School of Chemistry - Theses
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ItemSynthesis and Testing of diaryl sulphide based Fluorine-18 Radiotracers for Positron Emission Tomography of Hypoxic Tumours( 2019)Hypoxia is a critical physiological marker demonstrated in a variety of cancers, imaging it will provide valuable insight into prognosis and treatment. However, the slow kinetics of [18F]FMISO(1.2) means that there is a 2 hour delay between injection and imaging for patients. Fluorine-18 labelled Chloroethyl sulfoxides [18F]SO101 and [18F]SO201 were shown to have both faster kinetics and higher contrast compared to [18F]FMISO(1.2) in a rat model of ischemic stroke. Perceived toxicity from the nitrogen mustard analogues in [18F]SO101 and [18F]SO201 lead to structural changes resulting in [18F]SO501. [18F]SO501 demonstrated good uptake into hypoxic SK-RC-52 tumours while also clearing from muscle, giving good contrast and therefore high-quality images, however it had a low radiochemical yield of 2.5% making it impractical for routine clinical application. Structural changes were made to the base compound [18F]SO501 in order to adapt it to a different method of radiolabelling in an attempt to increase the RCY while maintaining its selectivity for hypoxic tissue. The modifications made included the introduction of a propargyl group for click chemistry, variable length PEG groups and alterations to the ester group from an ethyl ester to an isopropyl ester and in one case doing away with it entirely. Six different diaryl-sulfoxide radiolabelled compounds were synthesised for this project [18F]2.16, [18F]2.26, [18F]2.36, [18F]2.43, [18F]2.53 and [18F]2.63 from their respective diaryl-sulfoxide precursors 2.15, 2.25, 2.35, 2.42, 2.52 and 2.62. After in-vivo imaging in SK-RC-52 tumours xenografted onto BALB/c nude mice the most promising tracer [18F]2.16, which had the best tumour to muscle ratio of 1.6 at 60 minutes and 2.1 at 110min, underwent metabolism studies involving Rat S9 liver fractions.
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ItemDesigning New Singlet Fission Materials for High Performance Organic Solar Cells( 2019)Singlet fission (SF) is the photophysical process of splitting one singlet state into two triplet states. The first requirement for SF is that the first excited singlet state of the chromophore should be at least twice the energy of the first triplet state. In the last decade, SF has received a lot of attention as a way of converting high energy photon above the semiconductor bandgap to two lower energy excitons closer to the bandgap and so overcoming the Shockley-Quiesser limit (maximum theoretical efficiency of photovoltaic cells) of single-junction solar cells. However, the number of SF materials that can be included in photovoltaic devices is limited because of strict materials requirements. This is the main reason why only a small increase in the efficiency of photovoltaic devices by including SF materials has been reported so there is a need to design, synthesis and study new class of material for SF. A new strategy to design a class of intramolecular SF (iSF) material is reported to be coupling two strong acceptors with low triplet energy level with a strong donor (A-D-A). This model not only takes the advantage of providing an excited electronic state with significant charge-transfer character that facilitate SF but also allows us to choose units based on the energy level requirement. Using this strategy, I have designed and synthesized the small molecule (BDT(DPP)2) and polymer (p-BDT-DPP) systems by coupling benzodithiophene (BDT) as electron donor and bisthiophene-pyrrolopyrrole-dione (TDPP) as electron acceptor with low lying triplet energy level. Various steady state and time-resolved spectroscopic techniques such as ultrafast and nanosecond transient absorption (TA) spectroscopy were used to study the excited state mechanism in the candidate compounds. In most of highly efficient SF systems, a large degree of crystallinity is required, and the SF yield is highly sensitive to the crystal packing and intermolecular nearest-neighbour coupling. The first set of A-D-A material revealed that a stronger self-association is needed to drive SF in this class of material. To address this issue, a self-organizing core such as hexa-peri-hexabenzocoronene (HBC) is used as electron donor and is attached to TDPP as an electron acceptor and the results show a significant increase in the efficiency of triplet yield. It has been demonstrated that the chromophore packing has a significant impact on the SF parameters such as yield and rate and understanding this relationship will help us to understand SF mechanism better. To investigate this relationship, four perylenediimide (PDI) derivatives were studied for SF comprising the same PDI core but with different substituents at their imide positions, 4-butylphenyl, butyl-terphenyl, diisopropylphenyl and mesityl which display distinct molecular geometries with varied intermolecular pi-pi interactions. The results demonstrate that SF occurs with different rates and yields in the PDI derivatives. Also, the results show that both decay rate and SF rate are sensitive to intermolecular packing.
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ItemIncorporation of Quantum Dots into Optoelectronic Devices: Ligands as Charge Brigands( 2019)With their tunable and almost monochromatic emission over the whole visible spectrum, colloidal II-VI semiconductor quantum dots (QDs) are attracting significant interest as novel electroluminescent materials in light-emitting diodes (LEDs). Being processable in solution allows the deposition of large-scale films at low cost and brings QDs in a competitive position to their organic counterparts. Organic ligands capping QDs are used to maintain colloidal stability during synthesis and provide passivation in solution. While ligands remain invisible under optical characterisation, this thesis provides insights into the mechanisms by which ligands impact charge carrier dynamics within a light-emitting diode. In doing so, robust and bright QDs emitting at 410 nm are synthesized, passivated with ligands of various lengths and electrical conductivity and incorporated into an LED architecture. Based on Impedance Spectroscopy measurements ligands have been identified as a major obstacle for charges transiting to the QD to produce light: ligands act as brigands in trapping charges and prevent efficient charge recombination. A novel capacitance behaviour is described and attributed to the accumulation of charge carriers within the ligands during operation. Together with an inductive response in the impedance plane changes in capacitance can be used as a diagnostic tool to determine the recombination efficiency in a quantum dot light-emitting diode (QLED). By driving a QLED with a rectangular pulse accumulated charges lead to a delayed luminescence peak when the bias is turned off and can thereby be visualised. When a 5 nm thick aluminium layer is added into the hole transport layers, trapped charges can open a memory window and add a new device functionality to a QLED. This thesis concludes with ideas to overcome the ligand-dependent charge accumulation and suggests a novel type of QDs for a more efficient device performance.
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ItemDevelopment of novel cross-linked polymer inclusion membranes (PIMs) for the separation of metallic and non-metallic species( 2019)Separation based on polymer inclusion membranes (PIMs) has gained significant interest in recent years as an environmentally friendly separation technique. PIMs are generally classified as a type of liquid membrane in which the membrane organic phase (containing the extractant and in some cases a plasticizer or modifier) is immobilized within the entangled chains of a polymer. The majority of the extractants used in PIMs are liquids, although solid extractants such as trioctylphosphine oxide (TOPO) can also be used when liquified because of the presence of impurities (e.g., solvents). Different base polymers, such as poly(vinyl chloride) (PVC), cellulose triacetate (CTA), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), have been used as the polymeric support of PIMs. Although the extractants are the active PIM components, the nature of the polymeric support also plays a vital role in the performance of these membranes. In the research described in this thesis the structure of the PIM polymeric support has been altered using different cross-linking agents (i.e., polymer of monomers) and their effect on PIM extraction and separation performance has been studied.
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ItemInvestigation of optically transparent non-wetting coatings( 2019)Surfaces that exhibit extreme non-wettability are the result of the combination of surface chemistry and a high degree of roughness. Typically, such materials are visibly opaque, predominantly due to the enhanced light-scattering from the rough interfaces. In the present study, particle-based coatings with carefully controlled surface and bulk roughness parameters are investigated in multiple length scales to identify conditions under which extreme surface-phobicity and visible transparency can coexist. Visibly transparent micron-thick fumed silica nanoparticle (7–40nm) seeded sol-gel coatings were fabricated. Nano-scale surface and bulk features with varying degrees of water-repellency (hydrophobicity) were correlated with visible optical transparency. Furthermore, alternative tuneable hollow silica spheres in the sub- micron scale range were utilised to create a finely detailed range of roughness, which simultaneously changes both the refractive index through lowering relative optical permittivity and film density, and the surface wettability. Surface morphology and roughness of individual samples were examined in detail using atomic force microscopy, non-contact optical profilometry, scanning electron microscopy and synchrotron-based small-angle X-ray scattering (SAXS) in transmission mode. The latter was employed to investigate the nano-scaled common length scale (repeating) features in the coating. Coatings consisted of hierarchically ordered structures similar to fractals, with nano-scale (12–30nm) features superimposed on top of larger (200–400nm) sub-micron features displaying coexistence of optical transparency and water repellency. Extended surface studies were achieved by sputtering a thin (8–15nm) layer of sputter-coated Cr metal, which enhanced the surface X-ray scattering. Coatings fabricated using colloidal fractals with enrichment of both nano (20–30nm) and sub-micron (50–270nm) length scale on its surface structure displayed an enhancement to the roughness-induced water-repellency behaviour. Analysis of the bulk features alone was performed through the cross-sectional imaging under dual- beam FIB/SEM. Visible optical transparency in the film required nanoparticle cluster size to be between 130–180nm in length, to minimise the scattering of visible light. Alternatively, through the manipulation of the size of hollow core and silica shell thickness, the optical transparency at specific wavelengths of visible light correlated to the size of hollow silica spheres is enhanced without the loss of roughness. Hollow silica spheres within the sub-micron length scale (300–700nm) provide an alternative system for fabricating roughness-induced optically transparent non-wettable coating.
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ItemSupramolecular Assemblies of Cyclotricatechylene( 2019)This thesis presents the results of synthetic and structural investigations of novel cyclotricatechylene-based supramolecular assemblies. Cyclotricatechylene is a bowl-shaped tris-catechol that has been shown to associate with other chemical species through hydrogen bonding and metal coordination. The research focuses on the synthesis and characterisation of novel crystalline supramolecular assemblies of cyclotricatechylene. The compounds described in the four experimental chapters include assemblies of cyclotricatechylene and its related anions with s, p, d and f-block elements of the periodic table. The compounds have been characterised X-ray crystallography. Synthetic and structural investigations of compounds formed from the combination of cyclotricatechylene with s-block metal cations reveal a diverse array of network materials, with cyclotricatechylene in various protonation states. The s-block cations are commonly found to associate with the oxygen atoms of the ligand, however Rb+ and Cs+ also exhibit an affinity for the inner and outer aromatic surfaces of the ligand. Two compounds containing cyclotricatechylene ‘clams’, H[Cs(ctcH5)(ctcH5)] and [Cs(ctcH6)2]+ are reported, in which cyclotricatechylene is found in different protonation states. In these compounds, the large group 1 metal cation Cs+ associates with the electron-rich aromatic surfaces of the cyclotricatechylene bowls, an interaction present in many structures described in this thesis. Metal-cyclotricatechylene polymeric structures are reported, in which s-block metal cations are chelated by catechol(ate) oxygen atoms. These structures include 2D sheets containing Ca2+, Sr2+ and Ba2+ cations, [Cs2Li4(ctcH3)4]6- metallocycles that hydrogen bond to each other to form a 3D network that has the topology of diamond, undulating ‘honeycomb’ networks with Cs+ or Rb+, and a 3D network with the topology of the (10,3)-a net, containing Cs+ in cyclotricatechylene bowls and Sr2+ chelated by catecholate units. Four high-symmetry cubic structures formed from the specific combination of cyclotricatechylene with Cs+ or Rb+, K+, acetone, water and an oxyanion contain metallocubes of formula [K4(ctcH6)4(H2O)8]4+. The assemblies are arranged in a symmetrical manner, which reflects high level of complementarity in these crystalline supramolecular assemblies. The combination of cyclotricatechylene with vanadyl or uranyl units leads to the formation several large, anionic coordination ‘cage’ assemblies with fully deprotonated cyclotricatechylene. An aesthetically pleasing example is an assembly with trigonal prismatic geometry, of formula [(VO)9Cs6(ctc)6]18-, in which vanadyl oxo groups are directed both into and out of the cage. Systems containing the uranyl cation (UO22+) were found to exhibit considerable structural diversity that can be attributed to the formation small clusters of uranyl cations with oxo, hydroxo, peroxo and aqua ligands. The co-precipitation of uranyl-based side products provides significant challenges with respect to the characteristion of these materials. A robust tetrahedral assembly of cyclotricatechylene with silicon, [(PhSi)6(ctc)4]6-, was found to be identical in topology to, but much easier to characterise than, its d-block metal analogues. Unlike geometrically similar metal-based cages, all bonds within the anionic assembly are covalent. The cage has been shown to persist in the gas phase and also when crystals of the compound are boiled in water. The crystalline material can also uptake Cs+ cation guests, which occupy the bowls of the tetrahedra.
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ItemDevelopment and application of theoretical models for molecular magnetism( 2019)My thesis consists of two projects. In the first, I have worked on the development of scalar relativistic and spin-orbit coupling methods within the ab-initio framework of the package CERES, developed in our group. In the other project, I have explored for the possibility of attaining toroidal moments in magnetic rings with weak or zero spin-orbit coupling. I managed to theoretically identify entirely new families of molecules that have a degenerate ground state where it is possible to prepare a purely toroidal quantum state. In Project 1, I have implemented the Douglas Kroll Hess method of 2nd order in the quantum chemistry code CERES to incorporate the scalar relativistic effects. I have also explored approximations to the Breit-Pauli Hamiltonian and found that the bare one-electron operator is often sufficient to obtain reasonably good crystal field energy levels within the lowest spin-orbit multiplet. I also present a comparison between different mean-field approximations for incorporating the two-electron terms. In Project 2, I have theoretically investigated new spin-frustrated molecular triangles that show the first known example of a toroidal quartet, composed of two degenerate toroidal doublets, solely as a consequence of spin-frustration, and despite having no spin-orbit coupling. Finally, I have generalized these findings to extended odd-membered ring and managed to identify infinite families of molecular rings that show a ground multiplet composed of one or more toroidal doublets.
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ItemPorous coordination polymers for the capture of simple gases and environmentally harmful emissions( 2019)The thesis describes a synthetic and structural investigation of coordination polymers in addition to an analysis of their adsorption properties. In chapter 2 the synthesis and structure of Li+ based network materials are described. An open-type network of composition Li(paa)DMF (Hpaa = (2E)-3-(pyridine-4-yl)prop-2-enoic acid) was successfully synthesised. Exposure to the atmosphere, however, resulted in the material redissolving into mother liquor. Crystals of a dense Li(paa) network subsequently separated from the solution. Open-type frameworks have yet to be generated using the longer peb- (Hpeb = 4-[(E)-2-(pyridin-4-yl)ethenyl]benzoic acid) ligand. The coordination environment of Li+ ions in [Li2(peb)(H2O)7](peb)H2O is dominated by water molecules whilst the presence of a coordinated DMSO molecule in Li(peb)DMSO prevents the formation of channels. In chapter 3 the synthesis and structures of five framework materials analogous to Zn(hba) (H2hba = 4-hydroxybenzoic acid) are reported. The single crystal X-ray diffraction data of the structures are of poor quality, with broad streaky diffraction spots and low resolution, however X-ray powder diffraction unambiguously confirms that all frameworks adopt the same topology to that of Zn(hba). The tetrafluoro hba2- ligand did not form Zn(hba)-type frameworks. Instead two dense frameworks, Zn2(tetrafluoro hba)(OAc)2 and Zn(tetrafluoro hba)(MeOH)MeOH, were formed. Zn2(tetrafluoro hba)(OAc)2 is formed when Zn(OAc)2 is combined with tetrafluoro hba2- while Zn(tetrafluoro hba)(MeOH)MeOH is formed when Zn(SiF6) is used instead of Zn(OAc)2. Attempts to synthesise Zn(hba) family like frameworks with ligands related to cma2- (H2cma = (2E)-3-(4-Hydroxyphenyl)prop-2-enoate) have proven unsuccessful to date with the ligands HhpOa- and HhpHNa- (H2hpOa = 4-hydroxyphenoxyacetic acid and H2hpHNa = N-(4-Hydroxyphenyl)glycine) chelating to metal centres. The HhpOa- ligand formed a relatively simple mononuclear complex with Cu2+. The complexes participate in extensive hydrogen bonding resulting in a 3D hydrogen bonded network. The combination of HhpHNa- ligands with Zn2+, results in binuclear Zn2+ clusters, bridged by HhpHNa- ligands to form chains. These chains are linked through phenol-phenol and phenol-carboxylate hydrogen bonds to give a 3D hydrogen bonded network. In chapter 4 and 5 the sorption properties of the Zn(hba) family of networks are reported. The networks are robust and exhibit the capability of adsorbing a variety of small molecules including the gases N2, CH4, CO2, H2 and the anaesthetics, isoflurane, sevoflurane, xenon and nitrous oxide. The smaller non-intersecting channels in the Zn(hba) family of networks lead to lower overall gas uptake capacity, although the adsorption of gases at 100 kPa is comparable to MOF materials that do not possess open metal sites. Collaboration with Prof Cameron Kepert and Dr Peter Southon from the University of Sydney showed that Zn(hba) is capable of capturing significant quantities of sevoflurane and isoflurane well below the concentration of the anaesthetics exhaled by patients. Thermogravimetric analysis revealed that Zn(hba) is capable of retaining approximately 83% of captured isoflurane below 60 degrees Celsius. A prototype anaesthetic capture device was shown to capture 74% of the anaesthetic passed through an anaesthesia machine. The sevoflurane that was captured by the host in theatre was then transported to the candidate’s laboratory and separated from the host network by application of gentle heating under vacuum. The sevoflurane vapour was then condensed by cooling. The isolated sevoflurane was then characterised by NMR.
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ItemUltrasonic emulsification in biopolymer complex emulsion systems( 2019)An emulsion is a colloidal mixture of two immiscible liquids, in which one is dispersed into another with the help of shear forces and the presence of surface-active compounds. The range of applications for emulsions is enormous, with emulsions found in industries such as food, cosmetics, medicine and petrochemicals. Understanding how to control the physical properties of emulsions has been a long-standing research challenge. In particular, the ability to achieve long-term stability of emulsions is of great significance in many practical applications. The physical stability of emulsions can be improved with a reduction in the droplet size of the dispersed phase, which is determined by the extent and intensity of the emulsification process and the associated balance between droplet breakup and coalescence. High-intensity low-frequency ultrasound (US) is a promising high-shear emulsification method that leverages the physical effects created by acoustic cavitation. Biopolymers are naturally occurring polymers that have many applications in food and personal care products. In particular, biopolymer emulsions are found in many daily products. The ability to tailor the physical properties of such emulsions, including texture, stability and flow behaviour, is a focus of much research and development. Emulsions are commonly fluid suspension, however they can also undergo a solution-gel transition, greatly altering the macroscopic texture into a semi-solid material. Emulsion gel formation has been reported in the literature, however, little is understood about the role of the emulsification process, in particular, associated turbulent flow, on the mechanisms on emulsion gel transition. In this thesis, ultrasonic emulsification involving complex biopolymer systems has been studied. The thesis presents new fundamental understandings of this process, in particular the effect of the turbulent environment on biopolymer emulsion gel formation. This understanding has been used to develop a novel type of emulsion gel, for which the formation mechanism has been investigated and described. A novel demulsification technology has been also developed for enhanced oil separation from biomass systems. The basic concepts underlying emulsions, emulsification and biopolymers are introduced first introduced in Chapter 1 along with fundamentals of US and sonochemistry. In Chapter 2, a detailed review of the literature is presented describing the current understanding of emulsification in turbulent flows, the mechanism and control of ultrasonic emulsification, the mechanism of colloidal sol-gel transition in biopolymer emulsion systems, and flow-induced phase inversion. Additional attention is given to literature on casein micelles and dairy emulsion, as this was the system explored in most detail experimentally in the thesis. Knowledge gaps in the literature are identified and the research aims and thesis scopes placed into this context. The experimental details, including materials, methodologies and analytical techniques are presented in Chapter 3. The experimental research results are presented and discussed in Chapter 4 to 6. In Chapter 4, three essential experimental parameters in the ultrasonic emulsification process, namely sonication time, acoustic amplitude and processing volume, are individually investigated, theoretically and experimentally, and correlated to the emulsion droplet sizes produced. The results show that with a decrease in droplet size, two kinetic regions can be separately correlated prior to reaching a steady-state droplet size: a fast size reduction region and a steady-state transition region. In the fast size reduction region, the power input and sonication time can be correlated to the volume-mean diameter by a power-law relationship, with separate power-law indices of -1.4 and -1.1, respectively. A proportional relationship is found between droplet size and processing volume. The effectiveness and energy efficiency of droplet size reduction has been compared between US and high-pressure homogenisation (HPH) based on both the effective power delivered to the emulsion and the total electric power consumed. Sonication could produce emulsions across a broad range of sizes, while high-pressure homogenisation is able to produce emulsions at the smaller end of the range. For ultrasonication, the energy efficiency is higher at increased power inputs due to more effective droplet breakage at high US intensities. For HPH the consumed energy efficiency is improved by operating at higher pressures for fewer passes. At the laboratory scale, the US system requires less electrical power than HPH to produce an emulsion of comparable droplet size. The energy efficiency of HPH is greatly improved at large scale, which may also be true for larger-scale ultrasonic reactors. In Chapter 5, shear-induced emulsion gel formation has been demonstrated for the first time in a micellar casein emulsion system subjected to micro-turbulent environments created by ultrasonication and high-pressure homogenisation. Importantly, the emulsion and gel-like properties are stabilised solely by the casein micelles in combination with the droplet packing structure, circumventing the usual requirement for chemical surfactants and stabilisers. The mechanism of shear-induced emulsion gel formation has been investigated experimentally in relation to the roles of casein micelles, oil fraction and shear environments, and discussed in relation to existing theories. Based on this, the mechanism of gel formation has been proposed as a novel colloidal packing phenomenon, triggered by the formation of droplet breakup under micro-turbulent environments, which results in fractal packing of droplets and casein micelles over three orders of magnitude from 10-1 to 101 micron. In Chapter 6, the proposed mechanism underlying the shear-induced formation of casein micelle emulsion gels has been extended to other systems by providing a more general explanation on a fundamental level. The effect of micellar casein concentration on the sol-gel transition is investigated to reveal a shear- and concentration-dependency and non-monotonic rheological behaviour. A successful imaging protocol is developed to examine the in-situ interfacial rearrangement of micellar casein. The method involved substituting food oils with a volatile solvent, so that both the oil phase and water can be removed and the micellar bridging network inspected in detail by scanning electron microscopy. A large degree of interfacial deformation of micellar casein has been observed, from spheres to discs, which were further inter-connected to form cellular protein 3D networks. The combination of emulsion microstructure and the rheological profiles could be simply explained by the established sol-gel transition models in colloidal suspension systems. Rather, these experimental results are explained using a combination of two theories: random Apollonian packing and droplet size distribution scaling under turbulent flows. The existence of a sol-gel transition could be related to power-law correlations in the number size distribution of the droplets within a certain size range. The results confirm that the casein micelles and emulsion droplets could be unified as ‘spheres’ participating collectively in random close packing. The mechanism of sol-gel transition under turbulent flows has been proposed more generally as a result of turbulence-driven dynamic changes in the number size distribution of ‘spheres’. The formation of shear-induced emulsion gels has been then further extended with key criteria proposed, based on the new multi-theory mechanism framework. The understandings gained in this thesis are summarised and concluded in Chapter 7. Future research directions are also discussed based on these new findings. Highlights of two commercialisable extensions of the work of the thesis are also provided as supplementary material in Appendices A and B.
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ItemExponential iterative coupling for low dispersity conjugated polymers( 2019)Organic conjugated polymers form an interesting class of materials in organic electronics, which is expected to find many applications in the near future. Though polymerisation reactions can allow the rapid synthesis of systems with large conjugation lengths, conjugated polymers are most often obtained from step-growth polymerisation reactions. Therefore, they are prone to having broad molecular weight distributions, which can reduce synthetic reproducibility and hinder structure-property correlations. This thesis investigates exponential iterative coupling (IC) for producing discrete large conjugated molecules, whereby chain lengths double in each cyclic sequence of reactions while maintaining full control of molecular structure. I discuss the theoretical properties of general IC processes and show the contributions of each individual activation and coupling step towards the overall yield. This leads to the definition of the cycle yield to characterise IC processes. Having laid down the basic mathematical framework, a hybrid approach is also considered, where an initial disperse macromolecule sample is used in an exponential iterative process. I find exponential IC furnishes a mechanism capable of strongly decreasing the dispersity of a polymer sample, and may be a general basis for new syntheses aiming towards low dispersity polymer samples. Experimental investigation begins with the synthesis of functionally desymmetrised fluorene and thiophene monomers containing N-methyliminodiacetic acid (MIDA) boronate and trimethylsilyl functionalities as precursors to functional groups active in Suzuki-Miyaura coupling. Efficient and orthogonal activation of these groups is shown. Next, a prolonged selective coupling optimisation study is performed, eventually finding a set of conditions capable of yielding the doubly-protected bisfluorene in 60% cycle yield. The process is iterated, leading to the synthesis of up to a doubly-protected octafluorene. However, cycle yields quickly decline. This is attributed to a conflict between the hydrolytic instability of MIDA boronates and the necessity of trace amounts of water for an effective Suzuki-Miyaura coupling reaction. Seeking to generate a more robust exponential IC scheme, I then investigate 1,8-diaminonaphthalene (DAN) boronamides. The synthesis of a new doubly-protected fluorene monomer is performed in large scale, and another set of effective activation reactions is developed. With the new functional groups, the selective Suzuki-Miyaura coupling reaction is found to be far more reliable, and the synthesis of the doubly-protected bisfluorene is performed in an almost 10 g scale with a high cycle yield of 81%. Having observed deficiencies in both MIDA boronates and DAN boronamides as protected boronic acids, I analyse their shortcomings and propose a set of guidelines for new potential boronic acid protecting groups, providing structures for promising tridentate ligands; diphenolypyridine (DPPY), dianilinepyridine (DAPY), di(o-hydroxybenzyl)methylamine (DOMA) and di(o-aminobenzyl)methylamine (DAMA). Syntheses of DAPY and DOMA are shown. Synthesis of DPPY is optimised in large scale and the ligand coordinated to boronic acids. The resulting DPPY boronates are found to be exceptionally stable under a wide variety of conditions. However, retrieval of the boronic acid is found to be difficult, with deborylation being preferable to furnishing the free boronic acid. Nevertheless, the other proposed ligands may lead to new effective protecting groups.