Phenanthroline-modified DNA three-way junction structures stabilized by interstrand 3 : 1 metal complexation.

Incorporation of interstrand metal complexes into DNA is a versatile strategy for metal-dependent stabilization and structural induction of DNA supramolecular structures. In this study, we have synthesized DNA three-way junction (3WJ) structures modified with phenanthroline (phen) ligands. The phen-modified 3WJ was found to be thermally stabilized (Δ T m = +16.9 °C) by the formation of an interstrand Ni II (phen) 3 complex. Furthermore, Ni II -mediated structure induction of 3WJs was demonstrated with the phen-modified strands and their unmodified counterparts. This study suggests that ligand-modified 3WJs would be useful structural motifs for the construction of metal-responsive DNA molecular systems.