No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The research presented in this thesis explores the tropospheric photochemistry of various organic nitrates (RON02). Interest in the atmospheric community has flourished regarding these species due to their potential role in tropospheric oxidation processes. Initially, a brief introduction to the atmosphere is given and followed by a more detailed description of the tropospheric chemistry surrounding the formation and destruction of RON02. Cavity ring-down spectroscopy was employed to determine the N02 quantum yields from the photoexcitation of organonitrates at tropospherically relevant wavelengths between 290 and 315 nm. Alkyl nitrate (methyl, ethyl, n-propyl and isopropyl nitrate) photolysis was found to have pressure-independent N02 quantum yield of unity. The photolysis of an unsaturated dinitrate species at 290 nm was estimated to have a quantum yield of ~ 0.25. Gas and liquid phase RON02 absorption cross-sections were shown to decrease steeply with increasing wavelength (320 - 240 nm). These absorption cross-sections were combined with quantum yields to estimate atmospheric lifetimes. Theoretical calculations were performed to explore the electronic ground and excited state structures of alkyl nitrates and multifunctional nitrates. DFTIB3L YP calculations struggled to reproduce the energies of charge transfer transitions in multi functional nitrates and the CAM-B3L YP level of theory was shown to be more suitable. Global abundance and distribution of organonitrates was analysed using the global chemistry transport model, STOCHEM, with comparison made between model and field measured data. In general, the model reproduced field measured RON02 mixing ratios, highlighting the soundness of the peroxy radical and NOx budgets used in the model. Finally, the atmospheric fate of the organonitrates studied is discussed.

This Thesis is concerned with the preparation and study of photo active cyanometallate complexes. Chapters 2 to 4 focus on the photophysical and structural properties of these complexes when involved in hydrogen-bonded or halogenbonded supramolecular assemblies. The last two Chapters mainly deal with the synthesis of some new polynuclear cyanometallate complexes of osmium(II) and ruthenium(II) and report on their characterisation. Chapter 1: provides an introduction to supramolecular photochemistry of Ru(polypyridyl) complexes. The emphasis is on [Ru(bipy)(CN)4f', with a quick review of its main characteristics. Chapter 2: analyses the H-bonding interaction in solution (lH NMR, UV-Vis spectroscopy) and solid state between various cyanometallate complexes and the photoactive compound [Ru(bipY)2(H2biim)]2+. Strong charge-assisted H-bonded assemblies are formed in solid state and solution, and one assembly exhibits oxidative photo-induce electron transfer. Chapter 3: reports on the serendipitous isolation and structural characterisation of a ruthenium cyanide-bridged dinuclear complex. Chapter 4: describes the study of halogen-bonding interaction between [Ru(bipy)(CN)4f' and a series of halogen substituted pyridinium ions. Formation of halogen bonding is monitored by spectroscopic and X-ray characterisation. Halogen bonding is found to control association of the components in solid state, whereas in solution electrostatic interactions prevail. Chapter 5: deals with the preparation and structural and photophysical characterisations of a series of novel mono- and dinuclear osmium complexes, of the type [Os(ll-diimine)(CN)4f' and [Os2(Il-diimine)(CN)s]4-. In one such dinuclear complex, both electrochemical and TRlR data prove that electronic communication between the metal centres is solvent dependent. Chapter 6: represents an early stage in the development of a series of highnuclearity dendrimeric structures based on cyanometallate systems. Synthesis and preliminary characterisation of one trinuclear and one tetranuclear complex based on a [Ru(bpm)3]2+ core with peripheral {Ru(CN)4} 2- units is reported.

No description available.