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Elucidation of Photoinduced Energy and Electron Transfer Mechanisms in Multimodular Artificial Photosynthetic Systems

Description: Multimodular designs of electron donor-acceptor systems are the ultimate strategy in fabricating antenna-reaction center mimics for artificial photosynthetic applications. The studied photosystems clearly demonstrated efficient energy transfer from the antenna system to the primary electron donor, and charge stabilization of the radical ion pair achieved with the utilization of secondary electron donors that permits either electron migration or hole transfer. Moreover, the molecular arrangement of the photoactive components also influences the route of energy and electron transfer as observed from the aluminum(III) porphyrin-based photosystems. Furthermore, modulation of the photophysical and electronic properties of these photoactive units were illustrated from the thio-aryl substitution of subphthalocyanines yielding red-shifted Q bands of the said chromophore; hence, regulating the rate of charge separation and recombination in the subphthalocyanine-fullerene conjugates. These multicomponent photosystems has the potential to absorb the entire UV-visible-NIR spectrum of the light energy allowing maximum light-harvesting capability. Furthermore, it permits charge stabilization of the radical ion pair enabling the utilization of the transferred electron/s to be used by water oxidizing and proton reducing catalysts in full-scale artificial photosynthetic apparatuses.
Date: May 2017
Creator: Lim, Gary Lloyd Nogra

Reductive Functionalization of 3D Metal-Methyl Complexes and Characterization of a Novel Dinitrogen Dicopper (I) Complex

Description: Reductive functionalization of methyl ligands by 3d metal catalysts and two possible side reactions has been studied. Selective oxidation of methane, which is the primary component of natural gas, to methanol (a more easily transportable liquid) using organometallic catalysis, has become more important due to the abundance of domestic natural gas. In this regard, reductive functionalization (RF) of methyl ligands in [M(diimine)2(CH3)(Cl)] (M: VII (d3) through CuII (d9)) complexes, has been studied computationally using density functional techniques. A SN2 mechanism for the nucleophilic attack of hydroxide on the metal-methyl bond, resulting in the formation of methanol, was studied. Similar highly exergonic pathways with very low energy SN2 barriers were observed for the proposed RF mechanism for all complexes studied. To modulate RF pathways closer to thermoneutral for catalytic purposes, a future challenge, paradoxically, requires finding a way to strengthen the metal-methyl bond. Furthermore, DFT calculations suggest that for 3d metals, ligand properties will be of greater importance than metal identity in isolating suitable catalysts for alkane hydroxylation in which reductive functionalization is used to form the C—O bond. Two possible competitive reactions for RF of metal-methyl complexes were studied to understand the factors that lower the selectivity of C—O bond forming reactions. One of them was deprotonation of the methyl group, which leads to formation of a methylene complex and water. The other side reaction was metal-methyl bond dissociation, which was assessed by calculating the bond dissociation free energies of M3d—CH3 bonds. Deprotonation was found to be competitive kinetically for most of the 1st row transition metal-methyl complexes (except for CrII, MnII and CuII), but less favorable thermodynamically as compared to reductive functionalization for all of the studied 1st row transition metal complexes. Metal-carbon bond dissociation was found to be less favorable than the RF reactions for most 3d transition ...
Date: May 2017
Creator: Fallah, Hengameh

Disease Tissue Imaging and Single Cell Analysis with Mass Spectrometry

Description: Cells have been found to have an inherent heterogeneity that has led to an increase in the development of single-cell analysis methods to characterize the extent of heterogeneity that can be found in seemingly identical cells. With an understanding of normal cellular variability, the identification of disease induced cellular changes, known as biomarkers, may become more apparent and readily detectable. Biomarker discovery in single-cells is challenging and needs to focus on molecules that are abundant in cells. Lipids are widely abundant in cells and play active roles in cellular signaling, energy metabolism, and are the main component of cellular membranes. The regulation of lipid metabolism is often disrupted or lost during disease progression, especially in cancer, making them ideal candidates as biomarkers. Challenges exist in the analysis of lipids beyond those of single-cell analysis. Lipid extraction solvents must be compatible with the lipid or lipids of interest. Many lipids are isobaric making mass spectrometry analysis difficult without separations. Single-cell extractions using nanomanipulation coupled to mass spectrometry has shown to be an excellent method for lipid analysis of tissues and cell cultures. Extraction solvents are tunable for specific lipid classes, nanomanipulation prevents damage to neighboring cells, and lipid separations are possible through phase dispersion. The most important aspect of single-cell analysis is that it uncovers the extent of cellular heterogeneity that exists among cellular populations that remains undetected during averaged sampling.
Date: May 2017
Creator: Hamilton, Jason S

Synthesis of Gold Complexes From Diphosphine Ligands and Screening Reactions of Heterocyclic Acetylacetonato (ACAC) Ligands with Transitional Metal Complexes

Description: Syntheses of diphosphine gold (I) complexes from gold THT and two ligands, 4, 5-bis (diphenylphosphino)-4-cyclopenten-1, 3-dione (BPCD) and 2,3-bis(diphenylphosphino)-N-phenylmaleimide (BPPM), were done separately. The reactions happened under ice conditions followed by room temperature conditions and produced two diphosphine gold (I) complexes in moderated yield. Spectroscopic results including nuclear magnetic resonance (NMR) and X-ray crystallography were used to study and determine the structures of the products formed. Moreover, X-rays of all newly synthesized diphosphine gold (I) complexes were compared with the known X-ray structures of other phosphine and diphosphine gold (I) complexes. There were direct resemblances in terms of bond length and angle between these new diphosphine gold (I) complex structures and those already published. For instance, the bond lengths and angles from the newly prepared diphosphine gold (I) complexes were similar to those already published. Where there were some deviations in bond angles and length between the newly synthesized structures and those already published, appropriate explanation was given to explain the deviation. Heterocyclic ligands bearing acetylacetonate (ACAC) side arm(s) were prepared from ethyl malonyl chloride and the heterocyclic compounds 8-hydroxylquinoline, Syn-2-peridoxyaldoxime, quinoxalinol and 2, 6-dipyridinylmethanol. The products (heterocyclic ACAC ligands) from these reactions were screened with transition metal carbonyl compounds in thermolytic reactions. The complexes formed were studied and investigated using NMR and X-ray crystallography. Furthermore, the X-ray structures of the heterocyclic ACAC ligand or ligand A and that of rhenium complex 1 were compared with similar published X-ray structures. The comparison showed there were some similarities in terms of bond length and bond angles.
Date: August 2015
Creator: Nyamwihura, Rogers

Applications of Single Reference Methods to Multi-Reference Problems

Description: Density functional theory is an efficient and useful method of solving single-reference computational chemistry problems, however it struggles with multi-reference systems. Modifications have been developed in order to improve the capabilities of density functional theory. In this work, density functional theory has been successfully applied to solve multi-reference systems with large amounts of non-dynamical correlation by use of modifications. It has also been successfully applied for geometry optimizations for lanthanide trifluorides.
Date: May 2015
Creator: Jeffrey, Chris C.

Computational Studies of C–H/C–C Manipulation Utilizing Transition Metal Complexes

Description: Density Functional Theory (DFT) is an effective tool for studying diverse metal systems. Presented herein are studies of a variety of metal systems, which can be applied to accomplish transformations that are currently difficult/impossible to achieve. The specific topics studied utilizing DFT include: 1) C–H bond activation via an Earth-abundant transition metal complex, 2) C–H bond deprotonation via an alkali metal superbase, 3) and amination/aziridination reactions utilizing a CuI reagent. Using DFT, the transformation to methanol (CH3OH) from methane (CH4) was examined. The transition metal systems studied for this transformation included a model FeII complex. This first-row transition metal is an economical, Earth-abundant metal. The ligand set for this transformation includes a carbonyl ligand in one set of complexes as well as a phosphite ligand in another. The 3d Fe metal shows the ability to convert alkyls/aryls to their oxidized counterpart in an energetically favorable manner. Also, “superbasic” alkali metal amides were investigated to perform C—H bond cleavage. Toluene was the substrate of interest with Cs chosen to be the metal of interest because of the highly electropositive nature of this alkali metal. These highly electrophilic Cs metal systems allow for very favorable C—H bond scission with a toluene substrate. Finally, the amination and aziridination of C–H and C=C bonds, respectively, by a CuI reagent was studied. The mechanism was investigated using DFT calculations. Presently, these mechanisms involving the use of coinage metals are debated. Our DFT simulations shed some insight into how these transformations occur and ultimately how they can be manipulated.
Date: May 2015
Creator: Pardue, Daniel B.

Quantitative Chemical Analysis of the Soils of Erath County, Texas

Description: A chemical analysis of representative samples of Windthorst sand, Denton sand, and Denton clay has been made, and this analysis shows that their composition has a strict correlation with respect to their geological origins. The analyses of the different soils have shown the Windthorst sand to be highly deficient in all of the essential elements, whereas the Denton sand is deficient in only one; namely, phosphorus. The analysis of the Denton clay showed it to be highly fertile. From the consideration of the pH and the lime content, it has been determined to some extent what crops will grow in each of the soils.
Date: June 1938
Creator: Barnes, Benjamin F.

Organomagnesium Compounds in Benzene Solvent and Their Application in Synthesis of Organoberyllium Compounds

Description: The work reported by D. Bryce-Smith and G. F. Cox, along with several recent publications describing experimental results designed to elucidate the long disputed question of the structure of the Grignard reagent in ether stimulated the work reported here, in an effort to obtain additional evidence of the structure of the organomagnesium complex in benzene solvent. Since the primary objective of this work was to prepare organoberyllium compounds using the organomagnesium complexes in hydrocarbon solvents, it seemed an insight into the structure of these complexes would be beneficial in this work. The techniques used and experimental evidence obtained from the structure elucidation of the ethereal Grignard reagent have been most helpful in organization of the methods used to study the structure of organomagnesium halide complexes in benzene solvent. It seemed that an insight into the structure of these organomagnesium halide complexes in hydrocarbon solvents would be beneficial in accomplishing the second objective of this work. This objective was to prepare organoberyllium compounds using the organomagnesium halide complexes prepared in hydrocarbon solvents.
Date: January 1966
Creator: Selman, Charles M.

Chemical Cleavage of Human Phosphoglucose Isomerase at Cysteine

Description: The present study has resulted in the development of a procedure for the specific chemical fragmentation of human phosphoglucose isomerase into a minimal number of peptides. A two-cycle procedure for cleaving the protein with 2-nitro-5- thiocyanobenzoic acid results in four primary peptides and three overlap peptides. The peptides can be readily separated on the basis of their size by using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Preliminary peptide alignments have been considered, and amino acid analyses have been performed. End-terminal analyses of the enzyme revealed a carboxyl terminal sequence of Asp-Val-Gln and a blocked amino terminus. The cysteine cleavage procedure provides an excellent method for the identification and location of specific genetic mutations of human phosphoglucose isomerase.
Date: December 1975
Creator: Conn, Worth R.

Magnetic Properties of Metal(II) Schiff Base Complexes

Description: Ligands prepared from various combinations of aldehydes and ketones with the appropriate aminealcohol were complexed with cupric acetate monohydrate. The complexes with O,NO or N,N,O donor atoms were synthesized to study the influences of the ligand on molecular structure, spin-spin interaction, and on the value of the exchange integral. The magnetic data indicated that of the eight Cu(II) complexes discussed, two behaved differently from known analogous compounds. Cu (benzoylacetone :ethanolamine) was compared to Cu(acac:ethanolamine), and Cu(pyrr:oaminophenol) was compared to Cu(acac:o-aminophenol). Each pair of complexes was postulated to have the same molecular structure. The synthesis and characterization of Mn(pyrr:oaminophenol) 2H2 is also discussed. The following physical data were collected and discussed: elemental analysis, melting point, molecular weight, infrared spectra, electronic spectra, and magnetic susceptibility.
Date: May 1976
Creator: Hines, Mary Katherine

Synthesis and Study of Glutaryl-S-(ω-aminoalkyl)-L-cysteinylglycines as Inhibitors of Glyoxalase I

Description: This thesis describes the synthesis and preliminary enzymatic study of glutaryl-S-(8-aminooctyl)-L-cysteinylglycine and glutaryl-S-(10-aminodecyl)-L-cysteinylglycine as inhibitors of glyoxalase I. These analogs of glutathione were prepared as potential ligands for affinity chromatography purification of glyoxalase I. The compounds were synthesized by a seven-step procedure in overall yields of 24% for the octyl analog and 33% for the decyl analog. Both compounds exhibited mixed type inhibition of the enzyme, with the decyl derivative being more inhibitory than the octyl derivative. The inhibition was nonlinear (parabolic) for both compounds. Although less inhibitory than the corresponding S-substituted glutathione derivatives, these analogs are promising candidates for affinity chromatography ligands. Such compounds may also be useful in studying the mechanism of glyoxalase I.
Date: May 1975
Creator: Phillips, Gerald Wayne

Magnetic Properties of Copper (II) Complexes of Schiff Bases

Description: The synthesis and characterization of two new Schiff base copper(II) complexes are reported. These are Cu(acac: 2-amino-l-phenylethanol) and Cu(acac:2-amino-l-butanol). The ligands, derived from acetylacetone and the appropriate aminoalcohol, are dibasic tridentates with 0,N,O donor atoms. The magnetic properties of the complexes were studied at several temperatures between 78 OK and 296 OK. The magnetic moment of Cu(acac:2-amino-l-phenylethanol) varied little with temperature, and that of Cu(acac:2-amino-lbutanol) increased as the temperature was lowered. This is in contrast to the magnetic moment of Cu(acac:ethanolamine), which decreases as the temperature decreases. Molecular weight data, infrared spectra, magnetic data, electronic spectra, and electron spin resonance spectra of both complexes are reported and discussed.
Date: August 1975
Creator: Jones, William James

Inhibitors of Dihydrofolate Reductase, 8-Oxapteridines

Description: The biological activities of some homeosterically related analogs of dihydrofolic acid have been examined involving pyrimido[4,5-b][l,4]oxazine (8-oxapteridine) derivatives. It is anticipated that these compounds might interfere with the essential intermediary metabolic functions of the vitamin and thus serve as potential chemotherapeutic agents. Preliminary toxicity studies in microbial assay systems were disappointing; however, inhibitory effects were demonstrated in cell free enzyme systems. A comparison of the structure/activity relationships was determined using two folic acid coenzyme systems, dihydrofolate reductase and thymidylate synthetase. The 2-amino-4-hydroxy-6-(substituted)-8-oxapteridines were generally more effective inhibitors than the corresponding 2,4-diamino analogs. The relative biological activity of a series of 2-amino-4-hydroxy-6-ω-phenylalkyl derivatives were examined, and the most active derivative was the 6-phenylethyl analog which appears to function as a mixed-type inhibitor involving partially competitive and partially non-competitive inhibition.
Date: December 1974
Creator: Lin, Shwu-Ching H.

Copper (II) Complexes with Deprotonated N-(2-hydroxyethyl)ethylenediamine

Description: This thesis reports the synthesis and characterization of two new copper(II) halide complexes with deprotonated N-(2-hydroxyethyl)ethylenediamine behaving as a bidentate. The magnetic properties of the new copper(II) complexes were studied from room temperature to liquid nitrogen temperatures. The magnetic data show that both complexes exhibit antiferromagnetic interactions with a singlet ground state and a thermally accessible triplet excited state. Magnetic data and infrared spectra indicate the complexes are halogenbridged. Deprotonation at an amine nitrogen is based on the presence of a hydroxyl stretching band in the infrared spectra. Electronic spectra and infrared spectra indicate the complexes are square planar. Elemental analyses, infrared spectra, electronic spectra, electron spin resonance spectra, and magnetic data are reported and discussed.
Date: December 1975
Creator: Miller, Toney G.

Denaturation, Renaturation and Other Structural Studies on Phosphoglucose Isomerases

Description: Structural properties of phosphoglucose isomerases isolated from a variety of species have been compared by peptide fingerprinting, predicted amino acid sequence homologies and by denaturation and renaturation studies. The enzymes are more readily denatured in guanidinium chloride than in urea, and the isomerase isolated from yeast is more stable toward acid pH than the rabbit muscle enzyme. The rates of guanidinium chloride-induced denaturation are markedly increased by ionic strength and decreased by substrates, competitive inhibitors or glycerol. The enzyme can be renatured, but only in the presence of glycerol. The renaturation process is dependent on protein concentration and temperature and provides a method for the formation of mixed species heterodimers.
Date: December 1975
Creator: Young, Clint D.

Electrodeless Discharge of Isopropyl Alcohol

Description: Gases at satisfactory pressures fluoresce in the presence of radio frequency radiation (6). Such fluorescent gases have been used to probe fields of radio frequency oscillation and their emission spectra have been recorded and studied. Ions with multiple charges also exist in these gases, (6). In 1941 Oliver (12) observed the fluorescence of an isobutane- isobutene gaseous mix flowing to a pump through a glass tube which was wrapped by a spiral antenna of a sevenmegacycle transmitter. A white deposit was noticed at a bend in the tubing on the pump side of the fluorescing section of the gas (12, p. 8). In 1957 Blacknall (3) studied the fluorescence and reaction products of propylene in the antenna region of sevenmega- cycle radiation, The oscillator employed by Blacknall was an ARC-5/T-22 military surplus transmitter of range 7.00 to 9.10 megacycles, which he operated at 7.00 megacycles. Blacknall observed a drop in pressure and the formation of a brown deposit in the region of the coil. Blacknall did not report an analysis of this product. In 1959 Armstrong (1) repeated Blacknall's experiments and modified Blacknall's apparatus into an improved design. He also performed an analysis on Blacknall's product. Blacknall used a vertical open-end mercurial manometer with which to measure pressure in his system and as a result introduced mercury vapor into his system. Armstrong tried to minimize the amount of mercury introduced by covering his manometric mercury with a layer of octyl sebacate, "octoil". Armstrong used a spiral-would antenna wrapped around his reaction vessel and reported the formation of spiral brown rings coincident with the copper wire of the antenna. There was a white product deposited in a spiral interlaced with the spiral of dark brown material. No definite identification was reported by Armstrong other than reporting, his solid material as isotactic ...
Date: August 1965
Creator: Bryant, Franklin Delano

The Crystal and Molecular Structure of 2, 2' bipyridylglycinatochloro Copper (II) Dihydrate

Description: The three-dimensional x-ray structure of 2,2'-bipyridylglycinatochloro copper(II) dihydrate has been fully refined to a final R factor of 0.081. The bipyridyl and glycine ligands are arranged about the central copper atom in a square planar configuration while the chlorine atom is 2.635 angstroms above this plane directly over the copper atom. This unusually long distance is explained by the positioning of a glycine group on the opposite side of the square plane, resulting in a distorted octahedral arrangement. Also, the chlorine atom is linked to three oxygen atoms via hydrogen bonding, thus stabilizing the distorted octahedral complex.
Date: May 1975
Creator: Neitzel, Conrad J.

The Vacuum Ultraviolet Spectra of Cyclohexane, Cyclohexene, 1,4-Cyclohexadiene, Isotetralin, and Several Methyl Substituted Analogs

Description: A paucity of literature exists on the Independent System analysis of adjacent, parallel transition dipoles. Applying this theory and certain spectral information semiemperical calculations were made to predict absorption profiles and band intensities. To aid in the assignment of the 7*+7 absorption bands it was necessary to obtain the vacuum ultraviolet spectra of cyclohexane and cyclohexene. Because the spectra of these molecules contained sharp, atomic-like absorption bands a Rydberg series could be fitted to certain absorptions, thus the determination of their ionization potentials. Using Independent System analysis profiles and intensities of 7*+q-- absorption bands ins 'several methyl substituted 1,4- cyclohexadienes and isotetralin were predicted where general agreement was found with observed experimental spectra.
Date: December 1974
Creator: Tidwell, Edgar Rhea

Studies of L-Asparaginase from Lactobacillus Plantarum

Description: This study is concerned with the regulation of Lasparaginase (LA) in the cell-free crude extracts from Lactobacillus plantarum (ATCC8014). A previously reported finding that adenosine triphosphate (ATP) inhibits the action of LA in crude extracts was confirmed. The study was extended to include the mono-, di-, and triphosphates of adenosine, guanosine, cytidine, and uridine. These compounds were also shown to inhibit LA activity. These andother studies revealed that LA appears to be an allosteric type enzyme exhibiting positive homotropism with respect to substrate and heterotropism with respect to the nucleotides tested. The regulation of LA activity by high energy compounds, when coupled with asparagine synthetaseL suggests a relationship between amide synthesis-amide degradation and the energy levels of the cell.
Date: May 1979
Creator: Nalepka, Edward R.

Isolation and Characterization of Proteus vulgaris Methylglyoxal Synthetase

Description: Methylglyoxal synthetase, which catalyzes the formation of methylglyoxal and inorganic phosphate from dihydroxyacetone phosphate, was found in extracts of Proteus vulgaris. An efficient purification procedure utilizing ion exchange column chromatography and isoelectric focusing has been developed. Homogeneity of the enzyme preparation was confirmed by polyacrylamide gel electrophoresis and rechromatography.Two components of methylglyoxal synthetase were obtained upon isoelectric focusing. A comparison of the chemical and physical properties of the two components was carried out. The enzyme is a dimer. In the presence of inorganic phosphate, the hyperbolic saturation kinetics with dihydroxyacetone phosphate are shifted to sigmoidal.
Date: May 1975
Creator: Tsai, Pei-Kuo

Studies Concerning Asparagine Metabolism in Lactobacillus plantarum

Description: This study is concerned with the metabolism of L-asparagine in Lactobacillus plantarum (ATCC 8014). Theprimary area of investigation is the preliminary characterization of a previously unreported L-asparaginase enzyme in L. plantarum. This L-asparaginase was determined to be an inducible enzyme with variations in its activity level according to the L-asparagine level in the growth medium. L-Glutaminase could not be induced in this organism by L-glutamine, nor would L-glutamine induce the asparaginase activity. These and other studies with amino acid analogs demonstrated the high specificity of both induction and enzymic activity of the asparaginase. Various physical properties of the enzyme were studied. The enzyme was found to be inhibited by adenosine triphosphate (ATP). This inhibition appears to be cooperative in nature and of the type exhibited by allosteric enzymes. These studies should be confirmed on a highly purified enzyme as these preliminary experiments were performed using a crude cell-free extract.
Date: May 1974
Creator: McCue, Bette Ann

Isozymes and In Vivo Activity of Triosephosphate Isomerase

Description: The distribution of isozymes of triosephosphate isomerase was normal in all human tissues examined. This finding argues against the existence of tissue-specific isozymes. Normal distributions of isozymes were also found in patients with cri-du-chat syndrome. Thus it is unlikely that a gene for triosephosphate isomerase is located on the short arm of chromosome five in man. When triosephosphate isomerases from a wide range of species were examined by starch gel electrophoresis, definite evolutionary patterns were found. Kinetic studies were conducted on human triosephosphate isomerase under conditions simulating the intracellular environment of the erythrocyte. Calculations using the kinetic parameters obtained indicate that even in triosephosphate isomerase deficiency disease, enough enzyme activity remains that the rate of glycolysis should not become inhibited.
Date: May 1974
Creator: Snapka, Robert Morris