Rational Design of a Red-Light Absorbing dinuclear Ruthenium (II) Complex with Photodynamic potential

Abstract

Abstract

Conventional chemotherapeutic agents often suffer from systemic toxicity, poor selectivity, and the emergence of drug resistance, highlighting the urgent need for alternative anticancer strategies. In this context, light-activated therapies have emerged as promising minimally invasive approaches for controlled cancer treatment. However, the development of single molecular systems capable of integrating multiple photoinduced therapeutic mechanisms remains challenging. Herein, we report the rational design, synthesis, and comprehensive characterization of novel multifunctional bimetallic ruthenium complexes incorporating three photoactive units within a single molecular scaffold. The complexes exhibited favorable photophysical properties, efficient light absorption, and enhanced reactive oxygen species generation upon 690 nm LED irradiation. Computational investigations provided insight into the electronic structure and excited-state behavior, revealing potential photoinduced pathways associated with the multinuclear architecture. In addition, combined electrochemical analyses revealed the formation of Ru-DPP-Ru-DNA supramolecular assemblies, providing evidence of DNA binding while maintaining the electrochemical activity of the Ru(II) centers. ROS generation studies demonstrated a predominant Type II pathway involving singlet oxygen production, together with a minor contribution from Type I ROS. In vitro biological studies demonstrated neglible dark toxicity alongside moderate photocytotoxic activity under red light irradiation. This work presents the first example of DPP ligands scaffolds incorporated in a metal coordination sphere, a promising strategy for the development of next-generation bimetallic complexes as potential multimodal photoresponsive therapeutics for cancer treatment.