Thesis (PH. D.)--University of Chicago, 1919. / "Private Edition Distributed by the University of Chicago Libraries, Chicago, Ill." "Reprinted from the Journal of the American Chemical Society, vol. XL, no. 7, July, 1918 and vol. XLII, no. 12, December, 1921." Includes bibliographical references. Also available on the Internet.

Cataract disease affects millions of people worldwide. It is characterized by the accumulation of light-scattering bodies within the lens that reduce visual acuity. Cataracts are effectively treated surgically, but at great expense, costing Medicare $3.4 billion in 1997. Development of an alternative therapy for this disease would provide medical and economic benefits. We have investigated a novel antioxidant, the superoxide scavenger Mn(III)-salophen, as a therapeutic agent in the selenite cataract model. Mn(III)-salophen has been shown to protect E. coli colonies against oxidative stress but was untested in a eukaryotic system. A total dose of 300 mmol/kg, given IP in four equal 75 mmol/kg doses spaced four hours apart, protects 75% of neonatal rats from nuclear cataract development five days after selenite injection. Selenite is toxic through its reaction with the endogenous antioxidant glutathione (GSH). The reduction of selenite to selenide through an intermediate, selenodiglutathione (GSSeSG) leads to generation of superoxide radical, one of several toxic oxygen species that can damage the lens. Mn(III)-salophen causes an in vitro preservation of the lifetime of GSSeSG by interrupting the reduction of selenite. We have established that the reduction of GSSeSG to selenide does not use GSH as a reducing agent, but rather depends upon electrons generated in the earlier reduction of selenite to selenodiglutathione. These electrons can be intercepted by known one-electron scavengers, arresting the metabolism of GSSeSG. Extensive proteolysis of lens crystallins and loss of calcium homeostasis occur in cataractous lenses from a rat treated with sodium selenite. The visual protection with Mn(III)-salophen is accompanied by a partial loss of the calcium homeostasis, a net increase in sodium, and calpain-mediated proteolysis of à -crystallins similar to lenses from animals treated with selenite alone. Although preservation of alpha-crystallins may contribute to the greater transparency in the protected lens, generalized à -crystallin proteolysis is insufficient for cataract formation. From these experiments we propose that Mn(III)-salophen minimizes the oxidative stress imposed upon the cell by interfering with the metabolism of selenodiglutathione. This allows the cell to compensate for the loss of cation homeostasis and prevents aggregation of proteolyzed crystallins into cataracts. / Ph. D.

Boron arsenide is a compound main group semiconductor with a theoretical band gap in the range of 1.1 to 1.6 eV. Despite this ideal band gap, experimental studies of boron arsenide are very limited. In the present work, single source precursors with covalent bonds between boron and arsenic and labile ligands have been designed and synthesized. These precursors underwent thermal or chemical treatment to produce boron arsenide materials. Boron arsenide has also been prepared as a thin layer deposited on a boron substrate and a p-type photoelectrode was prepared from this material. The structure of the product was identified on the basis of X-ray diffraction and scanning electron microscopy, and the surface composition was determined by means of X-ray photoelectron spectroscopy. The electrode was found to be photoactive under both visible and UV-visible light irradiation and displayed a photocurrent of approximately 0.1 mA/cm² under UV-visible light irradiation at an applied potential of -0.25 V vs. Ag/AgCl. The valence band was estimated to be -5.1 eV. The indirect band gap, as determined from incident photo-to-electron conversion efficiency plots, is 1.46 eV. An ester-fuctionalized salophen aluminum complex that features a polymerizable bithiophene as the ester R group has been designed and synthesized. Metallopolymers of this type offer the additional advantages of processability and uniformity of the resulting films. The new salophen complex exhibited emission in the blue region at 491 nm with a quantum yield of 8.19%, which is significantly larger than that of the isolated ligand. Electropolymerization of this complex on a platinum button electrode resulted in the formation of an electrically conductive polymer that is also ionically conductive at low scan rates. In the polymeric form, the emission wavelength was found to be red-shifted to 505 nm. / text

This thesis deals mainly with two oxidation reactions: water oxidation and aerobic oxidation, both of which have been applied in a biomimetic fashion. In the former reaction molecular oxygen is generated whereas in the latter it was used as terminal oxidant in oxidation reactions. The first part of this thesis describes the synthesis of different ruthenium and manganese complexes that could potentially act as catalysts for water oxidation. This part includes a discussion of the stability and reactivity of a new manganese(III) amide-type complex, that has been used as a catalyst for both epoxidation of stilbene and alcohol oxidation. The second part of this thesis discusses the synthesis of two new hybrid catalysts consisting of hydroquinone linked cobalt(II) salophen and cobalt(II) salmdpt, which have been used as oxygen-activating catalysts in aerobic oxidation reactions. The former catalyst was applied to the Pd-catalyzed reactions such as 1,4-diacetoxylation of cyclohexadiene whereas the latter was applied to the Ru-catalyzed oxidation of secondary alcohols to ketones. Moreover, these two hybrid catalysts could be used in the Pd-catalyzed carbocyclization of enallenes. In all cases molecular oxygen was used as the stoichiometric oxidant.

The effect of Mn(III)-salophen, a superoxide scavenger, against oxidative stress was evaluated in <i>Escherichia coli sodA- sodB-</i>. Oxidative stress was imposed by exposure of the cells to paraquat or hyperoxia. Cells were grown in LB medium overnight, washed and resuspended in the indicated glucose/salts medium supplemented with casamino acids. The effect of Mn(III)-salophen in the oxidative stress model <i>in vivo</i> was measured in terms of the cell growth. Mn(III)-salophen ( 60 nM) completely protected <i>E. coli</i>JI132<i>sodA- sodB-</i>against 1.0 μM paraquat. Equivalent amounts of Mn(III) acetate, a Mn(III)-salophen component, also protected against paraquat toxicity in aerobic <i>E. coli</i> JI132<i>sodA- sodB-</i>. Fe(III)-salophen which has no superoxide scavenging activity, did not protect the cells against paraquat toxicity. The protective effect of Mn(III)-salophen against the paraquat toxicity was proposed to come from the intracellular superoxide scavenging activity of either the complex itself, its component Mn(III), or both, but not by inhibiting the uptake of paraquat. The protective effect of Mn(III)-salophen and Mn(III) in the glucose/salts medium containing casamino acids was also observed in <i>E. coli sodA- sodB-</i> in 100% and 50% oxygen. Hyperoxia increases intracellular levels of superoxide radicals that are intercepted by Mn(III)salophen and Mn(III). / Master of Science

The development of selective and sensitive sensors for anionic species in water is a growing field of research. In particular, the detection of fluoride in aqueous samples is of great interest because of health related problems attributed to this anion. Furthermore its small size and its high hydration energy make it a particularly <p>challenging species to recognize in water. <p>Uranyl-salophen receptors have shown to be good receptors for this anion in organic solvents due to their hard Lewis acid character which makes them good binders for the hard Lewis base fluoride. However they are not water soluble. <p>The incorporation of uranyl-salophen receptors 1-3 within cationic micelles (CTABr and CTACl) will make them “water-compatible” and give us the possibility to study the behaviour of these system in water. The 3 receptors shown <p>in figure 1 were studied in this thesis. Preliminary work had already been reported on receptor 1 in CTABr micelles. Binding affinities studies showed that these receptors have binding constants for fluoride of the order of 104 M−1 which is two orders of magnitude higher than <p>the value obtained for the same receptors in a less competitive solvent such as methanol. This suggests that the micellar environment has an effect, not only on the solubility of the receptors in water, but also for the binding process. <p>Physico-chemical studies were undertaken on the system in order to obtain some structural informations. Dynamic Light Scattering experiments showed an increase in the size of the CTABr micelles upon receptor’s incorporation but not on the CTACl ones. <p>NMR studies, including chemical shift variation measurements, nOe and Paramagnetic Relaxation Enhancement (PRE) experiments, were undertaken in order to analyse the location and orientation of the receptors in the micelles. Results indicate that receptor 1 is located at the micellar surface, in CTABr micelles and a little deeper in CTACl micelles, orienting the receptors binding site towards the exterior of the micelle. Receptor 2 is more buried inside the micelles compared to receptor 1 but with a similar orientation. Receptor 3 is the most deeply buried <p>in the micelles, and the experiments suggests that no preferential orientation is adopted. <p>A systematic study of the factors affecting PRE measurements was also undertaken showing the dependency of this measurements on the surfactant concentration, the nature of the counterion and the ionic force. A method, based on the normalization of the relaxivity values to the value obtained for the micelle polar head is proposed in order to avoid all the variations due to the experimental conditions and thus enabling the comparison of different systems. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished