Thesis (M.S.)--University of South Florida, 2003. / Title from PDF of title page. Document formatted into pages; contains 64 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references.

Thesis (M.Sc.)--York University, 2007. Graduate Progamme in Chemistry. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38764

Axenic cultures of Chiamydomonas ulvaensis [CCAP 11/58], Scenedesmus brasiliensis [CCAP 276/1 B] and Ochromonas danica [0CAP933/28] were screened for their ability to grow on and remove phenol from their incubation media. Neither C. ulvaensis nor S. brasiliensis removed the phenol substrate as rapidly as 0. danica which is a nutritionally versatile chrysophyte. 0. danica was found to grow on phenol and p-cresol as the sole C-source at concentrations up to 4mM in cultures grown in both photoheterotrophic and heterotrophic conditions. The alga would not grow on cresols or xylenols unless phenol was present. Oxygen uptake and turnover studies confirmed that the enzymes involved in phenolic catabolism were inducible and that the organism showed a decrease in activity resulting from the position and number of the methyl substituents on the aromatic ring. [U- 14C]Phenol was completely mineralised with some 65% of the 14C-label appearing as 14CO2, approximately 12% remaining in the aqueous medium and the rest accounted for in the biomass. Analysis of the biomass showed that 14C-label had been incorporated into the protein, nucleic acid and lipid fractions; phenol carbon is thus unequivocally assimilated by the alga. Phenol-grown cultures of 0. danica converted phenol to catechol which was further metabolised by the meta cleavage pathway. 2-Hydroxymuconic semialdehyde and pyruvate, characteristic products of meta cleavage, were found in incubations of catechol with cell-free extracts of phenol-grown cells together with the appropriate enzyme activities. This is , as far as I am aware, the first definitive identification of the meta cleavage pathway for aromatic ring degradation in a eukaryotic microorganism.

Quinine is an alkaloid natural product isolated from the bark of the cinchona tree. It has long served as a synthetic target due to its antimalarial properties. The total synthesis of quinine can be envisioned employing a recently developed catalytic enone cycloallylation methodology. This new process merges phosphine organocatalysis and transition metal catalysis. The pursuit of quinine details the first application of this novel method in organic synthesis. Herein, phosphine-catalyzed transformations of [alpha, beta]-unsaturated compounds as well as a historical overview of the alkaloid target are thoroughly reviewed. The following chapters discuss both racemic and asymmetric approaches toward quinine, including the completion of a formal synthesis. Not only has the cycloallylation proved successful in this synthetic application, but this body of work has seen the development of many highly selective transformations. / text

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

This thesis reports the study of molecular and electronic structure of iridium containing diatomic molecules using the technique of laser ablation/reaction with free jet expansion and laser induced fluorescence (LIF) spectroscopy. The iridium containing diatomic molecules studied in this research are iridium phosphide (IrP), iridium boride (IrB) and iridium oxide (IrO). These molecules were produced by the reaction of Ir atoms ablated by a pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser and 1% PH3, 0.5% B2H6 and 6% N2O gases to produce IrP, IrB and IrO molecules respectively. Pulsed tunable lasers: a dye laser and an optical parametric oscillator (OPO) laser system were used to cover the spectral region between 390 and 650 nm in obtaining electronic transitions of the iridium containing diatomic molecules. The recorded electronic spectra of IrP, IrB and IrO molecules yields information on the bond length and electronic structures. For the IrP molecule, five electronic transitions, namely the [21.2] 3Σ+ – X1Σ+, [21.7]1Σ+ – X1Σ+, [23.6] 0+ – X1Σ+, [23.7] 0+ – X1Σ+ and [23.9] 0+ – X1Σ+ transitions, have been recorded and analyzed. The bond length, r0, and the ΔG1/2 of the ground state of 193IrP molecule was determined to be 1.9928? and 569.77 cm-1 respectively. For the IrB molecule, four new electronic transition systems, namely the [18.8]3Δ3 – X3Δ3, [21.1]3Φ4 – X3Δ3, [22.8]3Φ3 – X3Δ3 and [22.4]1Φ3 – a1Δ2 transitions, were observed and analyzed rotationally. The bond lengths, r0, of the upper states of 193IrB were determined to be within 1.72 and 1.80?. For the IrO molecule, five electronic transitions from two different lower states were recorded and analyzed, namely the [17.6] 2.5 – X2Δ5/2, [17.8] 2.5 – X2Δ5/2, [21.5] 2.5 – X2Δ5/2, [22.0] 2.5 – X2Δ5/2 and [21.9] 3.5 – Ω = 3.5 transitions. The ground state of IrO has been confirmed to be 25/2. The bond length, r0, and the ΔG1/2 of the ground state of 193IrO molecule was determined to be 1.726 A and 900.00 cm-1 respectively. For all the transitions observed, rotationally-resolved transition lines were fit to theoretical models to obtain molecular constants for both the upper and lower electronic states. Typical molecular transition linewidths obtained was larger than 0.1cm-1, which is likely to be due to unresolved hyperfine structure in the rotational lines. In addition, the observation of isotopic spectrum confirmed the assignment of vibrational quantum number. Molecular and electronic structures of these iridium containing diatomic molecules were discussed using a simple molecular orbital theory. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

The syntheses, structures, photophysical properties and applications of three types of photoluminescent organoplatinum(II) complexes containing N-heterocyclic carbene (NHC) ligands are described. The tetradentate dianionic bis(phenolate-NHC) type ligands provide a superior scaffold for constructing thermally stable and efficient deep-blue phosphorescent Pt(II) complexes with λmax of ~440-460 nm and solid-state emission quantum yields of ~30%. Highly efficient blue OLEDs with CIEx, y of (0.19, 0.21) were fabricated based on these emitters with maximum brightness, peak current efficiency and power efficiency of ~9500 cd m^(-2), 24 cd A^(-1) and 17 lm W^(-1), respectively. Structural modification by extending the π-conjugation of the tetradentate bis(phenolate-NHC) ligand leads to strongly phosphorescent platinum(II) complexes with long-lived emissive electronic states that can be used as a luminescent sensor for oxygen. DFT/TDDFT calculations and time-resolved spectroscopic characterizations were performed to gain insight into the structure-photophysics correlation. The N-heterocyclic carbene (NHC) ligand was incorporated into Pt(II) complexes containing tridentate deprotonated 1,3-bis(2-pyridyl)benzene (N^C^N) type ligand. In addition to the [(N^C^N)Pt(NHC)]PF6 type complexes with (N^C^N) in η3-tridentate coordination mode, Pt(II) complexes with η2-bidentate (N^CN) ligands, namely [(N^CN)Pt(NHC)2]PF6, have been isolated and structurally characterized. The highly phosphorescent [(N^C^N)Pt(NHC)]PF6 complexes were used for solution-processed green OLEDs fabrication. The peak current efficiency of 12.5 cd A^(-1) and maximum brightness higher than 2000 cd m^(-2) were achieved. The presence of the pendent pyridyl motif causes quenching of emission of the [(N^CN)Pt(NHC)2]PF6 complexes in solution at room temperature. Turning on solid-state emission of [(N^CN)Pt(nBu2Im)2]PF6 in the presence of an acidic vapor revealed its potential as a luminescent chemosensor. A class of dicationic platinum(II) terpyridyl complexes containing NHC ligand, namely [Pt(tpy)(NHC)](PF6)2, has been synthesized and structurally characterized. Even in the presence of the strong σ-donating NHC ligand, these complexes are non- or weakly emissive in solution at room temperature. However, this class of complexes displays intense emissions in solid state (298 K and 77 K), in glassy solution (77 K butyronitrile) and in PMMA (2 wt.%, 298 K). The ligand (terpyridine) displacement reaction arising from CN attack onto the Pt(II) center has been observed for [Pt(tpy)(nBu2Im)](PF6)2 leading to its application as a chemodosimeter for selective cyanide sensing in aqueous solution. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Since the discovery of superconductivity in Sr2RuO4, there has been intense research interest and efforts on its unconventional pairing symmetry. Although its normal state can be qualitatively described as a quasi-two-dimensional Fermi liquid, surprisingly, Sr2RuO4 turns out to be the prime candidate of the chiral p + ip superconductor, analogous to 3He-A. Such a state is of great interest surrounding, since under a certain conditions it hosts such exotic objects as half-quantum vortices and Majorana bound states, one possible route to an enigmatic quantum computer. Nevertheless, although it is well established now that this superconducting state has odd-parity, and most likely breaks time-reversal symmetry, the negative result on the search of edge current is one of the critical challenges to its chiral p-wave order. These serious discrepancies have even triggered a debate on the primary source of its superconductivity. Motivated by this debate, in this thesis we propose two independent methods to resolve this controversy via “smoking-gun" experiments. First, the vortex structure within the single-band and two-band models is studied within a mean-field theory. The pattern of the local density-of-state at zero bias shows significant anisotropy in the two-band model, while it is nearly isotropic in the single-band case. Also, the spin lattice relaxation rate at the vortex site is greatly enhanced in the single-band case but not in the two-band scenario. These important distinctions stem from the topology of different Fermi surfaces, and can be tested by using standard probes such as scanning tunneling microscope and nuclear magnetic resonance. In the second proposal, we focus on the two-band scenario, and apply a renormalization group theory to explain the form of spin density wave fluctuations. This theory not only reconciles the absence of long range spin density wave order with strongly enhanced fluctuations, but also unveils the mutual exclusion of these fluctuations and p-wave superconducting pairing. Such an exclusion is reflected in the suppression of the spin-spin correlation function at low energies, which can be measured in the inelastic neutron scattering experiment. This suppression, if not observed experimentally, would be a critical challenge to the two-band model, and an indirect but strong support to the assignment of the single γ-band as the primary source of the unconventional pairing. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy