A luminescence probe for c‐myc G‐quadruplex by a triphenylamine‐appended ruthenium complex

Due to the essential roles of G‐quadruplex in biological processes, the development of G‐quadruplex luminescent probe is becoming more and more important for further understanding of the functions of G‐quadruplex in biology. We herein reported that a ruthenium complex containing triphenylamine group exhibited “off–on” emission behavior after binding to G‐quadruplex in the presence of luminescence quencher [Fe (CN6)]4−. The Ru‐Fe system consists of a mixture of [Ru (phen)2(TPAD)]2+, where TPAD = N‐4‐(1H‐imidazo [4,5‐f] [1,10]phenanthroline‐2‐yl phenyl)‐N‐phenyl‐benzenamine and [Fe (CN6)]4−, which showed luminescent selectivity toward parallel G‐quadruplex (c‐myc). The detection limit was 159 nM for c‐myc. The ligand TPAD bearing nonplanar triphenylamine group and steric hindrance led to different DNA affinities toward various DNA structures. Luminescence experiments, CD spectra, G4‐FID, FRET (fluorescence resonance energy transfer) measurements, and molecular docking results indicated that different DNA affinities and binding modes of the complex toward various DNA structures result in the luminescence selectivity. A ruthenium (II) complex containing triphenylamine group was developed as a G‐quadruplex DNA luminesecnt probe toward G‐quadruplex DNA in the presence of [Fe (CN)6]4−.