Further developments have been carried out to improve the resolution and sensitivity of the spectrometer by introducing a dual phase lock-in amplifier and using new software to enhance the flexibility of the computer interfaced with the spectrometer. The spectrometer has been utilised to study a variety of molecular orientations on an alumina substrate. These have included an investigation to distinguish optical and geometrical isomers together with some alkynes in order to explore the validity of the previously proposed Selection Rule. The new observation that the triple bond is detected even when parallel to the substrate surface is reported. An attempt to study the polymerisation of ethylene on an alumina substrate has been carried out and some evidence is presented to support an increase in polymerisation with time. It has been shown that formic acid is produced 'in situ' within an aluminium-aluminium oxide-lead tunnelling junction from atmospheric carbon dioxide and water. A mechanism to account for this reaction is proposed. Junction structure has been studied particularly by utilising a modified crystal oscillator thickness monitor to investigate the influence of electrode and insulating oxide thickness both on junction electrical integrity and the mechanism of doping completed tunnelling junctions.

It is important for the pharmaceutical industry to be able to distinguish between amorphous and crystalline material, as an unexpected change in crystallinity can affect the character, efficacy and even safety of a medicine. There are currently many techniques that are used to distinguish between morphological forms, but these have many drawbacks, including cost and limit of detection. In this context there are currently no techniques that can be adapted for on-line analysis. To distinguish between amorphous and crystalline material, 0.1 % w/w phenol red, was added to sucrose, and dissolved in water. The solution was frozen before being freeze-dried, and the resultant amorphous excipient, with probe incorporated, was split into eight equal masses. The samples were then stored at controlled temperature and at a relative humidity unique to each sample. After storage for one week under these conditions, visual inspection of the samples showed that there were two distinct groups. Each sample was analysed by diffuse reflectance ultraviolet spectroscopy (DRUV) spectroscopy which confirmed the existence of two groups. The amorphous or crystalline nature of each sample tested by DRUV spectroscopy was independently verified by the following techniques: FT-Raman spectroscopy; differential scanning calorimetry; and X-ray diffraction. These techniques were also used to compare the excipient without the probe to that with the probe molecule to ensure that the presence of the probe molecule had not affected the sucrose. Once the experimentation had been concluded using sucrose as the pharmaceutical excipient, the sample set of excipients was increased to include lactose, trehalose and raffmose. All experiments conducted with the saccharides were in agreement with each other. SEM of amorphous and crystalline trehalose with and without the probe was also performed, which showed that crystalline trehalose with phenol red has a very disrupted surface compared to amorphous trehalose with phenol red, or trehalose without phenol red. Other experiments were conducted into probe choice and concentration, showing that the original choice of concentration for phenol red was the optimum choice. Reichardt's dye was chosen as a comparison probe to phenol red as Reichardt's dye is the most solvatochromic probe so far discovered. Reichardt's dye has very poor aqueous solubility, necessitating a change in method, so a rotary evaporator was used. A change in the wavelength in the DRUV spectra of any of the four saccharides used with phenol red was not observed with Reichardt's dye. DSC was used to confirm that each saccharide with Reichardt's dye had been made amorphous or crystalline. A mechanism of action for perichromism (the change in wavelength observed) with phenol red is suggested, and that is that perichromism occurs via hydrogen bonding, with potential changes to the planarity of the probe caused by different bonding mechanisms between the amorphous and crystalline surfaces. These studies show that perichromism is a quick, cheap technique that allows for a visual interpretation of morphological form of a pharmaceutical excipient, which could easily be adapted for use as an on-line pharmaceutical manufacturing test.

Enzyme immobilisation is the conversion of a soluble enzyme molecule into a solid particle form. This allows the recovery of the enzyme catalyst for its re-use and avoids protein contamination of the product streams. A better understanding of immobilised enzymes is necessary for their rational development. A more rational design can help enormously in the applicability of these systems in different areas, from biosensors to chemical industry. Immobilised enzymes are challenging systems to study and very little information is given by conventional biochemical analysis such as catalytic activity and amount of protein. Here, solid-state NMR has been applied as the main technique to study these systems and evaluate them more precisely. Various approaches are presented for a better understanding of immobilised enzymes, which is the aim of this thesis. Firstly, the requirements of a model system of study will be discussed. The selected systems will be comprehensibly characterised by a variety of techniques but mainly by solid-state NMR. The chosen system will essentially be the enzyme α-chymotrypsin covalently immobilised on two functionalised inorganic supports – epoxide silica and epoxide alumina – and an organic support – Eupergit®. The study of interactions of immobilised enzymes with other species is vital for understanding the macromolecular function and for predicting and engineering protein behaviour. The study of water, ions and inhibitors interacting with various immobilised enzyme systems is covered here. The interactions of water and sodium ions were studied by 17O and 23Na multiple-quantum techniques, respectively. Various pore sizes of the supports were studied for the immobilised enzyme in the presence of labelled water and sodium cations. Finally, interactions between two fluorinated inhibitors and the active site of the enzyme will be explored using 19F NMR, offering a unique approach to evaluate catalytic behaviour. These interactions will be explored by solution-state NMR firstly, then by solid-state NMR. NMR has the potential to give information about the state of the protein in the solid support, but the precise molecular interpretation is a difficult task.

The structural determination of the Pt(111)c(5x3)rect.-CO phase formed by 0.6 ML of adsorbed CO has been undertaken using scanned-energy mode photoelectron diffraction utilising the two distinct components of the C 1s photoemission peak. Earlier assignments of CO to atop and bridge sites have been confirmed as well as the respective 2:1 ratio of these assignments. Additionally, quantitative local structural details have been obtained. In particular, the Pt-C chemisorption bond lengths for the atop and bridging sites are 1.86 ± 0.02 Å and 2.02 ± 0.04 Å respectively. These values are similar to those obtained in previous studies for the 0.5 ML coverage c(4 x 2) phase involving an atop:bridge occupation ratio of 1:1. The results also indicate a definite tilt in the atop CO species of 10.7º +1.5º/-3.1º consistent with earlier investigations using electron-stimulated desorption ion angular distribution, LEED, Monte Carlo simulations and IR. The local structure of benzene adsorbed on Si(001) has also been investigated using scanned energy photoelectron diffraction. The standard butterfly (SB), tilted (T), tight bridge (TB), pedestal (P), twisted bridge (TB), and diagonal bridge butterfly (DDB) models were optimized and compared with the lowest R-factors being achieved for SB and TB models (0.2337 and 0.2641 respectively). Further optimization was performed for a mixed overlayer (0.25 ML) consisting of SB and TB structures in various proportions. A significant improvement in the Rfactor was achieved for a combined model in which 58 ± 35 % of the overlayer is composed of the SB structure. Using the structural data for the CO/Pt(111), and benzene/Si(001) adsorption systems, comparative simulations have been undertaken to explore the effect of using vertically and horizontally polarized radiation on PhD modulation amplitudes and more importantly the sensitivity of each method to various structural parameters. It has been shown theoretically that perpendicularly polarized photoelectron diffraction (PPPhD) yields modulation functions with intensities often being several times those observed in PhD. The new technique is shown to be more sensitive when the parameters involve mainly lateral displacements. The sensitivity of PhD on the other hand exceeds that of PPPhD only when dealing with bond lengths involving mainly vertical displacements. Parameters involving similar vertical and lateral displacements show similar sensitivities for both methods. Despite potential weaknesses such as a reduced signal to noise ratio and the sensitivity of PPPhD to the sample positioning, the potential gains of this technique especially when considering systems in which the adsorbates lie across the substrate such as benzene adsorbed on Si(001), make it ripe for experimental validation.

Solid acid catalysts are becoming of great importance within the chemical industry and their acidity is of great interest, as this determines their application, plus many of their catalytic properties can also be directly related with their acidity. There has been a drive towards heterogeneous solid acid catalysts because of the environmental concerns with safe handling and disposal of mineral acid homogeneous catalysts such as H2SO4, and their separation from the product. Objectives of this work have been to study a range of solid acid catalysts and establish a relationship between catalyst strength, activity, and structure, and then identify the influence of solvent and type of reaction on the catalytic properties of the catalysts to be studied. Acid catalysts have been chosen to represent a cross-section of the various types of catalysts in use. The solid acid catalysts being investigated include sulfonated polystyrene ion exchange resins, acid activated clays, zeolites, and heteropoly acid (H3PW12O40) supported on carbon and mesoporous silica. Supported heteropoly acids have been prepared by Dr A Lapkin, University of Bath in the collaborative part of the project. Catalysts have been characterised in terms of their surface areas, pore diameters, pore volumes, and crystallinity from nitrogen adsorption, powder x-ray diffraction, cation exchange capacity, and elemental analysis. The acidity of these catalysts has been studied by NH3 adsorption microcalorimetry. NH3 is assumed to adsorb stoichiometrically on surface acid sites and the molar enthalpy of ammonia adsorption is assumed to reflect the strength of the acid sites. The catalytic activities of the catalysts have been measured using two Brønsted acid catalysed test reactions (rearrangement of α-pinene and the hydrolysis of ethyl acetate). The correlation between characterisation results and catalytic data has been examined with emphasis being placed on the relationship between acidity measurements and the reaction medium or solvent. Conclusions that can be drawn from this work are that NH3 adsorption microcalorimetry is a useful technique for studying surface acidity of solid acids and that it does allow for some correlation to be drawn between catalytic activity and acidity, with the aid of additional catalyst characterisation techniques.

Three aspects of chemical and biochemical reactions were investigated. 1. The relative reactivities of pyrophosphate (phosphorus(V)) and pyro-di-H-phosphonate (phosphorus(III)) and its derivatives have been analysed at various pHs. The hydrolysis rate of pyro-di-H-phosphonate (PP(III)) was found to be higher than pyrophosphate at all pHs. Using ITC and NMR, pyrophosphate showed metal-ion complexing abilities whereas pyro-di-H-phosphonate showed weak or no complexing to metal-ions, although the rate of hydrolysis at pH 7 slightly increased compared to the spontaneous hydrolysis of PP(III). The enzymatic hydrolysis of pyrophosphate, which is thought to occur via MgPP(V)2-, occurs efficiently and is close to being diffusion controlled. Pyro-di-H-phosphonate on the other hand does not act as a substrate or as an inhibitor of pyrophosphatase. 2. Dichloromethane (DCM) is an alkylating agent for pyridine, producing methylene bis-pyridinium dication (MDP) upon refluxing the solution. The kinetics and mechanism of hydrolysis of methylene bis-pyridinium dication have been studied. Below pH 7 MDP is extremely stable and hydrolysis is first-order in hydroxide-ion. Above pH 9 an unusual intermediate is formed on hydrolysis which has a chromophore at 366 nm in water and its formation is second-order in hydroxide-ion. The carbon acidity of the central methylene group was also investigated kinetically using H/D exchange and the pKa was surprisingly high at 21.2 at 25oC (I = 1.0 M). 3. Isothermal titration calorimetry (ITC) is a technique mainly used by biochemists to obtain a range of physical and thermodynamic properties of a reaction. Analysing the data can become difficult when investigating complex reactions involving more than one step, for instance metal-ions binding to an enzyme. In this work models have been developed to simulate sequential reactions. These were used to simulate experimental ITC data for metal-ions: Zn2+, Co2+ and Cd2+ complexing to the active sites of BcII, a metallo β-lactamase responsible for antibiotic resistance, providing additional information on the mechanism by which this enzyme acts to deactivate β-lactam antibiotics. The simulations suggest that BcII has two very similar binding affinities to metal-ions which are filled sequentially.

Mechanistic studies are reported for the detritylation, coupling and sulphurisation reactions involved in oligonucleotide synthesis by the phosphoramidite method. Detritylation is the acid catalysed removal of a 4,4-dimethoxytrityl protecting group from the 5' protected nucleotide to give the 5' deprotected nucleotide and the 4,4- dimethoxytrityl carbocation. In the absence of water and at high acid concentrations the equilibrium favours carbocation formation. Equilibrium profiles show a sigmoidal shape rather than the expected hyperbolic curves and it is likely that residual water in the system reacts with the carbocation to form the 4,4-dimethoxytrityl alcohol. Results of kinetic studies of the detritylation reaction show that the detritylation reaction proceeds by a concerted general acid catalysis mechanism. The coupling step is the reaction between an alcohol and a phosphoramidite in the presence of an acidic activator, in this research the salt of saccharin and Nmethylimidazole. 31P NMR studies have shown that initial activation of the phosphoramidite forms a reactive saccharin adduct bonded through its carbonyl oxygen to phosphorus. Reaction of the alcohol and phosphoramidite in the presence of saccharin/N-methylimidazole salt shows second order kinetics. However, at high alcohol concentrations the reaction becomes independent of alcohol. This indicates a change in rate limiting step from the final alcoholysis step to the activation step. Phosphite sulphurisation was performed with the sulphur transfer reagent 3-amino- 1,2,4-dithiazole-5-thione (xanthane hydride). Contrary to the previously reported mechanism of sulphurisation, nucleophilic attack by the phosphorus upon xanthane hydride occurs on the sulphur adjacent to the thiocarbonyl group and not on the sulphur adjacent to the amino group. Kinetic measurements of the sulphurisation reaction show second order kinetics. Reaction constants determined from Hammett and Taft constants for triaryl and trialkylphosphites are -1.09 and -1.20 respectively. These reaction constants indicate partial formation of a positive charge in the transition state. The effect of solvent polarity on the rate of sulphurisation has shown a decrease in rate on increasing the polarity of the solvent. This has been attributed to an increase in the xanthane hydride stability in more polar solvents.

The initial objective of the work studied here was to investigate the effects of isomorphously-substituted transition metals in lattice sites in Layered Double Hydroxides (LDHs) in terms of basicity and catalytic activity in base-catalysed reactions and oxidation reactions. Experiments in which copper(II), nickel(II), cobalt(II), zinc(II) and iron(III) were substituted in the lattice of synthetic hydrotalcites showed that, on calcination, the resultant mixed oxides arising from hydrotalcites containing copper(II) exhibited the greatest enhancement of catalytic activity. Test reactions were the conversion of 4-methylpentan-2-ol to methylisobutylketone, the oxidation of benzyl alcohol and the Henry reaction between benzaldehyde and nitromethane. Results showed conclusively that copper(II) imparted base catalytic activity to the mixed metal oxides formed on calcination of the LDHs. This was confirmed through an extension to the study in which the copper(II) content in the LDHs was varied. It was shown that there is an optimum copper(II) loading, above which additional copper(II) is not effectively incorporated in the LDH lattice. Other supports for copper(II) as an oxide were investigated, on the basis that activity was linked to effective dispersion of copper(II) oxide. A series of copper(II) dispersions on zirconia, on silica and on magnesium oxide were prepared and tested. The zirconia-supported catalysts were the most active so work was concentrated on these. Two methods for preparing copper(II) oxide/zirconia were investigated, using a solid state reaction and using a sol-gel process. Catalysts were prepared with molar copper contents of from 2 to 60 mol%. It was possible to see from powder X-ray diffraction that copper(II) was dispersed in the zirconia matrix at levels up to about 20% depending on the synthetic method. And it was shown that base-catalytic activity of these materials correlated with the amount of fully incorporated copper(II). Activities of these were generally higher than the mixed metal oxides made from the LDHs. For comparison, another, different, approach to incorporating basicity in oxide supports was examined, in which alkylamino groups were tethered to silica supports, specifically a mesoporous molecular sieve form of silica, SBA-15. The activity of these materials were compared with those of the copper(II) based catalysts in the Henry reaction between nitromethane and benzaldehyde. An advantage of these catalysts was exploited by coordinating palladium(II) to the amine groups at different levels to impart oxidation catalytic activity. The resultant materials, in which only part of the amine functionality was coordinated by palladium(II), were tested as bifunctional catalysts, for combined oxidation and base catalytic activity, in the two step reaction between benzyl alcohol and nitromethane, which proceeds via an oxidation step to benzaldehyde followed by a base-catalysed step. The overall conclusion was that copper(II) is effective at imparting base catalytic activity to a range of support oxides, and that it does not have significant activity towards oxidation reactions., contrary to some claims in the literature. Oxidation activity can be obtained alongside base activity by preparing bifunctional catalysts but only through a different approach.

A series of multidentate N-donor ligands have been synthesised all containing pyridyl and pyridyl/thiazole units and their coordination behaviour is described. The ligands are classified into four types; i) terpyridine containing pyridyl/thiazole ligands (L1-3); ii) pyridyl/thiazole ligands containing a 3,3′-disubstituted bipyridine core. (L4-8); iii) 2,2′-bipyridine containing a crown ether moiety (L9-11); and iv) a 2,2′- bipyridine derived ligand containing a urea functional group in the 3,3′-positions (L12). Chapter II describes terpyridyl/pyridyl/thiazole ligands: - the synthesis of (L1-3) is described and the complexes ([Cu(L1)][ClO4]2, [Ni(L2)][ClO4]2, [Co(L2)][ClO4]2, [Cd3(L3)2][ClO4]6) structurally characterised. Partitioning of the ligands (L1-3) is dependant on the position of the thiazole ring within the ligand chain. This partitioning is found to occur at a position adjacent to that of the thiazole ring in all but the L2 ligand complexes, where it is partitioned preferentially at a position creating favourable coordination geometry for the metal ion. Chapter III describes 3,3′-disubstituted pyridyl/thiazole ligands (L4-8): - the novel potentially hexadentate ligands (L4, 5), the potentially octadentate ligand (L6) and the potentially tetradentate ligands (L7, 8) have been synthesized and structurally characterised. All ligands are found to partition at the central pyridine unit due to unfavourable steric interactions to form a pyridyl/thiazole/pyridyl-binding domain (L4-6) and the pyridyl/thiazole-binding domain (L7,8). The substituents are found to dominate the control of the formation of complexes produced ([Zn(L4)][ClO4]2, [Cd(L5)][ClO4]2, [Cd2(L6)2][ClO4]2, [Cd2(L8)2][ClO4]2). Chapter IV, Section 1 describes ditopic bipyridine/crown ether ligands: - the synthesis of (L9-11) is described and the Ru (II) complexes (L9-11) structurally characterised. The Ru(II) complexes of these 3,3′-disubstituted crown ether species were found to luminesce. Modulation of the luminescent properties of the ruthenium complex was investigated with a selection of common cations but resulted in little or no response. Chapter IV: - Section 2- Ditopic bipyridine/urea ligands: - the novel ligand containing urea substituent side chains (L12) has been synthesised and a ligand containing both pyridine and urea substituents has been synthesised and characterised. A ruthenium complex (X) was synthesised with ligand (L12) and (bipy)2RuCl2, the resulting structure confirmed via 1H & 13C NMR as well as electrospray mass spectrometry (ESI-MS). Unfortunately no complexes have been structurally characterised due to the instability and decomposition of the complex after a short period of time. The ruthenium complex however was found to luminesce; ligand/anion recognition studies with complex (X) and a selection of common anions showed a marked change, a ten fold increase in the luminescence was observed with the addition of H2PO4 - when in a non-aqueous solvent.

This thesis is concerned with the synthesis of β-sultams and the development of new routes for the synthesis of bicyclic versions of these molecules as potential anti-bacterials. The synthesis of 1-azetines, 1,2-thiazetin-1,1-dioxides and isothiazol-1,1-dioxides as precursors of bicyclic heterocycles is described. 1-Azetines were synthesised from azetidin-2-ones prepared via the [2+2] cycloaddition of alkenes with N-chlorosulfonyl isocyanate (CSI). They reacted with diphenylcyclopropenone or nitrile oxides to afford bicyclic systems whose reactivity was explored and afforded a range of heterocycles such as 1,2,4-oxadiazoles, pyridines or pyrimidines via novel reaction pathways. The synthesis of 1,2-thiazetin-1,1-dioxide through two routes will be discussed: the alkylation of 3-oxo-β-sultams to afford 3-ethoxy-1,2-thiazetin-1,1-dioxides, and the ring contraction of an isothiazol-1,1-dioxide to afford a 3-diethylamino-1,2-thiazetin 1,1-dioxide. The reactivity of these 1,2-thiazetin-1,1-dioxides towards diphenylcyclopropenone, 1,3-dipoles and dienes was studied and is fully described. In the course of chemistry mentioned above, a series of isothiazol-1,1-dioxides was synthesised. Their reaction with 1,3-dipoles to yield the corresponding bicyclic heterocycles is described.