Asymmetric transfer hydrogenation (ATH) represents a powerful methodology for the synthesis of chiral secondary alcohols. The synthesis of chiral propargylic alcohols by asymmetric transfer hydrogenation of acetylenic ketones has been applied to a number of applications including target oriented synthesis. In this thesis, the asymmetric transfer hydrogenation of a large number of functionalized alkyones and dialkyones has been fully investigated. Basic principles as well as detailed reaction conditions for the ATH of acetylenic ketones have been established. Chiral propargylic alcohols have been successfully prepared by a new method that was developed during this project and some of the products and strategies were used for the total synthesis of (-)-yashabushidiol B and panaxjapyne A. Moreover a group of aromatic ketones functionalized with the 1,3-dioxin-4-one scaffold were prepared and used as substrates for asymmetric transfer hydrogenation. Detailed reaction conditions such as catalyst loading, temperature, substitution effects and stability of substrates were fully investigated. Reduced products were prepared in a highly stereoselective manner and the utility of this method and the resulting chiral alcohols have been illustrated by the total synthesis of yashabushitriol. The application of ATH to the preparation of a highly optically pure ester for scanning tunnelling microscopy (SCM) dissociation and hierarchical assembly was also undertaken.

We investigate the synthesis and application of anisotropic hollow silica colloids as air voided opacity modifiers in dry polymer films in Chapter 1, with the aim of improving upon the light scattering efficacy of the commercially used isotropic hollow latex particles, ROPAQUE™. In order to generate anisotropic hollow silica particles we utilized a sacrificial templating method, ultimately leading us to investigate the opacifying power of hollow silica particles derived from a calcium carbonate template known as SOCAL P3. Initial investigations indicated that shell fragmentation and collapse of our “1st generation” hollow silica particles (with thin shells) led to a loss of opacity, as few air voids remained intact. Tuning the reaction parameters afforded hollow silica particles with thicker shells that displayed enhanced light scattering over the 1st generation hollow SiO2 particles and to SOCAL P3 when film thickness was accounted for. Chapter 2 is an extension of the work done in Chapter 1, wherein we aim to improve pigment dispersion (and consequently opacity) by grafting negatively charged, hydrophilic, polymer brushes to CaCO3@SiO2 particles. This confers enhanced colloidal stability to the particles through electrosteric stabilization. For this we first functionalize the surface with a tertiary alkyl bromide atom transfer radical polymerization (ATRP) initiator to furnish a surface capable of growing polymer brushes from. The initiator is anchored to the surface through siloxane bonds and an amide group, the latter to enhance hydrolytic stability over a wide pH range. We then used a SI-ATRP (where SI = surface initiated) in order to grow the polymer brushes, which we found to generate highly colloidally stable hollow SiO2 particles that demonstrate an enhanced contrast ratio to the sterically stabilized hollow SiO2-PVP particles used in Chapter 1. In Chapter 3 we investigate the multiple orientations of hematite superellipsoids (pseudocubes stabilized with PVP) trapped at an oil-water interface, through a combination of experiments and simulations. We find three orientations in all; two of which are thermodynamic minima and one which corresponds to a kinetically-trapped orientation. The latter results from some particles going through a negligible free energy gradient upon reorientation. Experimental and computational results for the relative balance of particle populations are found to be in excellent agreement with one another. We show that the final position of the particle is both a function of the free energy landscape and the precise orientation of the particle at the point of contact with the interface. A modified silica rod synthesis from an oil-in-water emulsion is demonstrated in Chapter 4, whereby we manage to asymmetrically include a manganese oxide head at one end of the rod to generate a colloidal “matchstick” morphology. Placing these particles into a solution of hydrogen peroxide as fuel facilitates their propulsion as they form an asymmetrical gradient of the breakdown products of hydrogen peroxide; water and oxygen. Adjusting fuel concentration alters the effective diffusion coefficient with a 1st order relationship. Furthermore, we demonstrate that these particles can undergo chemotaxis towards a higher concentration of fuel when placed into a fuel gradient. We rule out convection and other external forces as the reason for directional motion by simultaneously imaging catalytically inert microspheres which travel under convection in the opposite direction to that of the rods.

The structure and and optical properties of lithium niobate-tantalate have been studied with a focus on the Ta-rich end of the solid solution series. Structural studies using a range of X-ray and neutron powder diffraction measurements between -230 and 820 C have been performed on the full compositional range. Rietveld refinements of the collected diffraction data have allowed the structural changes to be investigated as a function of temperature and Ta content. To complement the structural investigations, the effect of the changes in the Li content in lithium tantalate has also been investigated. As the Li content is decreased or the temperature is increased, the Ta displacement and the octahedral tilt decrease which coincides with an increase in the birefringence. Crystals of lithium niobate-tantalate, across the full compositional range have been made using a lithium vanadate flux growth technique. Single-crystal diffraction measurements confirmed the results of the powder diffraction measurements; the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent and by comparison with the structural studies, have shown that the structures remain polar through the zero-birefringence points. Finally, a series of DFT calculations on the structures determined using Rietveld refinements of the neutron powder diffraction measurements on LT have been used to investigate the effect of each atom on the optical properties. The optical properties are insensitive to the position of the Li and depend on the O and Ta positions. The position of the Ta atom has the largest effect on the optical properties and the calculated birefringence increases with increasing temperature as expected from experimental measurements.

The work undertaken in this thesis focuses on the synthesis of biodegradable materials with desirable properties via the organic catalysed ring opening polymerisation (ROP) of cyclic monomers. Influence over the resulting polymer properties is obtained either through the careful design of catalyst or monomer. Chapter 1 reviews organic catalysts that have been developed for ring opening polymerisation, focussing on particular advantages and disadvantages of each and providing an overview of compatible types of cyclic monomers. (-)-Sparteine in conjunction with a co-catalyst is capable of synthesising isotactic PLA with very few stereoerrors, but its sudden commercial unavailability has led to a need for a replacement. Chapter 2 therefore focuses on the synthesis of benzyl bispidine, a (-)-sparteine analogue, demonstrating its almost identical behaviour as a ring opening polymerisation catalyst to produce polymers with optimal properties from lactide. Post-polymerisation provides access to functionalities not compatible with ROP, and allowing careful tailoring of polymer properties. Whilst a range of cyclic carbonate monomers have been designed to provide this ability after ROP, poly(carbonate)s with only low glass transition have been obtained. Chapter 3 describes the synthesis of 9-vinyl-2,4,8,10-tetraoxaspiro[5.5]undecan-3-one (VDC), a sterically bulky, vinyl functional cyclic carbonate and its subsequent ROP and thiol-ene functionalisation to yield functional poly(carbonate)s with improved thermal properties. In Chapter 4, work is undertaken to tailor the glass transition temperature of functional poly(carbonate)s. Copolymers of VDC with the allyl functional cyclic carbonate allyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate (MAC) are synthesised to demonstrate the ability to produce poly(carbonate)s with a predetermined glass transition temperature after post-polymerisation functionalisation depending on the initial monomer feed ratio. In Chapter 5 the results from the previous chapters are discussed, with the experimental data obtained for these chapters provided in Chapter 6.

This thesis explores the use of ring-opening polymerisation (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerisation to prepare linear and cyclic graft copolymers with a polycarbonate backbone. The solution properties and self-assembly behaviour of these linear and cyclic graft copolymers with hydrophilic side arms is also described. Chapter 1 introduces the polymerisation techniques used in this thesis, namely ROP and RAFT, and provides a review of the self-assembly of polymers that possess a cyclic topology. In Chapter 2, the synthesis and ROP of a novel cyclic carbonate monomer bearing pendent norbornene functionality is described. Successful postpolymerisation modification of the norbornene functionality is demonstrated for a range of addition reactions; 1,3-dipolar cycloaddition, inverse electron demand Diels-Alder reaction and radical thiol-ene addition, and is also shown to provide access to multi-functional polycarbonates. Attempts to prepare graft copolymers via the grafting of thiol-terminated polymer chains to the norbornene-functional polycarbonate backbone are also described. Chapter 3 describes the optimised synthesis of linear graft copolymers via the ROP of a RAFT chain transfer agent (CTA)-functional cyclic carbonate monomer and subsequent RAFT polymerisation to grow polymer chains from the RAFT CTA sites located along the resulting polycarbonate backbone. This methodology was used to prepare a polycarbonate-g-poly(Nisopropylacrylamide) amphiphilic copolymer and its self-assembly to afford degradable, thermoresponsive particles is demonstrated. In Chapter 4, the optimised procedures developed in Chapter 3 for the preparation of linear graft copolymers are applied to the preparation of welldefined cyclic graft copolymers with a degradable cyclic polycarbonate backbone and a range of side arm compositions. Chapter 5 investigates the solution properties and self-assembly behaviour of linear and cyclic graft copolymers with hydrophilic poly(N-acryloylmorpholine) side arms and a hydrophobic polycarbonate backbone, prepared using the methodologies developed in Chapters 3 and 4. Chapter 6 provides a summary of the key findings of Chapters 2 – 5 and Chapter 7 provides the experimental methods of this thesis.

A procedure for using Molecular Dynamics (MD) simulations to provide essential fl uid and interface properties for subsequent use in Computational Fluid Dynamics (CFD) calculations of nano-scale fluid fl ows is presented. The MD presimulations enable an equation of state, constitutive relations, and boundary conditions to be obtained for any given fl uid/solid combination, in a form that can be conveniently implemented within an otherwise conventional Navier-Stokes solver. The results presented demonstrate that these enhanced CFD simulations are capable of providing good fl ow field results in a range of complex geometries at the nano-scale. Comparison for validation is with full-scale MD simulations here, but the computational cost of the enhanced CFD is negligible in comparison with the MD. It is shown that this enhanced CFD can predict unsteady nano-scale ows in non-trivial geometries. A converging-diverging nano-scale channel is modelled where the fl uid fl ow is driven by a time-varying body force. The time-dependent mass fl ow rate predicted by the enhanced CFD agrees well with a MD simulation of the same configuration. Conventional CFD predictions of the same case are wholly inadequate. It is demonstrated that accurate predictions can be obtained in geometries that are more complex than the planar MD pre-simulation geometry that provides the nano-scale fl uid properties. The robustness of the enhanced CFD is tested by application to water fl ow along a (15,15) carbon nanotube (CNT) and it is found that useful fl ow information can be obtained. The enhnaced CFD model is applied as a design optimisation tool on a bifurcating two-dimensional channel, with the target of maximising mass fl ow rate for a fixed total volume and applied pressure. At macro scales the optimised geometry agrees well with Murray's law for optimal branching of vascular networks; however, at the nano-scale, the optimum result deviates from Murray's law, and a corrected equation is presented. However, it is found that as the mass flow rate increases through the channel high pressure losses occur at the junction of the network. These high pressure losses also have an impact on the optimal design of a network.

The objective of this thesis was to prepare thermoresponsive PEG-based homopolymers and copolymers by combination of cobalt-mediated catalytic chain-transfer polymerization (CCTP) and thiol-ene “click” chemistry and prepare well-defined glycopolymers via “living” polymerization and “click” chemistry. The effect of different catalysts for the nucleophilic mediated thiol-ene reaction was investigated using model compounds, both monomers and oligomers obtained by CCTP. Different catalysts, including pentylamine and hexylamine (primary amines), triethylamine (tertiary amine), and two different phosphines, dimethylphenylphosphine (DMPP) and tris(2-carboxyethyl) phosphine (TCEP), were investigated in the presence of different thiols. The optimum reaction conditions for nucleophile mediated thiol-ene click reactions were investigated. Thermoresponsive PEG-based homopolymers and copolymers of OEGMEMA obtained by CCT were modified using thiol-ene click chemistry with a variety of different functional thiol compounds to yield functional thermoresponsive polymers in high yield. The effect of different solvent systems for based catalyzed thiol-ene reaction was investigated in the presence of different functional thiols. The ATRP polymerization of TMS-PgMA and TIPS-PgMA and ROP polymerization of aliphatic polyester were investigated. A maleimide functional initiator was used in order to achieve post conjugation of nanoparticles for drug delivery. Moreover, the disulfide based bifunctional initiator was introduced into the midpoint of the polymer chain, which could break down to afford the corresponding polymer chain with thiol end group under the reducing condition. The thiol-terminated polymer was also post-functionalized via thiol-ene click chemistry. In addition, the aliphatic polycarbonate is a biocompatible and biodegradable polymer, which is widely used in medical and pharmaceutical applications. The subsequent introduction of sugar moiety to the reactive polymer chain via CuAAC click reaction and then the interactions between glycopolymers and lectins were investigated by Surface Plasmon Resonance (SPR) and Quartz Crystal Microbalance with Dissipation (QCM-D). The controlled SET-LRP polymerization of TMS-PgMA and SET-RAFT polymerization PgMA with the intact alkyne at ambient temperature were investigated. A maleimide functional initiator and CPDB, as the chain transfer agent have been employed. The introduction of maleimide moiety was to allow for post polymerization conjugation to peptides via reaction with cysteines. The subsequent introduction of sugar azides to click with the reactive polymer containing alkyne group and the glycopolymers through CuAAC was also investigated. The glycopolymer has been successfully prepared combining the SET-LRP/SET-RAFT and CuAAc click chemistry at ambient temperature.

A series of chiral di-, tri- and tetra amine ligands were synthesised from enantiomerically pure 1,2-cyclohexanediamine and 1,2-diphenylethanediamine and, in combination with Ru(II) or Fe(II), employed as asymmetric catalysts in the epoxidation of aromatic alkenes, hydrosilylation of acetophenone, nitro-aldol reaction and asymmetric transfer hydrogenation (ATH) of different ketones. A novel class of tridentate ruthenium catalysts of general structure 239 below were developed. Specifically, a novel class of tridentate ligand was synthesised and a derivative of (R,R)-N-tosyl-1,2-diphenyl-1,2-ethylenediamine ((R,R)-TsDPEN) and was found to provide the best activity and selectivity in reduction reactions with Ru3(CO)12. Reaction conditions were optimised using 239 for the ruthenium-catalysed ATH of a number of ketones. In particular, it was found that the presence of meta-methoxy substituent on the aromatic ring of the substrate yields optimal results under the ATH conditions employed for 48 h (98% conv., 94% ee). Also, aryl ketones substituted at the ortho position were reduced in almost quantitative yield, with enantiomeric excesses greater than 90% in some cases.

This work describes the use of electron spin resonance spectroscopy in investigations of the reduction of a number of organic compounds by solutions of sodium in liquid ammonia. Solutions of alkali metals in ammonia contain the ammoniated electron, in all its possible forms, and essentially this species is the effective reducing agent. The simple reduction step is the one-electron addition to a suitable substrate molecule, which may then undergo a number of successive reactions before a stable product is formed. The nature of the metal-ammonia solutions, and the paths the reductions may take are discussed in Chapter 2. The simple one-electron reduction product, a radical-anion, is often too short-lived to allow observation by normal static methods, and therefore a relatively high concentration of radicals must be artificially maintained to permit their detection. Basically two different approaches have been utilised: i. Stabilising the radicals either by direct production or trapping in solid matrix, therefore preventing the radicals from reacting, and ii. Production of a high steady state concentration of radicals in solution by either continuous electrolysis or buy use of a flow system, A brief discussion of the methods used in the study of transient radicals is given in Chapter 1. Generally the e.s.r spectra are less well-resolved in solid matrices than in solutions, and for species showing a large amount of hyperfine structure, production of the radicals in solution is preferred. A rapid mixing device has been developed to allow observation of transient intermediates by e.s.r. spectroscopy. The mixer was designed particularly for the type of system and experimental technique under consideration here, and is based on a design used in biological kinetic studies. Observations 2-5 msec. after mixing are possible, and this represents a considerable advantage over the widely used aqueous solution mixing device, where observations are made on a 10-2 sec. time scale. The mixing chamber and experimental technique are presented in Chapter 3. Analysis of the e.s.r. spectrum of a compound allows the calculation of its unpaired electron distribution, the coupling constants being related to the unpaired electron spin density. Spin densities have been calculated theoretically, and it has been found that simple Hückel calculations of pi-electron spin densities show good agreement with “experimentally” determined values. Accordingly, both Hückel and McLachlan spin densities have been calculated for most of the substrates used, and in general it is found that the McLachlan treatment gives better agreement with experiment than the simple Hückel model. A brief discussion of the relevant molecular orbital theory is presented in Chapter 1, and the computer programme used to perform the theoretical calculations is given in Appendix 3. Analysis of the e.s.r. spectra I sometimes very difficult if a large number of lines are present, and two computer programmes used for the simulation of single and mixed e.s.r. spectra are given in Appendices 2 and 3 respectively. In Chapter 4 is described the reduction of a number of aryl halides. With the exception of fluoro-substituted compounds, the halo-pyridines, pyrimidines, benzenes, biphenyls, and naphthalene, all give the e.s.r. spectrum of the radical-anions of the parent compounds on reduction. On the other hand, fluorine is retained as is evident from the spectra, for a much longer period, as shown by observation 0.1 and 1.0 sec. after mixing, while static experiments show some products to be stable for longer periods of time in this system. Mechanisms have been proposed to account for these reductions. Halobenzonitriles have also been studies and the results are in agreement with the proposed reduction mechanisms. Reduction of pyridine, pyrimidine and some simple ring-substituted compounds has been investigated, and their e.s.r. spectra characterised in most cases. Previous attempts to observe the pyridine radical-anion had failed, the spectrum of the 4,4’-bipyridyl being obtained instead. Observations 0.1, 1.0 sec. and 1 min. after mixing allow the reduction path of these nitrogen heterocyclics to be followed, and it is shown that pyridine, pyrimidine and simple alkyl- and alkoxy-substituted pyridines undergo dimerization to give exclusively the respective 4,4’-dimers, unless the 4-position is blocked. Pyridine-N-oxide undergoes a more complex reduction, giving pyridine-N-oxide, pyridine and finally 2,2’-bipridyl radical-anions. Pyridine-2-carboxylic acid gives a spectrum suggesting some form of nitrogen-hydrogen bonded species. Pyridine dicarboxylic acids all have on feature in common, a splitting from an extra proton which arises through a protonated nitrogen atom. Reduction of pyridine in the presence of excess ethanol also shows this feature, and its spectrum is due to C5H5NH. Calculation of the nitrogen sigma-pi interaction parameters gives values of QNN=+28.5 oe. And QCNN=-O.5 oe., in good agreement with results obtained previously. Theoretical calculations have been performed, and comparison with experiment has enabled the assignment of coupling constants to particular positions, and also gives the best set of parameter values required for the calculations, providing a check with values used for comparison with other measurements. The results are presented in Chapter 5. In Chapter 6 is described the reduction of benzoic acid and some of its simple ring-substituted derivate. Ionisation occurs initially, followed by reduction to give the corresponding radical-anions. These species are short-lived, as no spectra are obtained when observations are performed 0.1 sec. after mixing. No further paramagnetic products are found. Molecular orbital calculations have been performed for each compound, and excellent agreement with experiment obtained using the parameter values kC’-C=1, 2, kC-O-1, 6, hO-2.0 for the ionised carboxyl group. Reduction of nitro-substituted isophthalic and terephthalic acids shows the presence of two distinct species, one being unstable while the other is stable for more than one hour, in both cases. The unstable species show a large splitting from an extra proton which is thought to be attached to the nitrogen atom. This proton is lost to give the stable radicals, experimental evidence and comparison with computer calculations suggesting them to be the nitro-substituted radical-anions.

The aim of this work was to detect whether non-classical electron delocal1zation would occur between a negative charge situated at the.he 7-position of bicyclo (2,2,1) compounds or the 9-position of bicyclo (4,2,1) compounds and double bonds situated in other parts of systems of these types. . The method chosen for detection of such interactions was comparison of the rates of removal of protons, from those positions, in bicyclic compounds with and without olefinic bonds. In order to labilize the protons at the 7- and 9-positions it was decided to synthesize compounds with phenyl substituents at these po1nts. The key compounds required were 7.-phenylnorbornadiene and 9-phenylbicyclo (4.2.1) nonatrtene. The first was synthesized by a known route without difficulty and from it 7-phenlmorbornane and syn-7-phenylnorbornene. The synthesis of the second occupied the major part of the time available and was finally achieved by a method which was indicated, but not fully described, during the course of the work. Two earlier alternative methods failed. The rates of exchange of the benzylic protons of 7-phenynorbornane and cymene, used as an acyclic comparison, were measured and upper limits set on the rates of exchange of 7-phenylnorbornadiene and seen -7 – phenylnorbornene. At 110o the rates of exchange of the benzylic protons of 7-phenylnorbornadiene and syn-7-phylnorbornene are at 1 ast 140 and 260 times respectively less than that of 7-pheylnorbornane at the same temperature. Although these rate differences are in agreement with prediction of destabilizing non-classical interactions in compounds of this type they are not sufficiently great to prove it. An alternative explanation is that introduction of double bods into the norbornane skeleton increases the strain energy of the molecule and decreases the stabilization of the carbanion by conjugation with the phenyl group ; which would require a further increase in strain energy. In the case of 9-phenylbicyko (3.2.1) nonatriene to appears that treatment with highly basic medium causes several complex changes, probably involving the removal of the benzylic proton at a greater rate than that of cymene. On the basis of the strain energy argument it would be expected that the rate of removal of the benzylic proton form the compound would lie between the rates of sumene and 7-phylnorborane. Further experiment in the system may yield less equivocal information than the experiments of the bicycle (2.2.1) systems. A stabilizing interaction is predicted for anions of this type and hence reduction to the bicyclomonane should cause a diminution of the rate of removal of the benzylic proton. The strain energy argument would predict an increase in the rate of benzylic proton abstraction on hydrogenation to the bicyclononane.