Near-IR/Visible-Emitting Thiophenyl-Based Ru(II) Complexes: Efficient Photodynamic Therapy, Cellular Uptake, and DNA Binding.

Near-IR-emitting and/or efficiently photodynamic water-soluble Ru(II) complexes that hold great application potentials as photodynamic therapy and/or photodetection agents for cancers have been poorly explored. In this paper, the solvatochromism, calf thymus DNA binding, and singlet oxygen generation properties of a known ruthenium(II) complex of visible-emitting [Ru(bpy) ₂ (dtdpq)](ClO ₄ ) ₂ ( Ru1 ) and a new homoleptic complex of near-IR-emitting [Ru(dtdpq) ₃ ](ClO ₄ ) ₂ ( Ru2 ) (bpy = 2,2'-bipyridine, dtdpq = 2,3-bis(thiophen-2-yl)pyrazino[2,3- f ][1,10]phenanothroline) in water are reported. Moreover, DNA photocleavage, singlet oxygen generation in HeLa cells, cellular uptake/localization, and in vitro photodynamic therapy for cancer cells of water-soluble Ru1 are described in detail. The results show that Ru1 acted as potent photodynamic cancer therapy and mitochondrial imaging agents. Ru2 exhibited very strong solvatochromism from a visible emission maximum at 588 nm in CH ₂ Cl ₂ to the near-IR region at 700 nm in water and singlet oxygen generation yield in water (23%) and DNA binding properties (intercalative DNA binding constant on the order of 10 ⁶ M ^-1 ) comparable to those of Ru1 , which should make Ru2 attractive for the aforementioned applications of Ru1 if the water solubility of Ru2 can be improved enough for the studies above.