Synthesis and Characterization of DNA-Intercalating and Potential Photocleaving Ru(II)-bis(bipyridine)-Pteridinyl Complexes and Similar Co(III) Complexes

Posted May 13th, 2010 at 3:13 pm.

Erika Lippoldt

Mentors: Professor Sharon Burgmayer and Shannon Dalton

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Abstract. Small transition metal molecules have been the object of many studies due to their interactions with DNA and the resulting effects on the regulation of DNA transcription and replication, as well as their potential as pharmaceuticals. Ru(II) compounds are especially useful as probes due to their stability and photophysical properties. Bis(bipyridyl) Ru(II) complexes of pteridinyl-phenanthroline ligands have been of particular interest because pteridinyl ligands possess H-bonding patterns complementary to the purine and pyrimidine bases of DNA and RNA. The pteridinyl ligand of these Ru-pteridine complexes is capable of inserting itself between the base pairs of DNA, thus binding to DNA via intercalation. Other metal complexes, including certain Co(III) complexes, have been known to cleave DNA in the presence of light (photoactivated cleavage of DNA). Such metallointercalators are practical for their high affinity for double-stranded DNA and because they include a range of redox-active metal centers and ligands.

In my summer research, I will synthesize five Ru-pteridinyl complexes previously studied in this laboratory by varying the pteridinyl-phenanthroline ligands, in addition to which I will synthesize the DNA intercalator [Ru(bpy)2(dppz)]2+, which has been much studied in other laboratories and is used here as a positive control. The multiple-step synthesis is similar for each complex: 1,10-phenanthroline-5,6-dione is synthesized and then reacted with a diamino-pyrimidine to obtain the various ligands, which are then coordinated to RuII by reacting them with Ru(bpy)2Cl2 to obtain the final Ru complex of the form [Ru((bpy)2(L)]2+, where L stands for any of the five ligands. The ligands of interest are L-amino, L-diamino, L-pterin, L-allox and L-Me2allox. All synthesis products are characterized using 1H-NMR, IR and ESI-MS. In addition to these syntheses, I will investigate the synthesis of analogous Co(III)-pteridinyl or other metal-pteridinyl complexes, which will be explored as DNA cleaving agents. DNA cleavage studies could lead to the determination of the metallointercalator-DNA binding sites as well as the discovery of useful DNA manipulation techniques and potential pharmaceuticals.

Filed under: 2008,Burgmayer, Dr. Sharon,Lippoldt, Erika by Ann Dixon

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