https://search.dev.ndltd.org/etd/rice/oai:repository.rice.edu:1911/103630
type: CreativeWork
name: Part I. Cytochrome c oxidase active-site modeling: Synthesis and characterization of new unsymmetrical tris(imidazole- and pyridine-appended) picket-fence porphyrins and their metal complexes. Part II. Toward fullerene-based radiopharmaceuticals: High-yield neutron activation of endohedral holmium-165 metallofullerenes
description: Part I . Two new unsymmetrical picket-fence porphyrin ligands 1 and 2 and their metal complexes have been prepared as potentially improved structural models for the binuclear (Fe/Cu) Cytochrome c Oxidase (C c O) active site. 1 and 2 have a naphthyl porphyrin superstructure which has been specifically designed to confer long-term configurational stability and allow synthetic manipulations to be easily performed without fear of atropisomer interconversions. The compounds also incorporate a covalently-linked, axially-offset tris(heterocycle) coordination site for a copper ion, like that found in the native C c O enzyme. Monometallic complexes [M = Zn(II), Ni(II), Cu(II), Fe(III)] of the imidazole- and pyridine-appended porphyrin ligands have been prepared and fully characterized. Only the Fe(III) hydroxide porphyrin complex reacted further with Cu(II) salts to form a heterobinuclear species of as yet unestablished structure. The unexpected difficulty of forming binuclear species is attributed to the conformational flexibility of the OCH 2 spacer in 1 and 2 , which presumably does not encourage a favorable chelation conformation to be assumed. Part II . Endohedral holmium metallofullerenes, 165 Ho x @C 82/84 (x = 1,2), have been prepared by carbon-arc methods and separated from empty fullerenes by HPLC techniques. The 165 Ho metallofullerenes and empty C 60 were then bombarded with neutrons under differing flux conditions to understand the various modes of compound degradation and to maximize yields of activated 166 Ho x @C 82/84 [ 165 Ho(n,γ) 166 No]. C 60 survived irradiation to a fairly high extent (>80%) at total neutron doses of <10 18 n cm –2 (75% thermal neutrons), but fast-neutron damage progressed rapidly thereafter, leaving only a few percent of surviving material. Under identical flux conditions, the metallofullerenes were degraded much more quickly and extensively (<10% survival) than was C 60 . Furthermore, decomposition of the metal lofullerenes was shown …
abstract: Part I . Two new unsymmetrical picket-fence porphyrin ligands 1 and 2 and their metal complexes have been prepared as potentially improved structural models for the binuclear (Fe/Cu) Cytochrome c Oxidase (C c O) active site. 1 and 2 have a naphthyl porphyrin superstructure which has been specifically designed to confer long-term configurational stability and allow synthetic manipulations to be easily performed without fear of atropisomer interconversions. The compounds also incorporate a covalently-linked, axially-offset tris(heterocycle) coordination site for a copper ion, like that found in the native C c O enzyme. Monometallic complexes [M = Zn(II), Ni(II), Cu(II), Fe(III)] of the imidazole- and pyridine-appended porphyrin ligands have been prepared and fully characterized. Only the Fe(III) hydroxide porphyrin complex reacted further with Cu(II) salts to form a heterobinuclear species of as yet unestablished structure. The unexpected difficulty of forming binuclear species is attributed to the conformational flexibility of the OCH 2 spacer in 1 and 2 , which presumably does not encourage a favorable chelation conformation to be assumed. Part II . Endohedral holmium metallofullerenes, 165 Ho x @C 82/84 (x = 1,2), have been prepared by carbon-arc methods and separated from empty fullerenes by HPLC techniques. The 165 Ho metallofullerenes and empty C 60 were then bombarded with neutrons under differing flux conditions to understand the various modes of compound degradation and to maximize yields of activated 166 Ho x @C 82/84 [ 165 Ho(n,γ) 166 No]. C 60 survived irradiation to a fairly high extent (>80%) at total neutron doses of <10 18 n cm –2 (75% thermal neutrons), but fast-neutron damage progressed rapidly thereafter, leaving only a few percent of surviving material. Under identical flux conditions, the metallofullerenes were degraded much more quickly and extensively (<10% survival) than was C 60 . Furthermore, decomposition of the metal lofullerenes was shown …
author: Thrash, Thomas Pennix
language: eng
keywords: Chemistry, Nuclear chemistry, Pharmacology, Surgery, Health and environmental sciences, Pure sciences, Cytochrome c oxidase, Fullerene-based Holmium-165, Metallofullerenes, Neutron activation, Picket-fence porphyrins, Radiopharmaceuticals
date published: 1999
date modified: 2026-07-24T04:10:30Z
provider: Rice University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Rice University

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1911/103630