A Nitro‐Substituted Ruthenium Complex as a Luminescent Probe for G‐Quadruplex DNA

ABSTRACT The design and application of G‐quadruplex DNA (G4‐DNA) probes can enhance our understanding of their biological functions and contribute to the development of diagnostic or therapeutic drugs. Ruthenium complexes have attracted significant research interest as G‐DNA luminescent probs. However, most of ruthenium‐based G4 probes possess simple aromatic planar structures, which often results in poor recognition selectivity for G‐quadruplexes. To overcome this problem, here, we report a nitro‐substituted ruthenium complex ( RC1 ) that can serve as a G‐quadruplex DNA luminescent probe. The DNA docking and DNA binding experimental results have demonstrated that RC1 exhibited stronger binding affinity towards G4‐DNA than other DNA structures since G4‐DNA binding of RC1 enhanced the planarity and rigidity. RC1 displayed high luminescence response (7.10‐fold enhancement) to G4‐DNA (HTDNA) due to the effect of nitro group on the emission properties of ruthenium complex and enhanced the planarity and rigidity of the ligand. The G4‐DNA selectivity (5.6‐fold luminescence enhancement over ds‐DNA) may be attributed to the steric hindrance effect by the introduction of phenyl group. Therefore, the design of the nitro‐substituted Ru (II) complexes paves the way for an effective approach to Ru (II)‐based G‐quadruplex luminescent probes.