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Small particles of gold (< 100 nm) have attracted great interest among researchers due to the unique combination of their physicochemical properties. Among various research areas catalysis and bio-nanotechnology represent the largest areas of growth for gold nanoparticle research. Catalysts play a crucial role in the life of the modern society. More than 85 % of all chemical processes are catalytic, and this number is increasing every year. There is a constant demand to develop more efficient and durable catalysts in order to address increasing energy demands and environmental requirements. The first part of the thesis is focused on the study of catalytic activity of supported gold and mixed-metal catalysts, derived from atomically precise phosphine-stabilised gold and mixed-metal clusters in the liquid-phase oxidation of cyclohexene and one-pot synthesis of imines. Various characterisation techniques (TEM, diffuse-reflectance UV-vis, XPS, etc.) as well as kinetic studies were used in order to establish the optimal structure of gold catalysts. The effect of catalytic support, nature of hetero-metal atom for mixed metal-systems and type of catalyst pre-treatment were also examined. Gold nanoparticles are actively studied in various biomedical applications as they are offering new approaches to the detection and treatment of life-threatening diseases, such as cancer. The second part of this work discusses our preliminary investigations of biological activity of gold nanoparticles, stabilised with cancer-targeting molecules. In particular, the cytotoxicity of gold nanoparticles was studied using 11 different cancer and normal cell types. Gold uptake and particle localisation inside the cells were also investigated.

The development of sustainable, environmentally benign oxidation processes of organic compounds is an important task for chemical industry. This challenge can be addressed by designing catalysts that enable the utilisation of molecular oxygen as an oxidant. The work in this thesis is focused on the development of heterogeneous catalysts for the selective aerobic oxidation of various organic compounds. The first part of the thesis (Chapters 3 and 4) covers the study of bifunctional gold catalysts for the solvent-free aerobic oxidation of cyclohexene, with a particular focus on tuning the selectivity of the catalyst. Various characterisation techniques (such as TEM, diffuse-reflectance UV-Vis spectroscopy, XPS), catalytic experiments and kinetic studies were used to investigate the nature of catalyst functionality and establish the optimal structure of a gold catalyst. The second part of the thesis (Chapter 5) covers the study of the photocatalytic activity of hydrous ruthenium oxide deposited on TiO₂ in the aerobic oxidation of amines to nitriles under irradiation with visible light. The effect of the wavelength of the utilised light, applicability of the Sun as light source and water as a solvent were investigated. High catalytic activity of ruthenium-based catalyst was demonstrated for various benzylic and aliphatic amines. Various mechanistic studies were performed, based on which the mechanism of photocatalysis was suggested.

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A series of palladium and platinum complexes of verdazyl radicals were prepared to study the intermolecular magnetic exchange coupling. Reaction of bidentate verdazyl radicals with (RCN)2MCl2 (R = Me or Ph; M = Pd or Pt) yielded square planar (verdazyl)MCl2 complexes. The isolated complexes crystallized in either an infinite 1D array or as loosely associated p-stacked dimer pairs. Molecules stacked with either M–M or M–N(verdazyl) close contacts. Molecules that stacked with a M-M close contact exhibited weak antiferromagnetic coupling. Molecules that stacked with a M– N(verdazyl) close contact had coupling that was an order-of-magnitude weaker, but the type of exchange was also metal dependent. While the palladium complex exhibited weak antiferromagnetic coupling, the exchange in the analogous platinum complex was ferromagnetic. The difference between the two was attributed to increased spin leakage onto the platinum centre relative to palladium. The differing electronic behaviour of the two metals was evident in the data from EPR and UV/vis spectroscopies. Ruthenium complexes of a verdazyl radical were prepared by the reaction of a bidentate verdazyl with Ru(L)2(MeCN)2 (L = acac or hfac). The complexes were isolated in two or more oxidation states and all characterized by FT-IR, UV/vis/NIR, and EPR spectroscopies, and their structures determined by X-ray crystallography. Experimental data was further explained and supported with time-dependant DFT calculations which were performed by Dr. A. B. P. Lever at York University, Toronto, Ontario. When the complex contained an electron-rich metal fragment, Ru(acac)2, noninnocent behaviour was observed. There was a large degree of orbital mixing, so that the spin distribution was approximately 39% metal and 56% ligand. The contrasting complex with the electron-poor fragment, Ru(hfac)2, behaved more innocently, the majority of charge was localized and the spin was ligand-based. Verdazyl-bridged diruthenium complexes were prepared from a bisbidentate verdazyl and Ru(L)2(MeCN)2 (L = acac or hfac) to study the effect of a neutral radical bridge on mixed-valence properties. Structural data from X-ray crystallography, spectroscopic data from EPR, FT-IR, and UV/vis/NIR spectroscopies, and comparison to the mononuclear ruthenium-verdazyl complexes were used to assess the charge distribution in these complexes. The complex in which the verdazyl ligand bridged two electron-rich metal centres exhibited a NIR absorption at approximately 1716 nm. Together, this long wavelength transition and the structural data indicate a delocalized electronic structure, [RuIII−vd–−RuII « RuII−vd•−RuII « RuII−vd–−RuIII]. The EPR spectrum was also consistent with the delocalization of ligand spin onto the ruthenium centres. With the verdazyl bridging two electron-poor Ru(hfac)2 fragments, the spin is ligand-based and best described as RuII−vd•−RuII. Like the analogous mononuclear complexes, the dinuclear complexes were each isolated in their other accessible oxidation states. / Graduate / 0485

This work describes results obtained from detailed TEM, TED, HREM and SIMS analysis of the as-implanted and annealed microstructures of high dose (O.lxl0 17/cm2 to 1.7xl0¹⁸/cm²) oxygen implanted silicon (Si). Molecular oxygen (O₂⁺) has been implanted into Si wafers at equivalent energies of 200keV/O + , 90keV/O +, 70keV/O+ and 50keV/O+ to form, after annealing in flowing N₂ or Ar + ½ %O₂, buried SiO₂ layers below single crystal surface Si layers. This process is called Separation by the IMplantation of OXygen (SIMOX). The energies and doses investigated are potentially suitable for the fabrication of two types of "thin-film" SIMOX substrates, which have major potential benefits for high-performance CMOS devices. This work is concerned with investigating the as-implanted and annealed microstructures, understanding the basic processes and mechanisms taking place during implantation and annealing, and establishing optimum fabrication parameters. Similar microstructures and changes in microstructure as a function of the dose are observed for the different implant energies investigated. For all the different energies and doses investigated, SiO₂ precipitates are present after implantation. Five different precipitate morphologies are observed. The precipitate morphology depends on the oxygen concentration and the depth below the surface. The local and long range strain also play a role in determining the precipitate morphology. For doses of 0.5xl0¹⁸O/cm² to 0.7xl0¹⁸O/cm² at 200keV defects at the wafer surface are non-uniformly distributed across the implanted area. The regions of defects are in plan-view rectangular in shape with edges parallel to <100> directions. The percentage of the implanted surface that is covered by these rectangular regions depends on both the dose and the time-averaged beam current density. This is the first known report of such non-uniform distribution across the implanted area of defects at the wafer surface and their occurrence in regions with precise rectangular shapes. Previously unreported "line" defects below the peak of the as-implanted oxygen distribution for these energies are investigated. They are considered to be platelets on {100} planes and edge dislocation loops on {110} planes. After annealing, two major types of defects are present, threading dislocations in the surface Si layer and Si islands within the buried SiO₂ layer. Correlation of as-implanted and annealed microstructure suggests that the threading dislocations originate in the defects present at the wafer surface after implantation and grow down during annealing. The Si islands originate from Si isolated from the surface Si layer and the substrate during implantation or annealing. The optimum dose for forming a SIMOX structure at a particular energy with both a low threading dislocation density and a low Si island density is just greater than the minimum dose for forming a continuous buried SiO₂ layer after annealing. In order to try and reduce the density of Si islands within the buried SiO₂ layer, graded low energy implants and interim rapid thermal anneals are investigated. Their influence on the microstructure is reported. The experimental results enable, for the implantation and anneal conditions used, the likely threading dislocation and Si island density after annealing to be estimated for a particular dose and energy. Simple models have been proposed for calculating typical oxygen diffusion lengths during implantation, the thicknesses of the buried SiO₂ and surface Si layers after annealing and conversely the implant dose and energy required to fabricate a SIMOX substrate with a certain thickness of buried SiO₂ and a certain thickness of surface Si layer after annealing. Thin-film SIMOX substrates consisting of a thin surface Si layer above a thin buried oxide layer suitable for high-performance "fully depleted" CMOS devices have been successfully fabricated by implanting doses of ≥0.35 and ≥0.33xl0¹⁸O/cm² at energies of 90keV and 70keV, repectively. Thin-film SIMOX substrates with a thin buried oxide layer below a standard thickness surface Si layer suitable for radiation hard circuits with reduced circuit self-heating have been successfully fabricated by implanting doses of ≥0.56xl0¹⁸ O/cm² at an energy of 200keV.