Synthesis, crystal structure and anaerobic DNA photocleavage of ruthenium complexes [Ru(tpy)(dpoq)Cl]+ and [Ru(tpy)(dpoq)CH3CN]2 +

•Two new ruthenium complexes have been synthesized and characterized.•The complexes could photocleave DNA under anaerobic condition.•The anaerobic photocleavage functions via photoinduced electron transfer pathway.

Two new Ru(II) complexes [Ru(tpy)(dpoq)Cl]+1 and [Ru(tpy)(dpoq)CH3CN]2 +2 (tpy = 2,2':6',2''-terpyridine; dpoq = dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline) have been synthesized and characterized by elemental analysis, 1H NMR, electrospray ionization mass spectra (ESI-MS) and X-ray crystallographic study. The experimental results of spectra titration, thermal denaturation and viscosity measurements suggest that the two complexes intercalatively bind to DNA. When irradiated under light, the two complexes could efficiently photocleave DNA both under aerobic and anaerobic condition. The mechanism studies reveal that the photocleavage reaction functions through both oxygen-independent (photoinduced electron transfer, type III reaction) and oxygen-dependent (singlet oxygen generation, type II reaction) pathways and the oxygen-independent pathway is the major process. These complexes will be more promising photodynamic therapy (PDT) candidates used for treating hypoxic tumors.

Graphical abstractThe complexes could photocleave DNA both under aerobic and anaerobic condition. The photocleavage process was found to function through singlet oxygen generation and photoinduced electron transfer pathways.Figure optionsDownload full-size imageDownload as PowerPoint slide