Single oxygen-mediated DNA photocleavage of a di-bithiazolyl ruthenium(II) complex [Ru(btz)2(dppz)]2+

A novel di-bithiazolyl ruthenium(II) complex [Ru(btz)2(dppz)]2+ (btz = 4,4′-bithiazole; dppz = dipyrido[3,2-a:2′,3′-c]phenazine) has been synthesized and characterized. The DNA binding behaviors of this complex have been studied by spectroscopic and viscosity measurements. Results suggest that the complex binds to CT DNA via an intercalative mode. Upon irradiation at 365 nm, this complex was found to promote the cleavage of plasmid pBR322 DNA from supercoiled form I to nicked form II. The mechanism studies reveal that singlet oxygen 1O2 plays a significant role in the photocleavage.