A series of lacunary (XM$\sb{11}$O$\sb{39}\sp{\rm n-}$ and P$\sb2$M$\sb{11}$O$\sb{61}\sp{10-}$) and plenary (SiW$\sb{12}$O$\sb{40}\sp{4-}$ and P$\sb2$M$\sb{18}$O$\sb{62}\sp{6-}$) polyoxometalates (POM) were synthesized, analyzed and their solution chemistry with lanthanide cations was studied by a variety of physical methods. These lanthanide complexes are evaluated with regard to potential applications as magnetic resonance imaging agents. / For elemental analysis of POM, quantitative methods were developed using ICP-AES for the determination of B, Si, Ge, P and Mo and atomic absorption spectroscopy for Na. The two-step procedure minimizes interelement interferences using matrix matching of sample and standard solutions, offering comparable precision to classical methods. The FTIR spectra of POM in D$\sb2$O and in KBr demonstrated their aqueous stability, and provided evidence of similarities between the solution and solid state structures. / The thermodynamics parameters of complexation ($\Delta$G, $\Delta$H, and $\Delta$S) of Eu(III) with POM were studied at 1 M ionic strength. pK$\sb{\rm a}$ values for the lacunary POM indicate weak basicity with two protonations between pcH 7 and 2. $\sp7$F$\sb0 \to \ \sp5$D$\sb0$ Selective excitation spectra coupled with the computer program, SQUAD, were used to determine 1:1 and 1:2 stability constants and to calculate $\Delta$G$\sb{\rm 10n}$ (n = 1,2). The stability constants are discussed in terms of statistical, electrostatic and geometrical effects. The enthalpies of complexation, $\Delta$H$\sb{\rm 10n}$ (n = 1,2), were determined for the formation of the 1:1 and 1:2 complexes of Eu(III) by titration calorimetry. The entropies of complexation, $\Delta$S$\sb{\rm 10n}$ (n = 1,2), were calculated from $\Delta$G$\sb{\rm 10n}$ (n = 1,2) and $\Delta$H$\sb{\rm 10n}$ (n = 1,2) values. / In addition, the $\sp7$F$\sb0 \to \sp5\rm D\sb0$ selective excitation spectra of Eu(III)-polyoxometalate complexes were evaluated qualitatively. Based on the number of peaks, the number of inner sphere H$\sb2$O molecules and the known structures, binding sites were proposed for 1:1 and 1:2 complexes. / The Gd(POM)$\sb2$ complexes were kinetically unstable in Sprague-Dawley rat serum. In vitro challenges to Gd(POM)$\sb2$ by metal cations, DTPA, and DTPA-doped serum suggest instability in serum is due primarily to a transmetalation mechanism. / Source: Dissertation Abstracts International, Volume: 56-04, Section: B, page: 2008. / Major Professor: Gregory R. Choppin. / Thesis (Ph.D.)--The Florida State University, 1995.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77449 |
| Contributors | Crooks, William John, III., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 172 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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