resins is 1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid (HET acid). In the present investigation four different oligoesters are synthesized using HET acid as the diacid component and 1,2-ethane diol, 1,2-propane diol, 1,3-propane diol and 1,4-butane diol as the aliphatic diols. Melt condensation technique in vacuum is used for the synthesis of the oligoesters. The number average molecular weights of the oligoesters are determined using end group analysis. The degree of polymerization is estimated to be 3–5. The structural characterization is done using FTIR and NMR …

The 14N Quadrupole Coupling In Hexamethylene Triperoxide Diamine (Hmtd), John Persons, Gerard S. Harbison

Gerard S. Harbison Publications

Using high-field NMR, we have determined the magnitude of the nuclear quadrupole interaction in hexamethylene triperoxide diamine (HMTD), the explosive allegedly used in the London bombings of July 2005. The experimental quadrupolar coupling constant, 5.334 MHz, is in good agreement with quantum chemical calculations. The predicted single zero-field transition frequency should lie in a relatively empty part of the 14N nuclear quadrupole resonance (NQR) spectrum; the spin relaxation rate is reasonably fast.

Mechanism Of Rate-Limiting Motions In Enzyme Function, Eric D. Watt, Hiroko Shimada, Evgenii L. Kovrigin, J. Patrick Loria

Chemistry Faculty Research and Publications

The ability to use conformational flexibility is a hallmark of enzyme function. Here we show that protein motions and catalytic activity in a RNase are coupled and display identical solvent isotope effects. Solution NMR relaxation experiments identify a cluster of residues, some distant from the active site, that are integral to this motion. These studies implicate a single residue, histidine-48, as the key modulator in coupling protein motion with enzyme function. Mutation of H48 to alanine results in loss of protein motion in the isotope-sensitive region of the enzyme. In addition, k _cat decreases for this mutant and the kinetic …

Functionalization Of Resorcinarenes And Study Of Antimicrobial Activity, Kirankirti Muppalla

USF Tampa Graduate Theses and Dissertations

Cavitands are very important class of compounds in supramolecular chemistry. These molecules contain rigid enforced cavity,and have attracted considerable attention in supramolecular chemistry as building blocks for the construction of carcerands, hemicarcerands, and other host guests complexes. Nearly 40 years ago, Niederl and Vogel laid foundation for the study of such type of condensation reactions. In our laboratory we are involved in synthesis of resorcinarenes with readily available substrates such as resorcinol and aldehydes to form a cyclic tetramer.

Herein, I present detailed studies about the functionalization of the synthesized tetramers and their antimicrobial activity. Octahydroxy resorcinarenes were synthesized and …

Slow Turning Reveals Enormous Quadrupolar Interactions (Streaqi), John Persons, Gerard S. Harbison

Gerard S. Harbison Publications

We introduce a new solid-state NMR method, which uses very slow sample rotation to visualize NMR spectra whose width exceeds feasible spectrometer bandwidths. It is based on the idea that if we reorient a tensor by a known angle about a known axis, the shifts in the NMR frequencies observed across the spectral width allow us to reconstruct the entire tensor. Called STREAQI (Slow Turning Reveals Enormous Anisotropic Quadrupolar Interactions), this method allows us to probe NMR nuclei that are intractable to current methods. To prove the concept and demonstrate its promise we have implemented the method for several 79Br …

Synthesis And Characterisation Of Tetra-Tetrazole Macrocycles, Andrew Bond, Adrienne Fleming, Fintan Kelleher, John Mcginley, Vipa Prajapati, Signe Skovsgaard

Articles

The syntheses of tetra-tetrazole macrocycles, containing two bis-tetrazole units linked by a variety of alkyl chain lengths from four to eight carbons, are described. The crystal structures of three of these derivatives are reported, and the molecular conformation in the solid state is compared to that of one previously reported tetra-tetrazole macrocycle and to other bis- and tris(tetrazole)benzene structures. The macrocycle conformation is influenced by the length of the alkyl chain linker, the relative orientation of the tetrazole rings on the benzene ring, and by intermolecular interactions. In the macrocycles based on 1,2-bis(tetrazole)benzene, the adjacent tetrazole rings on the benzene …

Preparation, Spectroscopy, Antimicrobial Assay, And X-Ray Structure Of Dimethyl Bis-(4-Methylpiperidine Dithiocarbamato-S,S`)-Tin(Iv), Zia-Ur Rehman, Saira Shahzadi, Saqib Ali, Guo-Xin Jin

Turkish Journal of Chemistry

Dimethyl bis(4-methylpiperidine dithiocarbamato-S,S')-tin(IV) was synthesized and characterized by elemental analysis, IR and mass spectrometry, multinuclear NMR (^1H- and ^{13}C-NMR), and X-ray single crystal analysis. IR data showed that the ligand acts as a bidentate in the solid state. X-ray data showed the unsymmetrical nature of the ligand towards coordination to tin. It crystallized in the monoclinic P2_1/n space group. Its geometry is distorted octahedral. Antimicrobial activity data shows that the complex exhibits significantly more activity than the free ligand.

Solution Conformations Of Three Small Cluster Oligosaccharide Mimetics (Scom) From D-Glucosamine, D-Altrosamine, And (-)-Quinic Acid, Q. L. Nguyen, L. Olmstead, S. Bains, Andreas H. Franz

College of the Pacific Faculty Articles

Three small cluster oligosaccharide mimetics were synthesized, and their CDCl3 solution conformations were determined with NMR experiments. In this paper, we confirmed conformational similarities in rings A and B in all three compounds, and we provide the overall solution geometries. In all cases, an unusual cyclohexane twist-boat conformation with longrange 4 J-(W)-coupling was observed. The origin of the bias towards the twist-boat was attributed primarily to the fused ring system between the cyclohexane ring and the dioxacyclopentane (acetal) including hydrogen bonding. Temperature-annealed molecular dynamics simulations complemented the NMR experiments and supported the overall assignment.

Tailoring Branching For Poly (Arylene Ether)S Via Reactivity Ratio Controlled Polymerizations, Amanda Ike

Browse all Theses and Dissertations

The ability to control physical and mechanical properties of polymer systems has become an important aspect of polymer science. In order to tailor the branching in polymer systems, an understanding into the reactivity of the electrophilic sites in the monomer is important. Kinetic methods have been explored in order to determine the reactivity of monomers in preparing poly(arylene ether)s and to predict the degree of branching that will occur in a polymer of this kind. The reactivity of AB2 sulfones and phosphine oxides was explored, along with the reactivity of ABB'B'' sulfones. NMR spectroscopy was used as a probe into …

Probing The Association Behavior Of Hydrophobic Organic Compounds With Dissolved Humic Materials, Hadi M. Marwani

LSU Doctoral Dissertations

The association mechanism between hydrophobic organic compounds (HOC) and dissolved humic materials (DHM) has continued to be one of the interesting areas in environmental applications. The goal of the research reported in this dissertation is to investigate the association behavior of HOC with DHM. The first part of this research involves steady-state fluorescence measurements of these multi-component systems to study the effect of DHM content on the association mechanism of HOC, in particular using pyrene as a model. Results showed that steady-state fluorescence alone may not provide enough information about the quenching mechanism of pyrene with DHM. Lifetime based fluorescence …

Ab Initio Molecular Dynamics Simulations Of Methylaluminoxane (Mao) Synthesis By Hydrolysis Of Trimethylaluminum, Lacramioara Negureanu

LSU Doctoral Dissertations

MAO is the co-catalyst in the metallocene catalytic systems, which are widely used in single site olefin polymerization due to their high stereoselectivity. To date, the precise structure of MAO, the particular compound or compounds catalytically active in MAO, have eluded researchers. MAO, a white amorphous powder, is not a good sample for a direct spectroscopic characterization, and its NMR spectra are broad and almost featureless. Many structural models have been proposed but none are generally accepted. In the first part of this work the MAO formation mechanism was addressed. Molecular dynamics simulations at MP2 configuration interaction theory level have …

Negative Impact Of Noise On The Principal Component Analysis Of Nmr Data, Steven M. Halouska, Robert Powers

Department of Chemistry: Faculty Publications

Principal component analysis (PCA) is routinely applied to the study of NMR based metabolomic data. PCA is used to simplify the examination of complex metabolite mixtures obtained from biological samples that may be composed of hundreds or thousands of chemical components. PCA is primarily used to identify relative changes in the concentration of metabolites to identify trends or characteristics within the NMR data that permits discrimination between various samples that differ in their source or treatment. A common concern with PCA of NMR data is the potential over emphasis of small changes in high concentration metabolites that would over-shadow signifi …

Structure Elucidation Of Bioactive Compounds Isolated From Endophytes Of Alstonia Scholaris And Acmena Graveolens, Nicholas James Hundley

Theses and Dissertations

Alstonia scholaris is an evergreen tree native to Southeast Asia and Australia. It is commonly used as a medicinal plant throughout these regions. In the present study, an endophyte of the genus Xylaria was isolated from a stem of Alstonia scholaris, its mycelia and exudate extracted, and the extract assayed for growth inhibition of HeLa cancer cells in vitro. Several known compounds were isolated and identified based on NMR, infrared, and mass spectral data. The compounds identified are 19,20-epoxycytochalasin C; 19,20epoxycytochalasin D; and xylobovide. Two other compounds, fusaric acid and dehydrofusaric acid, were discovered in an endophyte of the Hypocreales …

1H, 13C, And 15N Assignments For The Archaeglobus Fulgidis Protein Af2095, Robert Powers, Thomas B. Acton, Yi-Wen Chiang, P. K. Rajan, John R. Cort, Michael A. Kennedy, Jinfeng Liu, Lichung Ma, Burkhard Rost, Gaetano T. Montelione

Robert Powers Publications

Structural genomics is providing a means to determine the molecular and cellular function for the vast amount of proteins in the Human proteome that lack any explicit experimental information by characterizing the complete range of protein folds (Montelione, 2001). The Northeast Structural Genomics Consortium (NESG; http://www.nesg.org/) is a pilot project funded by the National Institutes of Health Protein Structure Initiative, focusing on proteins from eukaryotic model organisms including humans. The thermophillic archaea Archaeglobus fulgidis AF2095 protein is an example of a protein of unknown biological function targeted for structural analysis by NESG. AF2095 belongs to the Pfam family PF01981 – …

Magnetic Resonance Studies On Lithium Intercalation Into Carbons, Xiao-Rong Zhou, Zhen-Ming Du, Lin Zhuang, Jun-Tao Lu

Journal of Electrochemistry

The electron spin resonance(ESR) and 7Li-NMR magnetic resonance (7Li-NMR) studies on lithium intercalation into carbons were reviewed based on recently published papers, including those by the authors of this review. Two kinds of electronic spins were found in ESR studies. One corresponds to the charge carrier electrons and is called the Pauli spin. From the ESR intensity of Pauli spins, the curve of the density of electronic states can be deduced for the carbon material studied and, in turn, the contribution of the band model mechanism to the lithium intercalation can be calculated for the given carbon sample. The other …

Applications Of Nmr To Structure-Based Drug Design In Structural Genomics, Robert Powers

Robert Powers Publications

Structural genomics is poised to have a tremendous impact on traditional structure-based drug design programs. As a result, there is a growing need to obtain rapid structural information in a reliable form that is amenable to rational drug design. In this manner, NMR has been expanding and evolving its role in aiding the design process. A variety of NMR methodologies that cover a range of inherent resolution are described in the context of structure-based drug design in the era of structural genomics.

Solution Structure Of B. Subtilis Acyl Carrier Protein, Guang-Yi Xu, Amy Tam, Laura Lin, Jeffrey Hixon, Christian C. Fritz, Robert Powers

Robert Powers Publications

Background: Acyl carrier protein (ACP) is a fundamental component of fatty acid biosynthesis in which the fatty acid chain is elongated by the fatty acid synthetase system while attached to the 4’-phosphopantetheine prosthetic group (4’- PP) of ACP. Activation of ACP is mediated by holo-acyl carrier protein synthase (ACPS) when ACPS transfers the 4’-PP moiety from coenzyme A (CoA) to Ser36 of apo-ACP. Both ACP and ACPS have been identified as essential for E. coli viability and potential targets for development of antibiotics.

Results: The solution structure of B. subtilis ACP (9 kDa) has been determined using two-dimensional and three-dimensional …

^{13}C-And ^{31}P-Nmr Study Of Tetracarbonylbis(Diphenylphosphino)Alkanemetal(0) Complexes Of The Group 6 Elements, Zahi̇de Özer, Sai̇m Özkar

Turkish Journal of Chemistry

Tetracarbonylbis(diphenylphosphino)alkanemetal(0) complexes of the general formula M(CO)_4[(C_6H_5)_2P (CH_2)_nP(C_6H_5)_2] (M: Cr, Mo, W; n: 1, 2, 3) were synthesized from the reaction of M(CO)_4(\eta^{2:2}-1,5-cyclooctadiene) with the appropriate ligand and characterized by means of IR and NMR (^{13}C and ^{31}P) spectroscopy. Spectroscopic data shows that two phosphorus atoms in the complexes are identical and occupy two cis-coordiantion sites in a pseudo-octahedral coordination sphere of the metal. The comparative study of the coordination shift and the ^{31}P-^{13}C coupling constant reveals that two carbonyl groups trans to one of two phosphorus atoms in the diphosphine ligand are shifted toward the lower magnetic field more …

Spectroscopic Investigation Of Ion Transport Mechanisms In Polyacrylonitrile Based Electrolytes, Zhaoxiang Wang, Biying Huang, Rongjian Xue, Xuejie Huang, Liquan Chen

Journal of Electrochemistry

Raman, IR, X-ray photoelectron (XPS), and NMR spectra of components in polyacrylonitrile based electrolytes have been studied. It is found that there are strong interactions among the components though different systems show different interaction characteristics. A concept of competition is proposed between the polymer matrix and the plasticizer on associating with the Li⁺ ions. By analyzing the important functions of the plasticizer, a possible mechanism of the ions transport in the polymer electrolyte is suggested.

A New High Pressure Sapphire Nuclear Magnetic Resonance Cell, Shi Bai, Craig M. Taylor, Charles L. Mayne, Ronald J. Pugmire, David M. Grant

Faculty Publications

A new version of a single-crystal sapphire high pressure nuclear magnetic resonance (NMR) cell is described that is capable of controlling the sample pressure independent of the temperature. A movable piston inside the cell adjusts and controls the sample pressure from ambient conditions to 200 atm within plus or minus 0.3 atm. The linewidth at half-height for a 13C spectrum of carbon dioxide at 15degrees C and 57.8 atm is found to be 0.5 Hz. The carbon dioxide gas/liquid phase transition is clearly observed by measuring 13C chemical shifts as the sample pressure approaches equilibrium. The time required for this …

Development Of New Methods For Assessing Solidification/Stabilization Of Hazardous Waste Using Solid-State Nuclear Magnetic Resonance Techniques (Ph.D Dissertation, Lsu), Michael A. Janusa

Faculty Publications

New methods for assessing solidification/stabilization (S/S) of hazardous waste using solid-state nuclear magnetic resonance are developed for the purpose of diagnosing on a microscopic level the performance of S/S as a hazardous waste disposal technique. There are four techniques developed and described in this dissertation: (1) Solid-state deuterium NMR spectroscopy is used to determine if a particular deuterated organic waste is effectively solidified/stabilized and to determine the lower limit of the bond strength between the waste and the cement matrix; (2) Constant time pulsed field gradient ^ NMR spectroscopy is tested on a liquid waste encapsulated within a solidified matrix …

Characterization Of Glycated Proteins By 13C Nmr Spectroscopy, Carolyn I. Neglia, Helga J. Cohen, Albert R. Garber, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

13C NMR spectroscopy has been used to characterize Amadori (ketoamine) adducts formed by reaction of [2-13C]glucose with free amino groups of protein. The spectra of glycated proteins were acquired in phosphate buffer at pH 7.4 and were interpreted by reference to the spectra of model compounds, N alpha-formyl-N epsilon-fructose-lysine and glycated poly-L-lysine (GlcPLL). The anomeric carbon region of the spectrum (approximately 90-105 ppm) of glycated cytochrome c was superimposable on that of N alpha-formyl-N epsilon-fructose-lysine, and contained three peaks characteristic of the alpha- and beta-furanose and beta-pyranose anomers of Amadori adducts to peripheral lysine residues on protein (pK alpha approximately …

Nmr Measurements On Intercalated 3r-Tas2.Ix (I=Nh3 And N2h4), N. H. Handly, Juana Vivó Acrivos

Faculty Publications, Chemistry

No abstract provided.

Part I: The Synthesis Of New Potential Insecticides. Part Ii: New Aromatic Nucleophililic Subsitution Reactions, Fluoroalkoxylation And N,N-Dimethylamination, Cesar Colon

Retrospective Theses and Dissertations

A series of routes are described for the synthesis of new potential insecticides which are symmetrical or asymmetrical similogs of 2,5-Bis (dichloropheny1)-1,3,4-oxadiazole and its precursor diacyl hydrazine. Also two new aromatic nucleophilic substitution reactions are discussed. Activated aryl halides are reacted with fluorinated alkoxide anions. In all cases, substitution of the halogen by a fluoroalkoxy group was observed, and activated aryl halides are reacted with HMPA as an N, N-dimethyl aminating agent. In all cases, substitution of the halogen by a dimethyl amino group was observed. The effect of the activating group and the leaving group is described and a …

The Synthesis Of Potential Insecticides: Haloalkoxy Phenyl Diacylydrazines And 1,3,4-Oxadiazoles, Kathleen S. Gibbs-Rein

Retrospective Theses and Dissertations

The syntheses of two classes pf compounds, diacylhydrazines and 2,5-disubstituted 1,3,4-oxadiazoles, intended for subsequent investigation of pesticidal activity are discussed. The experimental conditions and procedures necessary for the preparation of these potential insecticides are also revealed. Finally, spectral data are interpreted and explained, and recommendations for further research are given.

I. Studies Toward The Synthesis Of Echinodithianic Acid And Ii. The Temperature Dependent Nmr Spectrum Of Methyl N-Acetylsarcosinate, Alan Leroy Love

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Approaches to the preparation of echinodithianic acid (5) from 2,5-dicarbomethoxy-1,4-dithiane (1) were not successful, due to the inability to carboxylate or carboalkoxylate 1 at carbons 2 and 5. Studies toward the synthesis of 5 utilizing methyl 2-acetamidoacrylate (8) have been investigated. The electrophilic addition of sulfur dichloride to 8 yielded bis-(2-acetamido-2-carbo-methoxyvin-1-yl) sulfide, while the addition of thiocyanogen chloride to 8 produced methyl 2-acetamido-3-thiocyanato-acrylate.

As electrophilic additions of unsymmetrical dipolar reagents to methyl 2-acetamidoacrylate (8) are not reported in the literature, the addition of hydrogen bromide to 8 was studied to determine the orientation effect of the acetamido group.

Methyl 2-acetamido-2-bromopropionate …

Application Of The Sideband Technique To Wide-Line Nmr Spectra, Juana Vivó Acrivos

Faculty Publications, Chemistry

No abstract provided.