This thesis describes the synthesis and characterisation of novel flavin, imidazole and benzothiadiazole derivatives semiconductors with potential optoelectronic applications. The first chapter provides an introduction about organic optoelectronics and in particular about small molecule organic optoelectronic martials and their advantages and applications such as bulk heterojunction and Perovskite solar cells, nonlinear optic and hybrid light emitting diodes. Furthermore, the chapter includes an overview about flavin, imidazole and benzothiadiazole. Chapter two describes the successful synthesis and characterization a series of six diimidazole derivatives, these dyes gave promising results to be used as organic down-converting materials for solid states hybrid-LED to produce white light. The same chapter reports the synthesis and characterisation of two flavin derivatives, designed to be used also as a as organic down-converting materials for solid states hybrid-LED to produce white light. Chapter three, describes the synthesis and characterization of two novel imidazole derivatives. These two molecules were designed to be used as organic small molecules hole transport material for Perovskite solar cells. Chapter four, describes the synthesis of a bisflvin derivative are based on two isoalloxazine skeletons fused by a benzo unit. This compound prepared to be use as small molecule acceptors for bulk heterojunction solar cells. The same chapter also reports the synthesis and characterisation of double donor-acceptor systems, based on triphenylamine (TPA) as a donor and benzothiadiazole as acceptor linked ferrocene as π-conjunction unit. The aim is to use this compound as small molecule donor for bulk heterojunction solar cells. Finally, the last chapter describes the synthesis of three flavin derivatives, designed according to the donor-acceptor (D – A) geometry, to be used as organic small materials for non-linear optic second harmonic generation. Two of the compounds exhibit higher thermal stabilities and higher hyperpolarisabilities ( = 8660 – 9550 × 10-30 esu) respectively.

Polyoxopalladates (POPds) are an emerging class of unconventional polyoxometalates (POMs) which are particularly interesting due to the catalytic properties of palladium. Until recently, POPds were limited to low nuclearity {Pd12} and {Pd15} archetypes. However, in 2012, the giant {Pd84}Ac macrocycle was discovered, becoming the largest of this family to date. One of the major barriers to the discovery of POMs in general is that the chemistry relies heavily on crystallisation. The presence of POMs in solution is often overlooked if no crystalline products emerge. Furthermore, their behaviour in solution is not well-understood. This thesis expands on the family of POPd macrocycles and explores the supramolecular behaviour of the POPd macrocycles using solution analysis techniques such as SEC-HPLC, ESI-MS and NMR spectroscopy. In the first section of work, a new synthetic route to making {Pd84}Ac is reported, whereby palladium acetate is substituted for sodium acetate, allowing the carboxylate source to be added separately. This new synthetic route was investigated to explore the formation of novel macrocycles by varying the acetate ligand. Initial results showed this to be possible by substituting acetate for propionate. This yields a smaller {Pd72}Prop macrocycle, which was characterised crystallographically. An SEC-HPLC approach was then adopted to screen many small-scale reactions for the formation of other large palladium macrocycles, using a wide variety of carboxylate sources. This led to the discovery of {Pd84}Gly, an exact structural analogue of {Pd84}Ac. IMS-MS was employed to assess the relative sizes of the new macrocycles in solution, confirming the presence of {Pd72}Prop and {Pd84}Gly. The structure of {Pd84}Gly was later confirmed crystallographically. Having shown the screening method to be successful in detecting novel POPds in solution, this approach was expanded on. In the second section, SEC-HPLC was used to screen many small-scale reactions containing different combinations of polyphosphate solutions and carboxylate ligands, in the presence of Pd(NO3)2. SEC-HPLC indicated the presence of a variety of species larger in size than {Pd84}Ac, however further analysis using ESI-MS was not able to identify these products, most likely due to their decomposition under the mass spectrometry conditions, or poor separation in the SEC column. Over this course of this work, two smaller POPd clusters containing the squarate ligand were isolated: {Pd11} and {Pd8}. In the third section, two mass spectrometry techniques were employed to analyse the real-time self-assembly of the {Pd84}Ac, {Pd72}Prop and {Pd84}Gly macrocycles. Analysis was carried out using two methods: SEC-HPLC-MS and direct injection of a desalted sample (Desalted-MS). Initial results showed the loss of acetate ligands when using SEC-HPLC-MS, which was confirmed by comparing identical crystalline samples of {Pd84}Ac analysed with each technique. The {Pd72}Prop macrocycle was found to appear in solution after five days, and exhibits building units analogous to those seen in the assembly of {Pd84}Ac, suggesting a similar build-up mechanism to {Pd84}Ac. Likewise, {Pd84}Gly was found to appear in solution after four days and also exhibits the same analogous building units. Furthermore, a {Pd30} species was observed in SEC-HPLC-MS studies of the {Pd84}Gly reaction, indicating a possible template or smaller macrocycle which has not yet been isolated. In the final section, the molecular encapsulation potential of {Pd84}Ac was explored using 1D and 2D NMR techniques. Using 1H NMR spectroscopy, interactions were observed between {Pd84}Ac and a series of polyamine guests, indicating a fast exchange regime between the free and encapsulated guest molecules. Subsequent 1H DOSY NMR spectroscopy showed the diffusion coefficient of 1,8-diamionooctane matched that of {Pd84}Ac when the compounds were mixed, confirming the strong host-guest interaction. Following this, the [Ru(bpy)3]Cl2 (Ru-bpy) complex was selected as a potential guest within the {Pd84}Ac cavity due to its suitable size and photochemical properties. 1H NMR spectroscopy showed a significant shifts in the Ru-bpy 1H signals in the presence of {Pd84}Ac, indicating a fast exchange interaction. 1H DOSY NMR spectroscopy revealed the coefficient of the Ru-bpy complex was found to decrease dramatically when in the presence of {Pd84}Ac.

The field of hydrogen production and usage is a large section of the chemical industry. Hydrogen has been used in the energy, pharmaceutical and food industries, where its availability has helped develope a vast number of commodities for society. The challenges faced by science, originate from the H2 production method. Fossil fuel usage means that currently the production of H2 is linked to an unsustainable source. Gaseous hydrogen also has a complexity to its storage and utilisation, which requires the use of specialist equipment. In this thesis, the challenge of producing hydrogen is approached by using an electron-coupled proton buffer (ECPB) and water electrolysis. Using an ECPB, the drawbacks of current water electrolysis (mixing of gases, slow kinetics of the oxygen evolving side) can be mitigated by separating the hydrogen and oxygen evolving reactions in space and time. The thesis details catalytically evolving hydrogen from a reduced species using earth abundant materials, instead of rare metals, thus providing a path to lowering the costs of a H2 evolving system. ECPBs in alkaline conditions were investigated as previous work has only been conducted in acidic media. The reason for investigating alkaline water splitting is because it uses cheaper and more abundant materials in its construction. An anthraquinone structure was shown to act as an ECPB under basic conditions by splitting the oxygen and hydrogen evolving reactions in both space and time. Finally, a redox mediator acted as a liquid electron and proton store for the selective reduction of nitro groups on a variety of nitroarenes. By using a liquid redox mediator, the specialist equipment required to contain gaseous hydrogen is no longer required. The work herein shows various ways in which hydrogen can be produced and utilised that do not rely on conventional setups. By separating the standard water electrolysis into two parts using an ECPB, the typical drawbacks and requirements of rare metals can be circumvented. Lastly an unconventional but selective and simple transfer hydrogenation reaction has been shown to proceed using a redox mediator acting as an in-situ provider of electrons and protons to a reduction reaction.

The work presented within adapts BODIPY fluorescent dyes for two distinct purposes: to investigate drug delivery into parasites and to develop ‘self-reporting’ activity-based probes for protein profiling. Methods for the treatment of parasitic diseases (human, animal and plant) have recently focussed on techniques for improving the delivery of a drug into the host infected cell, followed by its subsequent uptake into the parasite. In an effort to develop new anti-parasitic agents, a new system was developed, that is able to deliver low molecular weight units, as well as larger biomolecules (13 kD), selectively across cellular membranes. The delivery system can be selectively tuned depending on the type of parasite being targeted (i.e. kinetidoplastida, apicomplexan, worms). Significantly, we have also been able to selectively target intracellular parasites without affecting uninfected host cells. This opens the tantalising opportunity to be able to use our system to deliver a variety of agents and vectors, with little or no toxicity, at all stages of the parasite’s life-cycle, including the intracellular stages. The second theme of the thesis is activity-based probes. Activity-based probes are small molecule modifiers of proteins that help elucidate the roles of these proteins in both healthy and diseased cells. Kinase’s have a central role in cell signalling and disease, thus has been significant effort towards the development and application of chemical probes in this field. The activity-based probes developed are based on afatinib, an irreversible inhibitor of EGFR, an ErbB family kinase. Deregulation of ErbB kinases has been implicated in several cancers. Afatinib forms a conjugate with cysteine residue in the active site of these enzymes. Probes have been prepared that incorporate functionalised BODIPY dyes. Upon reaction with thiols, the absorbance and emission profiles of the probes are modified. The probes are ‘self-reporting’ since formation of a covalent bond between the thiol and the probe can be monitored through absorbance or emission, allowing for easy detection.

The production of phosgene typically involves the gas phase reaction between carbon monoxide (CO) and dichlorine (Cl2) in the presence of an activated carbon catalyst. The first stage of the study investigated the kinetics of phosgene formation over a high surface area carbon catalyst. This included determining a rate law and an activation energy for the reaction. A reaction mechanism is proposed based on the experimental observations.

For more than a century, chemists and biologists have been trying to understand, and recreate, how life originated on planet Earth. The exact origin of life will never be known, however, chemical pathways that could have contributed to the formation of the first living systems can be reconstructed. Prebiotic research, in general, has been based around the formation of precursors found in modern biology, and their self-organisation under very specific reaction environments. This approach has yet to yield a living system. One of the possible reasons for this failure is the adoption of separate routes for the study of the two main precursors, nucleic acids and proteins. In this way, prebiotic researchers have been limited in their scope of investigation, precluding the more than likely possibility that precursors of amino acids and nucleotides were present on early Earth at the same time. In the work presented in this thesis, the formation of peptide and nucleotide building blocks from prebiotically plausible simple chemical mixtures was studied following a bottom-up approach, together with the assembly of building blocks to form polymeric structures. In addition, chromatographic analytical techniques and fully automated platforms were developed, thus enabling new discoveries and a novel approach for the study of the origin of life and creation of new life. The first part of this thesis demonstrates a proof of concept in the utility of long-term experiments for origin of life research, specifically aimed at the study of evolution in complex mixtures containing prebiotic building blocks. In order to achieve this goal, chromatographic analytical methods were developed and optimised to meet the challenge of analysing complex prebiotic reaction mixtures. In addition to this, two new fully automated platforms were developed, providing a means for non-stop reactions that were able to run uninterrupted with minimum maintenance. These platforms were used to study the environmental effect on the Miller-Urey reaction mixture, as well as to perform hydration / dehydration cycles for a long period of time. As consequence of the automated long-term experiments, two key concepts were demonstrated. First, changes in the chemical inputs or reaction environment not only modify the output of the reaction, but also its product distribution. Second, the importance of including recursion and small changes during the course of long-term reactions was highlighted. The second section focuses on the identification of the optimal and simplest reaction conditions for the formation of peptides through dehydration reaction of non-activated amino acids. This was achieved via the exploration of a broad parameter space (temperature, pH, number of cycles, reaction time and salt influence) using another automated platform. Peptide bond formation was observed by applying simple hydration/dehydration cycles to an aqueous solution of non-activated amino acids. By this method, unprecedented yields of up to 50% were achieved, in which the majority of products were oligomers (n ≥ 3), up to 20 amino acid residues long. The final part of the thesis describes the study of co-reactivity between peptide and mononucleotide building blocks under simple dehydration conditions. Different reaction parameters (temperature, pH, order of addition, reaction time and concentration dependency) were studied in order to obtain the optimal reaction conditions. These experiments were conducted in the absence of activated reagents or catalysts. Based on this investigation, the simultaneous formation of nucleotide and nucleoside structures, including different canonical nucleobases, under prebiotically plausible conditions was identified. Furthermore, a selective effect on the isomeric distribution of glycosylation products was observed when amino acids were included in the reaction media.

Ni-based electrodes have been extensively studied for hydrogen evolution reaction (HER) in alkaline electrolysers in an attempt to improve its electrocatalytic activity through alloying it with other metals and/or increasing the surface area. However, the role of microstructure on the electrochemical performance has received little attention. In this study, Ni-based catalysts have been prepared by a powder metallurgy technique including compaction and sintering of a mixture of Ni, starting alloy (consisting of Al3Ni and Al3Ni2) and binder. As-sintered samples were then treated in concentrated alkaline solution for leaching of Al. The microstructural properties are controlled by changing the parameters of the preparation process; i.e. sintering temperature, starting alloy to Ni ratio, leaching temperature and binder properties (concentration and particle size). Increasing the sintering temperature from 625 to 900 °C improved the mechanical strength but also increased the diffusion of Al from Al-rich phases into Ni, resulting in reduced Al-rich phases available after sintering. Since Al can only be leached from Al-rich phases, the specific surface area of micro- and mesopores (with the latter having a size range of 2-14 nm) created during the leaching reduced by almost 90 % from 625 to 900 °C sintering temperature. Although there was a ca. 15 times increase in the specific surface area by increasing the starting alloy concentration from 0 to 60 wt.%, the robustness of catalysts reduced since the compressibility of alloy powder is lower than that of Ni, resulting in increased macroporosity. This suggests that the starting alloy concentration should be in the range of 20-40 wt.% in order to achieve relatively robust and inexpensive porous catalysts without compromising too much the surface area. N2 sorption isotherms showed that leaching at 30 and 50 °C resulted in pores with a slit shape, whilst leaching at 60, 70 and 80 °C lead to ink-bottle pores. This was attributed to increasing leaching rate with higher leaching temperatures in comparison to speed of atomic rearrangement at the surface. Increasing the leaching temperature from 30 to 60 °C improved the specific surface area by almost 4 times, whilst leaching at 60, 70 and 80 °C gave similar surface areas. Greater binder concentrations led to increased macroporosity and surface roughness as well as greater numbers of windows between the adjacent cavities. Consequently, the mechanical strength of porous catalysts reduced due to the decrease in the wall thickness. It was also found that the size of the binder particles influences the robustness of the porous catalysts, with the smaller the binder size the greater the robustness. The comparison of trends in alkaline electrolyser cell voltage and compositional and microstructural properties showed that the surface area has a dominant effect on the electrocatalytic activity for HER in comparison to the composition of Ni-based electrodes. Despite greater Al contents, the cell voltage still decreased with increasing surface areas (with micropores accounting for ca. 80 %). However, it was found that the effective use of micro- and mesopores depends on the pore morphology, with slit-shaped pores being more effectively used during HER in comparison to ink-bottle pores which can be more subject to mass transport limitation. It was shown that H2 bubbles cannot form inside the micro- and mesopores, therefore generated H2 can only leave the pores through diffusion which appears to be favoured by a slit shape in comparison to ink-bottles. It was also found that increasing the amount of large macropores (> 15 μm) is not advantageous to the production of electrodes for alkaline electrolysers as it results in increased electrode thickness and reduced mechanical strength with no measureable improvement in electrochemical performance.

The design, synthesis and characterisation of a range of surfactant-based ligand architectures is presented. The amphiphilic ligands have been shown to form metallosurfactants with a wide range of s-, d- and f-block metals as well as being able to form stable micellar systems either through self-assembly or via doping into a carrier microemulsion. The overall aim of this work was to produce surfactant ligands capable of sequestering metal ions and localising them on the surface of micellar droplets within an oil-in-water microemulsion. Chapter Two investigates the formulation and characterisation of a 1-alkyl-3-methyl imidazolium based micellar system capable of forming stable microemulsions with extremely high oil loadings as well as acting as a carrier for more complex surfactants. This chapter also describes the synthesis and characterisation two novel macrocyclic ligand architectures designed to coordinate a range of s-, d- and f-block metals to form a series of metallosurfactants capable of aggregation in aqueous media. Chapter Three explores an array of acyclic surfactant ligands synthesised from ethylene diamine and diethylene triamine precursors and functionalised with poly-alcohol arms. These amphiphilic ligands were coordinated to Ni(II) and Cu(II) in order to gain insight into their coordination geometries via photophysical studies. Tensiometric investigations of the free ligands and their Sr(II) and Y(III) metallosurfactants assessed their microemulsion compatibility as alternatives to macrocyclic architectures. Chapter Four presents a series of cationic bis-cyclometallated Ir(IIII) complexes where the diimine ligand is a bipyridine species functionalised with a lipophilic alkyl chain and the cyclometallating ligands contain ethyl ester moieties which, upon deprotection, afford water soluble complexes. Combined tensiometric and photophysical studies found these species to be dual emissive as free complexes in solution, with emission arising from both ligand-centred and metal-to-ligand charge transfer mechanisms. Upon aggregation into micelles however, either a quenching of the ligand-centred emission or an enhancement of the metal-to-ligand charge transfer rendered the complexes mono-emissive. Chapter Five reports the synthesis and characterisation of three novel DO3A-based surfactant ligands incorporating pendent chromophores as antennae for near-IR sensitised emission from a range of Ln(II) ions. Luminescent lifetime studies determined that the ligands form 8-coordinate complexes with hydration states suggesting the presence of 0-1 inner sphere water molecules. Combined tensiometric and photophysical studies proved the metallosurfactants to be capable of self-assembly into micelles in aqueous media and found aggregation to have a notable effect on the local environment of the Ln(III) ions.

This thesis contains discussions and results pertaining to three distinct pieces of work, all related by an underlying theme: the use and development of computational techniques to discover and characterise novel metastable materials. Zinc oxide is a cheap and abundant material with many potential uses in the electronics and Optics industries. However, its wurtzite ground state structure gives rise to a number of undesirable properties. Thus, knowledge of how to stabilise more useful metastable phases is desirable. To that end, the mechanism of the pressure-induced phase transition between the zincblende and rocksalt polymorphs of the compound was deduced using transition path sampling. Following this, a novel technique combining TPS methods with metadynamics was applied to classify the free-energy landscape relevant to the transition pathway. This provided further information relating to the transition that would have been impossible to determine using path based analyses alone. Water ice exhibits a wealth of structural polymorphism, with at least eighteen phases known to experiment and many more configurations predicted. However, a true understanding of the transition pathways that link these structures remains elusive. Using both metadynamics techniques and a novel procedure known as rotational shooting, attempts to deduce pathways between different phases of ice have been made. The results presented include successful transformations between two crystalline phases of ice and several amorphous phases, as well as the possible elucidation of a novel ice polymorph. Crystal structure prediction remains a challenge in materials science. Using a random structure search technique, eight novel allotropes of carbon and three novel high-pressure polymorphs of zinc oxide have been found and subsequently characterised using density functional theory. Each of the materials displays its own unique array of properties, demonstrating both the variety exhibited by polymorphs of the same material and the ability of random structure prediction techniques to predict such dissimilar materials.

The purpose of this project is to enhance the photocatalytic activity of TiO2 for the photocatalytic reduction of aqueous nitrates for application as a solar-catalytic treatment of polluted water. The aim is also to establish a better understanding of the mechanisms by which noble metals enhance the activity of TiO2. Mono-metallic and bi-metallic Au, Ag and other M-TiO2 catalysts were prepared with the aim of improving charge-carrier separation,these catalysts were then characterised by XRD, BET and TEM. Preparation method variables such as calcination temperature and metal loading were investigated and found to have a large effect on catalytic activity. Metal loadings of between 0.3 and 0.4% were found to give the highest activity and this was concluded to be due to an optimum amount of surface coverage by small metal nanoparticles. The catalysts were found to be very selective towards nitrogen with Au catalysts tending to form ammonia at high conversions and Ag catalysts forming nitrite at low conversions. Bimetallic AuAg catalysts were prepared that had higher activities than their mono-metallic equivalents with 100% selectivity to N2. These catalysts were found to be highly reusable. None of the prepared M-TiO2 catalysts were found to have any visible-only activity for nitrate photo-reduction and the enhancement of photo-activity with the deposition of metals was concluded to be due to increased charge-carrier separation effects. Attempts were made at visibly-active TiO2 by N-doping but although UV-visible DRS analysis showed a redshift in the adsorption band of these catalysts and XRD found the anatase to rutile ratio to be near ideal no reproducible visible-light activity was achieved.