Synthesis of ruthenium(II) complexes as potential “turn-on” probe for c-kit1 G-quadruplex DNA

Herein, a series of ruthenium(II) complexes have been synthesized Ru[(NN)2(L)](ClO4)2 (NN1 = bpy, L1 = 2-(4-bromostyryl)-1H-imidazo[4,5f][1, 10]phenanthroline(BrSPIP), 1; NN2 = phen, L1 = BrSPIP, 2; NN1 = bpy, L2=2-styryl-1H-imidazo[4,5f][1, 10]phenanthroline(SPIP), 3; NN2 = phen, L2 = SPIP, 4) and investigated as potential probes of the G4 DNA conformation. Molecular docking simulation studies have found that all these ruthenium(II) complexes, especially 1 and 2, exhibit a high binding affinity for c-kit1 G4 DNA. Further studies revealed that the fluorescence intensity of both 1 and 2 can be significantly enhanced in the presence of c-kit1 G4 DNA. Moreover, the cells can be light up in the presence of 1 and 2. In brief, these ruthenium(II) complexes, particularly 1 and 2, are expected to be developed as potential probes for c-kit1 G4 DNA.