The π-electron donor system 9-(l,3-dithiol-2-ylidene)thioxanthene has been synthesised via Homer-Wadsworth-Emmons reactions of l,3-dithioI-2-phosphonate ester reagents with thioxanthen-9-one. The electrochemistry of a range of derivatives shows a single, two-electron oxidation wave, which is quasi-reversible. X-Ray crystal analysis reveals a folded structure. Compound 33c has proved to be a key building block which via lithiation chemistry has provided the hydroxymethyl derivative 37 and hence the synthesis of derivatives with covalently attached fluorenone, dicyanomethylenefluorene and PTM (4-[bis(2,3,4,5,6-pentachlorophenyl)methyl]-2,3,5,6-tetrachlorobenzoyl chloride radical) as electron acceptor substituents has been achieved. Electrochemical, spectroscopic and spectroelectrochemical studies have revealed the presence of intramolecular interactions in these compounds. 9-(4-Iodo-5-methyl-1,3-dithiol-2-ylidene)thioxanthene has been synthesised and shown to undergo clean metal-catalysed cross-coupling reactions under Suzuki and Sonogashira conditions, which is unusual for l,3-dithiol-2-ylidene derivatives. Aldehyde functionality has been attached to the 9-(l,3-dithiol-2-ylidene)thioxanthene core and reacting these aldehyde reagents with C(_60) and sarcosine gave covalent 9-(l,3-dithiol-2-ylidene)thioxanthene- C(_60) 1:1 diad molecules, and the analogous 2:1 adducts. A second series of compounds, with more extension of the π-system, eg compound 66a, has been synthesised and characterised by X-ray crystallography, a range of spectroscopic studies and by epr and electrochemistry.

ET charge transfer salts (where ET is <en>bis(ethylenedithio)- tetrathiafulvalene) have relatively simple quasi two-dimensional Fermi surface topologies, making them ideal for the study of the relationship between bandstructure and properties such as superconductivity. Experimental studies of the Fermi surface areas and associated effective masses have been carried out using the Shubnikov-de Haas (SdH) and de Haas-van Alphen (dHvA) effects. By comparing the experimental results to theoretical bandstructure calculations the strength of many body interactions has been estimated. High pressure magnetotransport experiments have been carried out on the superconductor κ-ET₂Cu(NCS)₂. The observation of SdH and magnetic breakdown oscillations has allowed the pressure dependences of the Fermi surface topology and effective masses to be deduced and compared with simultaneous measurements of the superconducting critical temperature. The data strongly suggest that the enhancement of the effective mass and the superconducting behaviour are directly connected. The results are compared with several current theories of superconductivity. The dHvA effect has been used to probe the superconducting mixed state of κ-ET₂Cu(NCS)₂. A recent model of the superconducting mixed state is applied to the experimental data in an attempt to determine the value and symmetry of the superconducting energy gap. SdH measurements up to 30 T have been used to study spin densitywave formation in α-ET₂KHg(SCN)₄, and the reasons why a very slight increase of the unit cell volume (i.e. replacing the K in α-ET₂KHg(SCN)₄ by NH₄) stabilises a superconducting state. Galvanomagnetic techniques have been used to measure the quasi onedimensional Fermi surface orientation below the spin-density-wave transition, and to accurately determine the shape of the quasi twodimensional Fermi surface above it. The application of pressure has been used to gradually reduce the onset temperature of a metal-insulator transition and to eventually stabilise a superconducting state in ET₃Cl₂2H₂O. The bandstructure of ET₃C1₂2H₂O has been investigated using the SdH effect whilst hydrostatic pressure has been used to pass through the superconducting part of the phase diagram.

This study is a systematic investigation of the parameters and conditions necessary for photo-induced radical copolymerizations of donor olefins with acceptor olefins in the absence of an initiator. Very few cases have been previously reported and no mechanistic details of the initiation have been proposed in the literature. Our results show that the photoinitiation depends on the relative donor and acceptor strengths of the monomers, as well as the solvent. The highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor must be at the appropriate energy levels in order to produce a radical initiating species upon photoexcitation of the electron donor-acceptor (EDA) complex. If the donor-acceptor interaction is too weak, no copolymerization occurs. The excited complex (contact ion pair) presumably decays back to the ground state faster than producing an initiating species. If the donor-acceptor interaction is too strong, the excited complex dissociates to the free ions which could initiate ionic homopolymerization rather than radical copolymerization. The solvent may also determine the course of the reaction. In two cases, copolymerizations, which could be photo-induced in 1,2-dichloroethane, could not be photo-induced in acetonitrile. Dissociation of the excited complex (contact ion pair) is favored in polar solvents, such as acetonitrile, which are able to stabilize the ion radicals. This initiation method produces high molecular weight copolymers that may be cast into transparent films.

Six electron-poor tetrasubstituted olefins were reacted with electron-rich comonomers. Of these, three {dimethyl dicyanofumarate (DDCF), dimethyl 1,1-dicyanoethylene-2,2-dicarboxylate (DDED), and dicarbomethoxymaleic anhydride (DCMA)} were found to polymerize with styrenes and vinyl ethers to form 1:1 alternating copolymers of low molecular weight. All polymerizations with vinyl ethers and DCMA required initiation, while the copolymerizations of DDED and DDCF with styrenes were spontaneous. Tetramethyl ethylenetetracarboxylate, diisopropylidene ethylenetetracarboxylate, and trimethyl cyanoethylenetricarboxylate failed to copolymerize under any conditions. The spontaneous reactions of these tetrasubstituted olefins can best be explained as proceeding via tetramethylene intermediates, resonance hybrids of biradicals and zwitterions. Spontaneous copolymerizations occur from biradical intermediates; cycloadduct formation occurs from both. Tetramethylene formation is electronically controlled during the reaction of DDED and electron-rich comonomers, as reflected by the structure of the isolated cyclobutanes. The orientation of this monomer is the copolymer with styrene is sterically controlled, as suggested by ('13)C NMR. Methyl 3,3-dicyanoacrylate, a new tetrasubstituted olefin, was found to spontaneously copolymerize with styrenes, and to form cyclobutanes with vinyl ethers. It could be copolymerized with vinyl ethers with radical initiation.

No description available.

Prior to the implementation of an enhanced bioremediation pilot study for a trichloroethene (TCE) source area at an industrial site in the United Kingdom (the Site), laboratory microcosm and column studies were performed. The purpose of this column study was to determine if TCE removal rates could be increased with the addition of partitioning electron donors and bioaugmentation with KB-1® culture. Three 1-meter continuous flow columns were constructed using aquifer solids from the Site and artificial groundwater. A TCE dense non-aqueous phase liquid (DNAPL) zone was emplaced in each column. SRS™, a commercially available emulsified vegetable oil (EVO) product, and n-butyl acetate (nBA) were evaluated as partitioning electron donors, while the third column acted as an unamended control. Both nBA and SRSTM were successfully used in previous microcosm studies with high concentrations of TCE (400 and 800 mg/L) to successfully promote the reductive dechlorination of TCE to ethene. Dechlorination of TCE to cis-1,2-dichloroethene (cis-DCE) with trace amounts of vinyl chloride (VC) and ethene, as well as sulfate reduction, were observed in the SRSTM column effluent while DNAPL was present. A dissolution enhancement factor of 2.1 was calculated. The TCE source zone was depleted after approximately 300 days of column operation. Following depletion of the TCE DNAPL, high concentration (~400 mg/L) of TCE amended artificial groundwater was pumped through the column to simulate high TCE concentrations in a plume down gradient from a source zone. Dechlorination of TCE via cis-DCE and VC to ethene was observed in the column effluent along with increases in Dehalococcoides (Dhc) counts. Sulfate concentrations increased during the plume phase while dechlorination to ethene still occurred indicating that complete dechlorination to ethene was possible in the presence of sulfate. Dechlorination of TCE to cis-DCE was observed, but neither VC nor ethene was detected in the nBA Amended column. The nBA was observed to degrade in the column to butyl alcohol and acetate, neither of which partition as strongly as nBA, and were not retained in the column. A continuous addition of nBA promoted the highest amount of cis-DCE production and sulfate reduction was also observed. Once the continuous addition was stopped, dechlorination and sulfate reduction halted indicating that electron donor retention in the column was not achieved. Dehalococcoides (Dhc) concentrations did not increase in the effluent of this column. A dissolution enhancement factor of 1.2 was calculated for the nBA column.

Prior to the implementation of an enhanced bioremediation pilot study for a trichloroethene (TCE) source area at an industrial site in the United Kingdom (the Site), laboratory microcosm and column studies were performed. The purpose of this column study was to determine if TCE removal rates could be increased with the addition of partitioning electron donors and bioaugmentation with KB-1® culture. Three 1-meter continuous flow columns were constructed using aquifer solids from the Site and artificial groundwater. A TCE dense non-aqueous phase liquid (DNAPL) zone was emplaced in each column. SRS™, a commercially available emulsified vegetable oil (EVO) product, and n-butyl acetate (nBA) were evaluated as partitioning electron donors, while the third column acted as an unamended control. Both nBA and SRSTM were successfully used in previous microcosm studies with high concentrations of TCE (400 and 800 mg/L) to successfully promote the reductive dechlorination of TCE to ethene. Dechlorination of TCE to cis-1,2-dichloroethene (cis-DCE) with trace amounts of vinyl chloride (VC) and ethene, as well as sulfate reduction, were observed in the SRSTM column effluent while DNAPL was present. A dissolution enhancement factor of 2.1 was calculated. The TCE source zone was depleted after approximately 300 days of column operation. Following depletion of the TCE DNAPL, high concentration (~400 mg/L) of TCE amended artificial groundwater was pumped through the column to simulate high TCE concentrations in a plume down gradient from a source zone. Dechlorination of TCE via cis-DCE and VC to ethene was observed in the column effluent along with increases in Dehalococcoides (Dhc) counts. Sulfate concentrations increased during the plume phase while dechlorination to ethene still occurred indicating that complete dechlorination to ethene was possible in the presence of sulfate. Dechlorination of TCE to cis-DCE was observed, but neither VC nor ethene was detected in the nBA Amended column. The nBA was observed to degrade in the column to butyl alcohol and acetate, neither of which partition as strongly as nBA, and were not retained in the column. A continuous addition of nBA promoted the highest amount of cis-DCE production and sulfate reduction was also observed. Once the continuous addition was stopped, dechlorination and sulfate reduction halted indicating that electron donor retention in the column was not achieved. Dehalococcoides (Dhc) concentrations did not increase in the effluent of this column. A dissolution enhancement factor of 1.2 was calculated for the nBA column.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 173-178). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--Bowling Green State University, 2007. / Document formatted into pages; contains xx, 166 p. : ill. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 327-343). Also available on the Internet.