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This thesis describes the work of two discrete projects. Chapters 2 to 3 detail the development of new enantioconvergent methodology - stereoretentive enantioconvergent multicomponent reactions. Chapters 4 to 5 detail the biomimetic total synthesis of the natural product ulodione A. CHAPTERS 2 TO 3: When using racemic substrates in asymmetric synthesis, a yield of 100% can only be achieved through the use of enantioconvergent reactions (cf. kinetic resolutions (KR), maximum 50% yield). There are three established approaches for achieving enantioconvergency; stereomutation (e.g., dynamic kinetic resolutions), stereoablation and stereodifferentiation. These three concepts all have their own particular advantages. However, they all suffer from common limitations in their substrate scope. The stereogenic elements of the starting material must be labile towards mutation, ablation, or inversion. Additionally, substrates containing multiple stereogenic elements are generally not amenable to any of these established approaches. This thesis describes our investigations into a new stereoretentive approach to enantioconvergent reactions. Stereoretention in enantioconvergent reactions is possible if the two enantiomers of a racemate are selectively coupled together to form a non-meso product. Uniquely, racemic substrates with robust and/or multiple stereogenic elements will be compatible with these enantioconvergent reactions. Our efforts to develop an enantioconvergent domino nucleophilic acyl substitution/SN2 reaction sequence are described. Chapter 2 focuses on the development of new kinetic resolution methodology of secondary alcohols and the application of this methodology to perform stereoretentive reactions. Chapter 3 focuses on the development of new kinetic resolution methodology of secondary amines and the application of this methodology to perform stereoretentive reactions. CHAPTER 4 - 5: The racemic natural product (±)-ulodione A was isolated by Lou and co-workers from the endolichenic fungus Ulospora bilgramii, alongside ulodione B. (±)-Ulodione A is a selective butyrylcholinesterase (BuChE) inhibitor. BuChE inhibitors pose good targets for the development of Alzherimer's therapeutics. The biological activity, along with the intriguing biosynthetic pathway proposed by Lou and co-workers made ulodione A an interesting target for a bioinspired total synthesis. This thesis describes our successful synthesis of (±)-ulodione A and our investigations into the biosynthetic pathway. During the synthesis, a bioinspired dehydrative/Diels-Alder domino reaction was developed using T3P as a phosphorylating reagent. Two, new, anticipated natural products (±)- ulodione C and D were also synthesised and characterised. The synthesis was achieved in two steps from commercially available starting material, with a 48% yield overall improving the only previous total synthesis of 9 steps with a 5 - 6% yield.

Developing a new drug storage system is imperative, especially for macromolecules with limited shelf-lives, pharmaceutical cures for unforeseeable epidemics, and drugs with short-lived therapeutic windows. In this work, calcite is proposed as a new system for drug storage. Since it is a single crystal, it is impenetrable by the primary agents of decay (oxygen, humidity and UV radiation). The system explored in this work achieved 20% occlusion in mass, which is 5% higher than the most excellent occlusion reported in the literature. This is the first evidence of a neutral capsule occluded inside of calcite, which breaks with the assumption that charge is a requisite for crystal-additive interactions. Using CLSM and FIB-SEM tomography, three-dimensional models are built of the occluded capsules in crystals. The occlusion patterns observed revolve around the third-order axis of symmetry. Size selectivity of around 1 µm has been calculated, although most of the occluded capsules observed are in the 100-300 nm range. We propose that this system be applied at the manufacturer scale and that the drugs stored in the crystals can later be processed into consumer-ready pharmaceuticals when needed. The pharmaceutical industry can apply this technology to control the spread of infectious diseases or simply profit from price fluctuations on synthetic precursors.

Phthalocyanines are planar aromatic macrocycles whose unique properties give them a wide variety of potential applications, particularly as pigments and dyes, but also in solar cells, photodynamic therapy and as catalysts. The latter in particular is of interest given the ability of phthalocyanines to complex all metal atoms, and so the further development of materials to allow the use of phthalocyanines in heterogeneous catalysis is an important field. To this end, this work describes the efforts which we have undertaken to incorporate different phthalocyanine ligands into novel materials, with a view to achieving sufficient porosity to allow catalytic applications. In seeking to develop phthalocyanine-based Metal Organic Frameworks (MOFs), we have employed both novel and previously reported ligands in MOF syntheses, and have obtained crystalline structures, though full structural elucidation remains elusive. Relatively low internal porosities have also been measured, likely due to the inherent aggregation tendencies of phthalocyanines. We also demonstrate the use of the tetraimidophthalocyanine functionality in the synthesis of a series of network polymers, using the tetracyclomerisation step for polymerisation. Whilst several examples are entirely non-porous as a result of dense packing of the phthalocyanine rings, we also report two novel polymers containing bulky functionalities to overcome this restraint, which do show greater internal surface areas. Finally, new molecular crystals are described, showcasing the incorporation of numerous tetraphenylporphyrin (TPP) ligands into a phthalocyanine molecular crystal system widely studied within the group. Extensive spectroscopic studies of the resulting interactions have been carried out, and these are compared to crystallographic data to give significant insight into the effect of variation of the metal centre and by substitution of different functionalities in the TPP.

The molluscicide metaldehyde has been frequently detected in ground and surface waters in concentrations exceeding the 0.1 μg L-1 EU regulatory limit, as industrial Granular Activated Carbon (GAC) has been proven inadequate in achieving efficient removal by adsorption. In the present work, Chapter 3.1 describes our research efforts to identify better adsorbents for metaldehyde. Several HCPs and Polymers of Intrinsic Microporosity (PIMs) were synthesised and tested for their metaldehyde adsorptive properties through batch equilibrium experiments. Upon comparison to benchmark adsorbents, a cost-effective HCP based on the TPB aromatic monomer, polymerised in the presence of AlCl3 and DCM, was identified as an excellent candidate for aqueous metaldehyde removal. Novel externally crosslinked analogues of the material were found to display enhanced adsorptive properties, and this was shown by gas adsorption data to be due a result of higher meso and macroporosities, which result in efficient intraparticle mass transport of metaldehyde to the micropores. Solid-state 13C NMR spectroscopy confirmed that the externally crosslinked networks contained a higher degree of alkyl-based linking units, in comparison to TPB-DCM for which Scholl coupling was prevalent. Further aqueous experiments including isotherm studies, adsorption kinetics and Rapid Small Scale Column Tests (RSSCTs) for the novel network derived from TPB & trimethylorthoformate (TMOF) crosslinker are discussed in Chapter 3.2. The overall findings suggest an exceptional maximum adsorption capacity for metaldehyde qmax = 125.00 ± 6.03 mg L-1, as determined from the Langmuir model, very fast kinetics following pseudosecond order kinetics with K2 = 0.15 ± 0.02 mg-1 g min-1, and excellent efficiency in RSSCTs, with 2500 column volumes of 0.5 mg L-1 metaldehyde-spiked water purified before breakthrough. Regeneration of the adsorbent thermally, and via solvent wash were shown to be possible but were not fully investigated. Pre-polymerisation modification of the TPB unit by the introduction of methoxy and hydroxy substituents was found to negatively affect the porosity and metaldehyde uptake of the materials produced, whereas no significant differences were observed for fluorine substituents. A magnetically responsive nanocomposite of TPB-HCP and functionalised magnetite particles was synthesised successfully and retained high metaldehyde affinity. Chapter 3.3 describes that synthesis of sulfonated HCPs and PIMs, through post-polymerisation modification routes, based on acetylsulfuric acid (ASA) and sulfuric acid/triflic anhydride (SA-TfA). The materials were characterised by SS ¹³C NMR, TGA and IR, which confirmed successful sulfonation, and the ion-exchange capacity (IEC) was determined by Boehm titration methods. The degree of sulfonation was found to greatly enhance Pb²⁺ uptake properties, despite the significant decreases in pore volumes and BET surface areas. Highly sulfonated adsorbents based on TPB, triptycene (tryp) and dibenzomethanopentace (DBMP) units, with IECs ranging between 4.2-6.5 mmol g⁻¹, were found to achieve similar removal efficiencies approaching 99% at initial Pb²⁺ concentration of 160 mg L⁻¹ and adsorbent dose of 1 mg L⁻¹. Isotherm studies on the DBMP-DCM/SA-TfA modified adsorbent further demonstrated the high affinity of the material for Pb2+, with the dataset showing a satisfactory fit for both Freundlich and Langmuir models, and excellent fit to the Dubinin-Astakov model, suggesting that a chemisorption process is prevalent. This was further supported by the Langmuir separation factor, as well as the observed shifts in Pb²⁺-induced sulfonic acid vibrational wavenumbers. Chapter 3.4 investigates the degradation of metaldehyde using the derived sulfonated adsorbents, through batch-type GC-MS and NMR experiments. A fast decline in the kinetics of the process was attributed to the narrow pore size distribution of TPB-DCM/ASA, in addition to the strong binding of metaldehyde degradation products to the material, which compete with metaldehyde for the catalytic sites. The breakdown of metaldehyde to acetaldehyde was observed by NMR, which showed additional conversion of acetaldehyde to a variety of products. The presence of paraldehyde, acetic acid, formic acid, acetone, CO₂ was observed in addition to poly(oxymethylene) glycol chains of various lengths. At high contact times, the presence of alkanes, olefins and various other unidentified compounds was confirmed by the ¹H-¹³C HSQC spectrum. It is speculated that the conversion is likely proceeding through aldol condensation to form acetaldol which forms crotonaldehyde upon dehydration, however, the high complexity of the redox conversion cycle did not allow for full mechanistic determination. The versatile catalytic activity of the adsorbent TPB-DCM/ASA is recognised and should be further investigated.

Redox flow batteries (RFBs) based on aqueous organic electrolytes are promising technologies for large-scale, safe and cost-effective electrical energy storage. The membrane separator is the key component in a RFB system to keep redox-active species separate in two half cells while allow free transport of charge-balancing ions. Delivering fast and selective ion transport is critical for battery performance yet remains a challenge for current RFB separators, owing to the difficulty in generating membranes with well-defined sub-nanometre channels to serve as efficient molecular sieves. In this thesis, a new family of ion-sieving membranes, based on Polymers of Intrinsic Microporosity (PIMs) with different backbones and integrating varied ion-conductive groups, are developed and function as efficient and stable separators in aqueous organic RFBs. PIMs are platform materials with distinct combination of properties including high microporosity, exceptional chain rigidity and good solution processibility. A range of dibenzodioxin-based PIMs with varied spirocyclic and bridged bicyclic structural units are synthesised and provide a versatile post-functionalisation to introduce ionisable amidoxime groups. These membranes demonstrate the feasibility of PIM-based membranes serving as ion-conductive and low-resistant separators in alkaline aqueous RFB systems. Further, negative-charged sulfonate groups are introduced into spirobifluorene-based PIMs which exhibit exceptional efficiency and stability for battery operation at near neutral aqueous electrolytes, outperforming identical RFB cells that use commercial benchmark Nafion® membranes. PIMs containing Tröger's base building blocks enable the introduction of quaternary ammonium groups together with simultaneous crosslinking network, or zwitterionic groups on amine sites. The combination of polymer rigidity, high microporosity and ion-conductive functionalities of PIMs facilitates the formation of well-confined and sub-nanometre pathway, allowing fast transport of charge-balancing ions whilst unprecedented blocking redox-active species through membranes, fulfilling the function as efficient RFB separators hence achieving impressive performance in RFBs. These proof-of-concept demos using functionalised PIM membranes as efficient molecular sieves can guide the development of new generation membrane separators for a range of clean energy technology applications.

Ligand-metal complexes have demonstrated high potential for catalytic control over the ring-opening polymerisation (ROP) of rac-lactide. Catalyst performance and control over the resultant polymer structure can be improved by altering the sterics and electronics of the catalyst system, through modifying the ligand substituents and/or incorporating a second (hetero)metal. The development of bimetallic catalysts through the incorporation of a secondary metal into homogenous catalyst ligand architectures is a rapidly developing field within inorganic chemistry. The work in this thesis aims to adapt the electronics of metal complex catalysts derived from salen-ligands, by modification of the phenolic substituents and through the formation of cooperative bimetallic catalysts active toward rac-lactide ROP. Chapter 2 reports four new AlCl-salen complexes featuring NEt2-substituents, which display high catalyst activities towards rac-lactide ROP (kobs < 1.9 x 10-3 s -1 ), with moderate isoselectivity (Pi = 0.7) via in situ activation with a single equivalent of propylene oxide. The inclusion of the Al-Cl bond within the catalysts rather than the more commonly utilised Al-alkoxide moiety serves to expand the scope of these complexes as well as to potentially increase catalyst stability. Incorporating Lewis basic NEt2 groups into the ligand scaffold not only improves the initiation efficiency but also avoids the need for a Lewis basic co-catalyst and excess epoxide. Notably, studies of the amino-substituted catalysts reveal that the formation of a hexacoordinate aluminate species may hinder rather than enhance catalytic activity. The effect of various ammonium salts have been investigated upon the polymerisation and are proposed to act as chain transfer agents, resulting in shorter chain lengths and reduced polymerisation rates. Chapter 3 describes the synthesis, characterisation and catalytic activity of a series of heterobimetallic complexes for rac-lactide ROP. Derived from an ortho-carboxylic acid modified salen ligand scaffold, these complexes combine aluminium with alkali or alkaline earth metals (lithium, magnesium, zinc or calcium). The asymmetric nature of the salen ligand allows for selective metal site binding, with different metals displaying preferences for different binding pockets and thus avoiding metal redistribution. Through the addition of secondary metals, catalytic efficiencies can be enhanced by a factor of up to 11 compared to the monometallic analogues. Mechanistic studies, in tandem with DFT (density functional theory) and AIMD (ab initio molecular dynamics) calculations, suggest that activity enhancements occur through mixed-metal cooperativity, incorporation of an additional monomer coordination site, increased complex rigidity and optimised geometry around the metal centres. These trends contradict some of the catalyst design principles that are widely accepted for monometallic catalysts, emphasizing the importance of understanding heterometallic cooperativity to exploit the full potential of heterometallic catalysts in cyclic ester ROP. While magnesium and zinc enhance the catalyst activity, lithium and calcium both reduce the polymerisation rate, highlighting the importance of the heterometal nature in achieving cooperative catalysis. Chapter 4 builds upon the work in Chapter 3, modifying the tetra-anionic ortho-carboxylic acid salen ligand into a di-anionic ortho-methyl ester salen scaffold. Mono-, homobi- and heterobi-metallic complexes containing lithium, aluminium and zinc have been structurally characterised and tested toward rac-lactide ROP. The activity of the homobimetallic zinc complex was 47 times higher than the monometallic analogue. X-ray crystallographic structures and DFT calculations highlight the importance of the secondary (hetero)metal electropositivity on the Zn-Cl bond length, which correlates to the initiation efficiency in both homo- and heterobimetallic complexes. This suggests that longer (and weaker) Zn-Cl bonds lead to faster initiation through ring-opening propylene oxide to generate an active metal-alkoxide species in situ. Notably, monometallic aluminium and zinc complexes can also catalyse rac-lactide ROP in the absence of an epoxide, which circumnavigates the need for the toxic propylene oxide co-catalyst.

Non-covalent interactions underpin a vast array of molecular recognition phenomena including drug binding and asymmetric catalysis. Interactions involving aromatic rings are particularly pervasive. Therefore, there is demand for a more thorough understanding of the physicochemical nature of these interactions Chapter 1 begins by reviewing the physicochemical basis of molecular recognition. The utility of molecular balances (and model supramolecular complexes) as platforms to measure and characterise non-covalent interaction is explored using illustrative examples. Chapter 2 introduces a novel class of molecular balances based on a terphenyl motif. These balances are then used to evaluate the nature of polycyclic aromatic stacking interactions. No solvent effect is observed, and the strength of the interaction is found to scale with the change in solvent accessible surface area between the two conformers. Electronic structure calculations and SAPT energy decomposition reveal that van der Waals interactions are the primary driving force for the folding equilibrium. Chapter 3 seeks to evaluate the consistent bias towards the anti-conformer observed in the terphenyl molecular balances. Ab initio calculations suggest that is due, at least in part, to favourable CH⋯π interactions that are formed in the anti-conformer. Balances that vary the nature of the CH⋯π interactions while preserving the stacking interaction are introduced, resulting in a solvent effect. A simple model is used to dissect out the solvent-independent interaction and SAPT energy decomposition is used to evaluate their nature. Chapter 4 investigates the effects of fluorination on both aromatic stacking and CH⋯π interactions. Molecular balances featuring fluorinated aromatic rings and/or methyl groups are compared. Molecular balances featuring tetra- or pentafluorinated rings exhibit a solvent effect that does not appear to be the result of a single dominant factor. Pairwise comparisons of SAPT calculations between analogous compounds are used to evaluate the differences between fluorous and non-fluorous interactions.

Phthalocyanines (Pcs) have a wide variety of applications as colorants, photodynamic therapeutics, photovoltaic materials, catalysts etc. Pcs tend to co-facially aggregate due to the π – π interactions between their aromatic macrocycles, which may hinder certain applications. The insertion of 2,6-di-iso-propylphenoxy substituents at the peripheral sites of the Pc [(dipPhO)8Pc] proved successful in preventing aggregation between the macrocycles while the bulky substituents created accessible voids towards the active metal centre. Upon crystallisation of various metal (dipPhO)8Pc derivatives, clathrates with an interesting cubic structure, where the volume occupied by the crystallisation solvent amounts to around 40% of the unit cell, were obtained. Suitably sized bidentate ligands act as wall-ties to stabilise the crystal structure upon removal of the solvents that otherwise would cause loss of crystallinity. We have found that there is an astonishing range of metal cations, axial ligands and molecular wall-ties that are compatible with the formation of the porous crystal. Preliminary data using a gas cell for the in-situ analysis of O2, NO and CO binding to the metal cation will be reported. In addition, the co-crystallisation of (dipPhO)8Pc with tetraphenyl porphyrin (H2TPP) and the in-situ incorporation of bidentate ligands and of metals in the macrocycle of the TPP will be demonstrated.

Polymers of Intrinsic Microporosity (PIMs) are a new class of microporous material combining excellent solution processability with great structural diversity. The microporosity of PIMs derives from the inefficient packing of rigid and contorted polymeric chains. PIM membranes show great potential in gas separations (e.g., CO2/CH4, CO2/N2, O2/N2, H2/N2). However, they suffer from a well-defined tradeoff relationship between gas permeability and selectivity. Novel PIMs were designed and synthesised to investigate structure-property relationships and to provide a guideline for designing a new membrane material, which can provide a good balance of gas permeability and selectivity. In the first part of this thesis, two fluorinated benzotriptycene polybenzodioxin polymers were prepared. These benzotriptycene-based PIMs exhibit ultra-high permeability with remarkable selectivity for carbon capture (CO2/N2) and natural gas purification (CO2/CH4), and defined the new upper bounds for these gas pairs together with four other benzotriptycene PIMs. In particular, the fluorinated polymers showed a better performance for CO2/CH4 and He/CH4 than alkyl substituted benzotriptycene based PIMs due to their higher solubility selectivity resulting from the low CH4 sorption in the fluorinated polymers. In the second part, a fluorinated and non-fluorinated benzomethanoanthracene PIMs (PIM OCF and PIM-OCP) were designed and synthesized in which fluorine atoms illustrated a minor effect on polymer microstructure confirmed by molecular simulation. The improved CO2/CH4 solubility selectivity exclusively derives from the inclusion of the fluorocarbon unit. The perfluoroalkyl chain substituent was also observed to reduce the CH4 sorption and improve the solubility selectivities of CO2/CH4, He/CH4 and H2/CH4, although the reduced size selectivity of perfluoroalkyl chain substituted polybenzodioxin polymer and low surface area of the perfluoroalkyl chain substituted Tröger’s base polymer limit their potential applications. In the last chapter, dibenzeno-6,13-methanopentacene (DBMP), a bridged bicyclic structure with a bulkier structure than that of triptycene, was utilized for PIM synthesis. The membrane of the homopolymer (PIM-DBMP) proved too fragile for membrane fabrication. Therefore, the potential of DBMP for gas separations was investigated using a series of copolymers composed of DBMP and 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane (TTSBI). The gas permeability of the copolymers demonstrated that the introduction of DBMP improves the gas permeability and selectivity simultaneously, overcoming the challenging tradeoff relationship. PIM-DBMP was further modified via amidoxime functionalisation, which was anticipated to improve the membrane’s mechanical properties. As expected, a robust membrane of amidoxime-PIM-DBMP was achieved which showed promising gas separation performance.

Hypervalent iodine oxidants have been used extensively in oxidative metal catalysis, especially in gold catalysis, where the redox potential of gold(I) to gold(III) is large. The reoxidation of gold(I) within an intramolecular gold-catalysed direct arylation reaction developed previously in the group occurs after the turnover-limiting step, and so cannot be studied by analysing the reaction rates. Competition reactions between ArIIII(OR)2 oxidants with different electronic parameters have been carried out to gain further understanding into the reoxidation of gold(I) under the following reaction conditions. It was found that the more electron-rich oxidant has a higher relative rate compared to electron poor oxidants and log krel gave the best correlation with σ+ of the para-substituent. This suggests that the oxidant undergoes an initial ligand dissociation step to give an iodonium species before the gold is oxidised, as opposed to forming a π-complex with the gold(I) intermediate. Contrary to this result, the relative redox potential of these oxidants, calculated by looking at the equilibrium position between an iodine(III) oxidant and an aryl iodide showed that the more electron-deficient oxidant has a higher redox potential, and is therefore the more oxidising oxidant when compared to electron-rich oxidants. This trend has also been illustrated by looking at the electrochemical reduction of the oxidants using square-wave voltammetry.

The growing environmental impact of plastic waste has led to extensive research into the life-cycle of polymeric materials. Reduction in the build-up of commodity plastics, such as poly(ethylene terephthalate), has been a hot topic. However, recycling poly(ethylene terephthalate) requires energy intensive conditions and further puri cation to obtain the starting material phthalic acid after polycondensation. Advances in monomer design have expanded the range of biodegradable polymers accessible to mimic the properties of commercial plastics, whilst giving the advantage of greener recycling methods. Benzodioxepinones with varying meta-substituents were subjected to ring-opening polymerisation, using an aluminium salen catalyst to a ord a series of novel aromatic-aliphatic polyesters. The polymerisation, catalytic degradation, and thermal behaviours of the polyesters were explored along with their crystallographic structure. The characteristic degradation of poly(2-(2-hydroxyethoxy))benzoate back to its cyclic monomer, through exploitation of the monomer-polymer equilibrium, outweighed the poor thermal properties (Tg (27 C)) of the polyester. The unique degradability and thermal properties of this polyester gave potential as use in copolymers and blends with poly(lactic acid). Copolymerisation with poly(lactic acid) improved the thermal properties of poly(2-(2-hydroxyethoxy)benzoate) and introduced UV-vis absorbing properties to poly(lactic acid). The copolymers were shown to catalytically degrade, via the use of aluminum salen complexes, and enzymatically degrade, via proteinase K. Altering the electron donating and withdrawing properties of the meta-substituents from hydrogen has been shown to tune the rate of degradation and the thermal properties and stability of the polyester. The polymerisation and depolymerisation kinetics showed faster rates for electron withdrawing groups with selective depolymerisation back to their cyclic monomers in 10 minutes at 110 C. The thermal characterisation showed varying glass transition temperatures from 29.7 C to 60.7 C, with electron withdrawing groups exhibiting higher values. An increase in the melting temperatures and the thermal degradation activation energies of the polyesters were also observed. The tunability and characteristics of this class of aromatic-aliphatic polyesters gives insight into replacing commodity plastics with polyesters that have the ability to be recycled selectively back to their monomers, thus minimising the amount of starting material required to reprocess the plastic.

Polymers of intrinsic microporosity (PIMs) owe their microporosity to their rigid and contorted structure which prevents efficient space packing. Their microporosity and processability make them attractive for many industrial applications, such as heterogeneous catalysis, gas separation membranes, hydrogen storage and adsorbents for organic compounds. Our goal in this project is to broaden the spectrum of PIM structures by preparing novel PIMs with potential for different industrial applications but focusing on gas separation membranes. Characterisation of the novel polymers was achieved to establish their chemical and physical properties including solubility, surface area, thermal stability and their molecular weight. In some cases, casting the resulting PIMs from solution enabled the formation of self-standing films which could then be analysed for their ability to separate different gas mixtures. Three different types of PIM were targeted during the PhD programme. Firstly, the preparation of Tröger's base (TB) containing hypercrosslinked polystyrene was attempted. The first step was the nitration of polystyrene by using different reaction conditions, with the aim to introduce the highest possible number of nitro groups, followed by the reduction of nitropolystyrene to the aminated polystyrene. Finally, hyper-crosslinking of the amino-polystyrene was attempted by formation of TB units between polymer chains. Secondly, new ladder and network PIMs derived from different catechols monomers with 2,3,7,8-tetrafluoro-5,5',10,10'- tetraoxidethianthrene were synthesised. This thiathrene-based rigid monomer increases the distances between two consecutive "sites of contortion" within the polymer chains and provides sulfonyl functional groups, which may influence the adsorption and gas separation properties of the resulting polymers. Thirdly, a series of novel microporous polyimides (PIMPIs) were prepared using different diamine monomers and thiathrene-based dianhydride monomers. All polymers were characterized by using NMR, IR spectrometers and their chemical and physical properties were measured using a variety of techniques. In addition, for some polymers successful film formation via casting from solution allowed the measurement of their gas permeability to assess their ability to separate gas mixture. All chemical procedures for the synthesis of monomers and polymers, properties of the resulting polymers and comparisons with existing polymers are described in this thesis.

Frustrated Lewis Pair (FLP) chemistry is a significant and growing field since it offers a novel non-metal catalyst for hydrogenation and small molecule activation. Once it was discovered, different FLPs with varying reactivity towards small molecules have been extensively investigated. Its research has mainly focused on small molecule-based FLPs, however, especially in the aspect of hydrogenation reactions. In the field of polymer chemistry, several examples of conventional Lewis pair adduct containing polymers have been reported but there has yet been no exploration of FLPs incorporated into polymers up to the date of this project. Dynamic crosslinked polymeric networks have attracted more attention in recent years as their shape can be post-modified after polymerisation due to their exchangeable crosslinks. This dynamic crosslinking also makes the material stimuli-responsive and provides self-healing properties. This thesis introduces the synthesis of a polymeric network with combined features of frustrated Lewis pairs and dynamic crosslinking. New monomers containing Lewis acid or Lewis base centres were designed and synthesised successfully. For the pair 4- styryl-diphenylborane and 4-styryl-diphenylphosphine, the two monomers were found to be able to bind together at high concentration in toluene so as to form a weak conventional Lewis pair (CLP) adduct. An FLP can be obtained when the phosphine monomer was replaced to its more hindered analogue, 4-styryl-dimesitylphosphine, which is reactive enough to form a complex with diethyl azodicarboxylate (DEAD), where the DEAD bridges the boron and phosphorous centres. The monomers obtained were copolymerised with styrene by RAFT polymerisations. It was also found to be possible to control both the molecular weight and the dispersity. The FLP polymers synthesised in this way were characterised by NMR spectroscopy and gel permission chromatography. The Lewis acidity of both the monomer and resultant polymer were tested using the Gutmann-Beckett Method, and a decrease in Lewis acidity was observed when the boron monomer was polymerised. The network was synthesised by addition of DEAD into the solution containing both Lewis acid and Lewis base polymers. A gel was quickly generated (in 10 seconds). The mechanical properties of the network formed were determined by rheology. The gel was responsive to heat, in that it would break and return to a polymer solution at high temperatures. The gel formed also shows the ability to self-heal with the assistance of a solvent after physical cracking. The synthesis of the next generation of polymeric FLPs was also examined. A much more Lewis acidic boron monomer, (2,3,5,6-tetrafluorostyryl)- bis(pentafluorophenyl)borane was synthesised. This boron monomer was paired with 4-styryl-dimesitylphosphine to form a reactive FLP that was able to activate small molecules, including dihydrogen molecules and carbon dioxide. The catalysis reactivity of the hydrogenation reactions of this FLP was also explored. The copolymers made from these reactions readily formed a supramolecular gel upon mixing, which also proved temperature responsive. These early-stage results proved that this new boron-monomer is capable of generating a novel stimuli-responsive smart polymer for carbon capture and hydrogenation catalysis. Except for the polymeric FLP, some early-stage research about polymeric CLP and novel synthetic methods for boron-monomers were also introduced and discussed.

This project was focused on the synthesis of novel phthalocyanines for the construction of porous molecular crystals that incorporate the desirable properties associated with phthalocyanine complexes. Conventional phthalocyanines are relatively insoluble, therefore, remain difficult to process, characterise and effectively crystallise. To counteract this problem, bulky 2,6-di-iso-propylphenoxy substituents were placed around the aromatic core of the phthalocyanine macrocycle and proved to successfully inhibit the co-facial aggregation which limits their solubility. These bulky groups also direct the crystallisation of the phthalocyanine macrocycle inducing a cubic packing arrangement with significant accessible solvent filled voids. The aim of this work was the modification of this 2,6-di-isopropylphenoxy substituted phthalocyanine to enhance the magnetic and catalytic properties and demonstrate its suitability as a platform for creating iso-reticular systems with increased functionality. It was anticipated that mixed double decker complexes of this derivative and another phthalocyanine macrocycle would form crystals with the same cubic spatial arrangement, while maintaining their high catalytic activity or single molecular magnetism behaviour. Firstly, a larger number of transition metals along with some lanthanide metals have been incorporated within this substituted phthalocyanine, extending the previous work on this system. Furthermore, the corresponding contracted macrocycle boron subphthalocyanine was also investigated. While the 2,6-diisopropylphenyl substituents did not greatly affect the electronic properties of the subphthalocyanine, the solid state properties of the material proved interesting. The lanthanide phthalocyanine complexes were further employed in the preparation of lanthanide double decker phthalocyanines that possess single molecule magnetic properties. While retaining this desired property, they also crystallised to produce clathrates with large solvent filled voids. A different double decker complex which contained two iron metal centres bridged by a single nitrogen atom was also prepared from the octa substituted 2,6-di-iso-propylphenoxy phthalocyanine and an unsubstituted phthalocyanine. This nitrido bridged di-iron phthalocyanine complex displayed similar catalytic activity to previously reported systems of this kind and crystallised to afford cubic crystals with large solvent filled voids. These were shown to be accessible by both solvent and ligand exchange. Suitable bidentate ligands for structural stabilisation could be also incorporated. Finally, the preparation of an alternatively substituted phthalocyanine for the construction of a potential porous molecular crystal was studied. By synthesising a hexamethylindan substituted phthalonitrile, it was possible to obtain a soluble phthalocyanine that crystallised to give a clathrate that contained large one-dimensional voids.

Polymers were synthesised containing the methanoanthracene (MA), methanopentacene (MP) and benzomethanoanthracene (BzMA) units to investigate their properties as gas separation membranes. For each monomer type, polymers were successfully synthesised using Tröger’s base (TB) chemistry and cast as free standing films from low-boiling point solvents. Gas permeability tests revealed high selectivities for most of the technologically significant gas pairs. Most interestingly, MA/dimethylethanoanthracene co-polymer, MP-TB and BzMT-TB polymers all show a high degree of selectivity in the separation of a number of technologically significant gas pairs when compared to other state-of-the-art polymers. In particular MP-TB has very high selectivity for the N2/O2 gas pair. Synthetic routes to MP-TB and BzMA-TB involve fewer steps and are significantly cheaper to implement compared to other state of the art TB polymers and high performance PIMs that provide data above the Robeson upper bounds due to their high permeability and selectivity. Co-polymers of MA were synthesised in 1:1, 4:1 and 9:1 ratios. Gas permeability data demonstrated that properties correlate with the monomer composition. Results indicate that inclusion of methano-bridged units into the polymers increased the rigidity of polymer chains, leading to smaller pore widths and improved selectivities compared to polymers such made from more flexible structural units. The first chapter of this thesis introduces the concepts of microporosity, permeability and membrane separation, and describes a number of polymers that have demonstrated properties of interest for separating gas mixtures. Chapter two describes the synthesis and gas permeability data of MA-TB polymer and a series of copolymers incorporating MA. Chapter 3 describes the synthesis of polymers containing the MP structural unit and describes the performance of MP-TB as a membrane for gas separation. Chapter 4 describes a number of polymers synthesised using the BzMA structural unit and chapter 5 reports the synthesis of a number of larger units derived from BzMA including benzomethanotetracene, benzomethanopentacene and dibenzomethanopentacene. Permeability data for TB polymers synthesised from BzMA-type monomers is reported in these chapters.

This project was focused on the synthesis of novel Polymers of Intrinsic Microporosity (PIMs) that are soluble in common low boiling point solvents so that self-standing films can be prepared for gas permeability measurements. The common building unit of these novel PIMs was triptycene and its derivatives. Modification of these triptycene compounds enabled the alteration of the polymeric backbone, so that we could tune the gas permeability properties. Modifications included the substitution of different functional groups (e.g. addition of methyl groups) and also the extension via benzoannulation of the triptycene structure. The synthesis of the PIMs was based around three different polymerisation techniques. The first one involved the formation of triptycene-based polyimides (PIs) using a triptycene based dianhydride, prepared in a multistep synthesis. Shorter and cheaper synthetic routes were attempted, but all to no avail. The resulting triptycene monomer was reacted with a variety of commercial and non-commercial bisanilines for the formation of several PIM-PIs, all exhibiting different performances. Robust self-standing films were obtained for two of these PIM polyimides. In addition to the formation of polyimides, the synthesis of Tröger’s Base (TB) polymers, also based on triptycene components, were achieved. This type of polymerisation involves the reaction between a “bisaniline” monomer and a source of “formaldehyde”, such as dimethoxymethane (DMM), in a strong acid media, typically trifluoroacetic acid (TFA). Modification of these triptycene-based bisanilines has led to the formation of TB-PIMs, all with distinctive gas permeation properties. TB-PIM copolymers (reaction between two different bisaniline monomers with DMM and TFA) were synthesised in an attempt to further tune the performance of the polymers. Finally, the preparation of polybenzodioxan polymers based around extended triptycene monomers (i.e. benzotriptycenes) was studied. By using a variety of substituted benzotriptycene biscatechol monomers and performing the polymerisation using tetrafluoroterephthalonitrile, in the presence of K2CO3, the synthesis of a series of substituted benzotriptycene polybenzodioxane polymers was successfully achieved and the polymers showed enhanced gas permeation properties.

The work reported in this thesis describes the successful preparation of three classes of polymer that were designed to possess intrinisic microporosity from a range of aromatic tetrahydroxy and diamine monomers. The tetrahydroxy family of monomers were used to prepare a number of polybenzodioxane polymers and co-polymers using the chemistry developed for the archetypal PIM-1. Two co-polymers formed films suitable for gas permeability measurements indicating that they transport gases at high selectivity but lower permeability as compared to PIM-1. The diamino-containing monomers were used to prepare a number of polyimides (PIM-PIs) using well-established polymerisation chemistry and also some Troger’s base polymers (PIMTBs) using a recently developed polymerisation method. A series of TB-PIMs with different substituents next to the amino group (H and CH3) and containing various pendant groups were prepared in order to establish structure-property relationships. Some of these polymers proved microporous with surface areas ranging from 22-510 m2/g. Unfortunately, none were suitable for film formation or gas permeation measurements. PIM-PIs were prepared from diamino monomers based on bulky 1,4-ditritylbenzene (BAB), adamantane (AD) and trifluorodiaminoaryl (TFA) units by reaction with commercial 4,4′- (hexafluoroisopropylidene)diphthalic anhydride (6FDA). Some of these polymers also demonstrated microporosity with surface areas ranging from 8-560 m2/g. Two polymers (PIM-AD5- PI and PIM-AD6-PI), exhibited good solubility, excellent thermal stability and intrinsic microporosity, with the introduction of highly rigid and bulky groups adjacent to the imide group. PIM-AD5-PI and PIM-AD6-PI demonstrate a very good combination of high permeability and good selectivity for CO2/CH4, H2/N2 and H2/CH4 gas pairs with data that lie close to the Robeson 2008 upper bounds, which is the benchmark for the evaluation of the potential of a new polymer for making gas separation membranes. Finally, a series of trifluoromethyl (CF3) containing PIM-PIs were prepared. Again, it was found that by increasing the rigidity of the polymers by increasing the number of methyl substituents a greater amount of intrinsic microporosity is generated by the polymer. Seven polymers of this series formed robust films suitable for gas permeability measurements and demonstrated good selectivity for CO2/CH4, O2/N2, H2/N2 and H2/CH4 gas pairs with data that lie near the 2008 upper bounds.

Polymers of Intrinsic Microporosity (PIMs) combine the desirable processability of polymers with a significant degree of microporosity generated from the inefficient packing of their rigid and contorted structures. They are attracting attention for a variety of applications including as membrane materials for gas separations. Over the last 30 years, membranes have become an established technology for separating gases and are likely to play key role in reducing the environmental impact and costs of many industrial processes such as O2 or N2 enrichment from air, natural gas upgrading and hydrogen recovery from ammonia production. This thesis describes the synthesis of a series of novel PIMs, primarily PIM-polyimide structures (PIM-PI) and investigates their potential in such applications. In particular, it focuses on the design and synthesis of solution processable PIMs in order to study how structural differences affect the gas permeability. The first section describes the synthesis of a variety of PIM-PIs using large bulky diamines derived from spirobisindane (SBI) and biphenylfluorene (BPF) structures which are useful monomers for achieving high BET (Brunauer-Emmett- Teller) surface areas (> 650 m2 g-1). The second section describes a whole series PIs based on novel and literature based Tröger’s base (TB) diamine monomers. Most of these exhibited good solubility, excellent thermal stability and intrinsic microporosity, with apparent BET surface areas in the range 450-739 m2 g-1. Notably, a polyimide derived from Me2TB and pyromellitic anhydride demonstrates gas permeability data above the 2008 upper bounds for important gas pairs such as O2/N2, H2/N2 and H2/CH4. The third section aims to enforce rigidity within the polymers further by incorporating differently substituted monomers based on rigid ethanoanthracene (EA) units. This includes the formation of a novel EA-EA based PI with an exceptionally rigid polymeric structure, possessing a BET surface area of 694 m2 g-1. In addition to very high permeability, this polymer demonstrates improved gas selectivity due to its enhanced performance as a molecular sieve, placing it amongst some of the highest performing polymers to date. The final section looks at other ways in which rigidity can be enforced including the formation of TB-polymers and thermally rearranged (TR) polymers and assesses their potential for future investigations.