Alexandra Kirsch

Mentor: Dr. Sharon Burgmayer

 

Abstract: The Synthesis and Characterization of Ru(bpy)2(L-pteridine) and Ru(phen)2(L-pteridine) complexes

 

 

Ruthenium (II) polypyridyl complexes are very important biochemical compounds due to their interactions with DNA. In this study, these complexes are analyzed to understand how their physical properties, chemical properties, and interactions with DNA are affected by structural differences of the L-pteridine ligands, and by exchanging the bipyridine (bpy) ligand for the phenanthroline (phen) ligand.

 

The Burgmayer group has currently synthesized thirteen [Ru(bpy)2(L-pteridine)]2+complexes. One facet of this summer research involves continuing the synthesis of [Ru(phen)2(L-pteridine)]2+analogs of the bpy versions that have already been made by the Burgmayer group. The phen complexes and the bpy forms differ by the presence of an additional benzene ring on the phen ligand (see figure 1).

 

 figure 2                figure 3

     (1)                                                                   (2)

Figure 1. (1) An example of a [Ru(bpy)2(L-pteridine)]2+ complex, where the L-pteridine is the L-pterin ligand. (2) The phen version of the same compound.

 

The other facet of this summer research involves examining the photocleavage and DNA intercalation abilities of both the phen and bpy versions of the Ru(L-pteridine) compounds. When certain complexes are exposed to UV light, they are able to nick DNA, a process called photocleavage. The photocleavage ability of the various compounds is analyzed using gel electrophoresis. The relative rates of the compounds to intercalate DNA, when planar portions of the molecule insert between the base pairs of DNA, are analyzed by viscosity tests. It is known that with certain Ru(bpy)2(L-pteridine) complexes, the L-pteridine ligand intercalates with DNA. This study of the intercalation of DNA has potential anti-cancer properties, in that compounds able to intercalate DNA could stopping the replication of cancerous cells. Our laboratory has previously compared select bpy compounds and their phen analogs and found that the phen forms of many ruthenium complexes have the greatest potential for antineoplastic activity in vivo due to their superior DNA intercalation and photocleavage attributes. One major goal of this research is to continue to compare the abilities of analogous phen and bpy compounds, in order to ultimately identify the molecule possessing the highest intercalation and photocleavage properties.