Bifacial Base‐Pairing Behaviors of 5‐Hydroxyuracil DNA Bases through Hydrogen Bonding and Metal Coordination

A novel bifacial ligand‐bearing nucleobase, 5‐hydroxyuracil ( U^OH ), which forms both a hydrogen‐bonded base pair ( U^OH –A) and a metal‐mediated base pair ( U^OH –M– U^OH ) has been developed. The U^OH –M– U^OH base pairs were quantitatively formed in the presence of lanthanide ions such as Gd^III when U^OH – U^OH pairs were consecutively incorporated into DNA duplexes. This result established metal‐assisted duplex stabilization as well as DNA‐templated assembly of lanthanide ions. Notably, a duplex possessing U^OH –A base pairs was destabilized by addition of Gd^III ions. This observation suggests that the hybridization behaviors of the U^OH ‐containing DNA strands are altered by metal complexation. Thus, the U^OH nucleobase with a bifacial base‐pairing property holds great promise as a component for metal‐responsive DNA materials.