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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Synthesis of novel pendant arm macrocyclic ligands as potential models for enterobactin

Cameron, Beth 09 July 2018 (has links)
A series of pendant arm tris-catecholate macrocyclic ligands were synthesized. The first, based on 1,4,7- triaminopropyl-1, 4, 7-triazacyclononane, was prepared via condensation with 2,3-dimethoxybenzoyl chloride. The deprotection of the catechol moieties was achieved with boron tribromide in 80% yields. The ferric complexes were characterized by electronic absorption spectroscopy. The second series of ligands described are based on the pendant arm macrocyclic ligand, 1, 4, 7-triaminoethyl-1, 4, 7- triazacyclononane. New routes to the preparation of this ligand were investigated; the best approach used chloroacetyl chloride as the reagent in functionalizing the nitrogen atoms of the triazacyclononane ring. The ligands, 1, 4, 7-tris-((2, 3- dihydroxyphenethyl) aminoethyl)-1, 4, 7-triazacyclononane (34) and 1, 4, 7-tris-((2, 3-dihydroxybenzyl)aminoethyl)-1, 4, 7- triazacyclononane (36) were prepared through a series of acid chloride condensation reactions, followed by reduction of the amides with diborane. The mononuclear ferric complexes of compounds 34 and 36 Were prepared and characterized by uv-visible spectroscopy. Mononuclear nickel, cobalt, and copper complexes of these ligands were also characterized by uv-visible spectroscopy. The binuclear complexes, Na[NiFe(34)] and Na[NiFe(36)], were prepared and characterized by electronic absorption spectroscopy. Tris-((2, 3-dihydroxybenzylamino)ethyl) amine, tris-((2, 3- dihydroxybenzoyl)aminoethyl)amine, and tris-((2 ,3-dihydroxyphenethyl)aminoethyl)amine were prepared by Schiff base condensation reactions, or acid chloride condensation of tris-(2-aminoethyl)amine and the appropriate catecholate moiety. The ferric complexes of these ligands were prepared and characterized by uv-visible spectroscopy. The A1(III) tris-((2,3-dihydroxybenzyl)aminoethyl)amine complex was examined by nmr spectroscopy. The Ni(II), Cu(Il) and Co(III) complexes were investigated by electronic absorption spectroscopy. The rates of base hydrolysis of [Co(tacn) (en)Cl]2+ (tacn=1, 4, 7-triazacyclononane), [Co(tacn) (amp)Cl]2+ (amp=2- aminomethylpyridine), [Co(tacn) (tn)Cl]2+, ufac-I- [Co(dien) (amp)Cl]2+ (dien=l,4,7-triazaheptane), ufac-Il- [Co (dien) (amp)]2+ and [Co (bicycloN5) C1]2+ (bicycloN5=1, 5, 8, 12, 15-pentaazabicyclo [10.5.2] nonadecane), were measured using stopped flow techniques. The base hydrolysis rates (kCH, M-1s-1; [ionic strength (M)]) are 9.66 [0.1], 154 [0.1], 40.6 [0.1], 334 [0.1], 762 [0.1], and 3X103 [1.0], respectively. The rate of [NCS-] anation of [Co (bicycloN5) (OH2)]3+, and the rates of [Br-] and [NCS-] anation of [Co (tacn) (en) (OH2)]3+ were measured as a function of pH. The pKa of the coordinated water molecules are 3.8 ([Co (bicycloN5) (OH2)]3+) and 6.5 ((Co(tacn) (en) (OH2)]3+) . The anation rates increase as the pH increases, indicating a base catalysed anation reaction through the deprotonation of the coordinated amine. In the case of the [Co(tacn) (en) (OH2)]3+ complex, the rate increases as the pH increases until the pH ~ 7, then there is no reaction after that point, suggesting some sort of blockage at the five-coordinate intermediate. / Graduate
22

Synthesis of camphor derived ligands for applications in asymmetric catalysis.

Boyle, Grant Alexander. January 2006 (has links)
Chiral crown ethers have recently been shown to be useful asymmetric catalysts in many carbon-carbon bond forming reactions. The design and synthesis of new chiral macrocycles and ligands for use in asymmetric catalysis is of great interest in the field of synthetic chemistry. Catalytic asymmetric Michael additions have been studied using chiral crown ethers as phase transfer catalysts. Many chiral crown ethers have been synthesised and tested in asymmetric catalysis but the design of these systems is still an area of much interest. The attempted synthesis of a new class of novel macrocycles such as 1 is described (chapter 2). The synthesis of a new class of chiral cage annulated macrocycles such as 2 is reported (chapter 3). The testing of these macrocycles as catalysts in the Michael addition of 2-nitropropane to chalcone was carried out with poor enantioselectivity being observed Recognition events in chemistry occur on a molecular scale that is difficult to monitor without the use of molecular devices. Photoinduced Electron Transfer (PET) systems have been the subject of much research over the past three decades. The attempted synthesis of the first chiral PET sensor 3 is described (chapter 4). / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2006.
23

Synthesis of macrocyclic 1,3-diketones from metacyclophanes and their applications in organic synthesis.

January 1994 (has links)
by Siu-leung Ng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 61-62). / Acknowledgments --- p.i / Content --- p.ii / List of Schemes --- p.iii / List of Tables --- p.iv / List of Spectra --- p.v / Abstract --- p.viii / Abbreviations --- p.x / Chapter I. --- Introduction --- p.1 / Chapter II. --- Literature survey / Chapter II.1. --- Ring expansion of cyclic enamines via a [2+2]cycloaddition --- p.4 / Chapter II.2. --- The Ito-Saegusa protocol --- p.6 / Chapter II.3. --- "The Suzuki-Watanabe-Noyori palladium(0)-catalyzed ring opening of cyclic α,β-epoxy ketones" --- p.7 / Chapter III. --- Synthetic plan --- p.9 / Chapter IV. --- Results and discussion / Chapter IV. 1. --- General routes to [n]metacyclophanes (24) and (n+2)- methoxy[n]metacyclophane 35 --- p.15 / Chapter IV.2. --- Birch reduction of 24 and 35 and ozonolvsis of 25 and 36 --- p.17 / Chapter IV.3. --- Synthetic applications / Chapter IV.3.1. --- Synthesis of heterocyclophanes --- p.27 / Chapter IV.3.2. --- Synthesis of exaltone (8) --- p.28 / Chapter V. --- Conclusion --- p.30 / Chapter VI. --- Experimental --- p.31 / Chapter VII. --- References --- p.61 / Chapter VIII. --- 1H and 13C NMR spectra of selected compounds --- p.63
24

Synthesis of [beta]-ketomacrolides via 1-oxa[n]meta-cyclophanes and a new route to (+-)-patulolide C.

January 1994 (has links)
by Fong Sun. / On t.p., "+" appears over "-". / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 41-43). / Acknowledgements --- p.i / Contents --- p.ii / Abstract --- p.iii / Abbreviations --- p.iv / Chapter I --- Introduction / Chapter I-1 --- General background --- p.1 / Chapter I-2 --- Literature survey --- p.3 / Chapter I-2-1 --- Ley's approach to β-ketomacrolides --- p.3 / Chapter I-2-2 --- Weiler's approach to β-ketomacrolides --- p.4 / Chapter I-2-3 --- Macrocyclic β-ketomacrolides formation through sulfide contraction ´ؤIreland's approach --- p.5 / Chapter II --- Result and Discussion / Chapter II-1 --- General strategy for the synthesis of 1 -oxa[n]metacyclophanes --- p.7 / Chapter II-2 --- l-Oxa[n]metacyclophanes as masked β-ketomacrolides synthons --- p.9 / Chapter II-3 --- Application to the synthesis of natural products --- p.10 / Chapter II-4 --- An alternate approach for the synthesis of (2E)-2-dodecen-l 1-olide´ؤA structural proof --- p.15 / Chapter III --- Conclusion --- p.17 / Chapter IV --- Experimental --- p.18 / Chapter V --- References --- p.41 / Chapter VI --- Spectra --- p.44
25

Part I, chemoselective and oxo-controlled s-oxidation of sulfides containing pyridine rings and olefinic double bonds: Part II, directed synthesis of all-Homocalix(n)arenes with various cavity sizes. / Chemoselective and oxo-controlled s-oxidation of sulfides containing pyridine rings and olefinic double bonds / Part II. directed synthesis of all-Homocalix(n)arenes with various cavity sizes / Directed synthesis of all-Homocalix(n)arenes with various cavity sizes

January 1999 (has links)
Ho-Fai Lee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 90-91). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abbreviations --- p.ii / Abstract --- p.iii / Chapter Part I. --- Chemoselective and Oxo-Controlled S-Oxidation of Sulfides Containing Pyridine Rings and Olefinic Double Bonds / Chapter 1.1. --- Introduction --- p.2 / Chapter 1.2. --- Results and Discussion --- p.5 / Chapter 1.3. --- Conclusion --- p.14 / Chapter 1.4. --- Experimental --- p.15 / Chapter 1.5. --- References --- p.32 / Chapter Part II. --- Directed Synthesis of all-Homocalix[n]arenes with Various Cavity Sizes / Chapter II. 1. --- Introduction --- p.35 / Chapter II.2. --- Previous Synthetic Routes for all-Homocalixarenes --- p.37 / Chapter II.3. --- Synthetic Plan --- p.39 / Chapter II.4. --- Results and Discussion --- p.41 / Chapter II.5. --- Conclusion --- p.55 / Chapter II.6. --- Experimental --- p.56 / Chapter II.7. --- References --- p.90 / Chapter Appendix --- 1H and 13C NMR Spectra / List of and 13C NMR Spectra of Part I --- p.92 / 1Hand 13C NMR Spectra of Part I --- p.93 / List of 1H and 13C NMR Spectra of Part II --- p.100 / 1H and 13C NMR Spectra of Part II --- p.102
26

Structural studies and modelling of novel macrocyclic plant peptides with multiple disulphide bonds

Koltay, Anita Claire, 1963- January 2001 (has links)
Abstract not available
27

Syntheses and studies of sapphyrins and anion receptors

Cho, Dong Gyu, 1970- 29 August 2008 (has links)
Polypyrrolic (or aromatic) macrocycles have attracted considerable recent interest due to their potential utility in various applications, including as novel materials, anion receptors, and therapeutic leads. In order to explore further the range and utility of this generalized class of molecules, various sapphyrin and sapphyrin analogues were synthesized. Among the new compounds prepared is an inverted sapphyrin, a species that displayed weak, but noticeable aromaticity. Another new system, benzoxasapphyrin was found to display a reduced anion binding affinity compared to other analogous macrocycles. Finally, several derivatized sapphyrins were prepared as potential anticancer leads. Separate from the above, efforts were made to develop anion receptors based on the indole motif. This substructure plays a key role is stabilizing a range of non-covalent interactions in complex biological structures. However, prior to the present study, indole-type hydrogen bonding donors had not been widely used to prepare synthetic anion receptors. Accordingly, a diindolyl quinoxaline system was prepared; it served to demonstrate that small molecule indole receptors can effectively bind phosphate anions in organic media. Finally, a set of cyanide anion indicators were prepared; these were predicated on the use of a cyanide-specific reaction, namely the benzil rearrangement reaction. The benzil reaction-based indicators produced in this way were found to be quite selective for the cyanide anion in organic solvents. Further, their study helped provide insights into the mechanism of this as-yet not fully studied reaction. In the context of developing this specific anion indicator, a review of other reaction-based indicators was reviewed. This is provided in Chapter 3. / text
28

Crown ethers as potential lead (II) specific probes : a thesis submitted for the degree of Doctor of Philosophy /

Caiazza, Daniela. January 1999 (has links) (PDF)
Thesis (Ph.D.) -- University of Adelaide, Dept. of Chemistry, 1999. / Errata pasted onto front end-paper. Bibliography: leaves 173-188.
29

Synthesis and characterization of some organoruthenium complexes with macrocyclic amine ligands /

Choi, Mei-yuk. January 1999 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 131-145).
30

A ring expansion approach to roseophilin

Salamone, Samuel G. Stiegman, Albert E. January 2005 (has links)
Thesis (M.S.)--Florida State University, 2005. / Advisor: Albert E. Stiegman, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Jan. 24, 2006). Document formatted into pages; contains xiv, 89 pages. Includes bibliographical references.

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