Luminescence probe studies of ionically conductive membranes : zirconium phosphate sulfophenylphosphonate and Nafion /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The chemical microenvironments within the inorganic membrane zirconium phosphate sulfophenylphosphonate (ZrPS) and the organic membrane Nafion were studied with luminescence probe methods. These two ionically conductive membranes incorporate the optical probe ion tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)3[^2+]) via ion exchange. Ru(bpy)3[^2+] shows pronounced spectral shifts in both its absorption and emission spectra (relative to water) when incorporated into ZrPS. Similar spectral shifts have been observed for Ru(bpy)3[^2+] in other chemical microenvironments (e.g., micelles, clays, vesicles). These shifts have been explained by invoking microenvironment-induced changes in the chemical, structural, and electrochemical characteristics of the complex itself. We show in this dissertation that none of these explanations applies to ZrPS. Rather, the observed spectral shifts when Ru(bpy)3[^2+] is incorporated into ZrPS result from interactions of the complex with the phenyl rings of the host and the bipyridyl rings of neighboring complexes. The X-ray photoelectron spectroscopy of unexchanged and Ru(bpy)3[^2+] exchanged ZrPS was studied. The binding energies obrained for the elements in ZrPS and Ru(pby)3[^2+] are similar to the binding energies observed in α-zirconium phosphate and in Ru(bpy)3[^2+] salts. However, some differences in binding energies arc observed which result from the influence of the sulfophenylphosphonate group of ZrPS. No alteration of the electronic properties of the metal complex within ZrPS is observed. Luminescence time resolved studies show that the heterogeneity of the chemical microenvironments in ZrPS and in Nafion affects the lifetime of Ru(bpy)3[^2+]. The decay kinetics of the probe ion are shown to depart from simple first-order behavior. Albery's model of a continuous distribution of rate constants is used to explain the decay kinetics. The oxidative quencher methylviologen (MV[^2+]) reacts with Ru(bpy)3[^2+] in ZrPS in a combined dynamic plus sphere of action quenching mechanism... |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xv, 170 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |