Mentor: Professor Sharon Burgmayer and Shannon Dalton
Intercalating molecules have potential as pharmaceuticals and probes of the replication machinery because intercalation distorts the helical shape of DNA, causing inhibition or replication enzymes, which can be useful for cancer treatment. Intercalation occurs when the planar aromatic ring of a molecule inserts itself between the base pairs of a DNA strand, resulting in a lengthening, stiffening and unwinding of the DNA double helix. In the area of DNA intercalation studies, transition metal intercalators have been a rich source of experimental date due to its redox and photophysical properties that make it possible to utilize multiple techniques to study DNA intercalation processes. The close structural similarity between nucleic acids and certain pteridines, particularly between guanine and pterin, suggests the possibility that C-pterin pair can mimic C-G hydrogen bonding. With this in mind, Ruthenium-polypyridyl complexes are studied. Previous studies have shown the ruthenium (II)-bis(bipyridine) complex of dipryidophenazine, [Ru(bpy)2(dppz)]2+, to have such intercalative capabilities.
During my summer research, I will continue to test intercalative capabilities of the ruthenium complexes designated [(bpy)2RuII(L)] where L stands for one of three variable pteridinyl-phenanthroline ligands is described. The three ligands, phenathroline-dimethylalloxazine, phenathroline-pterin and phenathroline-diaminopyrimidine were previously synthesized and characterized using 1H NMR, IR and ESI-MS. Each of the ligands was then reacted with Ru(bpy)2Cl2 to make the different [(bpy)2RuII(L)] complex, [(bpy)2RuII(L-Me2allox)](PF6)2, [(bpy) 2RuII(L-pterin)](PF6) 2 and [(bpy)2RuII(L-amino)](PF6)2. In addition, fluorescence spectroscopy, circular dichroism spectroscopy, plasmid unwinding gel electrophoresis, viscometry and thermal denaturation titrations will be used to investigate the interactions of these complexes with DNA.