School of Chemistry - Theses
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ItemSynthetic and structural investigations of coordination polymers and oligomers( 2011)Novel oligomeric species and coordination polymers have been synthesised and characterised using single crystal X-ray diffraction methods. The electrochemical, magnetic and gas sorption properties of some of these compounds have also been investigated. Chapter 2 describes the preparation and characterisation of coordination complexes containing the di-anionic 2,5-dihydroxybenzoquinone and chloranilate ligands, which have been produced by in situ generation of dhbq2- or can2- from 1,2,4,5-tetrahydroxybenzene or 3,6-dichloro-1,2,4,5-tetrahydroxybenzene, respectively. A one-dimensional polymer of composition Zn(dhbq)(H2O)2⋅4H2O was prepared, and the dehydrated solid has been shown to sorb approximately 0.9 mol of H2 per mol of Zn(dhbq) at 87 K. The ability of the solid to sorb CO2, CH4 and N2 has also been investigated. Several two-dimensional polymers with (6,3) topology have been synthesised. The electrochemical properties of one of these compounds, (PMePh3)2Cd2(dhbq)3, have been studied using solid-state cyclic voltammetry. Also, several examples of 3D Zn-dhbq and Mn-can coordination polymers of (10,3)a topology have been prepared. In several other compounds, the nature of the added counter cation salt was found to affect the connectivity of the resulting network. Chapter 3 contains the details of investigations into 9-substituted-2,3,7- trihydroxyfluor-6-ones. The crystal structures of various salts of the mono-cations of the 9-methyl-, 9-(4-pyridyl)-, 9-(3,4-dihydroxyphenyl)-, and 9-phenyl- fluorones are described, in addition to that of a protonated and reduced bis-fluorone of composition (C13H8O5)(C6H4)(C13H9O5)+. The tri-anion of the 9-phenyl fluorone (Z3-) was used to produce a series of [4+4] metallocycles of composition [(MO2)4Z4]4-. The packing of these metallocycles is reasonably uniform in the presence of the polyaromatic cations PMePh3+, PBzPh3+, Ph3PNPPh3+, AsPh4+ or PPh4+, and in most cases a polyaromatic cation is located in the centre of the square metallocycles. Mass spectrometry experiments show that the metallocycles remain intact in the gas phase. The topology of the 3D metal-tpt networks was found to depend heavily on both the connectivity of the metal centre and on the relative rotation of the three- connecting tpt ligands. For example, tetrahedral CuI centres in combination with the trigonal tpt ligands produced a boracite network of composition [CuI3(tpt)4]3+, although tetrahedral ZnII centres in combination with tpt produced a network with C3N4 topology in Zn3(tpt)4(ClO4)6.Three different networks that contain square planar four-connecting CuII centres were produced - twisted boracite networks of composition CuII3(tpt)4(PF6)6 and CuII3(tpt)4(SiF6)3; a Pt3O4-like network in the compound CuII3(tpt)4(SiF6)3(H2O)2; and a network that occurs in the compound CuII3(tpt)4(ClO4)6, which bears a resemblance to the PtS net. A series of hydrated linear polymers containing the bridging mucate or saccharate dianions in combination with either 2,2`-bipyridine (bipy) or 1,10- phenanthroline (phen) form the basis of Chapter 5. The polymers of composition M(sacc)(phen) (M = Mn, Co or Zn) and M(muc)(phen) (M = Mn or Cd) were found to be essentially isostructural, despite the differing chirality of the mucate and saccharate ligands. Similar chains are also present within Cu(sacc)(bipy), although the CuII centres have square planar coordination environments. Interestingly, the compounds M(sacc)(bipy) (M = Ni or Zn) contain two distinct types of M(sacc)(bipy) chain - one containing only Δ metal centres, the other containing only Λ metal centres. In all compounds discussed in this chapter, both inter-chain hydrogen bonding interactions and π-stacking of the aromatic bipy or phen ligands play important structure-directing roles. The CO2 sorption properties of the representative compounds Co(sacc)(phen) and Cu(muc)(phen) were investigated. Reaction of Cu(NO3)2, 1,10-phenanthroline and potassium hydrogen saccharate in methanol was found to produce two similar yet distinct clusters, both of composition CuII21(sacc)6(phen)12(NO3)12 (the 'Diabolecules'). Structural details of these two clusters are presented in Chapter 6. In both Diabolecule clusters, the saccharate ligand is present in an unprecedented penta-anionic protonation state. Face-to-face aromatic interactions between the phen ligands are an important feature of the packing of both types of cluster. Mass spectrometry experiments show that the cubic cluster remains intact in the gas phase.
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ItemSynthesis and biological applications of phospholipid-based chemical probes( 2010)Phosphoinositides play significant roles as secondary messengers to regulate a broad range of intracellular processes in a spatio and temporal manner, including signal transduction pathways, cell motility and cytokinesis, excocytosis and endocytosis, vesicular trafficking, as well as control of ion channels, pumps, and transporters. Their regulatory functions are achieved by directly recognition and interaction with a variety of phosphoinositide-binding proteins. Synthetic chemistry has played a defining role in further understanding of phosphoinositide interactome. Total syntheses of the palmitic acid and amino-terminal PI(3,4)P2 derivatives were performed. The dipalmitoyl derivatives were incorporated to form liposomes, and the amino-terminal analogues were conjugated to Affi-Gel 10 resins, both of which were used as affinity probes for proteomics studies via affinity experiments to investigate phosphoinositide interacting proteins/protein complexes. With colorectal carcinoma cell cytosolic extracts, 282proteins/protein complexes were identified as PI(3,4,5)P3 binding proteins. A morecomprehensive proteomic study was carried out for PI(3,4)P2 with cell extracts fromcytosol, membrane, and nucleus of colorectal carcinoma cells, giving 1134 proteins as PI(3,4)P2 interacting proteins/protein complexes including 126 proteins containing known phosphoinositide binding domains. Additionally, a number of novel proteins were identified as potential phosphoinositide binding proteins in our studies. The molecular functions, protein networks, and biological processes of identified proteins were analysed by submission to various databases to provide better knowledge of the involvement of phosphoinositides in intracellular signalling pathways. Therefore, our bioinformatics studies using phosphoinositide affinity probes provide initial detailed assessment of PI(3,4,5)P3 and PI(3,4)P2 interactome and suggest potential phosphoinositide functions and specificities for further biochemical characterisation by using other alternative biological techniques. Cardiolipin (diphosphatidylglycerol) is a unique phospholipid predominantly existing in the mitochondrial membranes throughout the eukaryotic and prokaryotic kingdom. It has been subsequently studied as the key phospholipid stimulating mitochondrial enzymes and regulating the mitochondria energy metabolism and cell apoptosis by interactions with a number of mitochondrial proteins. An amino-terminal cardiolipin derivative was totally synthesised and immobilised to Affi-Gel 10 beads to afford a novel cardiolipin affinity matrix. Pull-down experiments were undertaken; the results confirmed the binding interaction between cardiolipin and the HR1 domain of PRK2 protein. Furthermore, a novel cardiolipin biosensor chip has been developed by immobilisation of the amino-terminal cardiolipin derivative to the gold surface, and used as a powerful biological tool for clinical diagnosis of antiphospholipid syndrome (APS) via surface plasmon resonance (SPR) experiments. In order to facilitate protein co-crystallisation processes, a novel PI(4,5)P2 derivative containing adamantanecarbonyl groups as replacements of acyl side chains has been synthesised; synthesis towards metabolically stabilised phosphatidylinositol phosphorothioate derivatives was also undertaken.