By synthesising S-2-phenyl-Af-(4-nitrophenyl)aziridine from S-phenylglycinol, it has been demonstrated that the aziridination of styrene by N-(4- nitrobenzenesulfonyl)imino phenyliodinane, (nosyliminophenyliodinane, PhlNNs) in the presence of tS',AS'-2,2,-isopropylidene-bis(4-phenyl-2-oxazoline), catalysed by copper(II) triflate in CH3CN solution or heterogeneously by CuHY, has predominantly an /-configuration. The enantioselectivity of the aziridination of styrene by Af-arenesulfonylimino-phenyliodinanes catalysed by copper-exchanged zeolite Y (CuHY), in conjunction with a chiral bis-oxazoline ligand, has been re examined. In the case of PhlNNs, it is shown that the product mixture of enantiomeric aziridines, on treatment with hexane, gives rise to a solid phase of low enantiomeric excess (ee) and a solution phase of high ee. Separation of the solid phase and recrystallisation afforded a true racemate (racemic compound), which has been confirmed by X-ray crystallography. The aziridine obtained from the solution phase could be recrystallised to produce the pure enantiomer originally in excess. A consequence of the new findings is that previous reports on the enantioselectivity of copper-catalysed aziridination, both in heterogeneous and homogeneous conditions, should be regarded with caution if the analytical procedure involved HPLC with injection of the enantiomeric mixture in a hexane-rich solvent. Such a method has been used in previous work from this laboratory, but has also been used elsewhere, following the procedure developed by Evans and co-workers when the (homogeneous) copper-catalysed aziridination by PhlNTs was first discovered. Evidently, the change of substituent in the benzenesulfonyl group reduces the solubility in hexane, affording a solution phase of enhanced ee.

Methane activation over molybdenum trioxide and gold catalysts supported on magnesium oxide were studied employing state of the art computational modelling. The localisation of electrons at a terminal oxygen point defect on MoO3(010) was well represented by DFT+U whereas conventional DFT failed to localise the two unpaired electrons on Mo. The hybrid DFT functional PBEO was employed within a cluster model and a spin population of 1.96 was calculated for Mo and used to fit the Dudarev's parameter U-J at a value of 6.3 eV. The asymmetric oxygen centre was found to be the preferred adsorption site for both hydrogen and methyl radical adsorption, losing its asymmetric character. Mo exhibited the weakest interaction with the adsorbates and methyl was found to be weakly adsorbed between Mo and its closest asymmetric oxygen, suggesting mobility on the surface. A transition state for methane activation was located with hydrogen and carbon respectively interacting with terminal oxygen and Mo. A Bader charge analysis of this transition state coupled with a spin population analysis indicated a heterolytic cleavage. An activation energy of 129.7 kJ mol"1 was calculated using the NEB method. On MgO(001), atomic gold was found to preferentially adsorb at five-coordinated oxygen sites and the Au-O bond was partially covalent in nature. F centres represented anchoring points with increased adsorption energy and charge transfer to Au. A three-dimensional growth was favoured over two-dimensional growth and the adsorbed Auio clusters were negatively charged at the interface. Atomic gold on the oxygen kink site of MgO(1310) presented an adsorption energy 0.30 eV higher than that on a five-coordinated oxygen centre of MgO(001). Auio was also found to strongly interact with the oxygen kink site of MgO(1312). Hydroxyl groups were employed to tailor the gold oxidation state and CO was used as a probe molecule. For both atomic gold and Auio, the CO stretching vibrational frequency increased with the oxidation state. CO had an unfavourable binding energy on Au(III) but was strongly adsorbed on Au(I). An increase in the number of adsorbates reduced the negative charge of Auio, also increasing the CO stretching vibrational frequency and bringing it closer to the experiment. It is thus expected that CO will bind to Au8+ particles in the working catalyst.

This thesis investigates potential classes of compound for use as immunohistochemical markers. A range of ligands and their corresponding metal complexes have been screened for their ability to catalytically reduce silver ions in a Timm's type reaction. Chapter two focuses on the preparation and testing of bidentate tertiary phosphine metal complexes. The functionalised ligands, l,2-bis-diphenylphosphino-4-methoxy- benzene, l-diphenylphosphino-2 (diphenylphosphino)-methyl -4-methoxybenzene and the corresponding platinum complexes have been prepared. Platinum complexes of 1,2- bis diphenylphosphinoethane were also synthesised. These platinum complexes were found to reduce the silver in times ranging from 5 minutes to in excess of 30 minutes. Chapter three focuses on the preparation of marker systems based on platinum and palladium complexes of weso-tetraarylporphyrins. 5,10,15,20-Tetra(4- hydroxyphenyl)porphyrin and 5,10,15 -tri-(4-tolyl)-20-(4-hydroxyphenyl)porphyrin have been prepared from the corresponding anisole and 3,4,5-trimethoxybenzoic acid phenyl ester derivatives. A number of symmetrical and unsymmetrical porphyrins bearing aryl phosphate esters derived from diethyl-4-formylphenyl phosphate and diethyl-4-formyl-2- methoxyphenyl phosphate have been prepared. The reaction of 5,10,15,20-tetra-(4- hydroxyphenyl)porphyrin or 5,10,15,20-tetra-(4-hydroxy-3-methoxyphenyl)porphyrin with chloro diethylphosphate in the presence of either sodium hydride or triethylamine failed to afford the corresponding tetra-phosphorylated products. The reaction between 5,10,15,20- tetra-(4-hydroxyphenyl)porphyrin palladium and chlorodiethylphosphate in the presence of triethylamine afforded a mixture of phosphorylated products. None of the prepared complexes displayed the ability to reduce silver ions in a Timm's type reaction. Chapter four describes the design and synthesis of 4-phenyl-2,2':6',2"-terpyridines functionalised with a PEG chain terminating with a reactive group suitable for bio- conjugation. 4'- (2-(2- 2-(l,3-Dioxo-l,3-dihydro-isoindol-2-yl)-ethoxy -ethoxy)-ethoxy)- phenyl - 2,2':6',2"-terpyridine was prepared using two methods starting from either 4- hydroxybenzaldehyde or (4-hydroxyphenyl)-2,2':6',2"-terpyridine. Base hydrolysis converted the phthalimde moiety to the free amine which was subsequently treated with l,5-difluoro-2,4-dinitrobenzene. This ligand was not water soluble. The addition of two morpholinomethyl pendent groups via a Mannich reaction did not dramatically increase the solubility in water. A number of transition metal complexes were prepared and tested. Chapter five presents a novel one-pot synthesis of 'mixed' 7V-arylated 1,4,7- triazacyclononane (tacn) ligands. Using this methodology tacn ligands functionalised with two nitrophenyl groups and either a benzaldehyde (L32a), benzoic acid (L32ba), benzyl ester (L32Benzyi), alcohol (L32Aic), tolyl (L32T) or napthoquinone (L32Q) groups have been prepared in yields ranging between 39 and 64 %. Hydrogenation of L32t afforded L32tr. Reaction with Ni(II) perchlorate afforded the air stable complex Nin(L32TR) C104 2, which was found to catalyse the reduction of aqueous silver ions via a Timm' type reaction in 3 minutes. Attempts to attach both a porphyrin and a terpyridine sub-unit are also presented.

The interaction of carbon black with an acrylic resin in aqueous solution has been investigated by rheology. Two carbon blacks Raven L and Raven M, with similar particle size and surface characteristics but quite different particle morphologies, have been examined. In the absence of polymer, stable aqueous dispersions could not be obtained. Stable dispersions could be obtained however upon addition of polymer to a level corresponding to a ratio of 50mg of polymer per 13m2 of surface area (i.e.l5wt% particles). These stable dispersions exhibit flow typical of concentrated dispersions - Newtonian behaviour up to some apparent "yield" or critical value. Above which shear thinning is observed. This critical stress increases with increasing polymer concentration. At low polymer concentrations, the dispersions are predominantly viscous at low shear stresses. The phase angle decreases significantly over a narrow shear stress range and the rheology tends to more elastic behaviour. At higher shear stresses, the dependence on particle morphology is weak. Furthermore, increasing the pH of the aqueous dispersions has little effect, but changing the adsorbent does alter the rheology somewhat. In addition to Raven L and Raven M, other carbon blacks were also investigated in which the surface chemistry had been modified by ozonolysis. In addition to aqueous systems, a selection of oil based systems have also been investigated. Here, four carbon blacks were used with a bitumen binder: the low-medium structured fine particle (Raven L), the medium-high structured fine particle (Raven M), a low-medium structured coarse particle (N772) and a medium-high structured coarse particle (N660). For these systems, the rheology and the dispersion colour properties have been investigated. Finally, a rheology study on the effect of bimodal dispersions was undertaken.

The work presented in this thesis is based on studies concerning structural properties of molecular solids, and is composed of three different parts. First, structural aspects of solid state dimerization reactions have been studied using 1H NMR and powder X-ray diffraction. The experiments are based on the photoreactions of cinnamic acids in the solid state. These materials show photochemical behaviour upon irradiation by UV light. The /-phase (photoreactive polymorph) of 4-cMoro-/ra s-cinnamic acid was chosen as the primary material for study, and a combination of powder X-ray diffraction and solution state 1H NMR spectroscopy techniques have been used to follow the evolution of the solid-state photoreaction, and to determine the structural evolution of the photoproduct. In addition, the structure of a photoreactive material (the /-phase of 4-fluoro-/raws-cinnammic acid) that cannot be prepared as a single crystal suitable for single crystal X-ray diffraction has been determined directly from powder X-ray diffraction data. This research exploits modern developments in the application of powder X-ray diffraction techniques in order to obtain new levels of understanding of a classical solid state reaction. The second part of this thesis is based on the investigation of transport of molecules through linear tunnels in solid organic inclusion compounds (host-guest systems). This project is focused on incommensurate inclusion compounds in which guest molecules are contained within a system of one-dimensional tunnels (with a diameter of about 5.5 A) in a crystalline urea host structure. It was shown previously that net transport of guest molecules in one direction along the crystal can be achieved by insertion of new guest molecules at one end of the crystal (by dipping it into the liquid phase of another potential guest), with the original guest molecules expelled from the other end of the crystal. Such phenomena have considerable potential as the basis of selective micro-scale separation techniques, based on discrimination of molecular size, shape and chirality. In the present work, the spatial distribution of the guest molecules in the crystal has been studied together with the changes in the spatial distribution of the guest molecules as a function of time during the transport process. This process has been investigated directly by using confocal Raman microspectrometry as an in situ probe of the molecular transport process. The data obtained from such experiments have provided access to information on the kinetics of the transport process and the time-dependence of the spatial distribution of guest molecules within the channel system. A model has been developed to understand the kinetics of the transport process, leading to detailed mechanistic insights. The last part of the thesis is focused on the design of hydrogen-bonded organic complexes. Underlying all structural aspects of organic molecular crystals is the fundamental question of what factors control the molecular packing arrangement, and an important related issue is how to apply an understanding of these factors in the design of crystals with desired structural properties. The work has focused on the study of components with hydrogen bonding capability (urea/diols and /-phenylenediamine/diols), with a view to the formation of hydrogen-bonded complexes with predictable structural features. Optical microscopy, single crystal X-ray diffraction, powder X-ray diffraction and confocal Raman microspectroscopy have been applied in this work.

A Coordination chemistry based historical perspective of contrast agents which are utilised in various imaging modalities, forms the basis of Chapter 1. Chapter 1 also highlights the various latest advancements and the challenges confronted therein. Chapter 1 culminates in highlighting the need for dual purpose contrast agents. Chapter 2 and Chapter 3 deals with rx)lyarnino poly carboxylate derivatives based on EDTA and DTPA respectively. Chapter 2 sheds light upon Teslascan and other related manganese based potential contrast agents. It also highlights the emergence of Mn (II) as the direct competitor for Gd (HI) in the face of Nephrogenic Systemic Fibrosis (NSF) reported for Gd based contrast agents. The chapter culminates in describing the synthesis of a library of EDTA bisamides, including four new EDTA bisamides. Chapter 3 in turn takes a detailed look at a series of DTPA analogues and DTPA bisamides synthesized by scientists all over the world. It also highlights the various synthetic methodologies undertaken by the able scientists. The chapter culminates in describing four new multidentate ligands synthesized in this project, namely two new DTPA analogues and two new DTPA Bisamides. It has been shown that the synthetic methodology utilised to synthesize symmetric naphtha derivative L5 is fairly unique. Chapter 4 and Chapter 5 report the investigations carried out on these new multidentate ligands in terms of relaxometry, potentiometry and luminescence. Interesting results were obtained from relaxometric and luminescence measurements. For instance, symmetric naphtha derivative, reported a relaxivity of 8.8 mM'V1, relaxivity obtained for Mn (II) complex of EDTA bisamide of 4-aniinomethylpyridine is also highly commendable. Investigations on the optical properties of the multidentate ligands require a separate chapter. Thus it is has been allotted Chapter 5. DTPA bisamide of N, N-Bis (tert- butoxycarrx)nyl)memyl-2-bromcmylamine was found to quench the fluorescence upon binding with Cu (II), indicating its application as luminescent sensor for Cu (II).

Equilibrium geometries, interaction energies and harmonic frequencies of (NH3)n (n = 2 5) and NH4+(NH3)n (n = 2 5) were computed using correlated electronic calculations (MP2) in conjunction with aug-cc-pVXZ (X=D, T, Q) basis sets and the Counterpoise procedure. The zero-point energy (ZPE) on the relative stability of the clusters was estimated using harmonic frequencies. For both pure and protonated ammonia clusters we found that using basis set superposition error (BSSE) corrected forces or freezing the monomer structure to its gas phase geometry had only a weak impact on the energetics and structural properties of the clusters. For pure ammonia clusters, (NH3)n (n = 2 5), we found that low lying isomers for (NH and (Nfls have similar binding energies, perhaps suggesting the presence of a very smooth energy landscape. The harmonic frequencies highlighted the presence of vibrational fingerprints for the presence of double acceptor ammonia molecules. In addition, many-body effects for n = 2 4 were investigated we found the 3-body effects to account for 10-15% of the total interaction energy and 4-body effects to be negligible. Under these premises, a model pair interaction fitted to ab initio data for rigid ammonia molecules was developed. It was extended with a description of polarisation effects, introduced by using a noniterative form of the charge-on-spring model, the latter accounting for more than 95% of the dipole induction energy and of the increased molecular dipole. This model was used to optimise putative global minima for (NHs)n (n = 3 20) the structure and energetics of the clusters with n = 2 5 were found to be in good agreement with previous ab initio results. For larger isomers our model predicts larger binding energies than previous analytical surfaces, and also predicts a reorganisation of the energy ranking and a different global minimum structure. For protonated ammonia clusters, we have found two general types of isomeric structures, globular and linear, the former showing larger binding energies. Harmonic frequencies reveal that the signature of these clusters is given mainly by NH4+. In agree ment with the literature we also found that higher frequencies for the N-H vibrational modes of the NH4+ are seen upon increasing cluster size. Finally, the vaporisation en ergy computed in this work compares well with previous theoretical and experimental data.

No description available.

The palladium-catalysed phenylacetylene oxidative carbonylation (PCPOC) reaction operates in both oscillatory and non-oscillatory modes. In oscillatory mode oscillations have been observed in pH, reaction heat (Qr), redox potential and gas uptake. This work documents the steps towards understanding the process and uncovering the reaction mechanism. An extensive experimental study was undertaken involving small-scale (25 mL) experiments on the catalytic system and large-scale (450 mL) experiments on the whole reaction system. The large-scale experiments on the whole system included studies at temperatures from 0-40 °C. The effect of increasing the concentration of water in the system by increasing the solvent volume ratio of water from 0% to 40% was also studied. Decreasing the reaction temperature is known to affect the period and amplitude of the pH oscillations but this work found that it also changes the selectivity of the reaction: the major product is dimethyl (2Z)-2-phenyl-2-butenedioate at 40 °C whereas at 0 °C the major product is 5,5-dimethoxy-3-phenyl-2(5H)-furanone. Increasing the concentration of water in the system affected product selectivity and the oscillatory pH behaviour. As the water concentration increased, pH behaviour changed: the regular shark fin waveform observed when no water was added to the system gradually became step-wise oscillatory behaviour. The small-scale experiments uncovered the link between the mono-carbonylation of phenylacetylene and the generation of H+. They also showed the autocatalytic nature of the reaction between the PdI2 catalyst and carbon monoxide as well as the involvement of water in H+ generation. Based on the experimental findings a tentative model was produced using BatchCAD which accounted for the key features of the observed pH behaviour. The modelling study showed the need for autocatalysis in the model producing the best fit when HI catalysed the reaction between PdI2, CO and H2O.

Smart hydrogels are macromolecular networks that can exhibit significant and reversible changes in volume upon application of an external stimulus such as pH or temperature. These polymers are well suited for use in delivery systems, tissue engineering and actuation, although currently volume changes must be externally initiated and release is often uncontrolled. Gels able to self-oscillate and distribute absorbed moieties in a controlled regime can be realised by coupling such smart materials to oscillatory chemical reactions that oscillate in the relevant stimuli to induce a volume change within a polymer gel. This work comprises of the synthesis and characterisation of a pH-sensitive hydrogel that has shown to be a good candidate for combination with appropriate oscillatory reactions. Genipin-crosslinked chitosan-poly(vinyl pyrrolidone) hydrogels were synthesised and investigated for their potential to be coupled to chemical oscillators. This semi-interpenetrating network combines biocompatibility, low toxicity, biodegradability and haemocompatibility attributes using genipin, a natural crosslinking agent with low cytotoxicity that autofluoresces upon crosslink formation. Effects of gel composition, gelation time and post synthetic manipulation on the structure, swelling, responsiveness and the mechanical properties are evaluated. Particular emphasis is placed upon improving network stability via freezing and thawing hydrogels for various timescales and cycles. Mechanical properties of the hydrogels were determined via uniaxial compression tests in multiple environments where they may find application. These results are related to the morphology and swelling potential of the networks. Further to determining volume variations gravimetrically, the hydrogels are also characterised optically, examining the change in surface area and height of the specimens. The force response upon swelling and collapse is investigated under an oscillatory regime and subsequently applied with the bromate-sulfite-ferrocyanide oscillatory reaction. In view of prospective applications, the potential of the hydrogel to release absorbed constituents from within the matrix is also determined. This thesis aids the development towards applications in controlled, pulsatile and sustained actuation and release.