Photoactive Ru II –Polypyridyl Complexes that Display Sequence Selectivity and High‐Affinity Binding to Duplex DNA through Groove Binding

The duplex‐DNA binding properties of a nonintercalating polypyridyl ruthenium(II) complex that incorporates a linear extended ligand with a catechol moiety has been probed with a variety of photo‐ and biophysical techniques. These studies reveal that the complex groove binds to DNA sequences biphasically, and displays binding constants equivalent to those of high‐affinity metallointercalators. The complex also displays preferential binding to AT‐rich sequences. Changes in the structure of the coordinated catechol ligand and the incorporation of intercalating ancillary ligands into the complex were found to modulate both the optical‐binding response and binding parameters of the system, which indicates that the catechol moiety plays a crucial role in the observed enhancement to binding affinities.