Copper(I) Complexes With Phenanthroline‐Functionalized NHC Ligands Achieve Effective Anticancer Activity via Mitochondrial and Endoplasmic Reticulum Stress.

ABSTRACT Copper complexes exhibit promising anticancer properties, which can be further promoted by suitable ligands. In this study, we synthesized and investigated the anticancer effects of three copper(I) complexes with N‐heterocyclic carbene (NHC) ligands derived from phenanthroline‐functionalized imidazole salts. The synthesis of these NHC‐copper(I) complexes (<bold>Cu1</bold>‐<bold>Cu3</bold>) was meticulously characterized using NMR and elemental analysis; their crystal structures were further delineated by X‐ray diffraction. Our findings illustrate the unique geometric configurations of these complexes: <bold>Cu1</bold> features a dinuclear arrangement with off‐linear geometry; <bold>Cu2</bold> and <bold>Cu3</bold> are characterized by a bi‐copper core stabilized by two phenanthroline‐modified carbene ligands. Crucially, in vitro cytotoxic evaluations revealed that these complexes possess suitability anticancer activity. Among them, <bold>Cu2</bold> exhibited enhanced cytotoxicity activity, achieving a half‐maximal inhibitory concentration (IC50) of 4.36 ± 0.25 μM in colon cancer cell line HCT‐116, markedly surpassing the efficacy of cisplatin. Subsequent investigations elucidated that <bold>Cu2</bold> notably increases intracellular reactive oxygen species (ROS) levels and induces mitochondrial membrane depolarization and endoplasmic reticulum stress, leading to oxidative stress‐mediated apoptosis of colon cancer cells. [ABSTRACT FROM AUTHOR]