• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 57
  • 8
  • 4
  • 4
  • 2
  • Tagged with
  • 85
  • 85
  • 26
  • 22
  • 12
  • 7
  • 7
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 4
  • 4
  • 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.
31

Synthesis of corroles and furochlorophin as photosensitizers for photodyanmic [i.e. photodynamic] therapy (PDT) /

Kong, Pak Wing. January 2005 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references. Also available in electronic version.
32

Solution chemistry of calix[4]arene amide derivatives : applications in radiopharmaceuticals

Al Jammaz, Ibrahim J. January 1998 (has links)
Following an overview in the field of calixarene chemistry given in the introduction, this thesis reports, i) The synthesis of p-text-butylcalix[4]arene tetraacetamides, thiophosphates and derivatives containing mixed functional groups and the characterisation by IR, NMR and microanalysis. ii) The solution thermodynamic of p-tert-butylcalix[4]arene tetradiisopropylacetamide and the transfer thermodynamics of this ligand from acetonitrile to various solvents. iii) Spectrophotometric, potentiometric and calorimetric studies on the interaction of p-tert-butylcalix[4]arene tetraacetamides and metal cations in butan-l-ol and in water saturated butan-l-ol at 298.15 K. Metal-ion complexes of p-tert-butylcalix[4]arene tetradiisopropylacetamide were isolated and characterised by IR, NMR and spectroscopy and microanalysis. In butan-l-ol, the selectivity of this ligand for metal cations follows the sequence Na+ > Cd2+ > Pb2+ > Zn2+ > Ag+. However, this sequence is altered in the water saturated solvent to an extent that the strong complexation observed for this ligand and zinc(II) in butan-l-ol is non-existent in the water saturated solvent. Using complexation data in conjunction with solution data of the host, the guest and the resulting complex, enthalpies of coordination (referred to the process which reactants and the product in the solid state) were calculated. iv) Extraction experiments in the water-butan-l-ol solvent system at 298.15 K in the presence of p-tert-butylcalix[4]arene tetradiisopropylacetamide were performed. The higher extraction of lead(II) relative to other metal cations from the aqueous solution to the organic phase in the presence of the ligand at low hydrogen-ion concentration is demonstrated. The extraction of radioactive lead(II) by the same ligand was investigated as a function of i) the pH of the aqueous phase ii) the ligand concentration in the organic phase. vi) A new polymeric material was obtained by attaching the ligand to the polymer. Final conclusions are drawn and suggestions for further work in this area are given.
33

An Approach Towards the Total Synthesis of Clonostachydiol

Maiti, Tushar B. (Tushar Baran) 08 1900 (has links)
The syntheses of the unsymmetrical 14-membered bismacrolides have been reviewed. A total synthesis of clonostachydiol, the latest to join this family, has been attempted using trimethylsilyl acetylene as the builiding block and palladium catalyzed reactions for the formation of key bonds. The alkyne groups were introduced by Stille coupling of trimethylstannylethynyltrimethylsilane with an acid chloride for one fragment and by addition of lithiotrimethylsilyl acetylene to an aldehyde for the other. Lactic acid derivatives were chosen as starting materials for both fragments, thus introducing two of the chiral centers. The remaining stereocenters were introduced using stereoselective reductions of ketones.
34

Synthesis and characterization of b-substituted porphyrins and their metal complexes: Monomer, Dimer and coordination polymer.

January 1996 (has links)
by Xiang Zhou. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references. / Acknowledgment --- p.i / Abstract --- p.ii / Abbreviations --- p.iii / Table of Contents --- p.iv-v / Chapter Chapter I --- Synthesis of β-substituted porphyrins --- p.1 / Chapter I-1 --- Introduction --- p.1 / Chapter I-1-1 --- Activation of alkanes: the biomimetic approach --- p.2 / Chapter I-1-2 --- Electronic effects in β-substituted porphyrins --- p.5 / Chapter I-1-3 --- Synthetic approach to β-substituted porphyrins --- p.7 / Chapter I-2 --- Results and discussions --- p.14 / Chapter I-2-1 --- Bromination of porphyrins at β-positions --- p.14 / Chapter I-2-2 --- Synthesis of boronic acids --- p.17 / Chapter I-2-3 --- Synthesis of β-substituted porphyrins --- p.18 / Chapter I-2-4 --- Uv spectra --- p.25 / Chapter I-2-5 --- "Crystal structures of H2TPP(Ph)4, H2TPP(Me)4, H2TPP(Tol)8 and H2TMP(Ph)8" --- p.26 / Chapter I-3 --- Conclusion --- p.43 / Chapter I-4 --- Experimental section --- p.44 / Chapter I-5 --- References --- p.58 / Chapter Chapter II --- Synthesis and Properties of Diporphyrins --- p.63 / Chapter II-1 --- Introduction --- p.63 / Chapter II-1-1 --- Linear dimers --- p.64 / Chapter II-1-2 --- Cofacial porphyrins (or strati-bisporphyrins) --- p.68 / Chapter II-1-3 --- Synthetic approach --- p.71 / Chapter II-2 --- Results and discussions --- p.73 / Chapter II-2-1 --- Synthetic strategy --- p.73 / Chapter II-2-2 --- Synthesis of diporphyrins via condensation and Suzuki cross- coupling --- p.75 / Chapter II-2-3 --- Synthesis of diporphyrins via Suzuki cross-coupling and condensation --- p.75 / Chapter II-2-4 --- Metalation of diporphyrins --- p.78 / Chapter II-2-5 --- Spectroscopy --- p.81 / Chapter II-3 --- Conclusion --- p.89 / Chapter II-4 --- Experimental section --- p.90 / Chapter II-5 --- Reference --- p.100 / Chapter Chapter III --- Novel Rhodium Porphyrin Complexes: Intermolecular Activation of Arene Carbon-Hydrogen Bond and Formation of a Nitrile-Bridged Coordination Polymer --- p.104 / Chapter III-l --- Introduction --- p.104 / Chapter III-1-1 --- Activation of C-H bonds --- p.104 / Chapter III-1-2 --- Activation of C-H bond by rhodium porphyrin complexs --- p.106 / Chapter III-2 --- Results and discussions --- p.108 / Chapter III-2-1 --- Synthesis of rhodium porphyrin complexes --- p.108 / Chapter III-2-2 --- Proton NMR --- p.112 / Chapter III-2-3 --- UV and binding studies of rhodium porphyrin complexes --- p.115 / Chapter III-2-4 --- IR spectra --- p.117 / Chapter III-2-5 --- Crystal structures of rhodium porphyrin complexes --- p.118 / Chapter III-3 --- Conclusion --- p.148 / Chapter III-4 --- Experimental section --- p.149 / Chapter III-5 --- References --- p.154 / Appendix --- p.157 / NMR Spectra --- p.159
35

Part I, synthesis, spectroscopic properties and aggregation behavior of substituted 2,3-naphthalocyanines: and, Part II, synthetic studies of substituted dicyano-anthracenes and tetracens(sic). / Synthesis, spectroscopic properties and aggregation behavior of substituted 2,3-naphthalocyanines / Part II, synthetic studies of substituted dicyano-anthracenes and tetracens / Synthetic studies of substituted dicyano-anthracenes and tetracens

January 1999 (has links)
by Michael Tsang Ming Choi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 85-90). / Abstracts in English and Chinese. / ACKNOWLEDGMENT --- p.i / TABLE OF CONTENTS --- p.ii / LIST OF FIGURES --- p.iv / LIST OF TABLES --- p.vi / ABBREVIATIONS --- p.vii / ABSTRACT --- p.viii / 摘要 --- p.ix / Chapter PART I. --- "SYNTHESIS, SPECTROSCOPIC PROPERTIES AND AGGREGATION BEHAVIOR OF SUBSTITUTED 2,3- NAPHTHALOCYANINES" / Chapter 1 --- INTRODUCTION --- p.2 / Chapter 1.1 --- "Synthesis of 2,3 -Naphthalocyanines" --- p.6 / Chapter 1.2 --- Aggregation Phenomena of Phthalocyanines --- p.14 / Chapter 1.3 --- Phthalocyanines with Crown Ether Voids --- p.20 / Chapter 2 --- RESULTS AND DISCUSSION --- p.26 / Chapter 2.1 --- "Synthesis of Substituted 2,3-Naphthalocyanines" --- p.26 / Chapter 2.2 --- Synthesis of Substituted Phthalocyanines --- p.29 / Chapter 2.3 --- "Characterization of 2,3-Naphthalocyanines and Phthalocyanines" --- p.31 / Chapter 2.4 --- "Aggregation Behavior of Octasubstituted 2,3-Naphthalocyanines and Phthalocyanines" --- p.34 / Chapter 2.5 --- Liquid Crystalline Properties of64 --- p.43 / Chapter 2.6 --- "Synthesis of a Crown Ether-Substituted 2,3-Naphthalocyanine" --- p.45 / Chapter 2.7 --- Conclusion --- p.48 / Chapter 3 --- EXPERIMENTAL SECTION --- p.49 / Chapter 3.1 --- Materials --- p.49 / Chapter 3.2 --- Physical Measurements --- p.49 / Chapter 3.3 --- General Procedure for the Preparation of Dinitriles --- p.50 / Chapter 3.4 --- General Procedure for the Cyclization of Dinitriles --- p.53 / Chapter PART II. --- SYNTHETIC STUDIES OF SUBSTITUTED DICYANO-ANTHRACENES AND TETRACENES / Chapter 1 --- INTRODUCTION --- p.57 / Chapter 2 --- RESULTS AND DISCUSSION --- p.63 / Chapter 2.1 --- Synthesis of Substituted Anthracenes --- p.63 / Chapter 2.2 --- Synthesis of Substituted Tetracenes --- p.72 / Chapter 2.3 --- Conclusion --- p.77 / Chapter 3 --- EXPERIMENTAL SECTION --- p.78 / REFERENCES --- p.85 / Chapter APPENDIX --- Crystallographic data of dimer of anthracene118 --- p.91
36

Molecular engineering of N-heteroacenes and macrocyclic arenes: design, synthesis and properties. / 氮雜並萃和共軛芳烴大環的分子工程: 設計, 合成和性質研究 / CUHK electronic theses & dissertations collection / Dan za bing cui he gong e fang jing da huan de fen zi gong cheng: she ji, he cheng he xing zhi yan jiu

January 2013 (has links)
He, Zikai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
37

The corrole ring : synthesis, functionalisation and reactions of a biomimetic macrocycle.

Zipp, Caitlin 04 March 2014 (has links)
The lability of cobalt(III) in vitamin B12 is thought to come about as a function of its coordination environment. The thermodynamics and kinetics of ligand substitution reactions of vitamin B12a were compared to those of a synthetic, more electron rich, corrole-based biomimetic model. The feasibility of corrole synthesis was established with the synthesis of several corroles with different meso substituents. The biomimetic model was designed such that the central meso position bore a substituent with a terminal imidazole (referred to as the ‘tail’) which might act as an axial ligand for a coordinated cobalt ion while the remaining two meso positions bore water-solubilising glucose substituents. Unfortunately, the biomimetic model was water soluble below pH 4 only. This rendered the model unsuitable for the present study and these water solubilising groups were not incorporated into the final model. The model system used in this work is [10-(2-{[4-(1Himidazol-1-ylmethyl)benzoyl]amino}phenyl)-5,15-diphenylcorrolato]cobalt(III), referred to as DPTC-Co Intermediates of the ‘tail’ meso substituent were found to be polymorphic and five pairs of polymorphs were identified. Polymorphism arose from differences in weak termolecular forces and these differences were evaluated. The stability constants for the binding of various neutral N-, P- and S-donor ligands and anionic N-, S-, I- and C-donor ligands to both vitamin B12a and DPTC-Co were determined in a buffered 80:20 methanol:water solvent system. The more stable binding of neutral ligands to DPTC-Co and anionic ligands to vitamin B12a indicates that the interaction between the metal and an incoming ligand is indeed affected by the metal’s coordination environment. Cobalt(III) in DPTC-Co appeared to favour softer ligands while harder ligands were favoured by vitamin B12a. Kinetic studies showed that the coordination of cyanide to cobalt in vitamin B12a was faster than in DPTC-Co. The reaction between cyanide and vitamin B12a was found to be entropically driven while the reaction with DPTC-Co was enthalpically driven. This suggests that while the reaction between cyanide and vitamin B12a is faster, the reaction between cyanide and DPTC-Co is electronically more labile. The coordination environment of cobalt has been seen to significantly affect its chemistry. Coordination by the more electron rich corrole macrocycle led to a softer and more electronically labile metal then when coordinated by the corrin macrocycle of vitamin B12a.
38

The supramolecular chemistry of cucurbituril molecules

Lorenzo, Susan, Chemistry, Faculty of Science, UNSW January 2006 (has links)
The set of molecules cucurbit[n]uril (Qn) are macrocycles composed of n glycoluril monomers linked by methylene groups. These molecules have two oxygen-ringed portals of a diameter slightly smaller than their internal cavity diameter. This thesis describes syntheses, crystallisations, crystal structure determinations, crystal packing analyses and force field calculations exploring the supramolecular chemistry of Qn molecules and their derivatives. Qn acts as a host for guest molecules and at the outset of this project no metal containing molecule had been encapsulated in a Qn molecule. One aim of this project was to prepare such complexes. This was achieved with the synthesis and characterisation of crystalline {[cis-SnCl4(H2O)2]@Q7}2(SnCl6)3(H3O)6(H2O)23. Other compounds prepared and characterised crystallographically in the course of this project are: [(Q6)(Na3(H2O)8)]2[CoCl4]4[Co(H2O)6]2[CoCl(H2O)5]2(Cl)4, (Q5@Q10)(CH3COOH)(Cl)2(H3O)2(H2O)26, (Cl@Q5)4Q6(SnCl6)8(H3O)20(H2O)24, (Q8)3(PtCl6)4(H3O)8(H2O)x, (Q8)2(PtCl6)3(H3O)6(H2O)18, (Q7)(Cr3O10)(H3O)2(H2O)x and (Q6)(SnCl6)(H3O)2(H2O)x. While the smaller Qn (n = 5?) retain their circular forms, the larger Qn (n &gt 8) are less rigid and distort to accommodate larger guests. After analysis of the crystal structures of these Qn compounds and those listed in the Cambridge Structural Database, the principal packing motifs of the Qn molecules were elucidated. The most common is the portal-to-side interaction in which the portal oxygen atoms of one Qn approach the hydrogen atoms around the equator of another Qn. Force-field calculations on guest@Qn complexes were conducted to determine the mechanism for the formation of these complexes. A comparison of the intermolecular interactions of phenylated systems and comparable fluorinated phenyl systems was made using both crystal packing analyses and forcefield energy calculations. Intermolecular energy parameters for these calculations were derived and validated in this work. The principal fluorinated species studied was the [B(C6F5)4]?anion. Examination of its crystal structures found that the substitution of the hydrogen atoms by fluorine atoms is influential enough to alter the predominant intramolecular conformation. It is the ???flipper?conformer, between pairs of perfluorophenyl groups, that is overwhelmingly the favoured conformation and this has a strong effect on the types of phenyl embraces that a [B(C6F5)4]?anion will form. While the parallel 4PFE, the offset parallel 4PFE and the orthogonal 4PFE are all observed the 6PFE is not.
39

The study of molecular assemblies formed via non-covalent interactions between calixarenes /

Lee, Eun-ju, January 2003 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 84-86). Also available on the Internet.
40

The study of molecular assemblies formed via non-covalent interactions between calixarenes

Lee, Eun-ju, January 2003 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 84-86). Also available on the Internet.

Page generated in 0.0431 seconds