Thesis (Ph.D.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 221-233.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 254-271). Also available on the Internet.

Thesis (Ph. D.)--Memorial University of Newfoundland, 1997. / Blbliography: leaves 238-245.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 254-271). Also available on the Internet.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 117-123.

In this diploma thesis a detailed investigation of the step-by-step reduction mechanism of cone-mono-, di-, tri and tetranitrocalix[4]arenes (in non-aqueous DMF) is presented. The intramolecular interaction of reducible (and reduced) centers and its consequences for the geometry of the starting molecule was discussed including the character of radicalic intermediates and their spin state. It was found, that the electrochemically generated radical anions of nitrogroups (unlike their starting electroneutral state) can act as ligands. Therefore, a study of complex formation equilibria of cone-tetranitrocalix[4]arenes with alkali metal cations followed. The possible use of a "stereoelectrochemical" approach (the relationship between geometry or conformation of the molecule and its electrochemical data) was demonstrated in describing and explaining conformational and electrochemical differences between two isomeric dinitrocalix[4]arenes. Finally, a new series of 1,3-alt-tetranitrothiacalix[4]arenes was electrochemically characterized and compared with the "classic" calixarene derivatives. Key words: electrochemistry, calixarenes, stereochemistry

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No description available.

[pt] O comportamento eletroquímico de eletrodos de pasta de carbono quimicamente modificados com os seguintes calixarenos: 4- sulfcalix[4]areno e 4-terc-butilcalix[4,6,8]areno foi investigado na presença de alguns cátions (Sb 3+, Se4+, Mn2+, Cd2+, Zn2+, Cu2+, Pb2+, V4+ e V5+) através das técnicas de voltametria de pulso diferencial, onda quadrada e voltametria cíclica. Estes estudos foram realizados para demonstrar a utilização dos calixarenos como moléculas hospedeiras de íons metálicos ou metalóides bem como a formação de complexos. No estudo eletroquímico dos calixarenos foram feitos sucessivos voltamogramas no modo pulso diferencial e em varredura linear (cíclica) sob diferentes velocidades de varredura, utilizando como eletrodo de trabalho de carbono vítreo e de platina sendo observado que na oxidação do 4-sulfcalix[4]areno e do 4-terc-butilcalix[4,6,8]areno ocorre a passivação ou acumulação na superfície do eletrodo. No estudo do processo eletroquímico observado na presença dos oito cátions (Sb 3+, Se4+, Mn2+, Cd2+, Zn2+, Cu2+, Pb2+ ,V4+ e V5+) utilizaram-se os seguintes eletrodos de trabalho: eletrodo de pasta de carbono quimicamente modificado com 4-terc-butilcalix[4]areno, eletrodo carbono e eletrodo de pasta de carbono não modificado. Maior atenção foi dedicada ao estudo do comportamento do 4-sulf-calix[4]areno na presença de V4+ e V5+ utilizando como eletrodo de trabalho, o eletrodo de carbono vítreo e os de pasta de carbono modificada e não modificada. Observou-se que, na presença deste íon metálico, o aparecimento no voltamograma de novos picos relacionados à formação de complexos. Uma corrente voltamétrica analiticamente útil foi obtida para oxidação do(s) complexo (s) (vanádio / calixareno). Sendo estimada a constante de formação dos complexos formados com vanádio. A interferência de alguns cátions (Sb 3+, Se4+, Mn2+, Cd2+, Zn2+, Cu2+, Pb2+) na análise de V4+ na presença de 4-sulf-calix[4] areno foi estudada, onde somente o íon Cu2+ não interferiu na análise. Curvas de calibração de V4+ foram construídas com eletrodo de pasta de carbono, eletrodo de pasta de carbono quimicamente modificado com 4-terc- butilcalix[4]areno e com eletrodo de carbono na presença de 4-sulf-calix[4] areno. / [en] The study of the electrochemical behavior of electrodes of carbon paste chemically modified with the following calixarenes: 4-sulf- calix[4]arene and 4-terc-butilcalix[4,6,8]arene was investigated in the present of cations (Sb3+, Se4+, Mn2+, Cd2+, Zn2+, Cu2+, Pb2+, V4+ and V5+) using differential pulse , square wave and cyclical voltammetry. Other electrochemical studies for each cited calixarene was investigated. Successive voltammograms in the way had been made differential pulse voltammetric and sweepings linear (cyclic) under different scan rates and observed that in the oxidation of the 4-sulf-calix[4]arene and 4-terc- butilcalix[4,8]arene passivation and accumulation in the surface of exactly. In the study of the electrochemical process observed in the presence of eight cations (Sb3+, Se4+, Mn2+, Cd2+, Zn2+, Cu2+, Pb2+, V4+ and V5+) the following electrodes of work was used: carbon paste modified with 4-terc-butilcalix [4]arene, electrode carbon and unmodified carbon paste electrode. Considerable attention was dedicated to the study of the behavior of the 4-sulfcalix[4]arene in the present of V4+ and V5+ using as work electrode the carbon and carbon paste modified with 4-terc-butil-calix[4] areno and unmodified. It was observed, in presence of this ion metallic, the appearance in the voltammogram of new peaks related to the formation of complexes. An analytical useful voltammetric current was gotten for oxidation of complex (calixarene / vanadium). The interference of some cations (Sb3+, Se4+, Mn2+, Cd2+, Zn2+, Cu2+, Pb2+) in the V4+ analysis in presence of 4-sulf-calix[4]areno was studied. Calibration curve gotten in presence of V4+ had been constructed with carbon paste modified with 4-terc-butilcalix[4]arene, unmodified carbon paste electrode and carbon electrode in the presence of 4-sulfcalix[4]areno.

No description available.