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Natural Photosynthesis process is the source of life; it converts the sunlight into chemical energy. This process takes place in the chloroplast of the green plants in a sophisticated and complex pathway. It involves electron transfer cascades from the photoexcited reaction centre to sustainable energy storage. As a route to develop new chemical systems for artificial photosynthesis in an efficient and fast electron transfer cascade, it is essential to propose three-dimensional molecular ensembles of both electrochemically and photochemically active systems. This thesis studies the behaviour of using L-cysteine and potassium iodide as electroactive species in a reduction reaction of chlorpromazine hydrochloride on glassy carbon electrodes and rotating glassy carbon disk electrodes with the aid of cyclic voltammetry and linear sweep voltammetry. The electrochemical characteristics of chlorpromazine hydrochloride (CPZ.HCl) in various concentrations, which induce catalytic oxidation reactions of different concentrations of the electroactive materials, are investigated. The experimental results show that the increase in oxidation peaks current of chlorpromazine hydrochloride depends on the concentrations of L-cysteine and potassium iodide. The current response was enhanced through fast transport via a rotating glassy carbon disk electrode. The peak potentials of chlorpromazine hydrochloride in the solution containing L-cysteine shift to more negative values for all concentrations and speeds; similarly for potassium iodide. The electrochemical reaction of chlorpromazine hydrochloride with the electroactive materials determined EC' reactions. The diffusion coefficient for chlorpromazine hydrochloride was found to be 1.28×10-6 m2 s-1. This thesis studies the adsorption and electrochemical investigation of one of the derivatives of chlorophyll-chlorophyllin, at gold and glassy carbon electrodes. Parameters such as the adsorption time, the electrolyte nature and concentration and chlorophyllin concentration were investigated. The use of chlorophyllin as a redox mediator was examined, with a gold electrode being employed. The importance of gold electrode surface preparation in determining the mechanism of redox was described, and the environment of adsorption process of the different concentrations of chlorophyllin on the surface of the gold electrode had been elucidated in this study. The electrochemical method shows that the cyclic voltammetry responses of studied adsorption chlorophyllin pigment on the gold electrode were more efficient than glassy carbon electrode, with processes being more favourable in aqueous solution. Third, the oxidation reaction of various concentrations of chlorophyllin is investigated in the bulk solution in the presence of Triton X 100 and potassium iodide. The extraction and identification of chlorophyll in fresh spinach were examined by using thin layer chromatography and UV-visible spectrophotometry techniques. The cyclic voltammetry for this pigment was elucidated in the presence of Triton X 100 and vitamin K1 at the gold electrode, the mechanism of this reaction was suggested to be EC'. Lastly, this study has emphasised chlorophyll a and Total chlorophyll (Tchl), based on the effect of electrode materials and diameter, pH, solvent and electrolyte. The inducing of electron transfer of Tchl pigment was examined in presence and absence of vitamin K1 through light and dark atmosphere. The system of chlorpromazine-lyotropic liquid crystal (CPZ-LLC) was highlighted in this thesis. The effect of parameters such as electrode materials, electrode diameters and CPZ.HCl concentrations in this system have been documented. The self-assembled phase was recorded using polarising optical microscopy and X-ray scattering. The CPZ-LLC system was fabrication into photogalvanic cells. The power conversion efficiency (PCE) of this cell is (0.58%), which is useful and novel.

Simulating human metabolism by electrochemistry (EC) and mass spectrometry (MS) provides an alternative approach to the existing in vitro and in vivo methodologies. Herein, screen printed electrodes (SPEs) were investigated as potent electrochemical tools with the aim of developing a microfluidic device with a SPE. The proposed chip could be used as a primary screening tool for phase II glutathione (GSH) adducts. The reusability of SPEs was investigated with solvent treatment, mechanical polishing, and electrochemical activation. However, damages to the three-electrode configuration and lack of reproducibility prevented the effective removal of deposited material. Thus, SPEs were used as single-shot sensors for micking phase I and phase II metabolism. The electrochemical reactions of dopamine, raloxifene, eugenol, and doxorubicin were examined initially on a bare SPE. Similar kinetics and reaction mechanisms were obtained as in previous studies with a glassy carbon electrode, confirming that SPEs can be used as cheaper alternatives. Controlled potential electrolysis (CPE) at the optimized potential was recorded for 30 min, in the presence of GSH, and subsequent offline MS permitted the detection of the corresponding GSH adducts of dopamine and raloxifene. Dopaminoquinone and raloxifene di-quinone methide were generated via dehydrogenation and reacted covalently with GSH. However, the GSH adducts for eugenol and doxorubicin were not formed, leading to the generation of unconjugated metabolites. For example, eugenol was electrolysed via a single electron transfer with the addition of a proton to the corresponding phenoxyl radical. However, the oxidation reaction of GSH to form glutathione disulfide (GSSG) prevented further stabilisation to eugenol quinone methide and subsequent GSH adduct formation, mimicking only the catalytic pathway and polymerisation process. In the case of doxorubicin, the GSH adducts were probably formed at extremely low concentrations that were below the detection limits of the mass spectrometer or the expected doxorubicin semiquinone C7 free radical was generated but its trapping was unlikely, as proposed in previous in vitro and in vivo studies, owing to its quick oxidation back to the parent drug. Also, the possibility of generating non-reactive and highly unstable electrochemical products which were not capable of forming GSH adducts was considered. Thus, dopamine and raloxifene were selected for experiments in the microfluidic device. In addition, as the behaviour of acetaminophen on SPE is well-known, it was considered suitable for investigation with the proposed chip. A polycarbonate disposable chip was developed, in which a 32 μL SPE- electrochemical cell was integrated with a serpentine channel. The chip was coupled online to an electrospray mass spectrometer for a semi-automated methodology. At an optimized flow rate of 5 μL min-1, 2.5x10-5 M solutions of dopamine and acetaminophen were allowed to electrolyse for 6.4 min in the SPE cell. The electrogenerated toxic intermediates dopaminoquinone and N-acetyl-p-benzoquinone imine reacted covalently with 5x10-5 M GSH and the resulting adducts were detected online by MS. Raloxifene failed to generate the GSH adduct in the microfluidic device owing to the requirement for lower flow rates that were incompatible with MS. In conclusion, a disposable and cost effective microfluidic device was developed for the simulation of phase II metabolism. This microdevice has the potential to reduce the expensive and time consuming use of the current in vitro and in vivo methodologies, in pharmaceutical industry and medical research.

There were two main aims of this thesis, both of which involved the synthesis, often using environmentally friendly (green) methods involving water as the solvent and reagent, and the analysis and determination of the physical properties of novel inorganic nanomaterials and nano-composites. The first part of this project was the study of the general methods for the preparation of titanium dioxide nanoparticles and the investigation of the most efficient ways of coating CP with these nanoparticles in order to improve UV-stability and also to increase the whiteness and reflectivity of the paper. The second part of this research involved investigation silicon diimide mesoporous gel as a basic stationary phase for thin film and column chromatography for acid-sensitive organic compounds. A number of different methods have been investigated in order to improve the UV-stability and also to increase the whiteness and reflectivity of paper by using titanium dioxide nanoparticles to modify the optical properties of the surface of cellulose products and especially writing paper. The bleaching and yellowing of paper in visible light has been a common problem in the paper industry for very many years. A thin, but very efficient surface coating would allow a lighter paper with less standard stabilisers and whitening agents to be manufactured with enormous savings in terms of the processing and manufacture of paper. A higher brightness and whiteness of paper would also increase the optical contrast of writing paper, for example. The methods investigated in this project to attain these objectives include: preparation of bigger titanium dioxide nanoparticle powder for coating solutions with and without the formation of seeds, in-situ coating of titanium dioxide nanoparticles on CP, preparation of titanium dioxide nanoparticles as stable colloidal solutions, coating CP with core/shell TiO₂/SiO₂ nanoparticles and coating CP with TiO₂/APTES nanoparticles. Two reaction approaches have been investigated to prepare titanium dioxide nanoparticles with a size of about 200 nm, i.e., preparation of titanium dioxide nanoparticles without seed formation and preparation of titanium dioxide nanoparticles with seed formation. In the preparation of the titanium dioxide nanoparticles without seed formation, different starting materials were used. The size of the secondary nanoparticles is about 120 nm for TiOSO₄.xH₂SO₄.xH₂O, about 50 nm for TiOSO₄.xH₂O and about 100-300 nm when using TiOCl₂ as the source of titania. Titanium dioxide nanoparticles with a size of about 200 nm were obtained using the method involving the formation of seeds. In in-situ coating about 200 nm of titanium dioxide were coated on CP surface in just 20 min by heating of the CPs in the TiOSO₄ solution at 110 oC. The results also show that the titanium dioxide particle size increase with increasing of reaction time. Stable titanium dioxide nanoparticle colloidal solutions have been prepared with TiOCl₂ as a starting material. Because of high photocatalyst activity of small titanium dioxide nanoparticle, the surface of TiO₂-RP and TiO₂-P25 nanoparticles were protected by APTES and silica to reduce the photocatalytic degradation of organic material support. In order to inhibit the photocatalytic degradation of organic material supports induced by small titania (TiO₂) nanoparticles, four kinds of titanium dioxide nanoparticles, that is, commercial P25-TiO₂, commercial rutile phase titanium dioxide (RA), rutile titanium dioxide nanorods (RP) and rutile titanium dioxide spheres (RP500), prepared from TiCl₄. Small titanium dioxide nanoparticles were coated with a thin, but dense, coating of silica (SiO₂) using a conventional sol-gel technique to form TiO₂/SiO₂ core/shell nanoparticles. These core/shell nanoparticles were deposited and fixed as a very thin coating onto the surface of CP samples via a wet-chemistry polyelectrolyte layer-by-layer approach. The TiO₂/SiO₂ nano-coated paper samples exhibit higher whiteness and brightness and greater stability to UV-bleaching than comparable samples of blank paper. Comparison of the physical property of TiO₂/SiO₂ core/shell with the result presented in literature for bulk titanium dioxide evidenced UV-stability, whiteness and reflectivity were improved in these core/shell coatings. Titanium dioxide nanoparticles have also successfully modified with (3-aminopropyl)triethoxysilane (APTES). Commercially available-P25-titanium dioxide nanoparticles and rutile titanium dioxide nanorods, prepared from TiCl4, were first modified with a thin layer of APTES. These APTES-modified-P25 titanium dioxide nanoparticles and rutile titanium dioxide nanorods were then deposited and fixed onto the surface of paper samples via a simple, dip-coating process in water at room temperature. The resultant APTES-modified-P25 titanium dioxide nanoparticle-coated paper samples exhibit much greater stability to UV-illumination than uncoated blank reference paper and very little, or no, photo-degradation in terms of brightness and whiteness, respectively, of the-P25-TiO₂-nanoparticle-treated paper is observed. There are many other potential applications for this Green Chemistry approach to protect cellulosic fibres from UV-bleaching in sunlight and to improve their whiteness and brightness. In the second part of this thesis mesoporous silicon diimide gel was prepared and used for the first time as a basic stationary phase in thin layer and column chromatography. Silicon diimide gel, Si(NH)₂, is the basic equivalent of silica gel, SiO₂, whereby the oxygen atoms of silica have effectively been replaced by nitrogen. Silica gel is the most commonly used stationary phase for thin film and column chromatography. However, it is lightly acidic and this acidity can lead to the chemical decomposition of acid-sensitive compounds during chromatography. The mesoporous silicon diimide gel used here was prepared and optimised using a sol-gel process developed previously at the University of Hull. It exhibits a large specific surface area, a weakly basic surface and it is ideal for the characterisation, separation and purification of acid-sensitive compounds. The nanoparticles and nanocomposite materials prepared in this thesis were characterized by appropriate combinations of analytical techniques, such as SEM, TEM, EDX, XPS, ICP, UV-Vis, ζ-potential, FT-IR, XRD, CHN and NTA. The BET surface area, whiteness, brightness and some of the nanocomposite materials were also determined and the values compared with standard materials.

The aim of this thesis was to develop a point of care (POC) device that could monitor progesterone and oestriol in saliva. These hormones have a key role to play in both female fertility and pregnancy. Understanding the concentration of progesterone in the body is key to understanding a patient’s fertility and pregnancy status. Combining progesterone and oestriol detection can give valuable insight into when labour may commence during pregnancy. This can be achieved by measuring the progesterone to oestriol ratio in saliva samples, throughout the pregnancy progesterone is the more dominant hormone but a few weeks before labour oestriol becomes the more dominant hormone. Saliva was chosen as the biological sample due to the ease of collection as well as it providing a better chemical understanding of the active hormonal concentrations compared to blood. Typical levels in saliva are <31 pg mL⁻¹ rising to >100 ng mL⁻¹ for progesterone and 0 - 5 ng mL⁻¹ for oestriol. The work presented began with the design of a chemiluminescence immunoassay which could be translated onto a microfluidic device, this approach would provide both good sensitivity and selectivity. Chemiluminescence was chosen as a detection system due to the high sensitivities that can be achieved with simple instrumentation where a CCD camera could be used to also obtain spatial information. The CL assay involved the chemical immobilisation of the antibodies onto glass slides. Silanisation with (3-aminopropyl)triethoxysilane (APTES) in combination with a N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide/N-hydroxysulfosuccinimide (EDC/sulfo-NHS) linker proved the most successful immobilisation method, with a LOD of 33 ±3 pg mL⁻¹ being achieved for progesterone in 10 mM phosphate buffered saline (PBS). This method however lacked reproducibility and did not transfer well on to polymer substrates or the microfluidic devices due to problems with the antibody immobilisation procedure. Immobilisation of anti-progesterone was then investigated on a range of electrode surfaces (Au, glassy carbon and ITO). This immobilisation procedure involved electrochemically depositing nitrobenzene onto the electrode surface followed by an electrochemical reduction of the nitro groups to the corresponding amine. To allow electrochemical detection ferrocene was tagged to the anti-progesterone antibodies to give a redox tag. The antibodies were then immobilised through an EDC/sulfo-NHS linkage. This method proved to be successful and very reproducible. By tagging ferrocene onto the antibody a rigid structure was achieved during the immobilisation procedure allowing the ideal antibody orientation, this process also allowed quantification of the concentration of antibodies on the surface (4.46 x10⁻⁷ mol m⁻²). Electrochemical based immunoassays were successfully carried with a 15 min incubation time for progesterone giving LODs of 1 pg mL⁻¹ for the gold and glassy carbon and 0.1 pg mL⁻¹ for the ITO. The ITO performed better than the other materials due to the electrode being uniformly flat enabling more efficient surface modifications. The methodology was also translated for use with artificial saliva with a LOD of 1.7 pg mL⁻¹ for progesterone. Once the electrochemical immobilisation platform had been shown to be successful this was taken forward as a potential route to carry out a CL immunoassay. This novel approach utilised the oxidised ferrocene tag on the antibody as the catalyst for the luminol CL reaction. A static system was devised in which the antibodies had been immobilised on to ITO using the electrochemical approach and the CL reagents added by pipette, LODs of 2.35 and 2.54 pg mL⁻¹ were obtained for progesterone and oestriol respectively in saliva after a 30 min incubation time. The static system could therefore be used as a POC device for these hormones meeting the aims of this thesis. The next step was then to start developing a more automated method within a flow cell. Initially the ITO electrode with the pre-prepared immobilised antibody and the oxidised ferrocene tag was incorporated into a macrofluidic device. The CL immunoassay was successfully carried out in the macrofluidic device although the LODs were an order of magnitude higher than those seen from the static system for both progesterone and oestriol in saliva due to the large volume of the flow cell. Finally the ITO electrode with pre-prepared immobilised antibody with the oxidised ferrocene tag was slotted into the microfluidic device that had been designed and measurement were made. There was however problems with the design and possible new designs are discussed.

Photoelectro analytical chemistry provides an elegant technique by which to explore, amongst others, various industrial and environmental applications. To this end, four areas of photoelectroanalytical chemistry are investigated in order to develop industrially - and environmentally - relevant galvanic and photogalvanic cells, together with exploring the electro-generation of an industrially important molecule and diffusion factors they may affect this generation. The first study is investigated a long-range charge transfer, using tert-butylferrocene (tBuFc) as model hydrophobic system. It is found that the apparent one-dimensional diffusion coefficient depends on the tBuFc loading. It is suggested that an efficient relay mechanism for electron transfer is through the partitioning of the oxidised form between the two subphases, with inter-pseudophase reaction. However, the second study investigated the normal lyotropic liquid crystals (in the lamellar or hexagonal phases) as a route to afford a structured, three-dimensional, quasi-biphasic framework within which electron transfer cascades may take place using cyclic voltammetry. It is shown that these can take place through reagent partitioning between the hydrophobic and hydrophilic subphases, and it is illustrated how the structure and its orientation, the nature of the ionic doping of the framework, and the hydrophobicity of the redox analyte may give rise to changes in the observed voltammetric waveshape. For the case of an artitifical mimic of the first few stages of Photosystem I, it is demonstrated that photo-induced electron transfer is likewise affected by the orientation, and develop a system of photon efficiency of ~0.1%. Thirdly, a novel attempt at power production was attempted with the construction and optimisation of a photogalvanic cell system. A literature review was conducted and a system proposed utilizing 10-methylphenothiazine (NMP) as a light harvester and zinc as a sacrificial electrode with tetrabutylammonium chloride (TBAP) as a supporting electrolyte and chloroform as a mediator. The study aimed to create a cell that could be produced using industrial run-off or other waste water supplies. A series of cells was produced with varying concentrations of both zinc and NMP solutions and the power conversions studied by producing a voltage-current plot for each system. A system that exhibited 9.02% conversion efficiency keep, future studies were conducted to show whether the zinc species effected the power conversion or if silver would act in a similar way. A mechanism was proposed for the power production process and so studies using 2, 4-Dichlorophenol (DCP) rather than chloroform we conducted; it was believed that the dissociation step for DCP was step wise rather than concerted. Lower power production was seen in these cells as predicted by the reaction mechanism. Tris - (4-bromophenyl) - amine (TBA), an alternative light harvester to NMP, was used to see if altering the active chemical agent resulted in efficiency change. Finally , A photogalvanic cell that employs 2,4-dichlorophenol as a fuel source, an N-substituted phenothiazine as light harvester, and sacrificial zinc anode is presented, and shown to afford a ca. 4% light-to-electrical power conversion efficiency in violet light.

The research presented in this thesis is focused towards the synthesis of a new kind of giant hybrid liquid crystal consisting of organic semiconductor molecules surrounding an inorganic semiconductor with a nanorod shape with the potential for use in photovoltaic solar cells. It is intended that such materials will combine the good processing properties of liquid crystals, such as low cost, alignment and photolithographic patterning, with the efficient light emission and electrical conductivity of inorganic semiconductors. Several syntheses of gold and cadmium sulphide nanorods were performed and optimised in order to increase the yield, aspect ratio and monodispersity of nanorods formed. Localised alignment according to Onsager theory was observed for nanorods produced with sufficient aspect ratio and concentration. Investigations into the formation of self-assembled monolayers were carried out using gold nanorods and alkanethiols. Organic synthesis of thiol-terminated ligand groups for attachment to both gold and cadmium sulphide nanorods was performed, and such materials were used for investigations into surface modification of the synthesised nanorods. However, no liquid crystallinity was observed for the organic-functionalised nanorods produced during these investigations. Metal (II) phthalocyanines were used to investigate the formation of chromonic liquid crystalline phases and demonstrated the possibility for an alternative route in producing hybrid inorganic-organic nanorod-like systems.

This thesis discusses and demonstrates the utility and advantages of redox catalytic reactions and small scale synthetic applications. In particular electro-catalytic reactions are investigated along with electrogenerated chemiluminescence (ECL). ECL is used both as a probe for investigating the redox reactions and as an analytical method. The first chapter reviews the current techniques and achievements found in the area of dynamic electrochemistry and electrogenerated chemiluminescence and discusses occurrence, mechanism and potentially useful reactions worthy of further investigation for analytical applications. In Chapter 3 the electrocatalytic ECL reaction of Ru(bpy)32+ with tertiary amines in particular with codeine as a model compound was investigated. The aim of the work was to develop a portable drug testing device, that gave good sensitivity and reproducibility. The Ru(bpy)32+ was immobilized within the sol-gel matrix to develop a sensor which could be used directly for measuring tertiary amine containing drugs in buffer solution without the need to add reagents. A system of three electrodes was used in which Ru(bpy)32+ was immobilised on to a glassy carbon working electrode. Initial work involved physical entrapment of the Ru(bpy)32+ within the sol-gel matrix however, problems occurred with leaching of the reagent from this matrix. This problem was overcome by the covalent attachment of a novel Ru(bpy)32+ derivative to the sol-gel matrix. Using this approach a calibration was obtained using ECL for the determination of codeine over the range 1E-3 to 1E-7 M in aqueous buffer with a limit of detection of 2.65E-6 M for codeine. Covalent attachment, as compared to the physical entrapment of CL reagent, was advantageous as it ensured homogeneous distribution of the reagent within the matrix and prevented leaching. This reduced analysis costs, extended sensor lifetime and gave a reproducible analyte responses. This method was, however, only suitable for drugs that were soluble in aqueous solution and an alternative approach was needed for insoluble compounds. Chapter 4 describes an alternative approach for ECL reaction of tris(2,2’-bipyridyl)ruthenium(II) with tertiary amine compounds. In this approach the electrode was modified using microdroplets of a highly hydrophobic tertiary amine (trioctyamine). As well as allowing for the analysis of compounds that were insoluble in aqueous solution, this setup allowed the investigation of the electron transfer reaction occurring on liquid|liquid interfaces. This mechanism was studied in fully protonated and deprotonated conditions. The extent of the electrochemiluminescence production was shown to be dependent on the degree of the interfacial protonation. Moreover, the data obtained enabled the estimation of the biphasic pKa, which was found to be approximately 10.8. Furthermore, the mechanism was studied in fully deuterated and dedeuterated conditions, in order to investigate the effect of the deuterium on the biphasic pKa. Results suggest that the pKa increases to 13.18 when deuterium is used instead of protons. In Chapter 5 a further electrocatalytic reaction was investigated. The reaction was that of vitamin B12a with trans 1,2-dibromocyclohexane (DBCH) in a homogeneous dimethylformamide media. The reaction was studied by cyclic voltammetry. Four peaks were seen due to the two chemically reversible redox (two electron process) couples for vitamin B12a/B12r (Co(III)/CO(II)L) and B12r/B12s (Co(II)L/Co(I)). When the bulk electrocatalytic reaction was tried in a “one pot” system, the reduction could not, however, be achieved; the cathodically synthesised Co(I)L was thought to be reoxidised at the anode. A “two pot” system did not have sufficient potential control and, therefore, chemical reduction was investigated instead. Four reducing agents (Na/amalgam, NaBH4/NaOH, DL-cysteine/alkali solution and Zn dust/NH4CL) were studied to reduce B12 to B12s for a simple biphasic batch reaction of vitamin B12s with DBCH. The mild reducing agent Na/amalgam was not successful but the other three methods were shown to give 100% yield if the reaction vials were rigorously shaken. This simple type of green, surfactant free reaction has not been previously reported. The reaction was then investigated in a microfluidic system. For this work the vitamin B12 was reduced before being introduced into the microfluidic device. NaBH4/NaOH and DL-cysteine/alkali solution were selected as the most compatible reducing agents for the microfluidic device. Two types of microfluidic device were employed, one with a T-shape channel, and one with a serpentine channel. The conversions obtained with the microfluidic device were much lower (approximately 10%) than for the simple batch reactions (100%). The yield increased as the flow rate decreased, and the residence time increased. Using the serpentine channel made no noticeable difference to the conversion rate. Problems were also seen due to the use of excess reducing agent prior to introduction of the reduced vitamin B12 into the microfluidic device, as this could cause blockages and bubbles. The main problem was, however, the lack of mixing in the device. One way to overcome this would be to use an ultrasonic transducer with the microfluidic device but although preliminary experiments were carried out, there was not time to fully investigate this approach.

Electroanalytical chemistry provides an elegant technique by which to explore, amongst others, various biological and environmental applications. To this end, four areas of electroanalytical chemistry are investigated in order to develop biologically- and environmentally-relevant sensors, together with exploring the electro-generation of a biologically important molecule and the diffusional factors that may affect this generation.The first study involves the dynamics of the bond cleavage involved in the electro-generation of nitric oxide from a range of N-nitrosoamines. Adsorption phenomena is found to be of pivotal significance in the release of nitric oxide from two of the compounds explored, namely cupferron and N-itrosodiphenylamine, whilst bis(nitroso)phenylenediamine released, as hoped, two moles of nitric oxide in a single step. The challenge is to isolate the product, and to determine which form of nitric oxide was generated, i.e. the cation, NO+ or nitric oxide, NO. Isolation remains a challenge, however analysis of the reaction mechanism does allow a prediction of the product, be it NO+ or NO. NO+ is a highly oxidising species and hence is difficult to isolate, therefore it is far more preferable to electro-generate NO, which cupferron was the only compound investigated that achieved this.The second study involved the investigation of axiosymmetric anisotropic diffusion to disc shaped microelectrodes, with theoretical expressions examined with experimental data in order to examine the factors. A ferrocene/PEG in acetonitrile system was examined in order to test this theory and to determine the effect of viscosity on the diffusion coefficients, and also if it was possible to investigate the anisotropy by effectively "blocking" either Dr or Dz. Excellent symmetry between theory and experiment was found, hence the focus turned to a ferricyanide in caesium pentadecafluorooctanoate/D2O system where once again the calculated value of root(Dr.Dz) affords a theoretical waveshape with reasonable agreement between theory and experiment. Potential step chronoamperometry then determined separate values for Dr and Dz, with the resulting values affording an anisotropic ratio of 1.7, suggesting radial diffusion dominance over planar diffusion.Third, the modification of electrodes is explored in order to develop biologically and environmentally relevant sensors. In a first strand, two liquid crystal ferrocene compounds are examined, immobilised on the surface of a glassy carbon electrode simply via solvent evaporation. Both compounds demonstrated typical ion transfer processes across the liquid | liquid interface, with both anion insertion and cation expulsion processes demonstrated. The differing voltammetry observed in the presence of different anions formed the basis of the anion sensor.In a second avenue in this modified electrode work a cation sensor is developed, working on the basis of a biofilm, i.e. developing a modification of the electrode surface to mimic the action of a biofilm in chelating with cations. With this in mind, a basal plane graphite electrode was modified with a diazonium salt and polyphenol, and through the introduction of alginic acid into the polyphenol layer a degree of selectivity between the Group 2 cations was demonstrated, although quantitative properties eluded the work.Last, an environmental sensor for cyanide was developed using an electrochemical probe, tetramethylphenylenediamine (TMPD). The reaction between the electro-generated TMPD.+ and cyanide is successfully followed colorimetrically, before product characterisation studies help to determine the reaction mechanism. Voltammetric studies form the basis of a sensor, with square wave voltammetry achieving a detection limit of 4.4 microM. The reaction between TMPD and cyanide allowed remediation studies to be undertaken, with river freshwater samples from North Yorkshire (54deg 15' 19.19" N, 1deg 46' 13.49" W) and the Rodalquilar mine, Spain, (36deg 50' 52.9" N, 2deg 02' 36.87" W) demonstrating the removal of cyanide by an impressive three orders of magnitude.