The first molecular scattering observed using the new Edinburgh electron diffraction apparatus is detailed in this thesis. The new apparatus utilises a phosphor screen/CCD detection system rather than the photographic plates more commonly used in electron diffraction studies. The electron beam is provided by a telefocus electron gun. Two molecular target sources have been investigated: a Campargue-type molecular beam and an effusive needle source. Calibration of the apparatus has been attempted using argon gas. Carbon tetrafluoride, CF<SUB>4</SUB>, has been used as a typical gas-phase molecule and its scattering investigated extensively, while preliminary results for a more complex molecule, 1,2,4,5-tetrafluorobenzene, are also reported. Finally, the structure refinement of di-<I>t-</I>butyl(trichlorosilyl)phosphane using data from the existing electron diffraction apparatus is reported.

The interface between two immiscible electrolyte solutions (ITIES) has been investigated for cyclic/linear sweep voltammetry of ion transfer, facilitated ion transfer and electron transfer. Approximate analytical solutions have been derived for the different geometries of liquid/liquid interfaces which are known, i.e. planar spherical/hemispherical, micro-hole and micropipette interfaces, for both reversible and quasi-reversible charge transfer. For planar ITIES the solution is the same as for linear diffusion for electron transfer at a metal/electrolyte interface. For spherical and hemispherical ITIES new solutions have been derived which allow a kinetic analysis to be carried out on cyclic voltammetric results, without the need to use extremely high sweep rates. The solution for a spherical interface is then used to approximate a solution for a micro-hole interface by applying the approximation that microdisc and spherical electrodes are equivalent when the ratio of the radii of the spherical electrode to the microdisc electrode is 2/π. This approximation is also used to evaluate a solution for ion transfers across an interface supported at the tip of a micropipette, where the system is also fully characterised experimentally for voltammetry. Using a similar numerical method as applied to the above problems a solution was evaluated for electron transfer across a planar ITIES for both reversible and quasi-reversible reactions. For all of these approximate solutions the trends found are the same as those seen from experimental results. A method is also presented for the kinetic analysis of 'steady-state' voltammetric waves for facilitated ion transfer across an ITIES supported at the tip of a micropipette. The technique is then used to evaluate the rate of K^+ facilitated by BD18C6 and Li^+ transfer facilitated by both ETH1810 and 2,9-dibutyl-1,10-phenanthroline. The use of liquid/liquid interfaces is also investigated as an assay method for catecholamines. As well as using ion transfer at ITIES as a method to determine catecholamines the use of enzyme coupled reactions, in conjunction with stardard redox electrochemistry or liquid/liquid electrochemistry, is also discussed.

The electrochemistry of solute species in ionic liquids is investigated by use of cyclic voltammetry. The cyclic voltammetry of transition metals of varying oxidation states are presented as well as the electrochemistry of uranium as both a solute and a metallic electrode in a variety of ionic liquids and comparisons are made between their behaviour. Transport properties of the solute species have been determined by the use of an electrochemical technique known as chronocoulometry. This involves the application of a potential step and the subsequent observation of the charge passed as a function of time to determine the diffusion coefficient of the solute. Diffusion data is collection at a variety of temperatures in order to obtain an Arrhenius plot, and thus obtain activation energies for diffusion for each solute species, and data have been compared and contrasted for the ionic liquids and solutes employed. Structural analysis of the ionic liquids has also been performed by utilising single crystal x-ray crystallography to study the interaction between both the anion and cation of the ionic liquid, and between solute species and the anion and cation of the ionic liquid. The crystal structure of 1-ethyl-3-methylimidazolium chloride that offers a significant improvement over previously published data is presented along with the crystal structure of a new ionic liquid, 1-ethyl-3-methylimidazolium dichloroargentate. Powder x-ray diffraction and Raman spectroscopy data are also presented as part of the structural analysis of these ionic liquid systems.

No description available.

The Introduction is concerned with some general aspects of organic electrochemistry. The Discussion is divided into two sections: electrochemistry in acetonitrile (Section A) and liquid ammonia (Section B). Practical aspects, e.g. solvent purification, cell design and electrode construction, are considered. Several supporting electroytes and electrode materials are also assayed. A comparison with results obtained by other workers has been made wherever possible and the influence of proton donors and supporting electrolyte cations on the reduction has been studied.

No description available.

In this thesis, ten different ligands were designed and synthesized in such a way as to provide metal containing SAMs. The metal binding sites of these ligands are derivatives of the tripodal ligand tris(2-pyridylmethyl)amine (TPA) and the tridentate amine bis(2-pyridylmethyl)amine (BPA), which have good molecular recognition properties in solution. As interface separating the electrode from the metal binding site and gold anchor group we have chosen a thiophenyl, thioethyl and thioctic acid groups. Electrochemical studies with [Fe(CN)₆]^3-/4- as redox probe in solution were carried out on SAMs of the TPA thioctic acid derivative L4  and its complexes Cu-L4, Zn-L4 and Fe-L4. Monolayers containing redox active Cu(II/I) ions accelerated the electron-transfer reaction (<i>k</i>_app= 2.78 x 10^-2 cm/s) more than those containing Zn(II) (<i>k</i>_app = 1.51 x 10^-4 cm/s) and Fe(II) (<i>k</i>_app= 1.40 x 10^-3 cm/s) ions. This is consistent with a mechanism for electron-transfer in which the Cu ions exit in different coordination environments and with different redox potentials, and are rapidly undergoing interconversion. The ability of this system to facilitate the electron-transfer process to the redox probe was used to develop a new cyanide sensor. Addition of cyanide ions increases the blocking behaviour of the SAM, suggesting the elimination of Cu from the SAM to form [Cu(CN)_n]^(n-1)-complexes. The cyanide detection limit was found to be 1 nM. Electrodes modified with the binucleating ligand 2,6-bis[bis(2-pyridylmethyl)amino-methyl]phenol thioctic acid derivative (bearing two BPA arms) L7 were also investigated. Metal containing SAMs can influence the electron-transfer process through the SAM to a solution containing a redox probe. This property can be used to develop new anion sensors in aqueous system.

No description available.

This thesis is concerned with the spectroscopic, electrochemical and spectroelectrochemical investigation of a range of transition metal species, all containing the ligand 2,2'-bipyridine (bpy). All the complexes studied exhibit rich electrochemistry and electronic absorption spectra. Chapter one details the electrochemical and spectroelectrochemical techniques used in this work, and presents a brief overview of the reasons why we study transition metal complexes in this manner. Chapter two is concerned with the solvent dependent behaviour of complexes of the form [M(bpy)<SUB>2</SUB>(CN)<SUB>2</SUB>] (M = Fe, Ru or Os). The electrochemistry, UV/visible spectroscopy and spectroelectrochemistry of these complexes in a range of solvents is described, and both reduced and oxidised forms of the complex are investigated. The solvent dependent characteristics of the complexes are compared with a range of solvent parameters, and show best agreement with Acceptor Numbers. Analysis of epr data for the oxidised complexes, and spectroelectrochemical experiments suggest that the solvent interaction responsible for this behaviour is minimised on removal of an electron. Chapter three details a range of mono- and bi-metallic complexes containing Ru(bpy)<SUB>2</SUB> or Fe(bpy)<SUB>2</SUB> units and poly-aromatic bridging ligands. The electrochemistry UV/visible spectroscopy and spectroelectrochemistry of these complexes is described. Chapter four details the attempted synthesis of three complexes utilising cyanide ligands as a bridge between two metal centres. These complexes are based around either a [Ru(bpy)<SUB>2</SUB>(CN)<SUB>2</SUB>] or [Pt(bpy)(CN)<SUB>2</SUB>] centre. The electrochemistry UV/visible spectroscopy and spectroelectrochemistry of the products is reported, and the likely nature of the products is discussed.

The dielectric properties of several ion forms of the synthetic crystalline zeolite Linde type-A have been studied in the frequency range 5 Hz to 100 MHz in the presence of varying amounts of adsorbed water. In addition the mixed Ca/Na form of type-A (i.e. the commercial 5-A) has been studied with ammonia, sulphur dioxide, carbon dioxide and n-pentane as the adsorbed phase in the frequency range 5 Hz to 150 kHz. A cell specially suitable for the above studies has been designed, and constructed, and satisfactorily operated. The cell enables the zeolite to be dehydrated at temperatures up to 5000C under a vacuum of 10-5 torr and tben equilibriated with any required pressure of any gaseous adsorbate before measurement. In all the ion forms studied several regions of dielectric relaxation have been observed. The results for water have been interpreted by considering two relaxation regions as being due to adsorbed water. A small proportion (about 20 per cent) apparently behaves as liquid water, the remainder having an ice-like character. In all the ion forms a region of dielectric loss may be attributed to movement, within the zeolite cavity, of the interstitial cations. The frequency of occurrence of this dielectric loss peak is dependent on the cation, the adsorbate and the adsorbate content. Temperature variation of this peak shows a linear relationship between the activation energy of the process and the radius of the cation concerned. The behaviour of this activation energy with temperature appears to imply a type of phase transition (freezing) of the adsorbed water. Dielectric isotherms for 5-A/I:I20, 5-A/NH3 and 5-A/S0 2 have been obtained and the results discussed in terms of the available smtes for adsorption. The isotherms indicate that a large proportion of 802 appears to have a relaxation time similar to that in the bulk liquid. The different behaviour of H20 and NH3 is attributed to the hydrogen bonding capabilities of the latter. Some variation of the dielectric properties of 4-A between different batches has been observed; this is attributed to varying amounts of sodium aluminate in the material. Values of apparent d.c. conductivity obtained during the course of the dielectric study, while in agreement with previous dielectric studies, are notably different from some published conductivity values. While the investigation shows that studies of dielectric relaxation can give considerable information concerning the adsorbate and adsorbent, results of molecular behaviour by other techniques are required to enable a convincing interpretation of the results to be made; these are not available.