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Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on February 26, 2008) Vita. Includes bibliographical references.

Thesis (M.S.)--Georgia State University, 2009. / Title from file title page. W. David Wilson, committee chair; Stewart A. Allison, Kathryn B. Grant, committee members. College of Arts and Sciences.Description based on contents viewed July 22, 2009. Includes bibliographical references (p. 85-87).

The tetraruthenium cluster H4Ru4(CO)12 has been studied for its reactivity with the unsaturated diphosphine ligands (Z)-Ph2PCH=CHPPh2, 4,5-bis (diphenylphosphino)-4-cyclopenten-1,3-dione, bis(diphenyphosphino)benzene and 1,8- bis(diphenyl phosphino)naphthalene under thermal, near-UV photolysis, and Me3NO-assisted activation. All three cluster activation methods promote loss of CO and furnish the anticipated substitution products that possess a chelating diphosphine ligand. Clusters 1, 2, 3 and 4 have been characterized in solution by IR and NMR spectroscopies, and these data are discussed with respect to the crystallographically determined structures for all new cluster compounds. The 31P NMR spectral data and the solid-state structures confirm the presence of a chelating diphosphine ligand in all four new clusters. Sealed NMR tubes containing clusters 1, 2, 3 and 4 were found to be exceeding stable towards near-UV light and temperatures up to ca. 100°C. The surprisingly robust behavior of the new clusters is contrasted with the related cluster Ru3(CO)10(bpcd) that undergoes fragmentation to the donor-acceptor compound Ru2(CO)6(bpcd) and the phosphido-bridged compound Ru2(CO)6 (µ-PPh2)[µ-C=C(PPh2)C(O)CH2C(O)] under mild conditions. The electrochemical properties have been investigated in the case of clusters 1 and 2 by cyclic voltammetry, and the findings are discussed with respect to the reported electrochemical data on the parent cluster H4Ru4(CO)12.

Les G-quadruplexes (G4) sont des structures d'acides nucléiques non-canoniques formées par des séquences riches en Guanines (G) principalement localisées dans les telomères et les régions promotrices des oncogènes. Elles sont constituées de l'empilement de plusieurs tétrades de G en présence de cations. En utilisant la spectroscopie par RMN, nous avons caractérisé l'interaction entre le ligand TAP et le G4 télomérique humain constituée de la séquence d(AG3(T2AG3)3). CD et RMN 1D 1H ont été utilisés pour suivre l'interaction entre les deux partenaires. RMN 2D a été utilisé pour attribuer sans ambiguïté toutes les résonances de 1H dans le complexe et d'explorer le site d'interaction. Un modèle illustrant l'interaction de TAP avec 22AG au niveau des sillons et boucles a été généré. Une autre partie de ce travail consiste en l'étude du G4 tétra-moléculaire formé par TG4T et son interaction avec des ligands G4 par la RMN dans les cellules. Des spectres 1H-15N HMQC ont été effectués à l'intérieur de Xenopus laevis et les lysats des cellules HeLa et comparés avec ceux observés dans les conditions in vitro ce qui a montré une bonne stabilité de G4 à l'intérieur de la cellule. En outre, l'interaction de d [TG4T]4 avec des ligands spécifiques de G4 présentant trois différents modes d'interaction a également été étudiée. Le ligand 360A a montré un comportement prometteur. Enfin, dans la dernière partie, différentes séquences de promoteur Kras ont été criblés par RMN pour sélectionner des candidats pour la détermination de structure haute résolution. Deux séquences différentes ont été sélectionnées et caractérisées par spectroscopie CD. La stabilisation des structures G4 formées par ces séquences en interaction avec différents ligands a également été étudiée. Une titration RMN 1D 1H entre 22RT et le ligand Braco19 a montré un comportement intéressant de k-ras G4 par la formation d'espèces intermédiaires lors de l'addition de Braco19. / G-quadruplexes (G4) are non-canonical nucleic acid structures formed by G-rich sequences mainly localized in telomeres and promoter regions of oncogenes. They are built from the stacking of several G-quartets in the presence of cations. Using NMR spectroscopy, we have characterized the interaction between the TAP ligand and the human telomeric G4 formed by the sequence d(AG3(T2AG3)3). CD and 1D 1H NMR spectroscopy were used to follow the interaction between the two partners. 2D NMR was used to assign unambiguously all 1H resonances in the complex and to explore the binding site. A model depicting the interaction of TAP with 22AG in grooves and loops was generated. Another part of this work consists in the study of tetramolecular G4 formed by TG4T and its interaction with G4 ligands by in-cell NMR. 1H-15N HMQC spectra were performed inside Xenopus laevis and HeLa cell lysates compared to those observed in vitro conditions showing a good stability of G4 inside the cell. Furthermore, the interaction of d[TG4T]4 with three G4 specific ligands presenting different mode of interaction was also investigated. The ligand 360A showed a promising behavior. Finally, in the last part, different sequences of Kras promoter were screened by NMR to select good candidates for high resolution structure determination. Two different sequences were selected and characterized by CD spectroscopy. The stabilization of G4 structures formed by these sequences in interaction with different ligands was also investigated. A 1D 1H NMR titration between Braco19 and 22RT showed an interesting behavior of k-ras G4 by the formation of intermediate species upon the addition of Braco19.

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