Chemistry section. (Abstracts of Papers Presented at the 111th Meeting).
A COMPUTATIONAL LOOK AT ARYL (CYCLOPENTADIELYL) BORONIUM IONS. William H. Ilsley, Middle Tennessee State University, Murfreesboro, Tennessee. Preliminary results of ab initio studies substituted arylboronium ions will presented. The effect of both the number and type of substituent on the predicted geometry will be discussed as well as the importance of relevant molecular orbitals in stabilizing the predicted geometries. Preliminary results suggest that most of these species exhibit linear geometry about the boron atom.
ELECTROCHEMISTRY OF MOLTEN NITRATE ELECTROLYTES AND APPLICATIONS FOR LITHIUM BATTERIES. Melvin Hiles, Middle Tennessee State University, Murfreesboro, Tennessee. Molten nitrate electrolytes exhibit much lower melting points than halide electrolytes. The best molten nitrate systems for lithium battery applications are the [LiNO.sup.3]-[KNO.sup.3] (42-58 mol%) eutectic that melts at 124[degrees]C and the [LiNO.sup.3]-[NaNO.sup.3] (56-44 mol%) eutectic that melts at 187[degrees]C. These melts are chemically stable towards decomposition up to 470[degrees]C. Thus both eutectics provide a wide liquid operating temperature range readily exceeding 200[degrees]C. Furthermore, these molten nitrate eutectics offer high ionic conductivities and low viscosities. The electrochemical reduction of LiNO3 yields insoluble Li2O that blocks further reduction of the molten nitrate and allows the electrostability region to be extended to the reversible reduction of lithium ions. This provides an electrochemical window of 4.5 V for the LiNOrKNO3 and LiNO3-NaNO3 eutectics. Therefore, the use of lithium anodes with 4 V cathode materials is possible in molten nitrate electrolytes that contain sufficient LiNO3. Lithiated transition metal oxide cathode materials such as LiMn2O4 are being investigated for high voltage lithium cells using molten nitrate electrolytes. Possible applications include military thermal batteries as well as batteries for geothermal bore holes and alarm systems.
SIGNATURES AS DESCRIPTORS IN TWO DIMENSIONAL QUANTITATIVE STRUCTURE RELATIONSHIP Donald P Visco Jr. and Ramdas S. Pophale*, Tennessee Technological University, Cookeville, Tennessee. To create a focused library of compounds with a desired property range, we developed a 2D-Quantitative Structure Relationship (QSR) using a new descriptor called signature. The signature features were explored with the help of three data sets. Activity of 121 HIV-l protease inhibitors, HPLC capacity factors of 22 energetic materials (two sub-sets, ODS, CPS) and octanol/water partition coefficient for 12865 compounds made up the three data sets. The results were achieved with a forward stepping regression method. The predictive ability of the QSRs was tested on test sets for every case barring the energetic materials. Multiple correlation coefficient, significance, and stability of coefficients were the criteria for the choice of the model parameters. The QSR coefficients for the energetic materials were used to form (linear) diop hantine equations. The equations were solved for sets of the targeted property. Solutions to these equations were used to determine compounds with the property in the given range.
EFFECTS OF EXPERIMENTAL CONDITIONS ON COVERAGE OF FUMED SILICA BY ORGANOSILANES. Celeste M. Matthews * and Andrienne C. Friedli, Middle Tennessee State University, Murfreesboro, Tennessee. Organosilanes have been used to coat silica gel for use in liquid chromatography and potential environmental applications due to their ability to physisorb small organic molecules. Three organosilanes (phenyltrichlorosilane, 1-phenyl-4-trichlorosilylbucane, and 1-phenyl-11-trichlorosilylundecane) were used to derivatize fumed silica with different surface characteristics. The amount of adsorption of an organosilane onto silica and the degree of physisorption and/or chemisorption of the organosilane films was assessed by Thermal Gravimetric Analysis. The temperature of the silica pretreatment, the identity of the organosilane, and the presence of base were varied to determine the effects on silica coverage. The silica was untreated, superhydrated, or heated to 150[degrees]C, 350[degrees]C, or 600[degrees]C prior to use. The organosilanes were used to derivatize Aerosil 380 in order for silane chain length to be compared. Decreasing coverage was found for increasing silica pretreatment temperatures while increasing coverage was found for increasing silane chain length. Triethylamine did not improve silica coverage.
NOVEL SELENIUM CONTAINING TRYPTOPHAN ANALOGS AND THEIR POTENTIAL USE IN THE DETERMINATION OF THREE DIMENSIONAL PROTEIN STRUCTURES. James A. Henderson *, Duane M. Hatch *, and Jeffrey 0. Boles, Tennessee Technological University, Cookeville, Tennessee. In the last decade the preparation of Selenomethione (SeMet) containing proteins has proved to be a valuable tool in the determination of three dimensional structure by Multiwavelength Anomalous Diffraction (MAD) techniques. Furthermore, selenium-77 nuclear magnetic resonance spectroscopy has been shown to be an important probe of enzymatic structure and function. Analogs of amino acids that occur at low natural abundance in proteins, such as L-methionine (Met) and L-tryptophan (Trp), are excellent tools for protein characterization since their structural and catalytic roles are minimal. The potential utility of a selenium containing tryptophan analog, [beta]-selenolo[3,2b]pyrrolyl-L-alanine ([3,2-b]SeTrp), has recently been demonstrated in the literature. This study shows promise for similar incorporations of its isomer, [beta]-selenolo[2,3-b]pyrrolyl-L-alanine ([2,3-b]SeTrp), adding to the arsenal of heavy-atom amino acid derivatives for use in the characterization of proteins. The synthesis and preliminary results of the bioincorporation of the [2,3b]SeTrp isomer will be presented.
DESIGNING METAL-CONTAINING LIQUID CRYSTALS BASED ON BIPYRIDINE LIGANDS. Robert E. Bachman, The University of the South, Sewanee, Tennessee. Metal-containing liquid crystals offer the opportunity to combine the unique properties of metal complexes with the technologically important property of liquid crystallinity. Bipyridine complexes are ubiqutous in inorganic coordination chemistry, displaying many unique properties such as photoluminescence and photocatalytic activity. However, bipyridine complexes have so far largely resisted efforts to be incorporated into liquid crystalline systems. We have recently succeeded in designing simple 4,4' derivatives of bipyridine that can be used to create liquid crystalline complexes with square planar platinum(II) fragments. In this presentation, we will explore the relationships between the molecular and supramolecular structures and the phase behavior of these complexes.
NUCLEAR QUADRUPOLE RESONANCE STUDIES OF WEAKLY COORDINATING ANIONS OF INTEREST IN INDUSTRIAL CATALYSIS. Gary P. Wulfsberg, Jamie Wilcox *, and Rachell Briggs, * Middle Tennessee State University, Murfreesboro, Tennessee Success of the metallocene polymerization process for producing polymers depends on the anion found with the organozirconium cation being as weakly coordinating to zirconium as possible. This is best achieved by halogenating the outside of a large anion of low charge. When heavier halogens are used, the coordinating ability of the anion can profitably be studied using [[Cl.sup.35], [Br.sup.81], and [I.sup.127] nuclear quadrupole resonance (NQR) spectroscopy. We have studied a series of salts and covalent derivatives of successively less-coordinating organic anions: Cl[CH.sub.2][CO.sub.2]; [Cl.sub.2][CHCO.sub.2]; [Cl.sub.3][CCO.sub.2]; [XCH.sub.2][SO.sub.3]; [Cl.sub.3][CSO.sub.3]. Coordinating ability of the oxygen atoms of the anion produces a dependence of the anion's NQR frequencies on the electronegativity of the metal, while there is no such dependence in purely ionic salts, where the NQR frequencies vary with the radius of the cation instead. (Supported by University Committees for Faculty Research and Non-Instructional Assignments.)
DETERMINATION OF AMMONIA IN DIESEL ENGINE EXHAUST. Tye Ed Barber, Norma L. Ayala, John M. E. Storey, Mike Kass, and John Thomas, Tennessee Technological University, Cookeville, Tennessee (TEB, NLA), and Oak Ridge National Laboratory, Oak Ridge, Tennessee (JMES, MK, JT). To meet new emission standards, diesel engine manufacturers are studying the use of exhaust aftertreatment systems for internal combustion diesel engines. One type of aftertreatment system under study uses urea ([CH.sub.4][N.sub.2]O) and a catalyst to reduce oxides of nitrogen (NOx) with a selective catalytic reduction (SCR) process. In these systems, a urea solution is injected into the exhaust upstream of the catalyst supported on a monolith. When the urea reaches the storage catalyst, it reduces the NOx. Under ideal, stoichiometric conditions, the reduction of NOx is very efficient. Under transient conditions and at low operating loads typical of engines, excess ammonia ([NH.sub.3]) can be formed and can be emitted. To study the catalyst be havior, a high-speed ultraviolet absorption spectrometer was constructed for analysis of engine exhaust. The system uses a long path, low volume gas cell with a high-speed photodiode array giving it a temporal resolution of approximately 50 milliseconds. In this presentation, the performance of the ultraviolet system will be discussed and compared to a commercially available photoacoustic analyzer for the analysis of [NH.sub.3].
METHODS DEVELOPMENT FOR THE DETECTION OF TRACE METABOLITES FROM THE BIODEGRADATION OF POLYCYCLIC AROMATIC HYDROCARBONS BY YEASTS. Huiyon Kim *, Ngee-Sing Chong, and Beng-Guat Ooi, Middle Tennessee State University, Murfreesboro, Tennessee. Gas chromatography-mass spectrometry (GC-MS) in conjunction with solid phase micro-extraction (SPME) has been used to characterize the biodegradation products of polycyclic aromatic hydrocarbons (PAHs) at trace levels in yeast cultures. The metabolites of PAHs such as phenanthrene and chrysene are characterized and compared to those produced by bacterial biodegradation performed in other laboratories. Derivatization techniques based on various reagents including trimethylchlorosilane, acetic anhydride, and trifluoroacetic anhydrides have been developed for the analysis of the hydroxy and dihydrodiol derivatives of the PAHs. The extraction efficiencies of different SPME fiber coatings such as Carboxene[TM], polydimethylsiloxane, and polyacrylate will be evaluated. The advant ages of using SPME for the study of PAH biodegradation are the ability to sample both the headspace and the liquid media, the "non-intrusive" nature of SPME or its adaptability for metabolite monitoring, as well as the low detection limits afforded by the SPME preconcentration of analytes prior to GC-MS analysis.
EFFECTS OF QUERCETIN AND GENISTEIN ON GLUTATHIONE LEVELS IN HUMAN MONOCYTIC PROGENITOR CELLS (U937 CELLS). William Boadi, Peter Iyere, and Samuel Adunyah, Tennessee State University, Nashville, Tennessee (WB, PI), and Meharry Medical College, Nashville, Tennessee (SA). Diets that contain an abundance of fruit and vegetables are protective against a variety of diseases, particularly cardiovascular disease and epithelial (but not hormone-related) cancers. The principal nutrients thought to provide the protection afforded by fruit and vegetables are the antioxidants and dietary fibre (non-starch polysaccharides). The effects of quercetin and genistein (both plant flavonoids and antioxidants) against iron ([Fe.sup.2+]) induced oxidation on glutathione (GSH) in human leukemia U937 cells were investigated. Cells were maintained at 37[degrees]C under 5% CO2 tension in RPMI 1640 medium containing 10% PBS and 50 units/ml each of penicillin and streptomycin. Following incubation for 24 h at 37[degrees]C, the cells were pelleted by low speed centrifugation, resuspended in 5% metaphosphoric acid (MPA), and centrifuged at 3,000 X g for 10 mm at 4[degrees]C. The supernatant was used to measure GSH levels as described by the GSH assay kit from Pierce (Cat. No. 354102). GSH levels were expressed as [micro]mols per milligram of protein. GSH levels increased in a dose-dependent manner with increasing quercetin and genistein levels. Of the two flavonoids, quercetin had more marked effect on enhancing GSH levels compared to their respective controls (P < 0.01). Our data demonstrate that quercetin and genistein application to human leukemia U937 cells before [Fe.sup.2+] exposure enhances U937 cell GSH levels. These observations suggest that flavonoids may be useful for prevention and treatment of metal-induced oxidation in leukemia cells.
A PORTABLE DEMONSTRATION OF VAT DYEING SIMULATED WITH INDIGO CARMINE. David G. Figueredo* and Martin V. Stewart, Middle Tennessee State University, Murfreesboro, Tennessee. An interesting chemistry demonstration for young students is the process by which blue jeans are dyed. However, the chemical reduction of water insoluble indigo to a water soluble leuco form makes this vat-dyeing procedure prohibitively lengthy and cumbersome. Blue indigo dye is reduced to its pale yellow leuco form by sodium dithionite (sodium hydrosulfite, [Na.sub.2][S.sub.2][O.sub.4]) over a steam bath. An immersed cloth removed from the vat and exposed to the atmosphere turns blue because the leucoindigo solution is oxidized back to the original water insoluble indigo. Sulfonation of indigo affords indigo carmine, whose sodium salt readily dissolves in water. Thus, substituting indigo carmine for indigo provides a demonstration that simulates all chemical aspects of the vat-dyeing process except the difficult and time consuming dissolv ing of indigo. This procedure was then packaged in a portable form for distribution to a diverse population of demonstrators during National Chemistry Week.
VIEWING SURFACES WITH ATOMIC FORCE MICROSCOPY Cameron K Gren*, Elizabeth A. Western*, and Andrienne C. Friedli, Middle Tennessee State University, Murfreesboro, Tennessee. Atomic Force Microscopy (AFM) is a common technique for imaging relatively fiat surfaces on the nano- and microscale. We have used a Thermomicroscopes Explorer AFM in contact, noncontact, and liquid contact mode to examine the topography of everyday objects as well as research samples. Examples of standard surfaces include a compact disc, aluminum grains, a soft drink bottle, an eprom chip, and a calibration grid. In each case, x, y, and z dimensions of features were measured. Research samples were planar and spherical surfaces coated with organic thin films. Substrates included silicon wafers, glass, mica, glass beads, and colloidal silica. In general, the lower limit of image resolution was 50 nm due to experimental configuration.
SYNTHESIS AND ANALYSIS OF SELENIUM ALKOXIDES. Tim Decha-Umphai* and Judith M. Iriarte-Gross, Middle Tennessee State University, Murfreesboro, Tennessee. Alkoxides have had a major impact in sol-gel chemistry. This process is used to synthesize glass or ceramic materials. Selenium alkoxides have already been synthesized, and very little is known about their chemistry. Further research and analysis of selenium alkoxide chemistry is needed. The synthesis of selenium alkoxides is being investigated using a non-hydrolytic sol-gel method. All intermediates and products are being characterized by H-l, C-13, and Se-77 NMR spectroscopy. The non-hydrolytic sol-gel synthesis and spectroscopic data will be presented and discussed.
SYNTHESIS AND QUANTITATIVE STUDIES OF TELLURIUM SILICATE SOL-GEL MATERIALS. A PROJECT SEED I RESEARCH SUMMER AT MTSU. Valencia Smartt*, Judith M. Iriarte-Gross, and William Ilsley, Middle Tennessee State University, Murfreesboro, Tennessee. In this research, tetraethyl orthosilicate, Si [([OCH.sub.2][CH.sub.3]).sub.4], was doped with telluric acid, Te[(OH).sub.6], or tellurium (IV) chloride, [TeC1.sub.4]. A sol-gel product was synthesized. The reaction time, pH, and quantity of reactants were varied. Intermediates and products were analyzed by IR spectroscopy. Computational calculations were conducted to determine the molecular geometries of the proposed intermediates and products. Results from this Project SEED I research project will be presented and discussed.
SYNTHESIS AND ANALYSIS OF SELENIUM SILICATE SOL-GEL MATERIALS. A PROJECT SEED RESEARCH SUMMER AT MTSU. Samuel Deputy*, Judith M. Iriarte-Gross, William Ilsley, Middle Tennessee State University, Murfreesboro, Tennessee. Selenium dopes sol-gel glasses were produced using selenious acid ([H.sub.2][SeO.sub.3]), or selenium (IV) chloride ([SeC1.sub.4]), as dopants within a tetraethyl orthosilicate, Si[([OCH.sub.2][CH.sub.3]).sub.4], sol-gel matrix. The pH of the system was varied as were reaction times. The intermediates and glasses were analyzed using IR spectroscopy. Computational calculations were conducted to identify the molecular geometries and energies of the compounds being studied. Results will be presented and discussed.
QUANTITATIVE SPECTROPHOTOMETRIC METHODS OF ANALYSIS FOR THE DETERMINATION OF TELLURIC ACID. Freneka F. Minter * and Judith M. Iriarte-Gross, Middle Tennessee State University, Murfreesboro, Tennessee. The purpose of this study is to see if small amounts of telluric acid, Te[(OH).sub.6] could be analyzed. There are many methods of analysis in the literature for the determination of Te[(OH).sub.6] but these methods are time-consuming and require careful control of the experimental conditions. In alkaline medium, tellurium (VI) absorbs strongly in the ultraviolet region, and a spectrophotometric method is based on this absorption. Using an ultraviolet spectrophotometric method in the determination of Te[(OH).sub.6] increases the ease and the speed of the determination of Te[(OH).sub.6] concentrations. This study describes a quantitative method for the determination of Te[(OH).sub.6] based upon its absorption in the ultraviolet region of the spectrum.
ABSORPTION STUDIES OF Cd(II) AND Cu(II) BY MONO-AND DI- THIOPHOSPHINIC ACIDS IMPREGNATED ON A SOLID SUPPORT. Nick Bridges * and Dale D. Ensor, Tennessee Technological University, Cookeville, Tennessee. Heavy metal contamination is a concern in the production of high purity mineral acids for agricultural uses or in analytical analysis. The heavy metals could be toxic to humans and animals or could render an unwanted interference in analytical analyses. The removal of Cd(II) and Cu(II) from mineral acids was studied using liquid extractants, Cyanex 301, containing dithiophosphinic acid groups and Cyanex 302, with monothiophosphinic acid groups, that had been impregnated with inert polymeric substrates. The thiophosphinic acid groups showed the strongest affinity for Cd(II), as would be predicted by the Hard/Soft acid and base concept. The dry weight distribution ([D.sub.w]) was measured in batch experiments and compared to see how changes in acid concentration or length of time of resin exposure affected the [D .sub.w]. The concentration of the acid affected the uptake of the metal ion, but had little effect on the rate of uptake. A competitive study was conducted to determine the effects of having the Cd(II) and Cu(II) ions in the same solution and how that affects the individual [D.sub.w] for each metal. In this study Cd(II) uptake was the highest when the Cu(II) concentrations were low. As the concentration of Cu(II) increased, the competition for reactive sites had a negative effect on the [D.sub.w] for Cd(II).
NEW INSIGHTS CONCERNING THE USE OF [beta]-CHLOROALANINE AND MONOVALENT CATIONS IN THE TRYPTOPHAN SYNTHASE SPECTROPHOTOMETRIC KINETIC ASSAY. Duane M. Hatch *, James A. Henderson *, and Jeffrey 0. Boles, Tennessee Technological University, Cookeville, Tennessee. Bacterial tryptophan synthase is a [[alpha].sub.2][[beta].sub.2] heterodimer that catalyzes the last two steps in the biosynthesis of L-tryptophan. The [[alpha].sub.2][[beta].sub.2] complex dissociates reversibly into two monomeric [alpha] subunits ([M.sub.r] 28,700) and one dimeric subunit ([M.sub.r] 86,000). The [alpha] subunit catalyzes the cleavage of indole-3-glycerol phosphate to indole and 3-glyceraldehyde 3-phoshate ([alpha] reaction), while the pyridoxal phosphate dependent [[beta].sup.2]-subunit catalyzes the condensation of indole with L-serine to form L-tryptophan ([beta] reaction). The physiologically important [alpha][beta] reaction is the sum of the [alpha] and [beta] reactions. Since this enzyme is currently getting much broader attention, we sought to reinvestigate the kinetic assay design and reaction conditions. Our preliminary results will be presented.
* Student author.
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|Author:||Howard, James C.|
|Publication:||Journal of the Tennessee Academy of Science|
|Date:||Jan 1, 2002|
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