Photophysical Investigations of Thiophene Azomethine Derivatives

Une série de dimères composés de thiophène-aniline encombrée stériquement a été synthétisée. Les différents processus de désactivation de l’état singulet excité ont été étudiés par UV-visible, fluorescence, phosphorescence, photolyse par impulsion laser et calculs théoriques. Les graphiques de Stern-Volmer obtenus à partir des expériences de désactivation des états singulet et triplet ont démontré l’efficacité de l’azométhine à désactiver les fluorophores. Les calculs semi-empiriques AM1 examinant l’effet des substituants encombrés ont démontrés que les groupements tert-butyls sur l’aniline ont moins d’influence sur la barrière de rotation N-aryl que les substitutions alkyles en ont sur la rotation de thiophène-C. Les calculs Rehm-Weller basés sur les potentiels d’oxydation et de réduction ont montré que l’autodésactivation de l’état excité des azométhines se fait par transfert d’électron photoinduit menant à une éradication complète de la fluorescence. Des complexes métalliques contenant des ligands azométhines ont aussi été préparés. Le ligand est composé d’une unité hydroxyquinoline lié à un cycle thiophène. Les données photophysiques de ces complexes indiquent un déplacement bathochromique aussi bien en absorbance qu’en fluorescence. Des dispositifs de détection d’ion métallique ont été préparés et un exemple à partir d’une solution de cuivre a montré un déplacement bathochromique.

Photoelectrochemistry with quinone radical anions: Kinetics of homogeneous redox catalysis

Cyclic voltammograms of quinones were recorded in acetonitrile in the presence of various substrates: carbonyl compounds, halobenzenes, Methyl Viologen and Neutral Red. When illuminated with light of λ >410 nm, catalytic waves were observed. From the ratio of the catalysed to uncatalysed peak current, electron transfer rate constants were calculated using the working curves of Saveant and coworkers. The values of these rate constants were compared with the values obtained by Shukla and Rusling for different systems using a similar method and with quenching rate constants calculated using Rehm-Weller-Marcus theory.

Photoelectrochemistry using quinone radical anions

The photoelectrochemistry of quinone radical anions has been demonstrated qualitatively by the photoassisted reduction of methyl viologen with benzoquinone and of neutral red with chloranil. Data were then collected for the estimation of quenching rate constants using Marcus-Weller theory. Reduction potentials of seven quinones were obtained in four solvents (and two aqueous mixtures) by cyclic voltammetry. The solvent effects on these potentials were studied by fitting them to the Taft relationship. The effects of proton donors were also noted. Absorption spectra of the radical anions were measured and the solvent effects noted and commented upon. From the molar absorption coefficients of the radical anions, the mean lifetimes of the excited states were estimated. Fluorescence spectra were obtained for anthraquinone and naphthaquinone radical anions and excitation energies were calculated. These values were estimated for the other quinones. Values of redox potentials for the excited radical anions were thence obtained. The Gibbs energies of the electron transfers between the excited quinone radical anions and the various substrates were obtained and hence the Gibbs energies of activation were calculated using the Marcus equation. The quenching rate constants were calculated using the Rehm-Weller equation and plotted vs. ΔG giving a characteristic Marcus plot including some data in the inverted region. The significance of the inverted region is discussed.

La asignatura pendiente con Sam Weller

Santamaría, José Miguel; Pajares, Eterio; Olsen, Vickie; Merino, Raquel; Eguíluz, Federico (eds.)

Équation de production: adaptation du modèle de Ricker à un stock de poissons exploité par différents engins

The authors have developed the method used by Pianet and Le Hir (Doc.Sci.Cent. ORSTOM Pointe-Noire, 17, 1971) for the study of albacore (Thunnus albacares) in the Pointe-Noire region. The method is based on the fact that the ratio between unit of effort and number of fish for two fishing gears is equal to the ratio of their catchability coefficients.

Port Weller Dry Docks Limited fonds, 1948-1986, n.d. (non-inclusive)

This archive contains materials relating to the Port Weller Dry Docks Limited. The bulk of the materials are correspondence. The collection also includes biographical information, photographs and media releases. The materials have been kept in original order, except where noted. The fonds contains materials relating to Port Weller Dry Docks Limited. The materials included correspondence, photographs, media releases including clippings, photographs and some biographical information. Also included are brochures and programs from ship christenings.

Port Weller Dry Docks collection, 1959-1967

Port Weller Dry Docks Limited was officially established on April 25, 1946, near Lock 1 of the Welland Canal. Charles A. Ansell was the company’s first President and General Manager. Initially, the company focused on repairing ships, but in June, 1951, built their first ship, the Scott Misener. In 1956, the Upper Lakes and St. Lawrence Transportation Co. purchased all of the shares of Port Weller Dry Docks Limited. In the mid-eighties, ULS (Upper Lakes Shipping) International (which owned the Port Weller dry docks), and Canada Steamship Lines, merged their operations. As a result, the Port Weller Dry Docks became a division of this newly formed company, known as Canadian Shipbuilding and Engineering Limited. In 2007, Seaway Marine & Industrial Inc. took over ownership of the Port Weller Dry Docks, but declared bankruptcy in July 2013.

L'experience effective vs l'experience potentielle dans l'estimation de l'e quation de salaire des femmes.

Rapport de recherche

Traité de l'ophthalmie, la cataracte et l'amaurose : pour servir de supplément au traité des maladies des yeux de Weller /

Mode of access: Internet.

Études sur l'équation [partial derivative sign]p̳u/[partial derivative sign]xp̳ + a̳[delta]m̳u̳=0,

On t.p. p̳ and m̳ are superscript; a̳ and u̳ are subscript.

Sur l'équation fonctionnelle de Fredholm et quelques-unes de ses applications.

Diss.--Paris.

Détermination d'une équation d'état moderne du noyau liquide/solide d'une étoile naine blanche

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.