Anionic polymerisation techniques have been optimised to develop a “one-pot”, facile method to produce both linear and branched polystyrenes utilising the “Strathclyde” route to highly branched structures. ATRP was investigated as a possible method but anionic polymerisation was found to give much better control over the size and structure of polystyrenes produced. Using this anionic polymerisation relatively monodisperse linear polystyrenes were synthesised with dispersity values as low as 1.03 for a polystyrene chain with a targeted degree of polymerisation (DPn) of 100 monomer units. A number of different structures of branched polystyrene were synthesised, and their different physical properties examined by viscometry measurements and differential calorimetry scanning experiments. It has been found that very dense, highly branched materials (with approximations of 48 polymer chains branched together) can be synthesised with a targeted primary chain DPn = 10 monomer units. Weight average molecular weight (Mw) values as high as 992,000 gmol-1 for branched polystyrene can be synthesised with a primary chain length of DPn =50 monomer units. Functional polystyrenes were synthesised both by initiation with an amine containing compound and sec-BuLi, resulting in chain end functionalisation, and also post-functionalised by sulphonation of synthesised polystyrenes, resulting in a statistical distribution along the polymer chains pendant groups. The hydrophilicity could be manipulated by the percentage of sulphonation. At over 30% sulphonation of the pendant polystyrene groups, the polymers become water soluble. Polymer nanoparticles have been synthesised by a nanoprecipitation method from functionalised branched polystyrene synthesised by anionic polymerisation techniques. Nanoparticles synthesised from DPn10 branched sulphonated polystyrenes were analysed by dynamic light scattering and found to be approximately 60nm with dispersity values as low as 0.15. They were found to be stable after 6 months ambienmt storage, and some preliminary testing on the encapsulation of Oil red suggests that the nanoparticles may be capable of encapsulating hydrophobic drugs.

This thesis aims at understanding the interaction between insulin and interfaces with a multi-disciplinary approach. We investigate three facets of the interaction. In the first part (chapter 4), we study the interaction of insulin with the air/water interface, for different oligomeric compositions of the solution phase. With the help of Sum Frequency Spectroscopy and calculations of the second order nonlinear susceptibility, we can show that insulin monomers segregate to the hydrophobic air/water interface. Since the insulin monomer is the key species to denature and refold to fibrils, our finding explains for the first time why agitation of insulin solutions and the accompanying increase in air/water interface area accelerates fibril formation. In the second part (chapter 5), we investigate the interaction of insulin monomers at low pH with model hydrophilic and hydrophobic solid surfaces. We use a combination of spectroscopic methods, like ATR FT-IR, XPS, SFG and QCM-D to characterise the silicon functionalised solid surface, to quantify the amount of adsorbed protein and to determine its secondary structure. We show that, contrary to physiological conditions, where insulin monomers are known to change secondary structure upon adsorption, an acidic environment leads to near-native adsorbed insulin, which is stable for at least a day. We further show that heat is needed to restructure the adsorbed insulin monolayer and that this restructured monolayer appears to provide the template for further growth. In the final part (Chapter 6), we apply a comparatively simple experimental method, Reflection Anisotropy Spectroscopy for the first time to the formation of amyloid fibrils at interfaces. In a comparison with FT-IR spectroscopy of our model solid surfaces, we show that a drastic change in the peptide backbone arrangement occurs at a hydrophobic surface, when FT-IR merely detects a thick layer with partial beta-sheet structure. We believe this structural change is the beginning of insulin fibril formation and we use the new tool to explore further changes in the adsorbed layer as it ages over several months.

The selective hydrogenation and dehydrogenation of organic molecules is a fundamentally challenging and an attractive transformation for both, industry and academia. However, catalysts capable of undergoing both transformations under environmentally benign conditions are rare. In this thesis, our contribution to the development of a “universal” catalyst capable of achieving both hydrogenation and dehydrogenation of a wide range of organic compounds under mild conditions is presented. A general introduction covering the recent developments in the area of transfer hydrogenation of C=X (X = O, N) bonds, relevant applications of cyclometalated half-sandwich complexes and previous work in the area developed within our group is described in Chapter 1. In Chapter 2, Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile, α-ester), α-keto esters, β-keto esters, and α,β-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50000 at pH 4.5, requiring no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β-functionalised secondary alcohols, such as β-hydroxyethers, β-hydroxyamines and β-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis. In Chapter 3, the cyclometalated iridium complexes are shown to catalyse the transfer hydrogenation of various nitrogen heterocycles, including but not limited to quinolines, isoquinolines, indoles and pyridiniums, in aqueous solution under mild conditions. The catalyst shows excellent functional group compatibility and high turnover number (up to 7500), with loading as low as 0.01% being feasible. In Chapter 4, cyclometalated iridium complexes are found to be versatile catalysts for the direct reductive amination of carbonyls to give primary amines under transfer hydrogenation conditions with ammonium formate as both the nitrogen and hydrogen source. The activity and chemoselectivity of the catalyst towards primary amines is excellent, with a substrate to catalyst ratio of 1000 being feasible. Both aromatic and aliphatic primary amines were obtained in high yields. Moreover, a first example of a homogeneously catalysed transfer hydrogenative direct reductive amination (DRA) has been achieved for -keto ethers, leading to the corresponding -amino ethers. In addition, non-natural -amino acids could also be obtained in excellent yields with this method. Following the success of hydrogenation, cyclometalated iridium complexes were also found to be versatile catalysts for the oxidant-free, acceptorless dehydrogenation of various N-heterocycles, including tetrahydroquinolines, tetrahydroisoquinolines, tetrahydroquinoxalines and indolines. This protocol was also successfully applied to the total synthesis of alkaloids as presented in Chapter 5. Chapter 6 describes the development of a new strategy for the oxidant- and base-free dehydrogenative coupling of N-heterocycles at mild conditions. Under the action of an iridium cyclometalated catalyst, N-heterocycles undergo multiple sp3 C-H activation, generating a nucleophilic enamine that reacts in situ with various electrophiles to give highly functionalised products. The dehydrogenative coupling can be cascaded with Friedel-Crafts addition, resulting in double functionalisation of the N-heterocycles. The dehydrogenation products could also be saturated under either hydrogenation or transfer hydrogenation conditions, giving rise to structurally diverse products. Final conclusion and perspectives of the research covered in this PhD thesis are presented in Chapter 7.

The formation of multi-functional thiol materials for “click” reactions in synthetic chemistry has been significantly under-represented due to added practices that are typically required when working with sulfur-containing compounds. An efficient and facile approach to approach to introducing multiple masked thiols at the surface of polyester dendritic materials is presented, avoiding these difficulties, by utilising a xanthate protecting group. One-pot xanthate deprotection and thiol-acrylate Michael additions from the xanthate-functional dendrimers (generation zero to two) has been accomplished for the first time, using three different acrylate substrates of varying chemistry. The dendrimers were fully characterised by 1H and 13C NMR, SEC and either electrospray or MALDI-TOF mass spectrometry, depending upon the generation and nature of the end groups. In a similar fashion, this one-pot methodology was extended to prepare twenty different surface functional LDHs via the use of xanthate functional ATRP dendritic macroinitiators (generation one to four) and six different acrylate monomers. Model reactions and kinetics studies showed that the presence of xanthates within the initiator structure did not complicate the ATRP of tBuMA. The LDHs were fully characterised by 1H NMR and SEC. In the final study, employing one-pot xanthate deprotection and thiol-acrylate Michael addition, four dendritic ATRP macroinitiators with hydrophobic and pH responsive peripheral functionalities were prepared. Polymeric surfactants comprised of LDHs and HPDs were synthesised, varying in end group composition using different dendritic macroinitiators, and through the use of mixed initiating system, using a non-dendritic component. O/w emulsions stabilised by surfactants comprised of linear polymers, LDHs, or mixed linear polymers/LDHs architectures showed coalescence over a long term stability study under neutral and acid conditions. In contrast, o/w emulsions stabilised by surfactants comprised of branched polymers, HPDs, or mixed branched polymer/HPDs architectures showed no coalescence over a long term stability study under neutral and acid conditions. Further dilution and thermal studies to probe emulsion systems stabilised via branched surfactant architectures resulted in emulsion breakdown.

Currently there is a huge amount of interest in the synthesis and electrical characterisation of single molecules that have the potential for use in electronic devices. In order for this technology to move forward it is necessary to gain insights into structure-property relationships at the nanoscale, as well as a basic understanding of the charge transport through various molecular architectures. It has previously been demonstrated that the electrical properties of redox active single molecules can be investigated as a function of potential. This thesis investigates the single molecule conductance properties of molecules incorporating a transition metal centre. The research presented in this thesis investigates two major studies. The first is a study into the electrochemical and conductance properties of a variety of transition metal based complexes. Initial electrochemical and conductance investigations of a series of pyterpy transition metal complexes showed a similar conductance for all the series, this was investigated in two different environments. The ligand was then varied and several ruthenium complexes were investigated, to investigate the anchoring group effect and to examine the length and conductance relationship. The data presented here demonstrates a higher conductance for methyl sulphide anchoring group than the pyridyl anchoring group. The data presented showed a low dependence on molecular length, suggesting a hopping transport mechanism. The conductance behaviour of two [M(pyterpy)2](PF6)2 complexes were investigated as a function of potential in an ionic liquid medium. The data presented exhibited an increase in conductance as the redox potential was reached. The second study investigated the conductance behaviour of two 6-porphyrin nanorings. This is the first conductance study on these porphyrin based complexes. The study investigated a ‘complete’ and ‘broken’ nanoring and showed a smaller than expected difference in conductance between them. This preliminary study has allowed for the development of the structure to investigate possible quantum interference effects.

Energy conversion between carbon monoxide (CO) and ruthenium tetraphenyl porphyrin (RuTPP) on Cu(110) surface has been investigated by means of vibrational sum frequency generation spectroscopy (SFG) and scanning tunneling microscopy (STM) in order to understand vibrational and chemical dynamics at surfaces. The study revealed that introducing porphyrins has considerable effect on the energy conversion between CO and copper, and also on the adsorbate dynamics, i.e. desorption of CO. CO/Cu(110), was first studied, showing that energy conversion between CO and copper becomes faster with increasing coverage of CO. This coverage dependence can be explained by the modification of the potential energy surface (PES) and gradual filling of density of states (DOS) around the Fermi level (EF). The results also indicate that the frustrated translation mode cannot be the dominant vibrational mode for electron coupling. For the study of the energy conversion between CO and porphyrin on Cu(110), the adsorption structure of RuTPP is first investigated using an STM, revealing that the ruthenium atom occupies the short bridge site of Cu(110). With increasing coverage of RuTPP molecules, surface supramolecular organization was formed and it was compared to theoretically calculated structures. The calculated structures are used for the modeling of the PES and DOS. The first discovery from CO-RuTPP/Cu(110) is the modification of the PES for the C-O stretch mode, showing a larger Morse anharmonicity cai_e and lower dissociation energy De than on a bare copper. The anharmonic constants are compared for various surfaces, which suggest the importance of considering local electric fields and the vibrational Stark effect to explain the large anharmonicity of oxidized and porphyrin covered surfaces. Inserting RuTPP also changes the desorption mechanism of CO by inelastic tunneling process from a one-carrier to a two-carrier process with lower threshold bias voltage. The resonant electron tunneling from occupied states of CO-RuTPP to an STM tip triggers CO desorption. The two-carrier process can be explained by tunneling of a second hole into an excited state, which was created by a hole tunneling into an adsorbate HOMO. On the other hand, facile laser-induced-desorption of CO was observed from CO-RuTPP/Cu(110), although, it shows a larger desorption energy of CO than on bare Cu(110). This can be explained by the enhancement of hot electron coupling via the DOS around EF. The coupling between the C-O stretch mode and hot electrons is also changed from a frequency redshift to a blueshift, indicating that the CO-Ru bond weakens, which can be caused by excitation of the CO-Ru stretch or bending of CO.

The primary aim of the work presented in this thesis was to design and synthesise well-characterised material that would exploit visible light to promote photocatalysis, involving the degradation of organic compounds in water, or generation of hydrogen from the water splitting reaction. In doing so, both environmental concerns, such as the removal of pollutants in wastewater, and energy concerns, such as the generation of a clean and safe form of hydrogen for use as a renewable fuel could be addressed. The approach used was to employ existing methods to synthesise high surface area quasi-amorphous material that is active in UV light for photocatalysis, and then design and employ post synthetic modification to promote the material for visible light photocatalysis. Niobium (V) oxide was synthesised in a high surface area form, successfully scaling up the synthesis from 2 g to over 200 g quantities of as made material. This UV active photocatalyst was fully characterized by methods including X-ray diffraction and thermal gravimetric analysis. The material was used to degrade the model dye Methyl Orange and generate hydrogen from a methanol / water solution without further modification. By adding platinum group metals (PGMs) to the niobium (V) oxide, a greatly enhanced efficiency for hydrogen generation was realized. A survey of metals (platinum rhodium and palladium) and weight percentages of metal added (0.01 – 1%) was carried out, with the PGM added materials characterised for hydrogen generation using a methanol / water sacrificial reagent system, as well as PGM dispersion, TEM imaging, EDX and X-ray photoelectron spectroscopy for characterising the higher weight percentage material. Finally, chromium (III) oxide was added to the surface of the niobium (V) oxide in various weight percentages (1% - 5%). The optical properties of this composite material, in comparison with the starting materials were investigated, in particular the difference in diffuse reflectance of the starting materials and composite were highlighted to demonstrate charge transfer between the chromium (III) on the surface, and niobium (V), in the bulk of the material, with the oxidation states being confirmed by XPS. Furthermore, this material was found to degrade methyl orange under visible light. An action spectrum was carried out measuring the quantum efficiency of the reaction at different wavelengths, which proved it was the chromium – niobium charge transfer absorbance in isolation that was responsible for the methyl orange degradation.

The work described in this thesis aims to present results regarding the exploration, validation and use of a novel rotor-stator type mixing equipment employing controlled deformation dynamic mixing (CDDM) technology in creating sub-micron emulsions for use in chemical reactions. Emulsification is the process by which one immiscible liquid (e.g. oil) is finely dispersed throughout another immiscible liquid (e.g. water) and stabilised, commonly through the addition of a surface active agent or emulsifier to the system. Specific focus was given to the emulsification of plant oils (such as sunflower seed oil) as a way of improving their available reactive surface area. The addition of emulsifiers in this case was used to sufficiently reduce the interfacial tensions, allowing for greater droplet break-up, and provide adequate emulsion stability. Further testing of these emulsions was performed within biphasic saponification and transesterification reactions, such as those commonly employed in the production of soap and biodiesel. It was hypothesised that by reducing the dispersed oil phase droplet size in the presence of an emulsifier, and thus increasing the surface area to volume ratio, reaction rates could be manipulated. Testing of this hypothesis showed that despite the presence of surfactant and, in the case of the transesterification reaction, water, the use of sub-micron oil droplets caused a decrease in the overall reaction time (time spent at reaction temperature and under agitation). In support of this work, high-throughput formulation (HT) and design of experiment (DoE) software was adopted to allow a quick and efficient way of screening which emulsification parameters had the greatest impact on the size of the droplets when emulsifying oil. For this work a standard emulsion containing silicone oil and Sodium Lauryl Ether Sulfate (SLES) was used. Following the identification of the optimum emulsification parameter set, work focused on the scaling up from small scale (50g) to pilot plant scale mixing devices (10kg – 300kg/hour) in order to formulate large quantities of emulsion. It was shown that the HT screening and DoE was sufficiently robust to predict emulsification parameters at scale. For an emulsion system of silicone oil and SLES, the formulation parameters that created an emulsion with the smallest droplet size using the high-throughput platform, also produced an emulsion with the smallest droplet size using the new pilot plant scale Ultra Mixing and Processing Facility (UMPF) fitted with CDDM technology. In order to characterise the emulsions created, laser diffraction measurements were used throughout this work (Malvern Mastersizer X & 2000) and “side by side” emulsification experiments were carried out using commercially available fluid processing units. Utilising either a rotor-stator type inline mixer (high shear Silverson 150/250MS mixer) or a high pressure valve type homogeniser (M-110S Microfluidizer Processor, Small Volume) the emulsions produced and processed on the respective equipment were compared with those produced via the CDDM in order to assess its capabilities and performance against two of the leading mixers available.

You’re surrounded by surfaces. Viewed from a macro perspective they might appear soft, brightly colored, or textured. Maybe you don’t think anything of them at all. But what happens when we take a closer look? Here, down at the nanoscale, chemical reactions at surfaces play a hugely important role in the world in which we live. Whether it’s preventing metal corrosion, or developing the latest fuel cell, the state of surface being investigated is crucial. Indeed, by intentionally modifying surfaces we can introduce desirable properties, all because we’re controlling what goes on at the molecular level. The first part of this thesis discusses the use of model surfaces to probe fundamental properties and processes. Firstly, model surfaces displaying well-defined chemical functionality are created using self-assembled monolayers (SAMs), and are subsequently used as a means to understand the primary interactions that occur between carbonaceous soot contaminants, and surfactant-like molecules in engine oils. The quartz-crystal microbalance (QCM) is employed as a means to determine minute levels of surface adsorption, and a structure-activity relationship for these molecules is suggested. Next, a new approach for profiling the activity of molecular adsorbates at carbon surfaces is introduced, which allows for the impact of individual surface features on resulting electrochemical activity to be determined. It is used to study the case of quinone adsorption at graphite electrodes, a currently debated topic, and it is revealed that current literature models regarding the activity of the basal surface need revision, with significant implications for carbon electrochemistry as a whole. The second part of this thesis turns to understanding and controlling surface modification processes. Through a range of complementary techniques, the ability of scanning electrochemical cell microscopy (SECCM) to control the extent of the aryl diazonium grafting process at sp2 carbon surfaces is demonstrated. Aryl diazonium chemistry as been identified as a route to band-gap generation in graphene electronics, and as such, controlled routes to localized surface modification are of great interest. Next, the versatility of SECCM for controlled surface modification is further demonstrated, where it is used as a method to draw intricate patterns of defined surface chemistry in graphene, with a strong focus on the production of integrated graphene circuits, a prospect often promised. Finally, a new methodology for the transfer of graphene synthesized via chemical vapor deposition (CVD) is introduced. Crucially, it yields graphene surfaces with distinctly low levels of contamination, an area that currently poses a problem in graphene research.

Researchers have looked at the possibility of using single molecules as functional building blocks in electronics circuits since the 1970s. The field of molecular electronics, despite its experimental and theoretical challenges, has continued to grow incessantly from a simple scientific curiosity to an emerging field with hundreds of publications per year. Thanks to the development of scanning probe microscopy a variety of techniques currently used to characterise the electrical properties of single molecules has been developed, and molecular systems mimicking the behaviour of traditional electronic components, such as transistors or rectifiers, have been prepared. Despite the obvious fact that supramolecular interactions must play a role in the charge transfer process, only a small number of reports on the subject have been published. In this thesis a set of molecular wires with an oligothiophene central unit, sandwiched between two insulating chains, has been used to probe the effect of such interactions on molecular conductance using several scanning tunnelling microscopy techniques. It has been found that the side-chain length has little effect on molecular conductance, but the presence of water in the surrounding environment triggers an increase in conductance and a switch in the behaviour from activationless to thermally-activated. Furthermore, upon exposure to electron-withdrawing small molecules, these oligothiophene molecular wires form charge transfer complexes, with conductance enhanced by a factor up to 100. Measurements performed in UHV confirmed the observed behaviour, and theoretical calculations were performed to explain it in the coherent tunnelling regime. A gateway state arising from coupling of the molecular backbone to the sulfur contacts accounts for the observed shallow decay of conductance with length, while shifting of transport resonances upon interaction with water and the appearance of interference features upon charge transfer complexation explained the temperature dependence and the conductance enhancement, with experimental observation closely matched by DFT calculations.