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<p> The organic ions studied in this thesis were generated in the rarefied gas phase of the mass spectrometer by electron ionization of selected precursor molecules. The characterization of their structure and reactivity was probed by using a variety of tandem mass spectrometry techniques. These include metastable ion spectra to probe the dissociation chemistry of the low energy ions and collision experiments to establish the atom connectivity of the ions. The technique of neutralization-reionization mass spectrometry (NRMS) was used to probe the structure and stability of the neutral counterparts of the ions. Computational results involving the CBS-QB3 model chemistry formed an integral component in the interpretation of the experimental findings.</p> <p> The above approach was used to study proton-transport catalysis in the formaldehyde elimination from low energy 1,3-dihydroxyacetone radical cations. Solitary ketene-water ions, CH2=C(=O)OH2·+, do not readily isomerize into its more stable isomer, CH2=C(OH)2·+. A mechanistic analysis using the CBS-QB3 model chemistry shows that metastable 1,3-dihydroxyacetone radical cations will rearrange into hydrogen-bridged radical cations [CH2C(=O)O(H)-H•••OCH2]·+, where the CH2=O will catalyze the transformation of CH2=C(=O)OH2·+ into CH2=C(OH)2·+.</p> <p> Metastable pyruvic acid radical cations, CH3C(=O)COOH·+, have been shown to undergo decarboxylation to yield m/z 44 ions, C2H4O·+, in competition with the formation of CH3C=O+ + COOH· by direct bond cleavage. Collision induced dissociation experiments agree with an earlier report that oxycarbene ions CH3COH·+ are formed but they also suggest the more stable isomer CH3C(H)=O·+ may be co-generated. Using the CBS-QB3 model chemistry, a mechanism is proposed to rationalize these results.</p> <p> Next, the isomeric ions CH3O-P=S·+ and CH3S-P=O·+ were characterized and differentiated by tandem mass spectrometry. Metastable CH3O-P=S·+ and CH3S-P=O·+ ions both spontaneously lose water to yield m/lz 74 cyclic product ion [-S-CH=]P·+. Using the CBS-QB3 model chemistry a mechanism is proposed for the water loss from CH3O-P=S·+ and CH3S-P=O·+. Our calculations also show that these two isomers communicate via a common intermediate, the distonic ion CH2S-P-OH·+, prior to the loss of water.</p> <p> The final component of this work details the computational study addressing the long standing question on the mechanism for the water elimination from metastable ethyl acetate radical cations. The CBS-QB3 results show that low energy ethyl acetate ions isomerize into ionized 4-hydroxy-2-butanone prior to the loss of water.</p> / Thesis / Master of Science (MSc)

<p> Cobalt-clusters are versatile reagents in organometallic chemistry. Their ability to protect an alkyne allows one to selectively manipulate a ligand without undergoing a competitive reaction from the alkyne. Cobalt-clusters geometrically modify linear alkynes to 136-145° degrees, thereby allowing for some non-traditional alkynyl chemistry to occur. In particular, the focus of this dissertation lies upon the chemistry of cobalt-complexed propargyl alkynols, the ability of cobalt to stabilize neighbouring cations generated from these alcohols, and the chemistry that can be accomplished by altering the steric and electronic effects. We have chosen to study the possibility of inducing migration of various substituents from one terminus of the cobalt-complexed alkyne to the alcoholic site of the propargyl group via protonation of the desired complex. While examining various silanes, and altering the propargyl alcohol itself, we have considered both steric and electronic effects, thereby determining the idealized conditions for such transfers to occur. Furthermore, in our attempts to successfully apply these migrations to several systems, we have acquired a diverse synthetic knowledge of propargyl cobalt-clusters and their intricate reactivity.</p> <p> An examination of the potential for allyl migrations in norbornyl derivatives revealed several fascinating transformations. Upon protonation with HBF4, [(2-endo-allyldimethylsilyl)ethynylborneol]Co2(CO)6, 63, suffers elimination of water or propene, to yield [(2-allyldimethylsilyl)ethynylborn-2-ene]Co2(CO)6, 68, [(2-endo-dimethylfluorosilyl)ethynylborneol]Co2(CO)6, 69, respectively, and, surprisingly, the tricobalt complex (2-norbornylidene)CHCCo3(CO)9, 70, In contrast, protonation of the terminal alkyne (2-endo-ethynylborneol)Co2(CO)6, 76, an anticipated precursor to 70, led instead to (2-ethynyl-2-bornene)Co2(CO)6, 78, and the ring-opened species (2-ethynyl-4-isopropyl-1-methylcyclohexa-1,3-diene)Co2(CO)6, 79. However, conversion of 76 to 70 was achievable upon prolonged heating at reflux in acetone, thereby also affording the corresponding alcohol, [2-(2-hydroxybornyl)]CH2CCo3(CO)9, 77. A mechanistic rationale is offered for the formation of RCH2CCo3(CO)9 clusters upon protonation of alkyne complexes of the type (RC≡CH)Co2(CO)6.</p> <p> Our interest in acid-promoted rearrangements in cobalt-clusters led us to novel propargyl radical chemistry induced by using particular solvents. The protonation of (1,1-diphenyl-2-propyn-1-ol)Co2(CO)6, 108, with HBF4 in dichloromethane generates the expected metal-stabilized propargyl cation, and also rearranges to give the tricobalt cluster Ph2C=CH-CCo3(CO)9, 33. In contrast, use of THF as solvent affords the radical (Co2(CO)6)[HC≡C-CPh2·], which dimerizes at the methyne position; subsequent cyclization and carbonylation yields 2,5-bis-(diphenylmethylene)cyclopent-3-en-1-one, 112.</p> <p> Furthermore, use of a fluorenyl substituent, instead of the diphenyl analogue, has uncovered a route to transition-metal peroxides of general synthetic potential. Treatment of benzyl- or vinyl-dimethylsilylethynylfluoren-9-ol[Co2(CO)6], 53 and 54, respectively, with HBF4 in diethyl ether or THF has afforded the very first known bimetallic transition metal peroxides, 124 and 125.</p> <p> Finally, the ability of cobalt-clusters to alter the geometry of cycloalkanes has been investigated. Treatment of 1-[axial]-(trimethylsilylethynyl)cyclohexan-1-ol, 129, with dicobalt octacarbonyl results in a conformational ring flip such that the bulky dicobalt-alkyne cluster moiety now occupies the favored equatorial site. However, when a 4-tert-butyl substituent is present, the coordinated alkynyl group retains its original axial or equatorial position.</p> <p> Complexation of trans-[diaxial]-1,4-bis(triphenylsilylethynyl)cyclohexan-1,4-diol, 142, brings about a chair-to-chair conformational inversion such that both cluster fragments now occupy equatorial sites. In contrast, cis-1,4 bis(triphenylsilylethynyl)cyclohexan-1,4-diol, 143, reacts with Co2(CO)8 to yield the twist-boat conformer, 145, in which the two axial hydroxy substituents exhibit intra-molecular hydrogen bonding. Likewise, the corresponding reaction of cis-1 ,4bis(trimethylsilylethynyl)cyclohexan-1,4-diol, 147, with Co2(CO)8 leads to a twist-boat, 149, but, in this case, the molecules are linked through intermolecular hydrogen bonds. The importance of X-ray crystallography in the unambiguous determination of molecular conformations has been emphasized.</p> / Thesis / Doctor of Philosophy (PhD)

In the search for molecular species in the interstellar medium and extraterrestrial planetary atmospheres, theoretical methods continue to be an invaluable tool to astronomically minded chemists. Using state-of-the art methods, this doctoral work characterizes the electronically excited states of interstellar radicals, cations, and even rare anions and also predicts the gas phase fundamental vibrational frequencies of the cis and trans-HOCO radicals, as well as the cis-HOCO anion. First, open-shell coupled cluster methods of singles and doubles (CCSD) and singles and doubles with triples-inclusion (CC3) are tested on the C₂H and C₄H radicals. The significant double-excitation character, as well as the quartet multiplicity of some states yields inaccurate excitation energies and large spin contamination with CCSD. CC3 somewhat improves this for select states, but discrepancies between CC and multireference results for certain states exist and likely arise from the lack of spin adaptation in conventional spin-orbital CC. Next, coupled-cluster methods predict the presence of an excited state of the closed-shell allyl cation and its related H₂CCCHCH₂⁺ cousin at 443 nm near an unidentified laboratory peak at 442.9 nm which is also close to one of the largest unattributed interstellar absorption features. Additionally, the dipole moments, electron binding energies, and excited states of neutral radicals and corresponding closed-shell anions of interstellar interest are also computed. These are calibrated against experimental data for CH₂CN⁻ and CH₂CHO⁻. Since coupled cluster theory closely reproduces the known experimental data, dipole-bound excited states for eight previously unknown anions are predicted: CH2SiN⁻ , SiH₂CN⁻, CH₂SiHO⁻, SiN⁻, CCOH⁻, HCCO⁻, SiCCN⁻, and SiNC⁻. In addition, we predict the existence of one rare valence-bound excited state of CH₂SiN⁻ and also SiCCN⁻ as well as even rarer two valence-bound states of CCSiN⁻. Lastly, the reaction of CO + OH and its transient potential intermediate, the HOCO radical, may be responsible for the regeneration of CO₂ in the Martian atmosphere, but past spectroscopic observations have not produced a full gas-phase set of the fundamental vibrational frequencies of the HOCO radical. Using established, highly-accurate quantum chemical coupled cluster tech- niques and quartic force fields, all six fundamental vibrational frequencies for 1 ²A′ cis and trans-HOCO and 1 ¹A′ cis-HOCO⁻ are computed in the gas phase. / Ph. D.

Extracellular polymeric substances (EPS) in activated sludge are known to account for the flocculent nature of activated sludge. Extensive studies over the last few decades have attempted to extract and characterize activated sludge EPS, but a lack of agreement between studies has also been quite common. The molecular makeup of EPS has, however, remained nearly unexplored, leaving their identity, function, and fate over various stages in the activated sludge system mainly unknown. In spite of their critical involvement in bioflocculation and long history of related research, our understanding of EPS is still greatly limited and better elucidation of their composition and structure is needed. The hypothesis of this research was that activated sludge floc contains different fractions of EPS that are distinguishable by their association with certain cations and that each fraction behaves differently when subjected to shear, aerobic digestion, anaerobic digestion and other processes. In order to examine this floc hypothesis, the research mainly consisted of three sections: 1) development of EPS extraction methods that target cations of interest (divalent cations, especially calcium and magnesium, iron, and aluminum) from activated sludge; 2) molecular investigations on activated sludge EPS using metaproteomic analyses, comprising sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and protein identification by liquid chromatography tandem mass spectrometry (LC/MS/MS), and hemaagglutination (HA)/HA inhibition assays; and 3) investigating the fate of EPS in sludge digestion using SDS-PAGE. Evaluation of prior research and data from preliminary studies led to the development of the three extraction methods that were used to target specific cations from activated sludge and to release their associated EPS into solution. These methods are the cation exchange resin (CER) procedure for extracting Ca²⁺+Mg²⁺, sulfide extraction for removing Fe, and base treatment (pH 10.5) for dissolving Al. The cation selectivity in the three extraction methods, the composition of EPS (protein/polysaccharide), amino acid composition, and a series of sequential extraction data established initial research evidence that activated sludge EPS that are associated with different cations are not the same. SDS-PAGE was successfully applied to study extracellular proteins from several sources of both full- and bench-scale activated sludges. The three extraction methods led to different SDS-PAGE profiles, providing direct evidence that proteins released by the three methods were indeed different sludge proteins. Another important outcome from this stage of research was finding the similarity and differences of extracellular proteins between different sources of activated sludge. SDS-PAGE data showed that many of CER-extracted proteins were well conserved in all the sludges investigated, indicating that a significant fraction of Ca²⁺ and Mg²⁺-bound proteins are universal in activated sludge. On the other hand, protein profiles resulting from sulfide and base extraction were more diverse for different sludges, indicating that Al and Fe and their associated proteins are quite dynamic in activated sludge systems. Protein bands at high densities were analyzed for identifications by LC/MS/MS and several bacterial proteins and polypeptides originating from influent sewage were identified in this study. This was also thought to be the first account of protein identification work for full-scale activated sludge. The analysis of SDS-PAGE post sludge digestion revealed that CER-extracted proteins remained intact in anaerobic digestion while they were degraded in aerobic digestion. While the fate of sulfide-and base-extracted proteins in aerobic digestion was not as clearly resolved, their changes in anaerobic digestion were well determined in this research. Sulfide-extracted protein bands were reduced by anaerobic digestion, indicating that Fe-bound EPS were degraded under anaerobic conditions. While parts of base-extracted proteins disappeared after anaerobic digestion, others became more extractable along with the extraction of new proteins, indicating that the fate of base-extractable proteins, including Al-bound proteins, is more complex in anaerobic digestion than CER-extracted and sulfide-extracted proteins. These results show that Ca²⁺+Mg²⁺, Fe³⁺, and Al³⁺ play unique roles in floc formation and that each cation-associated EPS fraction imparts unique digestion characteristics to activated sludge. Finally, since a considerably different cation content is quite common for different wastewaters, it is postulated that this variability is one important factor that leads to different characteristics of activated sludge and sludge digestibility across facilities. The incorporation of the impact of cations and EPS on floc properties into an activated sludge model might be challenging but will assure a better engineering application of the activated sludge process. / Ph. D.

La vacuolisation cellulaire induite par les médicaments cationiques est une cytopathologie qui transcende les classes pharmacologiques. Quoiqu'elle ait été largement rapportée in vitro à des concentrations suprathérapeutiques, plusieurs observations permettent de la soupçonner dans des contextes cliniques. De nombreuses questions entourant l'origine, les mécanismes et les conséquences de la cytopathologie vacuolaire restaient à être résolues. Cette thèse a permis dans un premier temps de modéliser la vacuolisation cellulaire en démontrant que les vacuoles: 1- se développent suite à une séquestration importante d'amine par un mécanisme de pseudo-transport dépendant de la Vacuolaire-Adénosine triphosphatase (V-ATPase); 2- possèdent sans doute de multiples origines intracellulaires dont le trans-Golgi; 3- évoluent vers la macroautophagie. Nos expériences de modélisation ont également établi les conséquences cellulaires (arrêt de l'endocytose et de la voie sécrétoire, arrêt de la mitose, la phospholipidose, etc.) et pharmacologiques (distorsions dans la puissance et la durée d'action des médicaments) de la séquestration ionique et la vacuolisation qui en découle. Finalement, les connaissances recueillies lors de la modélisation de cette cytopathologie ont été appliquées à différentes classes de molécules utilisées cliniquement (agonistes oadrénergiques, antihistaminiques, cosmétiques, antiarythmiques) afin d'évaluer l'implication de la séquestration cationique dans différentes réactions pathologiques (vacuolisation et toxicité tissulaire, corps lamellaires intracellulaires, épaississement de l'épiderme, hyperpigmentation cutanée, etc.). Ainsi, même si la cytopathologie vacuolaire n'est que peu connue du corps médical et des chercheurs en général, elle peut expliquer certains effets secondaires induits par les médicaments cationiques.

The possible effects of changes in the feeding pattern on activated sludge properties related to bioflocculation have been analyzed in lab scale sequencing batch reactors (SBR) in order to determine if these changes in effluent water quality and settling and dewatering properties are significant, so they can be considered in future studies or if they can be recommended as crucial when operating and designing wastewater treatment plants. The activated sludge process is widely used to treat wastewater from both industrial and municipal sources. Biomass from industrial facilities containing high monovalent to divalent ion content usually settles poorly, which leads to low quality effluents that fail to meet environmental requirements. Therefore, the combined effect of feeding pattern plus the addition of sodium to activated sludge reactors was studied in this experiment. A series of SBRs were operated at different sodium concentrations that ranged from 1.5 - 15 meq/L and different feeding times that ranged from 1 minute to 4 hours. Biomass samples were taken from each reactor to study the settling and dewatering properties and effluent samples were used to analyze the amount of organic matter and exocellular polymeric substances present due to deflocculation. As expected, the changes in feeding strategies affected all of the properties measured. When the feeding time was maintained low (pulse feed) the effluent quality and settling properties were the best. As the feeding time was increased the effluent quality, settling, and dewatering properties increased suggesting that the way in which the reactors were fed affected the overall bioflocculation process. The causes of the high deflocculation observed are not well understood, but data suggest that a microbial community change could have affected exocellular biopolymers which are believed to play an important role on bioflocculation. This research demonstrates the importance of the interaction between cation content and feeding pattern when operating a wastewater treatment plants and when reporting lab-scaled results related to settling and bioflocculation. / Master of Science

X-ray photoelectron spectroscopy (XPS) has been used to study the bonding of adsorbed metal cations to clay minerals. Binding energy differences of the adsorbed metal cations can be related to changes in the electron density or charge on the atom of interest. Adsorption experiments were carried out in aqueous solution at controlled pH's of 2, 4, 6, 8, and 10 for Ba²⁺, Co²⁺, Cr³⁺, adsroption on the clays kaolinite and ripidolite. Solution processes were monitored by measuring the solution concentrations of dissolved silica and the metal ions Fe³⁺, Mg²⁺, K⁺, Al³⁺, Cr³⁺, and Co²⁺ at the beginning and the end of the experiment. Atomic absorption spectroscopy was used to determine the metal ion concentrations and dissolved silica was determined spectrophotometrically as a molybdate complex. Examination of the adsorbed cation species on the clay surface by XPS indicated that the clays behaved as nucleation centers at or near the pH of precipitation of the cations. Further it was found that high spin Co²⁺ in solution became low spin Co²⁺ or formed a highly covalent bond when adsorbed on kaolinite at pH's 4, 6, and 7 and on ripidolite at pH 2 and 4. Finally, if the clay has a negatively charged surface which donates some of its charge to the positive cation, then the barium XPS data indicated that ripidolite has a greater negative surface charge than kaolinite. This idea was supported by calculations of the surface charge density from CEC and surface area data. / Master of Science

Activated sludge influent and effluent from five municipal wastewater treatment plants were analyzed to further elucidate the roles of aluminum, iron, and the monovalent to divalent cation ratio (M/D) on the influent and effluent characteristics of the systems. The size distribution of organic nitrogen, organic carbon, protein, humic acid, and polysaccharide was examined with respect to the concentration of cations in the activated sludge influent. It was found that the majority of organic nitrogen, organic carbon, protein and polysaccharides were found in material larger than 0.45μm in activated sludge influent. Humic acids were mostly found in material smaller than 0.45μm. Protein was the largest contributor to organic nitrogen and humic acids were the largest contributor to organic carbon. Using 0.45μm as a division between particulate and soluble material, the ratio of soluble to particulate material in activated sludge influent was found to be negatively correlated with the ratio of iron to aluminum. In activated sludge effluent, the majority of the organic nitrogen and protein was found in material larger than 0.45μm, while the majority of the organic carbon, humic acid, and polysaccharide were found in material smaller than 30kDa. Influent aluminum concentration had no observable effect on the concentration or distribution of organic nitrogen or organic carbon. Influent iron appeared to play a role in the flocculation of organic nitrogen and protein containing material between 0.45μm and 1kDa in size. A high monovalent to divalent cation ratio appeared to play a role in deflocculating organic nitrogen containing material larger than 1.5μm and increased the concentration of TOC smaller than 1kDa and the total polysaccharide concentration. Tertiary depth filtration removed all organic nitrogen and protein in material larger than 0.45μm, but a poor job of removing organic carbon from and an inconsistent job of removing polysaccharide from effluent Eight lab-scale activated sludge reactors were also run, but the data was not consistent enough for analysis and comparison with the municipal wastewater treatment plants. This thesis contains a series of four papers that each deal with a different aspect of the role of cations on activated sludge influent and effluent. The first paper focuses on activated sludge influent characteristics, the second on effluent organic nitrogen and organic carbon, the third on effluent EPS, and the last on the lab-scale reactors. The papers were divided in this way because of the unique analytical obstacles that were encountered with each set of data. / Master of Science

Depuis maintenant plus de trois décennies, le catalyseurs d oxydation et particulièrement les pérovskites sont étudiés pour leur activité en oxydation des composés organique volatils (COV). Malgré leur faible surface spécifique, les pérovskites présentent des activité tout à fait comparables aux catalyseurs traditionnels de type métaux nobles. Cet inconvénient a eu pour effet la mise au point de nouvelles méthodes de synthèse avec un but commun: accroître la surface spécifique de ces solides. Étant donné l'effet néfaste de l ' énergie thermique pour la cristallisation des pérovski tes, l'élaboration de voies de synthèse à basse température a été largement étudiée. Ce critère de température fait que le broyage réactif est une méthode potentielle pour la préparation de pérovskites avec une large surface spécifique. Plusieurs études ont été rapportées dans la littérature concernant les effets des cations A et B, dans la structure pérovskite AB03, pour l'oxydation de certains COY comme le CO et le CH4 . Cependant peu de travaux ont été réalisés sur l'oxydation catalytique du méthanol. C' est pourquoi la première partie de ce travail a été consacrée à l'étude de l'effet du cation B, dans la structure pérovskite, pour l'oxydation du méthanol. Un mécanisme d'oxydation du méthanol a été élaboré à partir des caractérisations de surface effectuées sur des pérovskites LaB03 (B = Co, Mn, Fe) préparées par broyage réactif. Ce mécanisme montre que la densité en oxygène à la surface du catalyseur est un paramètre essentiel pour l'oxydation du méthanol. Les carbonates mono- et bidentates ont été indentifiés comme les deux principaux intermédiaires réactionnels de ce mécanisme. Dans une seconde partie le changement de la terre rare a montré l'importance de l'électronegativité de la surface sur la stabilité des intermédiaires de réaction. Le rôle du 2 manganèse (IV) et des oxygènes sur-stoéchiométriques de la structure pérovskite AMn03 (A = Y, La, Pr, Sm, Dy) sur l'oxydation du méthanol a également été mis en évidence. Enfin dans la dernière partie de ce travail les effets des substitutions partielles, du lanthane par le cérium et du cobalt par le fer, sur la mobilité des oxygènes de la structure pérovskite ont été di scutés. Cette étude indique que le cérium joue un rôle de promoteur sur la mobilité de l'oxygène alors qu'inversement le fer tend à ralentir le transport de l' oxygène. Ainsi la présence de cérium et de fer dans la structure pérovskite influence l'activité catalytique de ces solides pour l'oxydation des COV.