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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.

[Beta]-hydride elimination, [beta]-hydrogen atom abstraction and [beta]-hydroxyl elimination of group 9 metalloporphyrins. / CUHK electronic theses & dissertations collection

January 2005 (has links)
beta-Hydroxylethyl rhodium porphyrins underwent selective carbon-carbon bond activation with ether at the Calpha-Cbeta position to give alkyl (Cbeta) rhodium porphyrins under mild conditions. Enhanced rates and yields were observed for electron-poor and non-planar rhodium porphyrins. The beta-hydroxylethyl rhodium porphyrins are proposed to undergo beta-hydroxyl elimination to yield cationic rhodium porphyrins which behave as Lewis acids and selective activation of Calpha-Cbeta carbon carbon bond is likely assisted by hydroxide. / beta-Substituted alkyl iridium porphyrins reacted with TEMPO via beta-hydrogen atom abstraction. The beta-aryl substituted radicals, stabilized by resonance, reacted with TEMPO and transformation subsequently occurred to give (ttp)IrCH 2COAr in high yield. For beta-non-aryl substituted radicals, fragmentation proceeded to give (ttp)IrII metal-centered radicals which then reacted with TEMPO via aliphatic carbon-carbon bond activation to give (ttp)IrMe. / Reversible 1,2-rearrangements of beta-nitrogen substituted alkyl metalloporphyrins proceeding via beta-hydride elimination and beta-amino elimination pathways have been observed. The rates and equilibrium positions were found to be dependent on the electronic nature of the beta-substituent. The mechanism of the 1,2-rearrangements is consistent with the beta-hydride elimination/metal-hydride olefin re-insertion mechanism. Competitive beta-amino elimination was identified in electron rich amino substituents. / The objectives of this research focus on studies of unusual reactivities of d6 cobalt, rhodium and iridium alkyl porphyrin complexes including beta-hydride elimination, beta-hydrogen atom abstraction and beta-hydroxyl elimination reactions. / Yeung Siu Kwan. / "December 2005." / Adviser: Kin Shing Chan. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6400. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Synthesis, characterization and kinetic studies of porphyrins with thiolated side chains for functionalization of paramagnetic iron-oxide- gold, core- shell nanoparticles

Eshilokun, Adeolu O. January 2011 (has links)
Thesis (PhD (Organic Chemistry) -- University of Limpopo, 2011. / 5,1 0, ,15,20-Tetrakis[3-(3-thioacetoxypropoxy)phenyl]porphyrin a photosensitizer for photodynamic therapy (PDT) was synthesized from 3-hydroxybenzaldehyde. Acid and alkaline hydrolysis of the thioacetoxypropoxyphenyl porphyrin was attempted to afford a free base porphyrin, 5,10, 15,20-tetrakis[3-(3-thiolpropoxy)phenyl]porphyrin but not achieved. Spectroscopic data indicates that partial hydrolysis occurred. 1HNMR, 13CNMR, UV-Visible and Infra-red spectrometers were used to characterize all the compounds. The synthesized porphyrin was immobilized on gold coated superparamagnetic iron oxide (Fe304@Au) nanoparticles for possible use as a carrier or drug delivery system for the porphyrin to cancer sites. The use of magnetic nanoparticles for biomedical applications have been proposed to a large extent for several years. In recent years nanotechnology has developed to a stage that makes it possible to produce, characterize and specifically tailor the functional properties of nanoparticles for clinical applications. This has led to various opportunities such as improving the quality of magnetic resonance imaging, hyperthermia treatment for malignant cells, site-specific drug delivery and the manipulation of cell membranes. To this end a variety of iron oxide nanoparticles have been synthesized. Using co-precipitation method, nanoparticles comprised of gold shell and magnetite/maghemite were synthesized by overgrowing the gold shell onto the magnetic seeds using sodium citrates as a reducing agent. Oxidized magnetites (Fe304) fabricated by co-precipitation of Fe2+ and Fe3+ in strong alkaline solution were used as magnetic cores. These magnetic nanoparticles were characterized by Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), and X-ray diffraction spectroscopy (XRD). The transmission electron microscopy (TEM) image indicated that the particles were well dispersed nd spherical in shape with an average size of 34 - 58 nm with the mean particle diameter of 42.41 nm :!: 12.03 nm and standard deviation of (a) 0.27 nm indicating broad size distribution for the superparamagnetic iron oxide nanoparticles (SPION), the particle diameters for the gold coated SPION are in the range 34-54 nm while the average particle size as determined from the TEM image for the selected fraction is 44.26 nm :t 6.93 nm. The relative standard deviation of the sizes of the nanoparticles is 0.16 nm and the TEM for the functionalized gold coated SPION shows monodispersed particles which appear in spherical, cubic, irregular hexagon and oblong shapes with an average diameter of 44.65 nm. The HRTEM image, shows the existence of lattice planes which confirms the crystallinity of the material. The spacing between adjacent lattice planes is about 0.23 nm which corresponds to the (311) interplanar distance of Fe304 nanocrystals. Atomic force microscopy (ATM) was used to confirm the transmission electron microscopy (TEM) and HRTEM findings. The UV-Visible absorption spectra of the deionised water used in the procedure of preparation of the as-synthesized nanoparticles showed no absorption peak in a wavelength range of 350-750 nm, but after introducing the suspension of the Au-coated magnetic nanoparticles, an absorption peak located at 526 nm appeared which is ascribed to the surface plasmon of nanosized Fe304@Au nanoparticles. The kinetic studies using UV-visible spectrometer and the HRTEM images confirmed the adsorption of the porphyrin macromolecules as a coat on the magnetites particles. At a 5000 revolution per second (rps), aliquot sample of the aqueous phase of the suspension of 0.002 mM Fe304@Au in contact with the organic phase solution of the porphyrin taken for absorbance measurement at every 600 s showed a decrease in the concentration of the suspension while a noticeable and appreciable increase was also noted in the concentration of the porphyrin macromolecules measured at a A max of 420 nm representing the functionalized sample. A new absorption peak of 535 nm was recorded for the nanoparticle/porphyrin phase. A clear magnetic behaviour was established from the two different samples (coated and functionalised samples) using superconducting quantum interference device (SQUID) magnetometer. No long-range cooperative behaviour is evident anywhere from room temperature down to 2 K, which attests to a characteristic length of the scale of the Fe-magnetic agglomeratios on the nano-scale. Being especially prone to intrinsic ferromagnetic ordering, any impurity form of Fe or macro-scale Fe aggregates would impart a very large and easily identifiable magnetic signal. Such a reponse was completely absent from these stud ies and hence testifies to the homogeneity quality of the materials under investigation. KEY WORDS: photodynamic therapy, photosensitizer, porphyrins, magnetites, maghemite, crystalinity, magnetic seeds, nanoparticles,

Cyclo[n]pyrroles and their applications

Lee, Jeong Tae, January 1900 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Development and implementation of ab initio methods for application to large molecules

Muller, Richard P. Goddard, William A., January 1994 (has links)
Thesis (Ph. D.)--California Institute of Technology, 1994. UM #94-27,307. / Advisor names found in the Acknowledgments pages of the thesis. Title from home page. Viewed 01/22/2010. Includes bibliographical references.

Voltammetric investigation of rhenium and technetium tricarbonyl prophyrins

Steiger, George Edward 05 1900 (has links)
No description available.

The stability and coordination chemistry of metalloporphyrin isomers and self-assembled helices of 2,2'-biimidazoles /

Fowler, Christopher James, January 2000 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references. Available also in a digital version from Dissertation Abstracts.

Syntheses and evaluation of novel porpholactones for photonic applications /

Lau, Kimberly Sui Fa. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 164-176).

Ambient gas effects on thin film porphyrins and on Al/Porphyrin/Ag electroluminescent and electrochemical devices /

Burgess, Robert Marshall. January 1986 (has links)
Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [123]-127.

Syntheses of polypyrrolic macrocycles

Danso-Danquah, Richmond Edward January 1986 (has links)
Pentaphyrins are pentapyrrolic macrocycles containing five bridging methine groups between the five pyrrolic subunits. The syntheses of decamethylpentaphyrin 71, 2-ethoxycarbonyl-3,7,8,12,13,17,18,22,23-nonamethylpentaphyrin 74, 2-ethoxycarbonyl-3,7,8,22,23-pentamethyl-12,13,17,18-tetraethylpentaphyrin 75, 3,12-dimethoxycarbonylethyl-2,7,8,-13,17,18,22,23-octamethylpentaphyrins 29 and the zinc complexes of 71 and 74 are described. The physical properties of the pentaphyrins show them to be aromatic like sapphyrins, porphyrins and corroles. This aromaticity is reflected in the large shielding of the NH protons and the deshielding of the methine protons in the nmr spectra and by their optical spectra, which exhibit Soret and visible bands similar to sapphyrins and porphyrins. / Science, Faculty of / Chemistry, Department of / Graduate

The application of high pressure liquid chromatography to the analysis of clinically important porphyrins

Carlson, Robert Eric January 1976 (has links)
The porphyrias are a group of acquired or inherited metabolic diseases characterised by the abnormal production and excretion of porphyrins and porphyrin precursors. The clinical evaluation and subsequent treatment of porphyria are dependent on the analysis of these compounds in urine, feces and blood because a wide array of overlapping physiological manifestations make direct clinical diagnosis difficult. The analytical techniques currently available are inefficient and do not have the capacity to separate or easily quantify complex mixtures of porphyrins. High pressure liquid chromatography (HPLC), on the other hand, can readily achieve complex separations and since the sample being analyzed remains in solution at all times its detection and quantitation are considerably simplified. Bearing these considerations in mind, we have developed new porphyrin isolation techniques and evaluated a variety of HPLC packing/ solvent systems for the analysis of the uro to proto porphyrins from urine and feces. The HPLC procedures are rapid and efficient and should be easily extended to other porphyric samples. The versatility of the HPLC system was demonstrated by the characterization of copper coproporphyrin from a porphyric fecal sample. We have also developed procedures for the qualitative analysis of the fecal sub-uro porphyrins and made prelminary progress toward the separation and characterization of this heterogeneous group of compounds. / Science, Faculty of / Chemistry, Department of / Graduate

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