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Johannes Gutenberg Universität Mainz

1. Heller, Jeannine. Structure formation as studied by EPR spectroscopy: From simple solutions to nanoparticles.

Degree: 2010, Johannes Gutenberg Universität Mainz

In this thesis, three nitroxide based ionic systems were used to investigate structure and dynamics of their respective solutions in mixed solvents by means of electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopy at X- and W-band (9.5 and 94.5 GHz, respectively). rnFirst, the solvation of the inorganic radical Fremy’s salt (K2ON(SO3)2) in isotope substituted binary solvent mixtures (methanol/water) was investigated by means of high-field (W-band) pulse ENDOR spectroscopy and molecular dynamics (MD) simulations. From the analysis of orientation-selective 1H and 2H ENDOR spectra the principal components of the hyperfine coupling (hfc) tensor for chemically different protons (alcoholic methyl vs. exchangeable protons) were obtained. The methyl protons of the organic solvent approach with a mean distance of 3.5 Å perpendicular to the approximate plane spanned by ON(S)2 of the probe molecule. Exchangeable protons were found to be distributed isotropically, approaching closest to Fremy’s salt from the hydrogen-bonded network around the sulfonate groups. The distribution of exchangeable and methyl protons as found in MD simulations is in full agreement with the ENDOR results. The solvation was found to be similar for the studied solvent ratios between 1:2.3 and 2.3:1 and dominated by an interplay of H-bond (electrostatic) interactions and steric considerations with the NO group merely involved into H-bonds.rnFurther, the conformation of spin labeled poly(diallyldimethylammonium chloride) (PDADMAC) solutions in aqueous alcohol (methanol, ethanol, n-propanol, ethylene glycol, glycerol) mixtures in dependence of divalent sodium sulfate was investigated with double electron-electron resonance (DEER) spectroscopy. The DEER data was analyzed using the worm-like chain model which suggests that in organic-water solvent mixtures the polymer backbones are preferentially solvated by the organic solvent. We found a less serve impact on conformational changes due to salt than usually predicted in polyelectrolyte theory which stresses the importance of a delicate balance of hydrophobic and electrostatic interactions, in particular in the presence of organic solvents.rnFinally, the structure and dynamics of miniemulsions and polymerdispersions prepared with anionic surfactants, that were partially replaced by a spin labeled fatty acid in presence and absence of a lanthanide beta-diketonate complex was characterized by CW EPR spectroscopy. Such miniemulsions form multilayers with the surfactant head group bound to the lanthanide ion. Beta-diketonates were formerly used as NMR shift reagents and nowadays find application as luminescent materials in OLEDs and LCDs and as contrast agent in MRT. The embedding of the complex into a polymer matrix results in an easy processable material. It was found that the structure formation takes place in miniemulsion and is preserved during polymerization. For surfactants with carboxyl-head group a higher order of the alkyl chains and less lateral diffusion is…

Subjects/Keywords: CW EPR; ENDOR; Nitroxid; Miniemulsion; Polyelektrolyt; CW EPR; ENDOR; nitroxide; miniemulsion; polyelectrolyte; Chemistry and allied sciences

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Heller, J. (2010). Structure formation as studied by EPR spectroscopy: From simple solutions to nanoparticles. (Doctoral Dissertation). Johannes Gutenberg Universität Mainz. Retrieved from http://ubm.opus.hbz-nrw.de/volltexte/2010/2404/

Chicago Manual of Style (16th Edition):

Heller, Jeannine. “Structure formation as studied by EPR spectroscopy: From simple solutions to nanoparticles.” 2010. Doctoral Dissertation, Johannes Gutenberg Universität Mainz. Accessed February 19, 2019. http://ubm.opus.hbz-nrw.de/volltexte/2010/2404/.

MLA Handbook (7th Edition):

Heller, Jeannine. “Structure formation as studied by EPR spectroscopy: From simple solutions to nanoparticles.” 2010. Web. 19 Feb 2019.

Vancouver:

Heller J. Structure formation as studied by EPR spectroscopy: From simple solutions to nanoparticles. [Internet] [Doctoral dissertation]. Johannes Gutenberg Universität Mainz; 2010. [cited 2019 Feb 19]. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2010/2404/.

Council of Science Editors:

Heller J. Structure formation as studied by EPR spectroscopy: From simple solutions to nanoparticles. [Doctoral Dissertation]. Johannes Gutenberg Universität Mainz; 2010. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2010/2404/


Johannes Gutenberg Universität Mainz

2. Elpelt, Christian. Modellkomplexe zur Untersuchung der Radikal-Metall-Wechselwirkung innerhalb des wasseroxidierenden Zentrums im Photosystem II.

Degree: 2008, Johannes Gutenberg Universität Mainz

Im Rahmen dieser Arbeit wurden zweikernige Modellkomplexe zur Untersuchung der Radikal-Metallwechselwirkung innerhalb des wasseroxidierenden Zentrums des Photo¬systems II synthetisiert und eine magneto-strukturelle Korrelation dieser Komplexe erstellt. Als Liganden wurden diverse sechs- bis siebenzähnige Chelatliganden verwendet, welche über zwei Koordinationstaschen und eine verbrückende Phenolatgruppe verfügen. Zwei daran gebundene Manganionen liegen in einer wohl definierten Umgebung nicht koordinativ gesättigt vor. An die freien Koordinationsstellen können weitere ein bis zwei Brückenliganden binden, bei denen es sich in dieser Arbeit hauptsächlich um Carboxylate handelt. Durch die Verwendung eines diamagnetischen Brückenliganden konnte die magnetische Spin-Spin-Austauschwechselwirkung zwischen den spintragenden Manganionen über die verbrücken¬de Phenolatgruppe bestimmt werden. Komplexe, welche über Manganionen in den gleichen Oxidationsstufen, aber über unterschiedliche Carboxylatbrückenliganden verfügen, weisen ähnliche magnetische Austauschwechselwirkungen zwischen den Metallzentren auf. Diese Beobachtung konnte durch eine strukturelle Ähnlichkeit dieser Komplexe erklärt werden. Mittels Aufsummieren der Bindungslängen der verbrückenden Phenolateinheit zu beiden Zentralionen kann innerhalb dieser Komplexe jeweils die Länge des Wechselwirkungspfades erhalten werden, welcher die magnetische Austauschwechselwirkung maßgeblich beein¬flusst. Je länger der Wechselwirkungspfad ist, desto kleiner ist die Austausch¬wechsel¬wirkung. Durch Austausch der diamagnetischen Carboxylate durch paramagnetische benzoat¬substituierte Nitronyl Nitroxid Radikale wurden den Komplexen ein bis zwei weitere Spinzentren hinzugefügt, welche mit den Spins der Zentralionen wechselwirken können. Simulationen der magnetischen Suszeptibilitätsmessungen liefern Werte für die magneti¬schen Austausch¬wechselwirkungen zwischen den Nitronyl Nitroxid Radikalen und den Manganionen, die in allen Fällen schwach ferromagnetisch zwischen 0 und 4,7 cm-1 sind. In einer Auftragung dieser Austauschwechselwirkungen gegen die Mangan-Carboxylat-Bindungs¬längen von strukturell charakterisierten äquivalenten acetatverbrückten Komplexen, kann eine lineare Abhängigkeit gezeigt werden.

In this work binuclear model-complexes have been prepared to investigate the radical-metal-interaction inside the oxygen evolving complex of Photosystem II, and a correlation between the structure and the magnetic properties of these complexes has been drawn. Six- and seven-binding ligands have been used, which contain two coordination sites and a bridging phenolate group in between them. Using these ligands, two manganese ions are placed in a well defined non-saturated coordination environment. One or two additional bridging carboxylate ligands can coordinate at the free sites. The spin-spin exchange interaction between the manganese ions through the bridging phenolate group has been measured by using a diamagnetic bridging ligand. It has been found out that complexes, which…

Subjects/Keywords: zweikernige Komplexe, Metall-Radikal-Wechselwirkung, Nitronyl Nitroxid Radikale, heterovalente Mangankomplexe, magneto-strukturelle Korrelation; dinuclear complexes, metal-radical-interaction, nitronyl nitroxide radicals, heterovalent manganese complexes, magneto-structural correlation; Generalities, Science

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Elpelt, C. (2008). Modellkomplexe zur Untersuchung der Radikal-Metall-Wechselwirkung innerhalb des wasseroxidierenden Zentrums im Photosystem II. (Doctoral Dissertation). Johannes Gutenberg Universität Mainz. Retrieved from http://ubm.opus.hbz-nrw.de/volltexte/2011/2604/

Chicago Manual of Style (16th Edition):

Elpelt, Christian. “Modellkomplexe zur Untersuchung der Radikal-Metall-Wechselwirkung innerhalb des wasseroxidierenden Zentrums im Photosystem II.” 2008. Doctoral Dissertation, Johannes Gutenberg Universität Mainz. Accessed February 19, 2019. http://ubm.opus.hbz-nrw.de/volltexte/2011/2604/.

MLA Handbook (7th Edition):

Elpelt, Christian. “Modellkomplexe zur Untersuchung der Radikal-Metall-Wechselwirkung innerhalb des wasseroxidierenden Zentrums im Photosystem II.” 2008. Web. 19 Feb 2019.

Vancouver:

Elpelt C. Modellkomplexe zur Untersuchung der Radikal-Metall-Wechselwirkung innerhalb des wasseroxidierenden Zentrums im Photosystem II. [Internet] [Doctoral dissertation]. Johannes Gutenberg Universität Mainz; 2008. [cited 2019 Feb 19]. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2011/2604/.

Council of Science Editors:

Elpelt C. Modellkomplexe zur Untersuchung der Radikal-Metall-Wechselwirkung innerhalb des wasseroxidierenden Zentrums im Photosystem II. [Doctoral Dissertation]. Johannes Gutenberg Universität Mainz; 2008. Available from: http://ubm.opus.hbz-nrw.de/volltexte/2011/2604/


Brno University of Technology

3. Černý, Miroslav. Vinylové předpolymery - metody přípravy a využití .

Degree: 2012, Brno University of Technology

Teoretická část práce se zaměřuje na blokovou radikálovou polymeraci styrenu, methyl methakrylátu, vinyltoluenu a paramethylstyrenu. Shrnuje současné informace o kinetice a možnostech provedení blokové polymerace. Experimentální část se zabývá přípravou polystyrenových předpolymerů blokovou polymerací s cílem nalezení optimálních podmínek přípravy předpolymerů pro následnou polymeraci do téměř 100% konverze. Hodnoty konverze byly stanovovány gravimetricky a molekulové hmotnosti byly získány na základě viskozimetrických měření pomocí Ubbelohdeho viskozimetru. K předpovědi konverze monomeru v daném čase polymerace byly v experimentální části provedeny simulace zaměřené na závislost konverze na času. Rozdíly mezi skutečností a simulací jsou malé ve většině případů a nalezená podoba výpočtů kinetického chování poskytuje uspokojivé výsledky. V závěru práce byl na základě naměřených dat navrhnut nový postup pro přípravu polystyrenových předpolymerů.; The theoretical part of this thesis is focused on bulk radical polymerization of styrene, methylmethacrylate, vinyltoluene and paramethylstyrene. It summarizes actual informations about kinetics and performance possibilities of bulk polymerization. Experimental part deals with polystyrene prepolymers preparation by bulk polymerization. The aim is to find optimal conditions for prepolymers preparation. Prepolymers should be usable for subsequent polymerization nearly up to 100% conversion. Conversion values were gravimetrically determined and molecular weights were obtained by viskosity measurements, which were realized by Ubbelohde viscometer. In the experimental part, there were performed simulations targeted on conversion dependence on time. The purpose was a prediction of monomer conversion at a given time during polymerization. Differences between reality and simulation were low in most of cases and the found form of kinetic behavior calculations provides satisfying results. In the conclusion of this thesis was suggested a new procedure for polystyrene prepolymers preparation. Advisors/Committee Members: Kučera, František (advisor).

Subjects/Keywords: styren; předpolymer; bloková polymerace; radikálová polymerace; 2- a 3-funkční iniciátor; živá polymerace; nitroxid; methyl methakrylát; styrene; prepolymer; bulk polymerization; radical polymerization; bifunctional and trifunctional initiator; living polymerization; nitroxide; methyl methacrylate

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Černý, M. (2012). Vinylové předpolymery - metody přípravy a využití . (Thesis). Brno University of Technology. Retrieved from http://hdl.handle.net/11012/4704

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Černý, Miroslav. “Vinylové předpolymery - metody přípravy a využití .” 2012. Thesis, Brno University of Technology. Accessed February 19, 2019. http://hdl.handle.net/11012/4704.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Černý, Miroslav. “Vinylové předpolymery - metody přípravy a využití .” 2012. Web. 19 Feb 2019.

Vancouver:

Černý M. Vinylové předpolymery - metody přípravy a využití . [Internet] [Thesis]. Brno University of Technology; 2012. [cited 2019 Feb 19]. Available from: http://hdl.handle.net/11012/4704.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Černý M. Vinylové předpolymery - metody přípravy a využití . [Thesis]. Brno University of Technology; 2012. Available from: http://hdl.handle.net/11012/4704

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.