LAUSR

The selective detection of G‐quadruplex DNA has the potential to reveal its biological function and provide important information for cancer diagnosis and treatment. Herein, a ruthenium(II) complex containing a two‐armed benzimidazole ligand (bimbpy) (RC1) has been developed as a selective luminescence probe toward G4 DNA. RC1 exhibited distinguishable luminescence response to G4 DNA, such as HTDNA, c‐MYC, and 22AG. Especially, in the presence of HTDNA, the luminescence intensity of RC1 increased to 6.1‐fold. The limit of detection is 30 nM for HTDNA. However, it showed a small change in luminescence intensity against doubled‐strand and single‐strand DNA. The DNA binding experimental results indicated that RC1 effectively stabilized G4 DNA through hydrogen bonds and π‐π stacking. The selectivity of RC1 to G4 DNA might be due to the increase in the rigidity of the two‐armed benzimidazole ligand after binding to G4 DNA. Therefore, the design of ruthenium(II) complexes with a two‐armed ligand will be an effective method to obtain Ru(II)‐based G‐quadruplex luminescent probes by adjusting the degree of rigidity of the two arms.