Phosphorogenic dipyrrinato-iridium(III) complexes as photosensitizers for photodynamic therapy

We have designed and synthesized a family of Ir(III) metal complexes coordinated with two cyclometalated bisfluorophenylpyridine ligands and an ancillary dipyrromethene which is functionalized with a mesityl group (Ir (dipy)-1), an alpha-chloroacetyl ester (Ir(dipy)-2) or a chain containing an ammonium cation (Ir(dipy)-3). The Ir (III) complexes feature a high triplet state population enabling red phosphorescence and efficient singlet oxygen generation. Ir(dipy)-2 and Ir(dipy)-3 are demonstrated to stain cells in both one-photon and two-photon confocal imaging. Moreover, Ir(dipy)-2 and Ir(dipy)-3 produce ROS in cells upon irradiation, inducing cell death by apoptosis. Colocalization studies in SK-Mel-103 cells show that Ir(dipy)-3 is partially accumulated in mitochondria and induces upon irradiation a disruption in their morphology. Overall our studies demonstrate that the prepared Ir(III) act as photosensitizers able to kill cells under irradiation, being suitable candidates for photodynamic therapy applications.

Automated summary

We have designed and synthesized a series of Ir(III) metal complexes with different auxiliary dipyrromethene ligands, which demonstrate potential applications in inducing cell apoptosis and disrupting cellular morphology.