DNA Interactions of the Functionalized (Mixed Polypyridine)ruthenium(II) Complex Bis(2,2′‐bipyridine‐κN1,κN1′)(methyl dipyrido[3,2‐a : 2′,3′‐c]phenazine‐11‐carboxylate‐κN4,κN5)ruthenium(2+) ([Ru(bpy)2(dppz‐11‐CO2Me)]2+)

Abstract A novel polypyridine ligand, dipyrido[3,2‐ a: 2′,3′‐ c ]phenazine‐11‐carboxylic acid methyl ester (=dppz‐11‐CO 2 Me), and its ruthenium(II) complex, [Ru(bpy) 2 (dppz‐11‐CO 2 Me)] 2+ ( 1 ), were synthesized and characterized. The binding properties of this complex to calf‐thymus DNA (CT‐DNA) were investigated by different spectrophotometric methods and viscosity measurements. The results suggest that the complex binds to DNA in an intercalative mode and serves as a molecular ‘light switch’ for DNA. When irradiated at 365 nm, the complex 1 promoted the photocleavage of plasmid pBR‐322 DNA.