Thesis (M. Sc.)--University of Hong Kong, 1970. / Typewritten.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xiii, 155 p.: ill (some col.). Includes abstract and vita. Advisor: Tammy Bray, Nutrition Program. Includes bibliographical references (p. 139-155).

The mechanisms involved in the breakdown of the protective ccides formed on Fe-9%Cr l%Mo have been investigated in both air and high pressure CO 2' The initial research programme was to investigate the microstructural changes which occurred with breakaway oxidation, a new EELS detector being cxi missioned to detenni. ne oxygen and raXbon levels. Oxidation in air was performed at temperatures between 500 and 1000'C. SEM and sane TEN cross sectional work was performed to determine the role of oxygen ingression, but prcblems in sample preparation made examination difficult. With cDcidation in high pressure OD2 the change from protective growth to breakaway is accanpanied by massive oxide growths usually at specimen corners. Microstructural changes also occur, with massive carbide growth acccrnpanying the changes in oxide structure. During oxidation, chemical exchanges between the oxidising gas, the metal and the inner oxide all contribute to the deposition of carbon at the metal/ oxide interface. This process generates internal stresses in the oxide, allowing microcracks to develop this enhancing the inward movement of the 002 and causing more, oxidation and carbon deposition. TEM cross sections were prepared to determine the mode of oxidation and the process by which carbon reaches the interface. In theory, EELS analysis allows identification of light elements Mi and above) but in practice the system proved very sample dependent, working well on thin films but very poorly on thick specimens (carbides). Evidence of the range of EELS mapping facilities are presented together with work on a new particle extraction system

A series of cyclometalated gold(III) complexes with N-heterocyclic carbine (NHC) or alkynyl as auxiliary ligand were synthesized and characterized. Complexes [AuIII(R1 –C^N^C)(NHC)](OTf) and [AuIII(C^N^C)(C≡CR2)] (HC^N^CH = 2,6-di(naphthalene-2-yl)pyridine; R1 = H or 4-methoxyphenyl; R2 =aryl) are emissive in solution at room temperature with quantum yields in the range of 0.65–11.4% and lifetimes ranging from 98 to 506 s. [AuIII(4-(4-OMePh)–C^N^C)(NHC)](OTf) showed prominent photochemical properties. This complex effectively catalyses photo-induced oxidation of secondary amines (to the corresponding imines) and -functionalization of tertiary amines in good to excellent yields; it also acts as a photosensitizer for hydrogen generation in a water/acetonitrile mixture, producing more than 350 turnovers of hydrogen after 4 hours of irradiation. Palladium(II) meso-tetrakis(pentafluorophenyl)porphyrin was found to be an efficient and robust catalyst for the photo-induced oxidative C–H bond functionalization reactions. Several kinds of -functionalized tertiary amines were obtained in good to excellent yields by irradiating a mixture of palladium(II) catalyst, corresponding tertiary amine and nucleophile under aerobic conditions. The nucleophiles for these reactions include cyanide, nitromethane, dimethyl malonate, diethyl phosphite and acetone. Two examples of novel intramolecularly cyclized amines were also described. Comparison of the UV-vis absorption spectra before and after reaction indicated that the palladium catalyst was highly robust. The practical potential of this catalyst was shown by the success in reactions at a low catalyst loading and on a large scale. The palladium(II) catalyst could also sensitize photo-induced oxidation of sulfide to sulfoxide and photo-induced hydrogen production in a water/acetonitrile mixture with up to 240 turnovers. [FeIII(L-N4Me2)Cl2][FeCl4] (L-N4Me2 = N,N’-dimethyl-2,11-diaza[3,3] (2,6)pyridinophane) was demonstrated to be an active catalyst for water oxidation. When cerium ammonium nitrate (CAN) was used as the oxidant, the iron(III) catalyst oxidized water to oxygen with up to 93 turnovers after 30 minutes in 0.1 M nitric acid, whereas changing the oxidant to sodium periodate (NaIO4) resulted in only 44 turnovers of oxygen after 30 minutes. The mechanism of the reaction was explored by high resolution electrospray ionization mass spectrometry (ESI-MS), 18O labeling, UV-vis absorption spectroscopy, kinetic plots and DFT calculations. In the case of using CAN, an FeIV-oxo species was detected by ESI-MS and UV-vis absorption spectroscopy. The rate of oxygen evolution was found to be linearly dependent on both concentrations of catalyst and oxidant. 18O labeling studies confirmed that the origin of oxo ligands was from water and was irrespective of the choice of oxidant. This reaction was proposed to involve a coupling between an FeIV-oxo species and a hydroxocerium(IV) radical. In the case of using NaIO4, an FeV-dioxo species was detected by ESI-MS as a major species, and a small amount of FeIV-oxo species was detected by UV-vis absorption spectroscopy. As the rate of oxygen evolution was found to be linearly dependent on the concentration of catalyst only, the reaction was proposed to involve a cis-FeV-dioxo species. DFT calculations showed that the cis-FeV-dioxo species was capable of oxidizing water to oxygen through the formation of an [FeIII(L-N4Me2)(OO?)(OH)]+ intermediate. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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published_or_final_version / abstract / toc / Chemistry / Master / Master of Philosophy

published_or_final_version / Chemistry / Master / Master of Philosophy

published_or_final_version / Chemistry / Master / Master of Philosophy

published_or_final_version / Chemistry / Master / Master of Philosophy