Phenazines and heterocyclic N-oxides have proven to be interesting classes of antitumoral as well as antibiotic agents . The natural product myxin (1-hydroxy-6-methoxyphenazine- N5, N10-dioxide) which belongs to both of these unique classes of molecules, has been found to cause bio-reductively activated, radical-mediated DNA strand cleavage via a de-oxygenative mechanism, making it a potential anti-tumoral as well as anti-bactierial candidate. In order to investigate as well as improve the bioactive properties of myxin, the following study was designed to synthesize glycosylated myxin analogs. A small catalog of these compounds were synthesized, some of them exhibiting comparable biological activity to that of myxin.

The synthesis, structure, and reactivity of some organometallic-fusedheterocycles were studied. This work was divided into three parts: first,thiapentalenyl tricarbonyl manganese complexes [Mn(CO)3{??5-SC7H3-1,3-(R)2}]were synthesized employing thiation on diacyl precursors; second, attempts toform the 5,5-fused ring pyrrole analogs to the thiapentalenyl complexes led to theformation of various amine and imine ligands and manganese complexes, but notthe desired ring-closed pyrroles; third, reductive amination on a ferrocenylmonoaldehyde substrate led to the formation of di(N-(ferrocenylmethyl))-Nmethylamineand its cyanoborane and cyanoborohydride analogs.Isolation of the desired thiapentalenyl manganese complexes wasaccomplished by first forming 1,2-diacylcyclopentadienes (fulvenes), convertingto the corresponding thallium salts [Tl{1,2-C5H3(COR)2}] employing thalliumethoxide, transmetallating with [Mn(CO)5Br], and ring closing using either P4S10or Lawesson's Reagent. Ring closure from the diacylmanganese complexes[Mn(CO)3{??5-1,2-C5H3(COR)2}] gave air stable thiapentalenyl complexes inmoderate to good yield and was tolerable to a variety of functional groups (aryl,arylacetyl, t-butyl). In the cases where 1,2-diarylacetyl complexes wereemployed, the isolated products were "quinoidal". While ring closure on thecorresponding diacylrhenium tricarbonyl complexes was not feasible, it wasobserved that these quinoidal thiapentalenyl structures could be formed on aruthenium Cp* moiety using the arylacetyl fulvenes.Various keto-amines or enol-imines could be formed from the 1,2-dibenzoyl fulvene employing primary amines (R = H, Me, OH, OMe). In thepresence of a reducing agent, neither reduction nor ring closure was observedfor any of the cases investigated. Formation of the corresponding manganesetricarbonyl complex for the methyoxyimine case was accomplished by reaction ofthe enol-methoxyimine with thallium ethoxide and then transmetallating with[Mn(CO)5Br]. Reaction of this keto-imine complex with various reducing agentsdid not lead to the desired 5,5-fused ring pyrrole complex but to reduction to thecorresponding alcohol.Diferrocenylmethyl methylamine complexes were obtained by reaction offerrocene monoaldehyde with ferrocenylmethyl methylamine in the presence of amild reducing agent (NaCNBH3). Isolation under anhydrous conditions gave theunexpected cyanoborohydride salt, di(N-(ferrocenylmethyl))-N-methylammoniumcyanoborohydride. Aqueous work-up gave the corresponding free amine.Conversion of the cyanoborohydride salt to the corresponding cyanoborane,di(N-(ferrocenylmethyl))-N-methylammonium–cyanoborane, was accomplishedby refluxing the cyanoborohydride salt in THF.

The purpose of this research was to investigate the microorganisms, genetics and biochemistry of anaerobic dechlorination of chlorinated ethanes, which are common groundwater contaminants. Specifically, this project used mixed microbial cultures to study the dechlorination of 1,2-dichloroethane (1,2-DCA), 1,1,2-trichloroethane (1,1,2-TCA) and 1,1,1-trichloroethane (1,1,1-TCA). A mixed microbial culture enriched from a contaminated multilayered aquifer in West Louisiana dechlorinated 1,2-DCA, 1,1,2-TCA, tetrachloroethene, trichloroethene, cis-dichloroethene and vinyl chloride (VC) to non-toxic ethene when amended with ethanol as the electron donor. 16S rRNA gene sequence analysis revealed the presence of the putative dechlorinating organisms Dehalobacter and Dehalococcoides spp. Denaturing gradient gel electrophoresis analysis and quantitative PCR (qPCR) with species-specific primers demonstrated that both organisms grew during the dichloroelimination of 1,2-DCA to ethene. Conversely, during the dichloroelimination of 1,1,2-TCA to VC only Dehalobacter grew, while during the reductive dechlorination of VC to ethene only Dehalococcoides grew. Further enrichment with 1,2-DCA, H2 and acetate yielded a co-culture of Dehalobacter and Acetobacterium spp. that did not dechlorinate other chlorinated ethanes or ethenes. Dehalobacter grew in the presence but not in the absence of 1,2-DCA, while Acetobacterium growth was not affected by 1,2-DCA. A novel putative Dehalobacter-associated 1,2-DCA reductive dehalogenase gene was identified and was shown to be transcribed only in the presence of 1,2-DCA. An enrichment microbial culture derived from a 1,1,1-TCA-contaminated site in the northeastern United States was also studied. This culture, referred to as MS, reductively dechlorinated 1,1,1-TCA to 1,1-dichloroethane (1,1-DCA) and then to monochloroethane (CA) when amended with methanol, ethanol, acetate and lactate. 16S rRNA gene sequence analysis revealed the presence of the putative dechlorinating organism Dehalobacter sp., whose growth during 1,1,1-TCA and 1,1-DCA dechlorination was confirmed by qPCR. In the presence of chlorinated ethenes, dechlorination 1,1,1-TCA by the culture MS was slowed, while dechlorination of 1,1-DCA was completely inhibited. Experiments with cell-free extracts and whole cell suspensions of culture MS suggested that chlorinated ethenes have direct inhibitory effects on 1,1,1-TCA reductive dehalogenase(s), while the inhibition of 1,1-DCA dechlorination may be due to effects on non-dehalogenase components of Dehalobacter sp. cells. Additionally, two novel reductive dehalogenase genes associated with 1,1,1-TCA reductive dechlorination were identified.

abstract: Contamination by chlorinated ethenes is widespread in groundwater aquifers, sediment, and soils worldwide. The overarching objectives of my research were to understand how the bacterial genus Dehalococcoides function optimally to carry out reductive dechlorination of chlorinated ethenes in a mixed microbial community and then apply this knowledge to manage dechlorinating communities in the hydrogen-based membrane biofilm reactor (MBfR). The MBfR is used for the biological reduction of oxidized contaminants in water using hydrogen supplied as the electron donor by diffusion through gas-transfer fibers. First, I characterized a new anaerobic dechlorinating community developed in our laboratory, named DehaloR^2, in terms of chlorinated ethene turnover rates and assessed its microbial community composition. I then carried out an experiment to correlate performance and community structure for trichloroethene (TCE)-fed microbial consortia. Fill-and-draw reactors inoculated with DehaloR^2 demonstrated a direct correlation between microbial community function and structure as the TCE-pulsing rate was increased. An electron-balance analysis predicted the community structure based on measured concentrations of products and constant net yields for each microorganism. The predictions corresponded to trends in the community structure based on pyrosequencing and quantitative PCR up to the highest TCE pulsing rate, where deviations to the trend resulted from stress by the chlorinated ethenes. Next, I optimized a method for simultaneous detection of chlorinated ethenes and ethene at or below the Environmental Protection Agency maximum contaminant levels for groundwater using solid phase microextraction in a gas chromatograph with a flame ionization detector. This method is ideal for monitoring biological reductive dechlorination in groundwater, where ethene is the ultimate end product. The major advantage of this method is that it uses a small sample volume of 1 mL, making it ideally suited for bench-scale feasibility studies, such as the MBfR. Last, I developed a reliable start-up and operation strategy for TCE reduction in the MBfR. Successful operation relied on controlling the pH-increase effects of methanogenesis and homoacetogenesis, along with creating hydrogen limitation during start-up to allow dechlorinators to compete against other microorgansims. Methanogens were additionally minimized during continuous flow operation by a limitation in bicarbonate resulting from strong homoacetogenic activity. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2012

No description available.

Orientador: Wilson F. Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T11:13:59Z (GMT). No. of bitstreams: 1 Rizzo_RicardoBuono_M.pdf: 2115132 bytes, checksum: 7aea5731fd5c49b280db63fc4f1f2aaf (MD5) Previous issue date: 2005 / Resumo: Neste trabalho foi estudada a eliminação dos solventes Percloroetileno (PCE) e Metil Isobutil Cetona (MIBK), em efluentes líquidos de uma planta industrial. A análise pelo período de 4 meses, mostrou valores médios de 17.565 mg/L de PCE e 41.340 mg/L de MIBK. Como tratamento inicial, foi avaliada a eficiência de um POA empregando o reagente de Fenton (H2O2 e Fe). No teste inicial com uma solução sintética a 5000 mg/L, de PCE, foi obtida uma destruição superior a 99% dentro de um período de 6 horas, empregando uma concentração de 1000 mg/L de H2O2 a 60% (m/m), sendo que a reação apresentou uma cinética de 1 ordem (k = 1,94 x 10 s). Para amostras do efluente, foram obtidas eficiências de destruição variáveis com as concentrações iniciais e dosagens aplicadas dos reagentes. Empregando dosagens de H2O2 : Fe (9000 mg/L : 900 mg/L), para uma amostra contendo 10.546 mg/L de PCE e 6.704 mg/L de MIBK, foram obtidas eficiências de remoção superiores a 99,9%, dentro de períodos de 3 horas de tratamento, com cinéticas variáveis entre 1 ordem e 2 ordem. A otimização dos reagentes demonstrou a necessidade de aplicar dosagem correta para obter a destruição total do PCE e MIBK. Com relação ao pH, foi observado que o ajuste para pH 3,0 promoveu um aumento da eficiência da destruição, contra o teste em pH 2,0. Para a maior dosagem de reagentes, observou-se um aumento de 6% na destruição. Paralelamente foi avaliada a eficiência da eliminação do PCE pelo processo de descloração redutiva por Ferro Zero Valente, com remoções de até 89,4%, e a geração do subproduto tricloroetileno. Finalmente, como proposta de trabalho foi estudada a combinação do processo redutivo (Ferro Zero Valente) e oxidativo (Fenton) como uma alternativa para a maximização da eficiência de tratamento e minimização de custos, visto que possibilita a destruição completa tanto do PCE quanto do MIBK dentro do período de 2 horas de tratamento, eliminando ainda a necessidade da adição de ferro. / Abstract: This work is about the removal of Perchloroethylene (PCE) and MethylIsobutyl Ketone (MIBK) in a liquid effluent from an industrial plant. A 4-month analysis has shown average levels of 17,565 mg/L of PCE and 41,340 mg/L of MIBK. Initially, the AOP using Fenton's reagent (H2O2 and Fe) was evaluated. First, a synthetic solution containing 5,000 mg L of PCE was tested and reached elimination greater than 99% within 6 hours of treatment, using a concentration of 1,000 mg/L of H2O2 at 60% (w/w). In this test, a 1 order kinetics (k = 1,94 x 10-4 s-1) was observed. For wastewater samples, using dosages of H2O2 : Fe (9000 mg L:mg L), an elimination destruction above 99,9% was obtained within 3 hours of treatment, for a sample containing 10,546 mg L of PCE and 6,704 mg L of MIBK. Data showed variations between 1st and 2nd order kinetics. Optimization of reactant dosage showed that it is necessary to apply the right dosage to get total elimination of PCE and MIBK. Regarding pH, it was observed that adjustment to pH 3 always gives better results than pH 2. For the greatest dosage of chemicals, an improvement of 6% in the destruction was observed. Simultaneously, a PCE elimination by reductive dechlorination using Zero Valent Iron with removal efficiencies up to 89.4% and generation of trichloroethylene as a by-product was evaluated. Finally, a combination of Oxidative (Fenton) and Reductive (Zero Valent Iron) processes was proposed as an alternative to improve the treatment efficiency and reduce costs. The application of this treatment made it possible to reach complete removal of both contaminants within 2 hours of treatment, besides allowing the elimination of the iron added. / Mestrado / Quimica Analitica / Mestre em Química

A novel platinum ligand complex (NCN)PtAr, ((κ-N,C,N- 2,6-bis (diethylaminomethyl)phenyl)(4- tert-butylphenyl) platinum(II)), was synthesized. A reaction of 1-Bromo-4-tert-butylbenzene Grignard with (NCN)PtCl, (where NCN = 2,6-bis(diethylaminomethyl)phenyl) yielded the (NCN)PtAr (where Ar = 4-tert­-butylphenyl). The product was then characterized with NMR spectra through 1H NMR, 13C NMR, COSY, HSQC, and HMBC to verify it structure.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24435号 / 理博第4934号 / 新制||理||1705(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 依光 英樹, 教授 若宮 淳志, 教授 畠山 琢次 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

This work focused on using a microbubble dispersion to deliver hydrogen and carbon dioxide to anaerobic consortia to stimulate their ability to reductively dehalogenate tetrachloroethylene all the way to ethene and ethane. A continuous flow system, consisting of six anaerobic soil column bioreactors, inoculated with sediments from Virginia Tech's Duck Pond, was used for this study. Two columns received microbubbles containing hydrogen and carbon dioxide, two received sodium propionate, and two were not fed a substrate. A 30 micromolar PCE solution was delivered to the consortia at 3 ml/min. Microbubbles containing a mixture of 90% hydrogen and 10% carbon dioxide were effectively produced in a closed spinning disk generator, and were acceptable for delivering the gases to the columns. After the biodegradation study was completed, the microbubbles were found to have a pH of 4.4, due to the carbon dioxide. Microbubbles amended with NaOH to 0.01 molar yielded pH neutral microbubbles with improved stability. Methane was measured in all six columns throughout the experiment, verifying that methanogens were present. Methane levels were highest in the propionate columns, showing the the methanogens there were more active. Methane levels in the microbubble columns were similar to those in the control columns. Propionate and acetate were not detected in the columns where propionate was fed, showing that proton reducers and acetoclastic methanogens were both active. Recovery of PCE and the degradation products was almost 90% in the microbubble and control columns where most of the PCE was recovered in the effluent. The predominant product in both systems was TCE, although some ethene was detected in all four columns. The control consortia produced TCE averaging about five micromolar while the microbubble columns averaged about two micromolar TCE. One of the components of the microbubbles probably caused the lowered amounts of PCE reduction. That some ethene was seen in the microbubble columns suggests different conditions can be found to stimulate the further reduction of PCE with hydrogen and carbon dioxide microbubbles. The product recovery in the propionate columns was about 64%. Over half of the injected PCE was dechlorinated to ethene and ethane. / Ph. D.

Microcosms were constructed from aquifer sediment samples taken from an actively degrading chlorinated solvent contaminated site located in Virginia Beach, Virginia. The objective of this study was to determine if and how the addition of cyclodextrin (CD) affects reductive dechlorination of chlorinated ethenes. After chlorinated solvent degradation rates were established in anaerobic and aerobic microcosms, 100 mg/L of CD solution was added for a period of 21 days. CD was then removed after 26 days to simulate the degradation response of the aquifer in a post CD injection environment. Degradation rates were determined by analyzing PCE, TCE, and cis-DCE concentration data over the various phases of the experiment. Results from this study indicated that chlorinated solvent degradation could be either impaired or facilitated by the addition of CD. CD appeared to stimulate one anaerobic microcosm (IY-2c) where daughter production had not previously occurred. The activity of this microcosm was greatly enhanced by the addition of CD (0 uM/day to 13.89 uM/day). However, biotransformation of PCE in another anaerobic microcosm in which reductive dechlorination was occurring, ceased after the addition of CD (IY-1a). In a third group of microcosms the rate and extent of reductive dechlorination was greatly enhanced by the addition of CD. The effect of adding CD was also found to be highly dependent on the redox conditions in the microcosm, specifically if the conditions were strongly reducing. The most active microcosms, found in the Aerobic Group, also had the lowest ferrous iron concentrations (3.57 mg/L for BY-1a, 2.25 mg/L for BY-1b, and 0.41 mg/L for BY-1c). The microcosm (IY-2b) that showed no daughter production had the highest level of ferrous iron (44.22 mg/L). This study presents a qualitative approach to the affect of CD on MNA. / Master of Science