Aquaporin 4 (AQP4) is a tetrameric water channel protein with a pore in each monomer. AQP4 is the most abundant water channel protein in the brain, highly expressed in astrocytes. AQP4 knockout mice are protected against cytotoxic brain oedema. A cytotoxic brain oedema is where the blood brain barrier remains intact and the oedema is thought to form as a result of deterioration of cellular metabolism. There is no generally accepted current therapy for cytotoxic oedema, in part due to a lack of understanding surrounding the cellular signaling events. Work from our laboratory on a novel trigger for sub-cellular redistribution of the homologous AQP1 kidney protein has allowed us to investigate this phenomena in AQP4. GFP tagged aquaporin constructs were created by inserting the Vector-N75 in the PcDNA-DEST47, by swapping out the ccdB gene which kills E.coli. The Vector-N75 doesn’t contain a stop codon and is instead followed by attb attachment sites then the GFP tag sequence. The cellular relocalisation of GFP-tagged AQP4 was exposed to a hypotonic extracellular environment transfected into a live Human Embryonic Kidney (HEK293) cell line using confocal microscopy. Relative membrane expression (RME) of the AQPGFP was measured by comparing the fluorescence intensity profiles of GFP tagged proteins across lines drawn using the image analysis software which bisect the membrane and cytosol of cells exposed to isotonic and hypotonic extracellular environments. These lines were drawn across the membrane, cytosol and opposite membrane, without bisecting the nucleus. These profile intensities were calculated using the software ImageJ. Cell volume was estimated by converting the image, in ImageJ, to a binary form, then, using the analyse particle function the cell was scanned to find the edge, an outline drawn and the area calculated. AQP4 rapidly and reversibly translocated to the cell surface in response to hypotonicity increasing RME from 29.3% ± 6.4% to 54.9% ± 6.6% (p<0.05; N=3). The cellular signaling required for this translocation response was investigated by exhibiting cells to different activation inhibitors. PKAi, Cytochalasin D, and extracellular calcium-free media were found to fully prevent the translocation and functional swelling response of HEK293 cells transfected with AQP4 (p [sic] Motif and conservation analysis was used to identify potential PKA activation sites. These sites were substituted from serine to both alanine and aspartic acid using site-directed mutagenesis (SDM). One, highly conserved serine residue of transmembrane region 1 (TM1) at position 52, when mutated to aspartic acid (S52D) lost the hypotonicity-induced translocation and cell volume increase (p<0.01; N=3 in all cases). The alanine substitution (S52A) was unaffected. Molecular modeling of AQP4 and the mutant suggest a potential hydrostatic interaction with nearby cysteine and serine residues of TM2. Consequently the S52 residue was mutated to leucine, which has a similar size but no charge to form the potential hydrostatic interactions with neighboring residues. S52L also removed the translocation and functional swelling in response to hypotonicity, suggesting steric hindrance as the most likely factor inhibiting the translocation process rather than the interaction with neighboring residues. This study demonstrates that a cellular signaling response to a change in tonicity of the cellular environment leads to AQP4 translocation to and from the cell surface. This involves the influx of extracellular calcium, the activation of PKA and cytoskeletal reorganization.

Redox active molecules are ubiquitous to nature and have properties that make them coveted targets for applications in areas of synthesis as well as for the development of materials. This thesis describes the synthesis and characterisation of several flavin donor-acceptor dyads designed around an oligothiophene donor backbone and a flavin acceptor moiety. These show potential applications as optoelectronic materials. It also describes the synthesis of a ferrocene-flavin tetracyanobutadiene super-acceptor compound which showed preliminary evidence of non-linear-optic effects. Finally, a novel method was developed to investigate the redox umpolung activated reactions of vinylferrocene. The vinyl group of vinylferrocene was activated by polarity inversion of ferrocene to ferrocenium and was able to undergo Diels-Alder cycloadditions with cyclobutadiene and furan, as well as, Markovnikov addition of thiols. These reactions were then used to explore the use of vinylferrocene as a redox auxiliary and as a redox active tag in polymers and have the potential to be used in nanoparticles as well as biological systems.

Selective hydrogenation of a multi-functional compound to achieve high yield of a particular product is often involved in the production of fine chemicals and pharmaceuticals. The control of selectivity can be difficult and can be affected by a number of variables such as the interaction of the reactants and intermediates with the catalyst, the particle size, promoters, steric factors and adsorption geometries. In this study, two selective hydrogenation reactions were studied namely the gas-phase hydrogenation of furfural to furfuryl alcohol and liquid-phase hydrogenation of 4-nitroacetophenone. The hydrogenation of furfural is the sole production route for furfuryl alcohol which is used widely in the chemical industry. However, a variety of products can be formed through the hydrogenation of furfural depending on the catalyst used. The industrial process is conducted at high temperature and pressure using a copper chromite catalyst. However, the main drawback of this method is the toxicity of the catalyst. In this study, silica supported copper catalysts proved to be active and selective alternative catalysts for the hydrogenation of furfural to furfuryl alcohol. The higher the copper loading the greater the furfural conversion as more Cu sites were present with both catalysts achieving 98% selectivity for furfuryl alcohol. Ceria was investigated as a promoter for copper catalysts and the incorporation of 1% CeOx was found to enhance the selectivity towards furfuryl alcohol. The presence of Ce3+ sites was thought to polarise the carbonyl bond facilitating nucleophillic attack by dissociated hydrogen present on Cu. However, 5% CeOx promoter was found to reduce the selectivity of the catalyst possibly by the blocking Cu active sites. Pd was also investigated as a promoter was found to enhance the activity and selectivity of the catalyst as it activated hydrogen allowing for more facile hydrogenation of the carbonyl group. Cu1132, a BASF copper-chromite catalyst used for the production of furfuryl alcohol by hydrogenation of furfural exhibited moderate activity but excellent selectivity towards furfuryl alcohol (almost 100%). For all catalysts, deactivation was observed over time on stream mainly due to carbon laydown. Polyaromatic coke formation on the surface of copper catalysts blocked pores and significantly reduced the activity of the catalyst. 5% Cu + 5% CeOx/SiO2 catalyst showed a slow deactivation compared to all of the other catalysts and post-reaction XRD suggested sintering was the cause of deactivation. TPD of 5% Cu + 1% CeOx/SiO2 showed desorption of furfural, 2-methylfuran and furan suggesting that the catalyst was poisoned causing deactivation. An important reaction in the pharmaceutical industry is the hydrogenation of 4-nitroacetophenone (4-NAP) which yields 4-aminoacetophenone (4-AAP); a chemical intermediate used in the production of the hypoglycemic drug acetohexamide. Further hydrogenation of the carbonyl group yields 1-(4-aminophenyl)ethanol (4-APE) which can be dehydrated to give a substituted styrene that can be polymerised. As the consecutive hydrogenation of 4-NAP has not been the subject of significant study, this reaction was systematically investigated using a series of Rh/SiO2 catalysts. Functional group hydrogenation followed the order NO2 >> C=O > Ph > OH with the nitro group being hydrogenated approximately an order of magnitude faster than the carbonyl group, while hydrogenation of either the phenyl ring or the alcohol function is a factor of two slower than carbonyl hydrogenation. This combination of kinetic controls allows high selectivity to 4-AAP (99%) and 4-APE (94%) to be achieved at different times in the reaction. The presence of 4-NAP inhibits 4-AAP hydrogenation due to strong adsorption of the 4-NAP while deuterium studies revealed the presence of a kinetic isotope effect for both 4-NAP and 4-AAP. Full kinetic analysis of the reaction system gave activation energies of ~48 kJ mol-1 for 4-NAP and 4-AAP hydrogenation, with orders of reaction of ~1 for hydrogen and a zero order dependence for 4-NAP. Although 4-NAP inhibits 4-AAP hydrogenation when present, 4-AAP hydrogenation is faster after 4-NAP hydrogenation than over a fresh catalyst. The reason for this may be that 4-NAP adsorption causes a surface reconstruction which allows easier hydrogen transfer or sub-surface hydrogen. The hydrogenation of both 4-NAP and 4-AAP showed an antipathetic particle size effect with an increase in TOF with increasing metal crystallite particle size. This suggests that the hydrogenation reaction takes place on the plane face surface as opposed to edge and corner sites. However the electronic changes in small metal particles of this size are also significant and it is likely that the antipathetic particle size effect is a combination of both an electronic and geometric effect. Addition of 4-methylcyclohexylamine (4-MCHA) to 4-NAP and 4-AAP hydrogenation systems results in an enhancement of rate for both reactants. For 4-NAP hydrogenation, this is due to electron donation from the acyclic amine causing a reduction of the reactant-surface bond strength since it is clear that 4-NAP forms a strong bond to the surface as shown by the zero order kinetics and the inhibition of 4-AAP hydrogenation, a reduction in the strength of 4-NAP adsorption would enhance the rate of 4-NAP hydrogenation. However, 4-AAP is not strongly bound to the surface so a weakening the carbonyl interaction is unlikely to lead to an enhanced rate. Just as the rate enhancement observed for 4-AAP hydrogenation after 4-NAP hydrogenation has been attributed to changes in hydrogen concentration in the rhodium by strong adsorption of 4-NAP, 4-MCHA is also strongly adsorbed which means it may promote 4-AAP hydrogenation by a similar process.

Cyclic Voltammetry, Surface Enhanced Raman Spectroscopy and SHell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) have been used to investigate two types of heterogeneously catalysed hydrogenation reactions – hydrogenation of selected alkynes and the Orito reaction. Using a spectro-electrochemical flowcell, which is designed and built in-house, the selectivity and reactivity of the reactions on platinum surfaces have been truly discovered. By studying hydrogenation of a range of alkyne molecules, including 2-butyne-1,4-diol, 2-pentyne, 4-octyne, propargyl alcohol and 2-methyl-3-butyn-2-ol, on different platinum surfaces, it was found that alkyne adsorption on Pt defect sites produces a long-lived di-sigma/pi- alkene complex which may undergo further hydrogenation to produce alkane. This complex may form on different surfaces with various orientations. However, depending on the specific molecules, the intermediate may not survive on some surfaces due to the steady state conditions arising from the catalytic reaction whereby adsorption of alkyne and hydrogenative desorption of reaction intermediates determines the overall surface coverage of intermediate as a function of potential. Alkene selectivity can be increased by blocking defect sites, using polyvinylpyrrolidone or bismuth, leaving only platinum{111} terraces available for catalysis. By studying ethyl pyruvate (EP) adsorption on different surfaces of platinum and palladium, it was found that EP half-hydrogenated state (HHS) is a critical intermediate of the hydrogenated product which only forms on the step sites of the platinum surface at the hydrogen evolution reaction potential. However, another new intermediate adsorbate, which is believed to be a η1 species and is believed to be a precursor of the HHS only forms on the terraces of the surface. By studying the surface intermediates formed during hydrogenation of EP at palladium modified platinum single crystal electrodes, it was found that there was no unequivocal evidence for bands pertaining to EP adsorption on palladium could be identified under hydrogenating conditions due to the reconstruction of the palladium adlayer to reveal Pt subsurface sites.

Polyurethane (PU) foams are widely used in the medical industry in the treatment of chronic wounds but the role of surfactants in the reaction process, which strongly influences foam structure and properties, is not well understood. In this research, a homologous series of non-ionic poly(ethylene oxide)-poly(propylene oxide)- poly(ethylene oxide) (Pluronic) block copolymer surfactants were studied, in order to elucidate the influence of surfactant structure on PU foam performance. The behaviour of aqueous surfactant stabilised foams was investigated using a combination of surface science techniques (foaming ability/stability, surface tension) and small-angle neutron scattering (SANS). SANS has been successfully implemented to probe the adsorbed Pluronic surfactant layer of dynamic foams in-situ in the neutron beam. We propose the air-water interface comprises a paracrystalline stack consisting of a minimum of 5 adsorbed surfactant layers, with thickness ranging from 80-200Å interspersed with somewhat thicker (200Å) films of water. Total adsorbed layer thickness correlates directly with aqueous foam stability. Correlations of aqueous behaviour to the cell structure and performance of PU foams manufactured on an industrial line were made in an attempt to determine the features of surfactant necessary to produce ‘ideal’ PU foam wound dressings. Analysis of foam cell size and fluid absorption properties demonstrated that greatest absorption was observed for small, fine cell size. This was typically produced by the smallest molecular weight,most hydrophobic surfactants of the series implying that the surface activity of the surfactant (i.e. its ability to reduce the surface tension of the system) is more important than its foaming behaviour. This study should provide a more rational approach when designing surfactant formulations for polyurethane foam systems.

The three-way catalyst (TWC) greatly reduces emissions of hydrocarbons, carbon monoxide and nitrogen oxides from gasoline powered vehicles. However up to 80% of all hydrocarbons are emitted in the first 120 seconds after the engine is started, before the TWC achieves light-off. Catalysts which are active at lower temperatures offer a potential solution to this ‘cold-start’ problem. Co3O4 is one of the most active transition metal oxide catalysts for the total oxidation of hydrocarbons. In this work the synthesis of bulk and supported cobalt oxide catalysts has been investigated. The catalysts were thoroughly characterised and tested for the total oxidation of propane, a model hydrocarbon. Variables in the mechanochemical synthesis and precipitation of bulk Co3O4 were studied. Cobalt hydroxycarbonate hydrate synthesised by both techniques was found to give rise to active and stable Co3O4 catalysts upon calcination. Small Co3O4 crystallites, high surface areas, weak Co3+-O bonds, and the absence of contaminants were found to be required for high propane oxidation activity. Deposition precipitation, wet impregnation and powder blending methods were investigated for supporting Co3O4 on a high surface area, non-porous silica. Wet impregnation from cobalt nitrate was found to be the most effective method of synthesising supported Co3O4 with minimal formation of undesired cobalt silicates. Activity increased with increased cobalt weight loading but supported catalysts displayed lower activity than bulk catalysts.

Terpenoids are the largest and structurally most diverse family of natural product. α-pinene, a monoterpene found in turpentine, is a precursor to several high-value monooxygenated terpenoids such as verbenone. It is produced naturally through the Mg2+ -dependent transformation of geranyl diphosphate (GDP) catalysed by (+)-α-pinene synthase (APS). Heterologous expression, purification and characterization of recombinant (+)-α-pinene synthase were performed. Several expression conditions and many purification methods were tried in order to get optimum results. After optimisation of His tagged α-pinene synthase (HAPS), chemoenzymatic synthesis of a simple two-step, one pot asymmetric synthesis from GDP of (+)-verbenone, an oxidation product of the monoterpene (+)-α-pinene, that is used to control attacks of pine trees by bark beetles is described. This method generates (+)-verbenone from GDP in good yield and without the need to isolate the intermediate (+)-α-pinene. Then, synthesis of some chemically modified GDP analogues to obtain (+)-α-pinene analogues was performed. These engineered (+)-α-pinene analogues may display enhanced biological activities due to the potential improvement of their physical properties. Finally, site directed mutagenesis strategy was employed to HAPS to examine the potential catalytic role of several aromatic amino acids, in stabilizing the carbocationic intermediates generated in the active site of HAPS during the natural conversion of GDP to the monoterpene (+)-α-pinene.

Methane is our most abundant hydrocarbon. However, this natural resource is not being effectively utilised. Currently, its primary industrial use is the manufacture of methanol through the intermediate formation of synthesis gas (H2 and CO). This is an energy intensive process requiring temperatures of up to 850 ⁰C and pressures of up to 100 atm. Clearly, a direct method of converting methane to methanol under mild conditions would provide many advantages. Au-Pd/TiO2 has already been shown to be an effective catalyst for the oxidation of methane with H2O2 at low temperature (50 ⁰C). In this work, the intrinsic activity of the Au-Pd nanoparticles and the role of the support in this reaction are investigated. This is achieved by comparing, in detail, the activity of Au-Pd/TiO2 with that of unsupported Au-Pd nanoparticles. The unsupported nanoparticles are not only found to be active for this reaction but in fact display superior activity compared to the supported nanoparticles. The basis for this difference in activity is investigated and shown to be caused by an increase in H2O2 decomposition which occurs when the particles are supported thus reducing oxidant availability for the methane oxidation reaction. Further investigations into the intrinsic activity of the unsupported Au-Pd nanoparticles, and the factors affecting it, are then carried out. A study was also carried out into the use of methyl hydroperoxide (a methane oxidation product) in combination with H2O2 to activate methane. The first stage of this study was to establish a method of producing methyl hydroperoxide and to this end several copper catalysts were prepared and tested. Cu/ZSM-5 was selected for this purpose and was used thereafter to produce methyl hydroperoxide for subsequent reactions with methane without the presence of a solid catalyst. The reaction conditions for the methyl hydroperoxide system were optimised and some preliminary investigations of the reaction mechanism were carried out.

The determination of pesticides and related materials in food and environmental samples is important and presents an enduring challenge to analytical chemists. For practicality it is important that as many pesticides as possible are compared using a common technique. Mass spectrometry is the method of choice for multi-residue detection techniques, because of its sensitivity and specificity. This thesis comprises a detailed analysis and critical review of the mass spectrometric behaviour of over 600 commonly encountered pesticides and related compounds. The work described in this thesis was undertaken in two tranches, one old and one new. The former experimental work was performed during the author’s employment at the Ministry of Agriculture, Fisheries & Food (Harpenden, Hertfordshire, UK) and at Unilever Research (Colworth House, Sharnbrook, Bedfordshire, UK). The data helped underpin the analytical work of the UK national pesticide residues monitoring surveillance team and the pesticide formulations safety team. Qualitative and quantitative aspects were both important, e.g. for identification and characterisation of active ingredients, contaminants and degradation products in technical pesticide formulations, as well as unambiguous detection and/or confirmation of residue levels in UK fruit and vegetables. The latter experimental work was undertaken recently (2015) at the Cardiff School of Chemistry during the preparation of this thesis. The newly acquired data helped confirm the validity and robustness of the original data, and helped to better understand them. Understanding the complex and sometimes unexpected behaviour of molecules during their extraction/analysis is essential, especially when performing trace analysis at the parts per billion level. Rationalisation of the mass spectrometric fragmentation pathways of these compounds was undertaken in order to better understand the fundamental processes taking place in the mass spectrometer. This improved understanding was essential in order to ensure the quality and validity of the data generated using these techniques. For comparison, some additional data are included, e.g. for chemical warfare agents, using literature data. Mass spectrometry was chosen because of its power as an analytical technique. General approaches and specific precautions which should be taken when using mass spectrometry for pesticide analysis are discussed and explained in this document and literature data were critically reviewed. It is hoped that these data and recommendations will find continued and future use as an adjunct to the plethora of literature data and MS instrument manufacturer databases.

This thesis describes the synthesis and characterisation of conjugated materials, and their optoelectronic applications. The first chapter introduces the concept of solar cells and describes the most common types of solar cells used nowadays, including examples of some of the best performing materials. The second chapter describes the donor-functionalised synthesis of a small library of DPP derivatives with optoelectronic applications. DPP derivatives were used to gain knowledge about the physical parameters contributing to better PCE in organic solar cells, others were used as donors for BHJSC giving a highest PCE of 1.76%. Finally one DPP derivative proved to be an efficient fluoride chemosensor, able to selectively detect fluoride in the presence of other anions by means of colour change (and absorbance in the near infrared), and a change in its 1H NMR spectrum. The third chapter describes the one-pot synthesis of BODIPY molecules that can be further tuned to adjust their photophysical properties. These derivatives were used as donors for BHJSC giving a highest PCE of 0.45%. The absorption and emission properties of the molecules were studied, and it was found that the intensity of the emission depends on the electron richness of the substituent in the meso position. Some derivatives proved not to be fluorescent, whereas others exhibited extremely small Stokes shifts, sometimes as low as 1 nm. Chapter 4 describes the synthesis of a spirofluorene and a copper complex derivative with the aim of preparing molecules that could self-assemble forming 3D networks, in order to improve the dimensionality of the system. Their photophysical properties were studied, and the molecules proved to be fluorescent with large Stokes shifts, sometimes up to 100 nm. Chapter 5 describes the synthesis of fullerene derivatives with optoelectronic properties. One of the most successful derivatives was involved in a supramolecular chemistry study, to investigate how recognition-mediated assembly can lead to effective charge transfer from a quantum dot. Finally Chapter 6 describes a series of dyes synthesised using a simple 2/3 step synthetic pathway. DSSC were fabricated and the best performing dye with a 2 step synthetic route gave a PCE of 2.32%, whereas the best performing dye with a 3 step synthetic route gave a PCE of 4.35%. The high PCE of these types of dyes considering their ease of preparation makes their large-scale synthesis commercially feasible.