The controlled formation of carbon-carbon bonds is the bedrock of organic chemistry, with the asymmetric construction of stereogenic carbon-carbon bonds remaining a key motivation for the development of novel synthetic methodologies. Transition metal catalysis provides an important strategy in the arsenal of the modern synthetic chemist. While there is a plethora of transition metal-catalysed cross-couplings for the formation of sp2-sp2 and achiral sp2-sp3 carbon bonds, there are relatively few methodologies for the selective formation of stereogenic sp-sp3, sp2-sp3 and sp3-sp3 carbon-carbon bonds, the number of which that involve highly reactive organometallic reagents are fewer still. Two methodologies that can enable this asymmetric coupling are copper-catalysed SN2’ allylic alkylation and transition metal-catalysed allylic substitution. The overall utility of both these methods is described in the introductory review, which seeks to compare and contrast the relative advantages and disadvantage of both approaches. The asymmetric formation of carbon-carbon bonds utilising unstabilised carbon nucleophiles is generally dominated by the copper-catalysed SN2’ allylic alkylation. However, the copper-catalysed reaction suffers from poor substrate scope, in which electronically biased or symmetrical substrates are required in order to ensure favourable regioselectivities. Another restriction is that, for the formation of a stereocenter, the reaction is mechanistically limited to disubstituted allylic substrates. These linear substrates often require a multistep synthesis which involves a selective olefination, as an isomeric mixture of alkenes would result in the erosion of asymmetric induction. In contrast, there has been very little development of the analogous transition metal-catalysed allylic substitution utilising unstabilised carbon nucleophiles, especially in comparison to the analogous methodologies utilising stabilised carbon and heteroatom nucleophiles. Despite the numerous potential advantages that are afforded by this approach, a general method for the regio- and stereoselective transition-metal catalysed allylic substitution utilising unstabilised carbon nucleophiles has yet to be reported. Chapter 2 describes the development of a novel regio- and stereoselective rhodium-catalysed allylic substitution reaction, which utilises benzyl magnesium bromide as an unstabilised carbon nucleophile. Following a brief introduction to the rhodium-catalysed allylic substitution reaction, this chapter is organised into four distinct sections. The first of these outlines the identification of a suitable nucleophile, and the subsequent development of reaction conditions for the regioselective alkylation of secondary allylic carbonates with a range of benzyl magnesium bromides transmetallated with zinc iodide. Then the next section will deal with studies toward the development of the stereospecific variant, these studies will highlight the main challenges of deploying a sp3-hybridised carbon nucleophile. This section will also determine the absolute stereochemical outcome of the reaction, thus confirming the inner sphere mechanism of the reaction. The third section will demonstrate that how the limitation of the stereospecific reaction, namely the fluxionality of the rhodium-enyl, can be utilised to develop a regio- and diastereoselective alkylation for the formation of 1,2-stereoarrays containing tertiary and quaternary carbon stereocenters. Finally, preliminary studies towards the expansion of this methodology to include an sp2-hybridised vinylic nucleophiles for the preparation of 1,4-skipped dienes will be detailed. Overall, we have developed a novel, highly regioselective rhodium-catalysed allylic substitution of secondary allylic carbonates utilising highly unstabilised carbon nucleophiles. We also have developed a highly diastereoselective allylic substitution for the construction of both tertiary and quaternary carbon stereocenters, which to best of our knowledge, has yet to be described in the context of rhodium-catalysed allylic substitution utilising an unstabilised carbon nucleophile. We have successfully carried out preliminary studies towards the development of a rhodium-catalysed allylic substitution utilising a vinyl organometallic reagent as nucleophile, as well.

The work presented in this thesis focuses on the synthesis of long axis A-site ordered perovskites, which have ordered oxygen vacancies. The materials discussed have also been assessed as potential cathodes for solid oxide fuel cells (SOFCs), targeting an intermediate temperature (IT) SOFC operating range of 500 800 °C. In chapter 3 of this thesis, a 16ap phase (ap = 1 perovskite unit, ABO3-δ), Y2.24Ba2.28Ca3.48Fe7.44Cu0.56O21-δ, was first observed in a powder X-ray diffraction (PXRD) pattern that resulted from the attempted Cu doping of a 10ap phase (Y0.9Ba1.7Ca2.4Fe5 xCuxO13 δ). This phase was indexed as ap √2 × 16ap × ap √2 by selective area electron diffraction (SAED). Mössbauer spectroscopy identified that Fe3+ existed in three different coordination environments and a Rietveld refinement was carried out using combined powder synchrotron (S) XRD and powder neutron diffraction (ND) data. High Angle Annular Scanning Transmission Electron Diffraction (HAADF-STEM) confirmed the A-site ordering from the refinement. The 16ap phase exhibited good thermal stability, CO2 stability and chemical compatibility with state of the art electrolytes (GDC, SDC and LSGM), as well as a close matching thermal expansion coefficient (TEC) with the same electrolytes. Although possessing low electronic conductivity, 3.5 S.cm-1 at 750 °C, a good area specific resistance (ASR) of 0.12 Ω.cm2 at 750 °C was achieved, within the IT-SOFC operating range. In chapter 4, a 10ap phase, Y0.9Ca2.4Sr1.7Fe5O13-δ (YCSFO), was discussed. The space group Imma was identified from SXRD data, while the structure was closely related to brownmillerite. A Rietveld refinement carried out with the addition of SXRD data collected at the K absorption edge for Sr determined A-site ordering. The ASR of YCSFO was three times higher than that of the 16ap phase, highlighting the ordering of oxygen vacancies. The final phases investigated in chapter 5 of this thesis belong to a family of Co doped 10ap phases (Y0.9Ba1.7Ca2.4Fe5 xCoxO13 δ). A range of compositions were synthesised by varying the cation ratios, in order to obtain high Co content phase pure samples. The highest Co content was x = 1.85 for compositions Y1.24Ba1.85Ca1.91Fe3.15Co1.85O13-δ (annealed in O2) and Y1.6Ba1.8Ca1.6Fe3.15Co1.85O13-δ. AC impedance measurements carried out showed that increased Co content reduced the ASR, with the values at 700 °C of 0.19 Ω.cm2 and 0.23 Ω.cm2 respectively.

There is accumulating evidence that reactive nitrogen species derived from nitric oxide metabolism are involved in cancer as they are able to damage DNA largely through oxidation or nitration of the guanine base. The 8-nitroguanine lesion is increasingly associated with cancers that result from chronic inflammation; however due to its instability, very little is known about this base modification. Consequently this thesis focuses upon establishing methods to detect and quantify the lesion and investigate enzymes potentially involved in repair systems directed against 8-nitroguanine in DNA. The approach outlined in this thesis utilises ribonucleoside analogues of the lesion which sufficiently stabilised the labile glycosidic bond. The 8-nitroguanine nucleosides were prepared prior to incorporation into the oligodeoxynucleotide sequences using the traditional 3’- to 5’-solid-phase phosphoramidite chemistry. A number of oligodeoxynucleotides of varying lengths containing a single modification, and dinucleotides containing two modifications were prepared. A variety of reactions of the 8-nitroguanine base both in nucleosides and oligodeoxynucleotides have been investigated. Studies revealed a different pattern of alkylation for the modified base when compared to results reported in the literature for the natural nucleoside. Thus demonstrating the dramatic effect that nitration has on the intrinsic reactivity of the nucleoside. In view of the susceptibility of nitro group to reaction with thiol nucleophiles, displacement of the nitro group from within nucleosides and oligodeoxynucleotides has been achieved. In particular a fluorescent nucleophile has been developed which stabilises the lesion and could enable direct detection of the levels of 8-nitroguanine in DNA. Using a variety of substrates prepared in this thesis, detection of the 8-nitroguanine base in oligodeoxynucleotides has been investigated using surface enhanced Raman spectroscopy in collaboration with Professor Steven Bell at Queen’s University, Belfast. The unique absorption profile of the 8-nitroguanine derivatives allows for signals exclusively associated with the lesion to be identified using this highly sensitive technique. The synthesis of 8-nitroguanosine triphosphate was investigated using a number of different approaches. Although the initial aim was not successful, the principles for the phosphorylation of a nucleoside have been shown. The problems encountered were attributed to the conformational constraints of the molecule.

This thesis describes the preparation of a new [4+6] porous organic cage, CC12. The new cage has a N2 SABET of up to 946 m2/g, as well as inherent selectivity of gases based on polymorphism. This new porous organic cage has also been reduced and catenated as seen with previous cages. Cages have also been formed from aliphatic diamines, highlighting importance of diamine length in formation of either [2+3] or [4+6] cages (Chapter 3). CC1 has been prepared and reduced in situ to yield RC1, while CC5 was also reduced to produce RC5. These reduced cages have provided a route towards decorated cages via nucleophilic addition/elimination with various acid halides. While no porous materials were observed by addition of bulky or aliphatic groups, this new class of decorated cages presented an excellent basis for further reactions on a 12-armed core, higher than that of POSS alternatives (Chapter 4). Finally, RC1 has been polymerised with bis-acid halides to yield networks with modest N2 SABET of up to 106 m2/g. Decorated cages were also successfully homo-coupled by Yamamoto and polymerised with Sonogashira methods to yield polymers with N2 SABET of up to 150 m2/g. Decorated cages were lastly hyper cross-linked to yield H2 selective polymers and co-polymerised with benzene to yield N2 SABET of up to 954 m2/g (Chapter 5).

The use of single molecules to construct electronic devices is an exciting prospect, and one that has long provided a driving force for research in the area of molecular scale electronics. In order for this emerging field to advance a deep understanding of the fundamental mechanisms that govern electron conduction at the molecular level is imperative. Recent developments in areas such as scanning tunnelling microscopy, have facilitated the determination of the electrical properties of single molecules tethered between two metallic contacts. The analysis and potentially tailoring of structure-property relationships is hugely important and could lead to new and unforeseen applications for this emerging field. The work presented herein details two major studies. The first is an investigation of the transport properties of a series of analogous molecules, which consist of a single benzene ring sandwiched between two alkyl chains of varying length. Prior to the work in this thesis one such molecule, and various substituted analogues thereof, had shown behaviour similar to what would be expected of a molecular equivalent of a double tunnelling barrier. The data presented here demonstrates a remarkably low dependence of this system on molecular length; this result contradicts the behaviour expected of a coherent transport mechanism. Moreover, the study of the orbital energies and densities of these molecules provides further evidence of a mechanism of conduction that is very different to that previously suggested for this system. The second study centres around the investigation of the conductance behaviour of 4,4’-bipyridine and some substituted analogues thereof; this study is presented in two parts. The first details attempts to synthesise planar analogues of 4,4’-bipyridine, as well the synthesis and reactivity of novel substituted bipyridines. The second part reports conductance data, electrochemical studies and theoretical calculations of properties of these molecules. The data presented provides new information regarding the relationship between electronic structure and conductance behaviour in this type of system.

The selective oxidation of organic compounds is one of the most attractive transformations for both, industry and academia. Industrial interest stems from the potential application of such oxidation methodologies in the economic, greener synthesis of valuable products, whereas academic research is challenged by the difficulties in achieving specific, direct functionalisation of the “inert” CH bonds in complex molecules. In this Ph. D. thesis, our contribution to the selective oxidation of organic substrates using a novel class of iron catalysts is presented. A general introduction covering the major challenges in the area of iron-catalysed selective oxidation of organic compounds is described in Chapter 1. Chapter 2 covers the design, synthesis and coordination properties of the novel PyBisulidine type ligands, which we have conceived for their potential use in selective oxidation, attempting to overcome some of the limitations of current methods. The efficiency of such PyBisulidine ligands is demonstrated in Chapter 3, where iron-PyBisulidine complexes are used for catalysing the aerobic α-oxidation of functionalised ethers. High catalytic efficiency, very good mass balance and excellent functional group tolerance were achieved with these catalysts under mild conditions. Such advantages stem from an unconventional reaction mechanism, involving the dehydrogenative oxygenation of the ether substrate to give a peroxobisether, followed by the cleavage of the peroxy bond to form two ester molecules. Unlike metalloenzymes and biomimetic iron complexes, H2 is released as the sole byproduct during the catalytic cycle. The oxidation mechanism is discussed in Chapter 4. Like natural dioxygenases, iron-PyBisulidine catalysts were found capable of promoting the aerobic cleavage of aliphatic C-C and C-O bonds. Even though biomimetic complexes are often seen as simplified models to study enzymatic processes, a more synthetic perspective of the selective aerobic cleavage of ethereal C-C and C-O bonds is described in Chapter 5.The great potential of such cleavages in organic synthesis is well exemplified in the iron-PyBisulidine catalysed direct conversion of natural isochromans into biologically active isochromanones with excellent selectivity. The ability of the iron-PyBisulidine complexes in catalysing aerobic C-C cleavages is further expanded in Chapter 6, where the oxidative cleavage of olefinic C=C bonds to carbonyl compounds is demonstrated. The catalytic reactions proceeded efficiently, showing a broad scope and a mechanism that involves the formation of dioxetane intermediates is postulated. Chapter 7 is an extension of Chapter 6, in which iron-PyBisulidine complexes were found to catalyse α-methylstyrene linear dimerisation under an inert atmosphere. Moreover, control in the regioselectivity of the double bond in the dimers can be achieved by modifications in the PyBisulidine ligands. Final conclusions and a perspective of the research covered in this Ph.D. thesis are provided in Chapter 8.

Porous organic cages have recently received much attention due to their synthetic tunability, solution processability, high gas adsorption capacities, and ability to selectively separate small molecules based on their size and shape. In this thesis, a range of novel porous organic cages are presented, with each possessing unique functionalities, pore structures and gas sorption properties due to the employment of synthetically-modified versions of traditional trialdehyde and diamine cage precursors. The introduction of new functionality into the cage structure, including methyl, hydroxyl and ethanoanthracene groups, highlights how subtle modification of the cage precursors can initiate significant changes in the self-assembly of the cage molecules. This in turn affects the pore dimensions, as well as the gas sorption and separation performance, of the resultant porous material. This strategy led to the successful isolation of an asymmetric cage molecule, which demonstrated the potential to separate noble gases, as well as the preparation of cages with diverse vertex functionality, molecular size and gas sorption properties. The ability of porous organic cages to selectively separate xenon from krypton gas was also investigated through the use of dynamic breakthrough measurements, with the performance of these cages surpassing all other porous materials evaluated to date.

This thesis describes the synthesis and application of complex metal oxide nanoparticles. The work is focussed on three core areas; the synthesis of CoFe2O4 nanoparticles and their application as CO oxidation catalysts, the controlled assembly of functionalised CoFe2O4 and BaTiO3 nanoparticles and the preparation and characterisation of magnetoelectric composites from chemically-bonded nanoparticle assemblies. Chapter 1 gives an introduction to the history of nanotechnology, recent developments in the synthesis of nanoparticles and other areas key to the work described herein. In Chapter 2 details the synthetic and analytical techniques employed. Chapter 3 describes the synthesis and characterisation of CoFe2O4 nanoparticles, and their application as catalysts in the CO oxidation reaction. Nanoparticles were prepared with a range of controlled sizes and were found to be active CO oxidation catalysts. Analysis of their size-dependent activity and stability is performed. Chapter 4 describes the assembly of CoFe2O4 and BaTiO3 nanoparticles by direct functionalisation of the nanoparticle surfaces using complementary organic functional molecules. Characterisation of the functionalised nanoparticles and assemblies is performed, and the extensibility of the developed functionalisation and assembly protocol is tested using particles with different sizes and morphologies. In Chapter 5 the assembled nanoparticles discussed in Chapter 4 are processed into dense ceramics with a view to preparing magnetoelectric composites. The magnetoelectric properties are tested, and optimisation of the ceramics is performed by modification of the starting nanoparticle sizes, composite composition and processing conditions. The composites are tested against control samples prepared by traditional grinding and firing, and characterisation of the ceramics using XRD and electron microscopy provides and insight as to why their magnetoelectric properties differ to those prepared by the traditional technique. The work contained in this thesis has been published in the following papers: - G. Evans, I. V. Kozhevnikov, E. F. Kozhevnikova, J. B. Claridge, R. Vaidhyanathan, C. Dickinson, C. D. Wood, A. I. Cooper, M. J. Rosseinsky, “Particle-size Activity Relationship for CoFe2O4 Nanoparticle CO Oxidation Catalysts,” J. Mater. Chem. 2008, 18, 5518. G. Evans, G. V. Duong, M. J. Ingleson, Z. Xu, J. T. A. Jones, Y. Z. Khimyak, J. B. Claridge, M. J. Rosseinsky, “Chemical Bonding Assembly of Multifunctional Oxide Nanocomposites,” Adv. Funct. Mater. 2010, 20, 231.

Conjugated microporous polymers (CMPs) are a class of amorphous materials with pore sizes in the micropore range (< 2 nm). CMPs have potential advantages over inorganic and inorganic hybrid materials due to the use of only the lighter elements in the periodic table and their stability as well as having the diversity of organic synthesis not available to activated carbons. Due to their sorption properties CMPs find applications as gas storage materials. By tuning the chemistry and designing the monomers around the chemistry ultrahigh surface areas can be achieved. This way, novel materials with good gas storage capabilities for hydrogen, carbon dioxide, and methane can be synthesised.

The aim of this work was to investigate heterogeneous catalysis of the deoxygenation of renewable feedstocks for value-added chemicals and fuels using heteropoly acids. The main focus was on H3PW12O40 (HPW) and its Cs acidic salt Cs2.5H0.5PW12O40 (CsPW), which have sufficiently high thermal stability, with decomposition temperatures of 450 and > 500 °C, respectively. These compounds have very strong Brønsted acidity and are well documented as acid catalysts. They were used for the deoxygenation and hydrogenation of propionic acid, methyl isobutyl ketone (MIBK) and diisobutyl ketone (DIBK) in the gas phase. For comparison, zeolite catalysts doped with Pt were examined for the deoxygenation of MIBK. CsPW was doped with Pd, Pt, Cu and Ru metals using the impregnation method, while Pt was doped on zeolites by ion exchange. The catalysts under study were characterised using various physical and chemical techniques. CsPW and CsPW-supported Pd, Pt and Cu catalysts were found to be stable in the deoxygenation of propionic acid. They retained the Keggin structure of their polyanion (primary structure), as well as the CsPW crystal structure (secondary structure), after reaction at 400 °C in H2, whereas HPW decomposed above 350 °C in N2. The reaction was found to involve several pathways including ketonisation, decarbonylation, decarboxylation and hydrogenation, leading to the partial or total deoxygenation of propionic acid. HPW/SiO2 and CsPW, both in H2 and in N2, exhibited ketonisation activity between 250 and 300 °C to yield 3-pentanone, CsPW being more selective than HPW. At 400 °C, HPW and CsPW were active for the decarbonylation and decarboxylation of propionic acid to yield ethene and ethane respectively. Loading Pd or Pt onto CsPW greatly enhanced decarbonylation in flowing H2, but had little effect in N2. Similar performance was exhibited by Pd and Pt on SiO2, giving almost 100% selectivity to ethene in H2. These results are consistent with the hydrodeoxygenation of propionic acid on Pd and Pt, suggesting that hydrogenolysis of the C-C bond plays an essential role. Cu catalysts were active in the hydrogenation of the C=O bond to yield propanal and 1-propanol. Turnover rates of propionic acid conversion on metal catalysts followed the order Pd > Pt > Cu. Pt/CsPW was found to be a very efficient catalyst for the selective one-step hydrodeoxygenation of biomass-derived aliphatic ketones MIBK and DIBK to yield 2-methylpentane (MP) and 2,6-dimethylheptane (DMH) under mild conditions at 100 °C and 1 bar pressure without isomerisation of the carbon backbone via a metal-acid bifunctional mechanism. For MIBK hydrogenation, the mechanism involves MIBK hydrogenation to MP-ol on metal sites followed by MP-ol dehydration on acid sites to form olefin and finally olefin hydrogenation to 2MP on metal sites. Pt/ZSM-5 matched the catalytic performance of Pt/CsPW at 200 °C, but considerable isomerisation of MP took place at this temperature. This shows that the strong acidity of CsPW is essential for the high efficiency of the Pt/CsPW catalyst.