Synthesis of Metal Bis(Terpyridine)-DNA Complexes for Use Towards the Assembly of Cubic Lattices

Abstract

There are two major goals for my project. The first is to create and characterize metal-ligand-DNA complexes that could be synthesized using traditional organic methods followed by solid phase techniques. The second is to demonstrate that these complexes with complementary DNA sequences could self-assemble into higher-ordered structures. In order to generate supramolecular DNA-metal structures such as cubic lattices, it is necessary to create an octahedral metal-ligand center tethering six DNA arms as a building block. The Iron/Ru (II) bis(2,2':6',2''terpyridine) derivatives were chosen because: (i) the complex is well known to present octahedral geometry; (ii) the coordination is very stable; and (iii) while previous work required the solid-phase synthesis of six DNA arms simultaneously--an inefficient process--by using terpyridine ligands we need only extend three arms at once. Thus, several terpyridine-linker compounds were synthesized via two different routes. A DNA 14mer was synthesized afterwards by "Reverse Coupling Protocol" on a solid phase synthesizer and the terpyridine was connected to it followed by elongation of the rest two DNA arms. The DNA-terpyridine complexes were evaluated by stepwise hybridization tests and gel electrophoresis with or without the assistance of radio labeling. In addition, the assembly of metal with the terpyridine-DNA complex was also characterized by adding different metal ions such as Iron (II) and Ru (II) to the complex. Various buffer conditions were applied in constructing those conjugates in order to help forming branched DNA-ligand-metal complexes with higher molecular weight.