Rational design of platinum(II) complexes with orthogonally oriented triazolyl ligand with emission enhancement characteristics for cancer chemotherapy in vivo

The mitochondria are essential for tumorigenesis and have been regarded as important targets in cancer chemotherapy. Herein, the mitochondria-targeted platinum(II) complexes have been prepared. The introduction of the triazole group with larger steric hindrance through post-click reaction converts the hybridization of carbon from sp to sp(2), endowing the complexes with an orthogonally oriented ligand with restricted rotation and emission enhancement characteristics. Methylation of the triazolyl ligand has led to platinum(II) complexes that can efficiently enter cancer cells and selectively accumulate in mitochondria, leading to significant enhancement in phosphorescence. In vivo anti-cancer investigations have demonstrated their distinct antitumor efficacy in substantial inhibition of tumor growth in breast cancer mice through dissipation of mitochondrial membrane potential, inducing apoptosis of tumor cell with negligibly systemic cytotoxicity.