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No description available.

No description available.

The coordination chemistry of eight chelating heterocyclic ligands is described. These ligands all contain heterocyclic ring systems with bridgehead nitrogens, and have received little attention in the literature. The ring systems examined are, specifically, imidazo[1,2-a]pyridine, imidazo[1,5-a]pyridine and triazolo[1,5-a]pyridine. The coordination complexes synthesised are mononuclear ruthenium(II) complexes, of the type [Ru(bpy)2(L)]2+. Complexes have been examined by a combination of 1H and 13C NMR, UV-visible spectroscopy, cyclic voltammetry, and X-ray crystallography, in order to study their metal-ligand interactions. A total of six complexes were analysed by single crystal X-ray diffractometry, and the resulting structures are described herein. In general, the inclusion of these ligands had the effect of raising the HOMO and lowering the LUMO, relative to the [Ru(bpy)3]2+ complex. As a result, the complexes were easier to oxidise, harder to reduce, and absorb visible light at longer wavelengths.

This thesis is concerned with the synthesis, characterisation and electropolymerisation of two species of functionalised heterocyclic compounds: a) thiophene and pyrrole monomeric systems b) thiophene, pyrrole and furan mixed trimeric systems. There are many motivations for introducing group substituents to conducting polymer systems e.g. plastic electronics such as new types of "smart" field effect transistors (FET) or modulation of LED emission frequency and sensors such as bio- or enzyme crown ether ion -sensors or even DNA detectors. The consequences of this usually result in poor electrical conductivity and/or physical properties of the materials. In this work we have sought to find routes to functionalised conducting polymer materials with good physical and electrical properties using two strategies (approaches): a) copolymerisation of functionalised monomers with unsubstituted compounds b) polymerisation of monosubstituted trimeric systems As a consequence thiophene and pyrrole <I>monomeric systems</I> were substituted with carbonyl and nitrile groups and characterised by cyclic voltammetry. These functionalised monomeric compounds underwent electrochemical homo- and/or copolymerisation. The resultant polymer films were analysed by absorbance/reflectance FT-IR and X-ray photoelectron spectroscopies. We have focused particularly on <I>trimeric systems</I> constructed from pyrrole, thiophene and furan units in which only the central ring bears functionality. Importantly our approach to the synthesis of these systems is based on a generic route involving ring closure reactions of substituted 1,4 diketones. Novel "2.5-Di(2-thienyl)" based trimeric systems, substituted at the β-position of the central ring, were synthesised. Electrochemical homopolymerisation of these single functionalised trimeric compounds gave fixed ratio copolymers, which are expected to exhibit high electrical conductivity. Particular interest was devoted to the electropolymerised poly-2, 5-Di-(2-thienyl)-3-pyrrole-valeric acid to investigate the bioelectrochemical interaction with the redox enzyme cyctochrome c. In every case useful data was provided, by analysing both, homo- and copolymer films, using a combination of spectroscopic techniques, including absorbance/reflectance FT-IR or X-ray photoelectron spectroscopy.

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The phototransposition reactions of thiophene- carbonitriles were shown to occur via the intermediate formation and isomerisation of 5-thiabicyclo[2˙1˙0]pent- 2-enes . Thus, irradiation of thiophene-3-carbonitrile in cyclohexane gave 5-thiabieyelo[2˙1˙0]pent-2-ene-2-carbonitrile as the primary photochemical product. Further irradiation produced thiophene-2-carbonitrile. The reaction was reversible, Addition of furan to 5-thiabicyclo[2˙1˙0]pent-2-ene-2- carbonitrile yielded a mixture of exo and endo-10,4-oxa thiatetracyclo[5˙2˙1˙0,sup>2,6</sup>˙ 0sup>3,5</sup>]dec-8-ene-2-carbonitrile. These two adducts were similarly formed upon irradiation of either thiophene-2 or 3-carbonitrile in furan.

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No description available.

The design and synthesis of two heterocyclic thioanalogues of 7-deoxy daunomycinone, 9-acetyl-6,9,11-trihydroxythioxantho{2,3-g}- and -{3,2-g}tetralin, was accomplished. Various synthetic methodologies to accomplish this were evaluated and two key steps necessary for this synthesis were developed. The first consisted of a novel annulative synthetic sequence utilizing a biacetyl synthon, 3,3-diethoxy-2-butanone cyclohexylimine, and an ortho bis-halomethylarene. The second consisted of the use of o-chlorosulfenylbenzoyl chloride as a thiosalicyclic acid equivalent. Model studies toward the further elaboration of these 7-deoxy aglycones to the active glycosides were also studied. / In addition, 1-{{2-{(2-dydroxyethyl)amino}ethyl}amino}-4-hydroxythioxanthone was prepared and found not to have antitumor properties against P-388 leukemia in vivo.