Chemistry Commons^™

Interfacial Electrochemistry In Metallic Film Fabrication, Eric S. Tuala

Masters Theses

An experimental determination of RC constant at the edge and the center of a disk electrode was done using in situ reflectance spectroscopy on a Au electrode immersed in HClO₄ as electrolyte. The RC constant at the edge of the disk electrode was found much smaller than that at the center. Such differences contribute to the selective removal of the deposited Cu on an Au disk electrode.

Furthermore, the electrochemical corrosion of Cu²⁺ towards Co electrode (called cementation reaction) was investigated using a Co/Pt rotating disk electrode. The Open Circuit Potential of Co electrode in CuSO₄ electrolyte …

Studying Carbon Dioxide Solvent Properties By Microwave Spectroscopic Investigations Of Vinyl Fluoride/Carbon Dioxide Clusters And Developing New Approaches To Decode Rotational Spectra, Prashansa Kannangara

Masters Theses

Supercritical carbon dioxide (sc-C0₂) is an excellent green solvent, but its properties are not thoroughly understood. For example, fluorinated compounds have higher than expected solubility in sc-C0₂. Microwave spectroscopy is one way to learn more about sc-C0₂ because it can be used to determine detailed structures of small clusters of molecules. The purpose of this investigation was to study weak hydrogen bonding interactions in complexes of fluorinated ethylene (solute) with carbon dioxide (C0₂, solvent). Investigations on dimers with one C0₂ molecule and fluorinated ethylene were carried out previously and found two different …

Solvation Properites Of Supercritical Carbon Dioxide Using Chirped-Pulse Fourier-Transform Microwave Spectra Of Carbon Dioxide / 1, 1-Difluoroethene (Dfe) Mixtures, Tulana Ariyaratne Subasinghe Arachchige

Masters Theses

Supercritical carbon dioxide (sc-C0₂) is a highly utilized industrial substance identified as an excellent solvent and a surfactant, which is cheaper and less hazardous than other typical solvents. The higher solubility of fluorinated hydrocarbons than their hydrocarbon (HC) analogs is not well understood and the theory behind the microsolvation of sc-C0₂ cannot be fully explained with the existing chemical information. Microwave spectroscopy is a good method of identifying the structural arrangement of clusters made from fluorinated HCs and C0₂. I n this project, microwave scans of the four different mixtures of 1 , 1-difluoroethene (DFE) …

Synthesis, Characterization And Mechanistic Studies Of Biomimetic Dinuclear Copper(Ii) Complexes, Millaniyage Nuwanthaka Prasad Jayaweera

Masters Theses

Dinuclear copper complexes are significant synthetic targets due to their use as model compounds for the active sites of type 3 copper proteins like catechol oxidase. A distinct class of ligands used in these studies are built on a phenol core to witch various donor side-arms were appended at the 2 and 6 positions of the arene ring. In our quest to quantify the influence of electron donating or withdrawing groups attached to the central arene ring, we have designed a set of ligands that, upon coordination to copper(II) centers, would produce complexes of the general structure. During this research …

Derivatization And Separation Of Natural Estrogens (Estrone, 17Β-Estradiol, And Estriol) Using Gas Chromatography With Flame Ionization Detection (Gc-Fid), Dena L. Guptill

Masters Theses

A major cause of concern for estrogens found in the environment is that even at very low concentrations (10-100 ng/L) they can have a negative effect on aquatic ecosystems by disrupting endocrine systems. Due to the increasing importance of monitoring the levels of estrogens in the environment, a detection method was developed to identify and quantify three natural estrogens (estrone, 17β-estradiol and estriol) using gas chromatography with flame ionization detection (GC-FID). In addition, the efficacy of two derivatizing agents, N,O-bis(trimethylsilyl) acetamide (BSTA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), was evaluated. The GC detector (FID) was most responsive with E3, followed by E1 and …

Reactions Of Modified Silica Gel Surfaces With Organometallic Compounds: Enhancing Olefin Polymerization Catalysts, Richard E. Diebel Iii

Masters Theses

Pretreated silica gels with distinct silica surfaces containing either isolated silanols, vicinal silanols, siloxanes, or some combinations of the three, were reacted with several organometallic compounds to determine how each compound reacted with the different silica surface species. The organometallic compounds used were trimethylaluminum, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, methylaluminoxane, dibutylmagnesium, and bis-cyclopentadienyl dimethyl zirconium.

These reacted silica gels were analyzed using diffuse reflectance infrared Fourier transform spectroscopy and ICP-AES elemental analysis. CH/Metal ratios were calculated using specific peaks in the IR spectra to elucidate the surface bonded species. Elemental analysis was used to determine how much metal was bonded …

Characterization Of The Lipopolysaccharides From Rhizobium Phaseoli Symbiotic Mutants, Francisca Garcia

Masters Theses

The lipopolysaccharides (LPSs) of the Rhizobium phaseoli CE3 and its mutants CE109, CE309 and the transconjugate Rhizobium leguminosarum LB2/109.11 were isolated and analyzed by gas chromatography (GC) and ¹H nuclear magnetic resonance (NMR) spectroscopy. CE3 is the wild type strain which is nodulation-proficient (Nod⁺). Strain CE109 and CE309 have a transposon, Tn5, inserted into Region I and Region III of their respetive chromosomes. Mutants CE109 and CE309 are defective in nodule development (Ndv^-). Transconjugate R. leg. LB2/109.11 has the DNA of the R. leg. LB2 wild type and also Region I portion of the CE109 …

The Purification And Partial Characterization Of The Surface Polysaccharides From Three Fast-Growing Rhizobium Japonicum Strains, Madhav P. Yadav

Masters Theses

The fast-growing strains of R. japonicum were originally isolated from China. They are acid-producing Rhizobia and are capable of nodulating soybeans. These isolates share a common host-specificity (Peking soybean) with the slow-growing R. japonicum strains even though their biochemical properties are more closely related to other fast-growing Rhizobium species. The surface polysaccharides from three fast-growing R. japonicum strains--USDA201, USDA205, and HC205--were isolated and partially characterized. Strain HC205 is a nod⁻ mutant of USDA205 which lacks the symbiotic plasmid. These surface polysaccharides consist of extracellular, capsular and lipopolysaccharides (EPSs, CPSs and LPSs). The EPSs from all three strains are very similar …

Internal Rotation Effects And Nuclear Hyperfine Structure In The Microwave Spectrum Of Propyne-Hf, Roger E. Bumgarner

Masters Theses

The microwave spectrum of the weakly bound propyne-HF/DF complex in the region between 6 and 16 GHz was analyzed. The spectrum was characteristic of a distorted T-shaped asymmetric top exhibiting torsional splitting caused by a low barrier to internal rotation of the methyl top relative to the propyne-HF frame. Deuterium substitution of HF confirms that the acid proton of HF is located between the F atom and the propyne triple bond. The spectroscopic constants given below are consistent with the fluorine atom being displaced toward the methyl group from a line perpendicular to and bisecting the propyne triple bond, suggesting …