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Metabolomics seeks to achieve a comprehensive quantitative analysis of the wide range of metabolites in biological samples. Analytical chemistry, and specifically 1H NMR, can provide spectra detailing the vast array of physio-chemical properties of the sample. The identification of characteristics in the spectra is known as metabolomic fingerprinting. However, the thousands of variables in the 1H NMR spectra, .relating to hundreds of metabolites, make the data sets extremely complex and difficult to interpret. The aim of this research was to develop analytical techniques to classify biological samples, which are able to identify the metabolites responsible for the differences between classes. Novel methods based on genetic programming have been developed which provide models that are able to classify samples at least as well as currently used chemometric pattern recognition approaches. Moreover these techniques have the advantage that they are significantly easier to interpret in terms of the original spectrum. Preprocessing the spectra using wavelet transforms has further increased the interpretability of the models. This adaptive binning method integrates the data in such a way that the bins represent peaks in the original spectra thereby reducing the dimensionality whilst maintaining the information. The preprocessing and genetic programming methods have been combined and developed in response to additio~al problems faced by time resolved metabolomics data, where both intra-individual (time dependent) and inter-individual variation are present. The methods were employed in the analysis of TSE infected sheep and cattle and, in both cases, enabled a diagnostic of the disease to be determined, allowing the specific compounds responsible for the disease to be identified.

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The work presented in this thesis concerns the synthesis and study of various RuII polypyridyl complexes and organic chromophores which incorporate strongly electron-accepting and π-conjugated pyridinium groups. Several of these compounds have been studied as potential sensitisers for solar cell applications.The N3 dye, cis-RuII(NCS)2(dcbpy)2 (dcbpy = 4,4'-dicarboxy-2,2'-bipyridyl) has been synthesised in pure form and excellent yield via ester hydrolysis of cis-RuII(NCS)2(Et2dcbpy)2 (Et2dcbpy = 4,4'-di(ethoxycarbonyl)-2,2'-bipyridyl). This well known complex is used as a benchmark for comparison purposes with our novel pyridinium compounds. A single-crystal X-ray structure has been obtained for the new complex cis-RuIICl(NCS)(Et2dcbpy)2.Three new 4,4':2',2":4",4""-quaterpyridinium pro-ligand cations along with several known ones have been synthesised and isolated as their chloride salts. Single-crystal X-ray structures have been determined for one of these salts and also for an unexpected protonated derivative. These pro-ligands have been used to prepare two series of RuII polypyridyl complex salts. A series of eleven new complexes of the form cis-[RuII(bpy)2(LA)]4+ and fourteen of the form cis-[RuIIX2(LA)2]4+ (bpy = 2,2'-bipyridyl; LA = quaterpyridinium-based ligand; X = NCS⁻ or Cl⁻) have been synthesised and isolated as their hexafluorophosphate salts. The various characterisation techniques used include 1H NMR spectroscopy and mass spectrometry. The UV-vis spectra show intense intraligand π→π* absorptions in the UV region and low energy metal-to-ligand charge-transfer (MLCT) bands in the visible. Small shifts in the MLCT bands correlate with changes in the electron-accepting strength of the ligand LA. The UV-vis absorption profiles of the salts cis-[RuIIX2(LA)2][PF6]4 cover the entire visible region extending well into the near-IR, with MLCT bands much more red-shifted than those of their cis-[RuII(bpy)2(LA)][PF6]4 relatives and the N3 dye. Cyclic voltammograms show quasi-reversible or reversible RuIII/II oxidation waves and ligand-based reductions. The variations in the redox potentials correlate with changes in the pyridinium substituents, and also with the MLCT energies. Single-crystal X-ray structures have been solved for three of the new cis-[RuII(bpy)2(LA)][PF6]4 salts. Four carboxylate-functionalised RuII polypyridyl compounds have been tested as dye sensitisers on both TiO2 and ZnO electrodes, but only low overall efficiencies are achieved. A series of eight new stilbazolium compounds has been synthesised and fully characterised as their hexafluorophosphate salts. Single-crystal X-ray structures have been determined for a new picolinium precursor and three of the ester-substituted stilbazolium compounds. The UV-vis spectra of these organic chromophores feature intense intramolecular charge-transfer (ICT) bands. Four acid-functionalised compounds have been tested as dye sensitisers on both TiO2 and ZnO surfaces, with the most encouraging preliminary results observed for the latter.Time-dependent density functional theory (TD-DFT) calculations were carried out on six of the new dye sensitisers to clarify their electronic/optical properties. TD-DFT-derived depictions of the lowest unoccupied molecular orbitals (LUMOs) show negligible electron density near the acid-functionalities. This factor, along with possible energy level mismatch of the excited-state donor orbitals with the conduction band edge of the semiconductor, may be the cause of inefficient electron injection and thus poor photovoltaic performance of our new pyridinium-based dyes.