Zugl.: Hamburg, Helmut-Schmidt-Universiẗat, Diss., 2008.

Zugl.: Hamburg, Techn. Univ., Diss., 2008

Cobalt(II) complexes with linear potentially pentadentate Schiff base ligands have been prepared and their reaction with dioxygen studied. The ligands were synthesized from salicylaldehyde and diamino compounds containing a central donor atom. Various derivatives were produced by using a substituted salicylaldehyde or by placing different groups on the compounds containing a central nitrogen donor. Those ligands containing weak central donors produce both four and five-coordinate complexes. The coordination number is determined by the electron density on the metal as well as the basicity of the central donor. The five-coordinate complexes assume a distorted trigonal bipyramidal structure, but the phosphorus containing complexes are believed to involve a different ligand arrangement from that of the other complexes. Most of the cobalt(II) complexes are stable in the solid state, but all react with oxygen in solution to some extent. A monomeric superoxo adduct was isolated with one of the complexes containing an unsubstituted central nitrogen donor. Other cobalt(II) complexes of this type react with oxygen to form dimeric peroxo adducts. An unusual dimeric dioxygen complex was obtained with a compound in which the central nitrogen donor is substituted with a methyl group. This adduct is believed to involve both superoxo and unreacted species. Comparison of the structure of precursors to that of a dimeric peroxo adduct suggests a different mode of bonding than that which occurs in dioxygen complexes with other types of ligands. The significance of this is explored in terms of the prevention of dimerization. / Ph. D.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--Chemical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Christopher Jones; Committee Member: Dr. Dennis Hess; Committee Member: Dr. Hang Lu; Committee Member: Dr. Marcus Weck; Committee Member: Dr. Pradeep Agrawal. Part of the SMARTech Electronic Thesis and Dissertation Collection.

No description available.

Zugl.: Berlin, Humboldt-Univ., Diss., 2008

The class of compounds known as the dibenzotetraaza[14]annulenes have been of particular interest over the past 25 years, with the initial impetus for research being the relationship they hold with the naturally occuring porphyrins. The main aim of the work undertaken was to establish the potential of dibenzotetraaza[14]annulene type systems for the development of novel materials whose applicable behaviour was likely to fall into one of the following three categories; liquid crystals, organic conductors, and chelating systems. Additionally the chemistry involved with the synthesis of these types of materials was interesting in its own right and provided a platform for the author to increase his own knowledge of chemistry. The research undertaken may be broadly classified into the following areas: 1. The preparation of linear Schiff base polymers, 2. The preparation of dibenzotetraaza[14]annulenes (metal complexes and free ligands), 3. The preparation of 1-D and 2-D unsymmetrical macrocyclic complexes, and 4. The preparation of polymeric materials incorporating dibenzotetraaza[14]annulenes both as part of the polymeric backbone and as pendant side chains in a comb type polymer. 1. The preparation of linear Schiff base polymers. The Schiff base condensation of phenylenediamines with malondialdehydes has enabled the preparation of materials of the type illustrated below. [chemical formula]. Examination of the materials by differential scanning calorimetry has shown that many of the materials exhibit interesting thermal transitions from one crystalline state to another. However the use of thermal microscopy has not shown any of these phases to be liquid crystalline transitions. 2. The preparation of dibenzotetraaza[14]annulenes (metal complexes and free ligands). An extensive array of dibenzotetraaza[14]annulenes have been prepared, generally by a one step process involving the reaction of ortho-phenylenediamine and various 2-substituted malondialdehydes in the presence of a suitable acid catalyst and solvent. [chemical formula]. 3. The preparation of 1-D and 2-D unsymmetrical macrocyclic complexes. The introduction of unsymmetricality into the dibenzotetraaza[14]annulenes has been of interest since dipole-dipole interactions between molecules may lead to enhanced crystalline stacking, which in turn has a direct effect on any liquid crystalline or semiconducting properties the material may exhibit. Consequently the preparation of unsymmetrical dibenzotetraaza[14]annulenes has been undertaken, which has often required extended stepwise synthetic reaction pathways involving the use of protecting reagents. Small quantities of pure materials have been prepared and are believed to be the first of their type. 4. The preparation of polymeric dibenzotetraaza[14]annulenes. The incorporation of dibenzotetraaza[14]annulenes into a polymeric system has been examined in two ways. The initial study concentrated on the incorporation of the macrocycle directly into the polymer backbone and involved the reaction of suitably functionalised dibenzotetraaza[14]annulenes with linking groups such as para-phenylenediamine. The additional study has focussed on a method of forming polymers which include the macrocyclic complexes as pendant side chains in a comb type polymeric arrangement (illustrated below). [chemical formula]. At present the prepartion of a polymer of this type has not been achieved. However an extensive study into the attachment of groups to the macrocycles which are capable of undergoing polymerisation has been undertaken which has established the potential use of the Gabriel synthesis of amines and the Wittig reaction as potential methods of attachment.

Dissertação (mestrado) - Universidade Federal de Santa Catarina. Centro de Ciencias Fisicas e Matematicas / Made available in DSpace on 2012-10-16T22:10:59Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T17:55:49Z : No. of bitstreams: 1 90932.pdf: 1736571 bytes, checksum: 9b5e57becaa70fc482282dcd39d1c725 (MD5) / A reação de hidrólise das bases de Schiff N-benzildenoanilina, 4-metóxi-N-benzilidenoanilina, 2-metóxi-N-benzilidenoanilina e 2-(2-etoxi)etóxi-N-benzilidenoanilina foi estudada a 25oC, na presença de sais de metais alcalinos e alcalino-terrosos em diversas concentrações. A força iônica foi mantida constante no meio etanólico aquoso (88%) através da adição de tetrafluoroborato de tetrabutilamônio. Os resultados foram explicados em termos de três fatores: a) o efeito inibitório da complexação do íon metálico com o átomo ligado ao anel; b) o efeito provocado pela associação do cátion com o átomo de nitrogênio imínico; c) o efeito templato, envolvendo a associação do íon metálico com os átomos de oxigênio da cadeia lateral.