Chemistry Commons^™

Piezomodulation Spectroscopy Of Molecular Crystals. I. Methods And Principles, J. Merski, Craig J. Eckhardt

Craig J. Eckhardt Publications

The effects of piezomodulation on the spectra (particularly reflectivity spectra) of molecular crystals for the strong, weak, and no coupling regimes are considered. The stress or strain modulation of the crystal is shown to affect the dispersion energy and exciton resonance interaction. The experimental approach is outlined. Methods of data analysis are described for obtaining differential changes in the real and imaginary parts of the dielectric function, for determining deformation potentials for vibronic transitions, and for applying the Seraphin coefficients. Previous microscopic theory for interaction of excitons with static lattice deformations is adapted for the modulated case. Application of classical …

Piezomodulation Spectroscopy Of Molecular Crystals. Iv. The First Singlet Systems Of Tcnq And Bdp, J. Merski, Craig J. Eckhardt

Craig J. Eckhardt Publications

The polarized modulated piezoreflection spectra of the first singlet system of TCNQ and BDP are reported. Kramers-Kronig transformations are obtained and polariton energy strain shifts are determined. In contrast to systems with negligible to intermediate coupling, the piezomodulation spectrum for the mixed transverse-longitudinal polaritons show strong deviations from the logarithmic frequency derivative of the corresponding reflection spectra. Progressions in the piezomodulation spectra in the energy region of the stop band are related to multiparticle states. Piezomodulation spectroscopy is shown to exhibit greatest deviation from derivative behavior when solid state effects become extensive.

Phase Transition Effects: A Crystallographic Characterization Of The Temperature Dependency Of The Crystal Structure Of The 1:1 Charge Transfer Complex Between Anthracene And Tetracyanobenzene In The Temperature Range 297 To 119 K, John J. Stezowski

John J. Stezowski Publications

Crystal structures of the charge transfer complex between anthracene and tetracyanobenzene, A:TCNB, C₁₄H₁₀: C₁₀H₂N₄, at three temperatures (297, 234 and 226 K) above the order–disorder phase transition at 206 K and at four temperatures (202, 170, 138, and 119 K) below it have been determined from x-ray diffraction data. The space group of the room temperature phase was assigned as Cm with a = 9.528(2), b =12.779(3), c = 7.441(2) Å and β=92.39(2) degrees at 297 K and for the low temperature phase is P21/a with a =9.457(1), …

The Kinetics Of Potassium Ferrate Oxidation Of Isopropyl Alcohol, Ethyl Alcohol, And Trimethylacetaldehyde, Ronald Lee Bartzatt

Department of Chemistry: Dissertations, Theses, and Student Research

Conclusion

The main emphasis of this thesis is to describe the reaction rates of potassium ferrate oxidation of various substrates, in relation to solution pH.

For trimethylacetaldehyde the order of dependence (slope ) from pH 7.85 to pH 9.45 is 0.951. This is calculated from - Log k_s versus pH graphing of the data shown in the esults. The correlation coefficient of this graphing is equal to 0.989 and y-intercept = −7.95.

For isopropanol the order of dependence from pH 8.23 to pH 8.44 is 2.45. The correlation coefficient = 0.973, and y-intercept = −18.77. From pH 8.44 to …

Purification, Growth, Structure, Optical And Electrical Properties Of Single Crystals Of The Π-Molecular Complex Of Phenothiazine With Pyromellitic Dianhydride, R. Anthonj , N. Karl, Beverly E. Robertson, John J. Stezowski

John J. Stezowski Publications

Single crystals of the black phenothiazine : pyromellitic dianhydride (PTZ:PMDA) 1:1 donor–acceptor complex, have been grown by sublimation from the zone-refined components. The PTZ:PMDA complex crystalizes with PĪ symmetry (Z = 2), a = 7.197(1), b = 19.072(5), c = 6.886(1) Å, α = 84.79(1) °, β = 72.98(1) °, γ = 85.72(2) ° at T = 23 °C. The crystal structure model was refined with 5214 data { (sin ζ/λ)_max = 0.8071 Å^–1} to give R = 0.049 and R_w = 0.089. The crystal packing consists of two polar endless ...DADA... stacks related to …

Gas Phase Hydrogen Permeation In Alpha Titanium And Carbon Steels, Donald L. Johnson, Kiritkumar K. Shah, Bruce H. Reeves, Vijay L. Gadgeel

Department of Chemistry: Faculty Publications

Commercially pure titanium rods were machined into hollow cylinders and gas-phase permeation and diffusion measurements obtained with a quadrupole residual gas analyzer at temperatures between 400-800°C and pressures between 0.533 and 266.6 Nrn^-2. Pressure dependence measurements established that phase boundary reactions as well as lattice diffusion control the transport process. Lag-time data yield excellent agreement with the diffusivity data of Wasilewski and Kehl and Papazoglou and Hepworth for the case where phase boundary reactions are taken into account. The best value of the diffusivity is D = 2.1 x 10^-2 exp (-50,40O/RT). Analysis of lag-time data reveals …

Synthesis And Characterization Of Bis(Fulva1ene)- Divanadium And The Crystal Structure Of Its Oxidation Product, Bis(Fulvalene)Bis(Acetonitrile)Divanadium(Iii)- (V-V) Bis(Hexafluorophosphate)-Acetonitrile (1/1), James Smart, Barry Pinsky, Michael Fredrich, Victor Day

Department of Chemistry: Faculty Publications

Because of the current interest in the structure and reactivity of coordinatively unsaturated metallocenes and the formally analogous metallofulvalene derivatives, we wish to report our initial synthetic, physical, and X-ray structural studies of the bis( fulva1ene)divanadium system.

Thermal Effects On The Optical Spectra Of A Polydiacetylene: Poly{1,2-Bis [4-(Isopropylcarbamoyloxy) -N-Butyl]-1-Buten-3-Ynylene}, H. Eckhardt, Craig J. Eckhardt, K.C. Yee

Craig J. Eckhardt Publications

The reflection spectra of single crystals of the polydiacetylene, IPUDO [R= (CH₂)₄OCONHCH (CH₃)₂], were measured between 25° C and 160° C. A nearly reversible thermochromic change is observed together with a variation of hysteresis upon cycling. The latter is attributed to annealing that permits the pendant groups to adopt a conformation which favors the butatriene-type configuration of the polymer at high temperatures. Intensities of the high and low temperature spectra obtained by Kramers–Kronig transforms are in excellent agreement with the spectral intensities of polydiacetylenes which are prototypes for the two configurations.

Metal Cluster Chemistry: Structure And Stereochemistry In The Polynuclear Rhodium Hydrides HNRhN[P(Or)3]2n, R. K. Brown, J. M. Williams, M. F. Fredrich, V. W. Day, A. J. Sivak, E. L. Muetterties

Department of Chemistry: Faculty Publications

Crystallographic analyses of x-ray and neutron diffraction data have provided a definitive structural representation of {HRh[P(O-i-C₃H₇)₃]₂}₂ and [HRh[P(OCH₃)₃]₂}₃. These polynuclear hydrides are generated from square planar H2Rh[P(OR)₃]₂ units by edge (hydrogen atom) sharing and by vertex (hydrogen atom) sharing to form the dimeric and trimeric structures, respectively. The square-planar units are held together through four-center and three-center two-electron Rh-H-Rh bonds in the dimer and trimer, respectively. The dimer and trimer molecules each add one molecule of hydrogen to …

Protein Synthesis In Rabbit Reticulocytes: Mechanism Of Protein Synthesis Inhibition By Heme-Regulated Inhibitor, A. Das, O. Ralston, M. Grace, R. Roy, P. Ghosh-Dastidar, H. K. Das, B. Yaghmai, S. Palmieri, N. K. Gupta

Department of Chemistry: Faculty Publications

Partially purified Met-tRNA_f binding factor, eIF-2, was phosphorylated by using heme-regulated inhibitor (HRI). Phosphorylated eIF-2 was freed from HRI by phosphocellulose column chromatography. Analysis by isoelectric focusing showed 100% phosphorylation of the 38,000-dalton subunit of eIF-2. Both eIF-2 and eIF-2(P) formed ternary complexes with Met-tRNA_f and GTP with almost the same efficiency, and in both cases the ternary complex formation was drastically inhibited by prior addition of Mg²⁺. However, whereas the ternary complexes formed with eIF-2 could be stimulated by Co-eIF-2C at 1 mM Mg²⁺ and dissociated by Co-eIF-2B at 5 mM Mg²⁺, …

Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Postribosomal Supernatant Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates And Inhibition Of Ternary Complex (Met-TrnaFMet•Eif-2•Gtp) Formation By Heme-Regulated Inhibitor, R. O. Ralston, A. Das, M. Grace, H. Das, N. K. Gupta

Department of Chemistry: Faculty Publications

During heme deficiency in reticulocyte lysates, a translational inhibitor (heme-regulated inhibitor, HRI) that blocks polypeptide chain initiation is activated. HRI is a protein kinase that specifically phosphorylates the 38,000-dalton subunit of the Met-tRNA_f^Met binding factor, eIF-2. Phosphorylation of eIF-2 by HRI prevents its interaction with at least two additional factors, resulting in a net reduction in formation of ternary complex (Met-tRNA_f^Met eIF-2•GTP) and AUG-dependent transfer of Met-tRNA_f^Met to 40S ribosomal subunits. A factor (sRF) that reverses protein synthesis inhibition in heme-deficient Iysates has been purified from reticulocyte postribosomal supernatant. sRF also reverses the inhibition …

Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Ribosomal Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates, R. O. Ralston, A. Das, A. Dasgupta, R. Roy, S. Palmieri, N. K. Gupta

Department of Chemistry: Faculty Publications

A ribosomal salt (0.5 M KCI) wash factor (RF) that reverses inhibition of protein synthesis in heme-deficient reticulocyte lysates has been resolved from the bulk of Met-tRNA_t^met- binding factor (EIF-1), Co-EIF-I, and EIF-2 (ternary complex dissociation factor, TDF). The purified RF restores protein synthesis activity of heme-deficient lysates to the level observed in the presence of hemin. No direct correlation exists between amount of EIF-i activity and ability to reverse inhibition of protein synthesis in heme-deficient lysates. Homogeneous preparations of EIF-i are completely inactive in reversal of protein synthesis inhibition in heme-deficient lysates. These findings suggest that …

Chemistry Of Low-Valent Molybdenum Phosphite Complexes: Models Of Seven-Coordinate Reaction Intermediates, E. L. Muetterties, J. F. Kirner, W. J. Evans, S. Abdel-Meguid, I. Tavanaiepour, V. W. Day

Department of Chemistry: Faculty Publications

A simple synthesis of the zerovalent complex Mo[P(OCH₃)₃]₆ has been devised from a potassium reduction of MoCI₄(tetrahydrofuran)₂ followed by reaction with trimethyl phosphite at 70°. Protonation of this octahedral complex gave only low yields of the expected seven-coordinate hydride, HMo[P(OCH₃)₃]₆+. The major product was an octahedral nonhydridic cation, Mo[P(OCH₃)₃]₅P(OCH₃)₂+, derived from proton cleavage of the P─O phosphite ester bond. This octahedral cation was stereochemically nonrigid, apparently through facile methoxy group migration. Close packing by methoxy groups …

Regulation Of Protein Synthesis In Rabbit Reticulocyte Lysates By The Heme-Regulated Protein Kinase: Inhibition Of Interaction Of Met-TrnaFMet Binding Factor With Another Initiation Factor In Formation Of Met-TrnaFMet.4os Ribosomal Subunit Complexes, R. S. Ranu, I. M. London, A. Das, A. Dasgupta, A. Majumdar, R. Ralston, R. Roy, N. K. Gupta

Department of Chemistry: Faculty Publications

Protein synthesis in reticulocytes and their lysates is regulated by heme. In heme deficiency a heme-regulated translational inhibitor (HRI) that blocks initiation of polypeptide chains is activated. HRI is a protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) that specifically phosphorylates the 38,000-dalton subunit of the Met-tRNA_f^Met indin factor (IF), which forms a ternary complex with Met- tRNA_f^Met and GTP, a finding that suggests that the inhibition by HRI involves the phosphorylation of IF. We have investigated the effect of HRI in the partial reactions of protein chain initiation in which the IF-promoted binding of Met-tRNA_{f …}

Observation Of Davydov Splitting In Pts Polydiacetylene Crystal Spectra, Hans Muller, Craig J. Eckhardt

Craig J. Eckhardt Publications

The electronic spectra of polydiacetylene crystals have often been typified by poly-2, 4-hexadiyne-1, 6-diol-bis-(p-toluene sulfonate) (PTS). The spectra of crystals of this polydiacetylene have been unique in that they have displayed a pronounced “doubling” of the 300 K spectral bands at temperature below 170 K. The reflection bands are also observed to undergo a continuous red shift with continued decrease of temperature. The reflection band observed at lowest energy at 300 K is resolved at 77 K into two clearly separated bands at 15,700 cm^-1 (Ib) and 16,050 cm^-1(IIb). A recent study by modulated piezoreflection …

Thermochromism In A Polydiacetylene Crystal, R.R. Chance, R.H. Baughman, H. Muller, Craig J. Eckhardt

Craig J. Eckhardt Publications

Specular reflection spectra are reported for a thermochromic polydiacetylene crystal, ETCD [substituent group – (CH₂)₄OCONHC₂H₅] over the temperature range 23–130°C. A reversible thermochromic phase change occurs at ~120°C and is accompanied by a 2750 cm^-1 blue shift in the reflection spectra. Evidence is presented which strongly suggests that the dramatic change in optical properties of ETCD at the phase transition is due to an acetylene to butatriene transformation in the bonding sequence of the polydiacetylene backbone.

Kinetics Of The Alkaline Tetramer Dimer Dissociation In Liganded Human Hemoglobin: A Laser Light-Scattering Stopped-Flow Study, D. P. Flamig, L. J. Parkhurst

Department of Chemistry: Faculty Publications

The first-order dissociation of tetrameric HbCO to the dimer has been studied over the pH range 10.30-11.57 in a light-scattering stopped-flow apparatus using argon-ion laser excitation. The first-order dissociation rate constant varies from 0.25 sec^-1 to 24.0 sec^-1 over this pH interval. A semilogarithmic plot of k versus pH has a slope of 2.56 at pH 11.07, the midpoint. The pH dependence of the dissociation of the tetramer is consistent with progressive titration of α₁-α₂ and β₁-β₂ salt bridges. At pH 10.66, the dissociation rates of HbO₂, HbCO, methemoglobin, and …

Piezomodulated And Specular Reflection Spectra Of A Polydiacetylene Crystal, Craig J. Eckhardt, H. Muller, J. Tylicki, R.R. Chance

Craig J. Eckhardt Publications

A class of potential quasi-one-dimensional organic conductors is the monocrystalline polydiacetylenes. These polymers can be obtained as single crystals that have high structural perfection and a chain configuration that permits extensive π-electron delocalization. The poly-2, 4-hexadiyne-1, 6-diol-bis-(p-toluene sulfonate) (PTS) has been the most extensively studied system and interest centers upon the extent of delocalization along the two chains compromising the P2₁/c unit cell.

An External Goniometer For Orientation Of A Cryostat, N.C. Lockhart, L.F. Nichols, Craig J. Eckhardt

Craig J. Eckhardt Publications

An economical two-circle orienting external goniometer has been designed and fabricated for an Andonian liquid helium Dewar. The Dewar can be tilted ±30° from the vertical in two perpendicular directions. The geometrical center of the Dewar's optical cavity moves a maximum of 1 mm when the cryostat is tilted the full 30°. The basic design involves the rotation of two concentric cylinders riding on bearing surfaces. Two chain belts and gear boxes are used as drive mechanisms.

A Crystalline Fragment Of The Double Helix: The Structure Of The Dinucleoside Phosphate Guanylyl-3',5'-Cytidine, Roberta Ogilvie Day, Nadrian C. Seeman, John M. Rosenberg, Alexander Rich

Department of Chemistry: Faculty Publications

The sodium silt of guanylyl-3',5'-cytidine crystallizes in a monoclinic unit cell with one molecule in the asymmetric unit. Each molecule is related to another molecule by a 2-fold rotation axis which results in the formation of an antiparallel; right-handed .double helix with complementary hydrogen bonding between the guanine and cytosine residues. The crystal is heavily hydrated with 36 water molecules in the unit cell. The geometry of this crystalline double helix is. very similar to those which have been derived from studies of fiber x-ray diffraction patterns of double-stranded RNA; even though the latter do not yield data at atomic …

Observation Of Excitons In A Molecular Liquid: Specular Reflection Spectrum Of Α -Methylnaphthalene, Craig J. Eckhardt, Leo F. Nichols

Craig J. Eckhardt Publications

The normal-incidence specular-reflection spectrum of liquid α-methylnaphthalene was obtained for the wavelength region from 215 to 400 nm. Comparison of the Kramers-Kronig transform of the reflection spectrum with the absorption spectrum of α-methylnaphthalene is cyclohexane shows the bands of the neat-liquid spectrum shift to lower energy and display significant broadening. These effects support the existence of excitons in molecular liquids.

Influence Of An External Electric Field On The Charge Transfer State Of The Tcne-Trans-Stilbene Molecular Complex, Craig J. Eckhardt

Craig J. Eckhardt Publications

An experimental investigation of the effect of an external electric field on the absorption spectrum of the tetracyanoethylene-trans-stilbene molecular complex in cyclohexane solution yielded values of 1.1±0.1 D for the ground state electric dipole moment and 10.5±0.9 D for the change of the electric dipole moment upon transition to the charge transfer excited state. The ground state electric dipole moment determined by the electro-optic effect is in agreement with the value of 1.4±0.5 D obtained from the dielectric constant measurements made on solutions of the complex. The directions of the transition moment, the ground state electric dipole moment, and the …

Rearrangements In The Synthesis Of Β-Ketoallyl Amines, Richard P. Rebman

Open Access Master's Theses (through 2010)

The work reported in this thesis is part of an integrated research program in progress at the University of Nebraska dealing with the mechanisms of addition, elimination, and substitution in α, β – unsaturated ketones and their halogen derivatives.

The essential scope of this research is the investigation of the mechanism(s) of substitution by amines on α – (bromomethyl)-chalcone.A knowledge of the mechanism(s) involved would be useful in elucidating some of the factors determining the structure of reaction products observed in other similar systems.

Advisor: Norman H. Cromwell

The Synthesis Of Some Decahydronaphthoic Acid Lactones, Robert C. Matejka

Open Access Master's Theses (through 2010)

The diterpenoid acids, dehydroabietic acid, podocarpic acid, abietic acid, and palustric acid, have been synthesized. This thesis records the successful completion of this task which involves a selective epimerization of C.8a. It is hoped that keto lactone on alkylation will give an intermediate of the type C.l epimers which is required for the synthesis of the abietic acid series.

Advisor: D. M. S. Wheeler

Electron Transport Particles From Bacillus Stearothermophilus, Ronald J. Downey, Carl E. Georgi, Walter E. Militzer

Department of Chemistry: Faculty Publications

DOWNEY, RONALD J. (University of Nebraska, Lincoln), CARL E. GEORGI, AND WALTER E. MILITZER. Electron transport particles from Bacillus stearothermophilus. J. Bacteriol. 83:1140- 1146. 1962-Electron-transport particles (ETP) have been isolated from Bacillus stearothermophilus. They are capable of oxidizing such substrates as succinate, malate, diphosphopyridine nucleotide, p-phenylenediamine, and hydroquinone. Difference spectra indicated bands of cytochromes a₃, b, and c. A chromatographic procedure for purification of cytochrome c has been described.

The role of quinonelike intermediates in the ETP was implied by the restorative effect of coenzyme Q and vitamin K₁ on material treated …

The Enzymatic Synthesis And Disproportionation Of Galactosyl Oligosaccharides, Carl L. Tipton

Open Access Master's Theses (through 2010)

It was the purpose of this experiment to obtain unequivocal evidence for the suggested structures of the new oligosaccharides and to obtain evidence in support of the transgalactosylation mechanism of action of the enzyme studied.

Five of the galactosyl oligosaccharides produced during the hydrolysis of lactose by an enzyme prepared from Saccharomyces fragilis have been isolated in chromatographically pure form.The three having the highest chromatographic mobilities have been shown to be 3-0-β-D-galactopyranosyl-D-glucose, 6-0-β-D-galactopyranosyl-D-glucose and 6-0-β-D-galactopyranosyl-D-galactose.The positions of the glycosidic linkages in these compounds were determined by use of the lead tetra-acetate oxidation procedure.These three disaccharides have been characterized by measurement …

A Survey Of The Effects Of Changes In PH, Solvent And Salt Concentration Upon The Rate Of The Periodate-Glycol Reaction, Jay E. Taylor, Benadetto Soldano, George A. Hall

Department of Chemistry: Faculty Publications

A quantitative study of the effect of the periodate- glycol complex upon the rate of the periodate-glycol reaction was made in an earlier paper. The data for the present paper were taken before those of the previously published paper and, for the most part, before the importance of the periodate-glycol complex had been recognized. It has not been possible therefore to interpret the present data with the degree of thoroughness of the earlier paper. However, certain very interesting conclusions can be made.
The Effect of Variation of pH.
Effect of Changes in Solvent.
The Effects of Certain Salts.

Fermentation Of Sugar Acids By Bacteria, Gordon B. Robbins, Keith H. Lewis

Department of Chemistry: Faculty Publications

Bacterial fermentation of the sugar acids has received little attention in comparison with the wide-spread use of the common aldoses and sugar alcohols. These acids, and especially their sodium salts, are well suited to bacteriological techniques because of their solubility and heat stability, yet their usefulness for investigating the relationship of chemical structure to biological utilization has only recently been recognized. Their application to systematic differentiation of bacteria has also been neglected.

Kendall, Bly and Haner (1923) concluded from a study of three monocarboxylic acids and three dicarboxylic acids that these compounds possessed little value for the differentiation of bacterial …

Syntheses In The Thiophene Series, Alfred William Weitkamp

Department of Chemistry: Dissertations, Theses, and Student Research

Summary

The Friedel-Crafts reaction has been used in the preparation of thiophene ketones, some of which were hitherto unknown. Certain limitations of the reaction have been noted.

The mercuration of thiophene ketones has been systematically investigated for the first time. Many new halogen derivatives of benzothienone have been synthesized. These were employed in the elucidation of the structure of a complex mercurial· derived from this ketone.

A new modification of an old reaction has been developed whereby benzothienone can be mercurated quickly and almost quantitatively. Interesting derivatives of this little known ketone have been synthesized. Chief among these are the …

Freestone County, Texas [Water Quality Survey Of Wells And Springs With Test Hole Data, 1936], Samuel F. Turner

United States Geological Survey: Water Reports and Publications

Introduction

The purpose of this survey was to obtain information concerning existing wells and springs and the quantity and quality of water they yield, and to put down test holes where additional information was needed.

This project was part of a statewide Works Progress Administration project known as a "Statewide Inventory of Water Wells," sponsored by the [Texas] State Board of Water Engineers. The Division of Ground Water of the United States Geological Survey cooperated in the technical direction of the project and the Bureau of Industrial Chemistry of the University of Texas furnished laboratory space and equipment and supervised …